Well Log Interpretation: Petrofisica Registros Electricos
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TENS_1 11000
LBF
1000
PEF_1 0
B/E
20
DRHO_1 -0.35
BS_1 IN
14
GAPI
100
1.95
DEPTH
GR_1 0
METRES
4
G/C3
IDPH_1 0.2
CALI_1 4
G/C3
0.15
RHOB_1
OHMM
NPHI_1 2000 0.45
V/V
IMPH_1
IN
14
0.2
OHMM
2.95
-0.15
DT_1 2000 140
US/F
1000
1000
100
100
10
10
1
1
40
1510.2
1515
CORE_SH.K_CORE_1 (MD)
1520
1535
1540
WELL LOG INTERPRETATION
1550
0.1
0.01
0.01
1560
0.050
0.000
1555
0.1
0.100
1545
0.200
1530
0.150
1525
CORE_SH.PHI_CORE_1 (V/V) 1565
0
9 Color: Maximum of FACIES_EZT.EF2ANDEXT_1
1570
Petrofisica Registros Electricos
RHO_MAA_1
K_CORE_1
3 0.01
MD
PHI_CORE_1
1000
0.2 SWE_1
V/V
CALCI_3MN_1
0 100
VOL_UWAT_1
0
0
0
0
0
0
0
0
0
0
GR_1
0
GAPI
1000 1
K_EZT_1
100 0.01
MD
V/V
0 0.2
SWE_1
1000 1
V/V
V/V
01
PHIE_1
0 0.2
V/V
0 PHIE_1
0.4 2.00 Geosciences – Reservoir Engineering 2.87 0.35 2.10 ENSPM Formation Industrie - IFP Training
2.00
OHMM
00
V/V V/V
EF_EZT_1
10
PAY_1 0 3 RESERVOIR_1 0 1.7
0
VSH_1
10
METRES
METRES
RT_1
3 0.01
DEPTH
G/C3
DENS_CORE_1
2.5
CORE_NO_1 SHOWS_1
2.5
PERFS.DESCRIPTION_1
FACIESLITH.VALUE_1
J. DELALEX
2.65 1.90 0.45 2.71 0.43
1.90
ELEVATION(TVD)
-0
Wells:
SAND_1 0 1.2
-1090
2.10
1515
-1091
0.3
WIRE_1.RHOB_1 (G/C3)
2.20
2.20
Call_Sup
0.25 -1095
2.30 2.40
-1096
1525
2.40
0.15
-1100
0.1
2.50
1520
2.30
0.2
2.50 1530
0.05
2.60
2.60 0
-1105 1535
2.70
2.70
2.80
2.80
2.90
2.90
3.00
3.00
Call_Inf
1540
0.450
0.400
0.350
0.300
0.250
0.200
0.150
0.100
PDVSA - EFAI LA TAHONA 120 January 15 – 19 2007 Color: Maximum of WIRE_1.GR_1
0.050
0.000
-0.050
1545
-1115
1550 -1118
WIRE_1.NPHI_1 (V/V)
0
Geosciences-Reservoir Engineering
1555
Well Log Interpretation – PDVSA – January 2007
© 2007 ENSPM Formation Industrie - IFP Training
-1110
FOREWORD
This document does not constitute in itself a written course on “ Well Log Interpretation ” , « Petrofisica Registros Electricos ». lt is a written support for short course of J.Delalex of ENSPM Formation Industrie - IFP Training, presented in LA TAHONA, Venezuela to participants of PDVSA – EFAI from 15th to 19th January 2007. Thanks to the contribution of S.Boyer of ENSPM - IFP School and B.Michaut of ENSPM Formation Industrie - IFP Training . It was built by assembling various documents from different origins; most of the diagrams and drawings presented and not identified, are taken from Schlumberger documents or from the ENSPM course documents of the authors. Other documents come from brochures , web site information or released field cases. The document is presented as a synthesis of key points, where the participants may add their own comments in following the course. Some parts of these pages have been left blank to be filled in by the participants, in order to help them become more efficient. Other pages have been left blank intentionally for their personal notes. The charts the most used in conventional log interpretation are presented in the appendix section. Several practical applications will be made under the supervision of the instructor and will enable the participants to understand and assimilate the well log interpretation.
Note to participants : As this present document is the very first complete reviewed version of the course in powerpoint format , you may find possible typing errors on the figures, in the text or in the equations . I will be very grateful if you could forward them to me and this will help me to make the course more professionnal . Jacques Delalex Jacques.delalex @enspmfi.com January 2007
Geosciences-Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2007 ENSPM Formation Industrie - IFP Training
For more information, the participants are invited to consult the bibliography included at the end of this booklet.
TENS_1 11000
LBF
1000
PEF_1 0
B/E
20
DRHO_1 -0.35
BS_1
GAPI
100
1.95
DEPTH
14
GR_1 0
G/C3
IDPH_1 0.2
0.15
2000 0.45
V/V
IMPH_1
IN
14
0.2
1000
1000
100
100
10
10
1
1
2.95
NPHI_1
OHMM
CALI_1 4
G/C3
RHOB_1
IN
METRES
4
-0.15
DT_1
OHMM
2000 140
US/F
40
1510.2
CORE_SH.K_CORE_1 (MD)
1515
1520
WELL LOG INTERPRETATION
1525
1530
1535
1540
0.1
0.1
1545
Petrofisica Registros Electricos
1550
0.200
0.150
0.100
0.000
0
0
0
0
0
0
0
0
0
0
-0
GAPI
1000
K_EZT_1
100 0.01
MD
0.2
SWE_1
1000 1
0 0.2
SWE_1
1000 1
V/V
0 100
VOL_UWAT_1
V/V
V/V PHIE_1
V/V
0 0.2
V/V
0
0
PHIE_1
01
V/V
9
VSH_1
00
V/V
EF_EZT_1
10
3
RESERVOIR_1 0 1.7
0 10
SAND_1 0 1.2
-1090
1515
Geosciences – Reservoir Engineering 2.30 ENSPM Formation Industrie - IFP Training
0.25 0.2
1520
-1095
-1096
2.40
0.15
-1091
Call_Sup
1525
0.1
2.50
2.50
0.05
2.60
-1100
2.60
1530
0
2.70
2.70
-1105 1535
2.80 2.90
2.80 PDVSA - EFAI 2.90 LA TAHONA 3.00 January 15 – 19 2007
Call_Inf
1540
0.450
0.350
0.300
0.250
0.200
0.150
0.100
0.050
0.000
-0.050
3.00
0.400
-1110
1545
-1115
1550
WIRE_1.NPHI_1 (V/V) 0
-1118
120 Color: Maximum of WIRE_1.GR_1
1555
1
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
WIRE_1.RHOB_1 (G/C3)
0
MD OHMM
METRES
METRES
3 0.01
J. DELALEX 2.20
2.20
2.40
3 0.01
Wells:RT_1
GR_1
2.10
0.3
2.30
G/C3 DENS_CORE_1
2.87
0.35
1570
2.10
2.5 2.5
CALCI_3MN_1 Color:PHI_CORE_1 Maximum of FACIES_EZT.EF2ANDEXT_1 PAY_1
K_CORE_1
DEPTH
2.00
0 RHO_MAA_1
CORE_NO_1 SHOWS_1
0.4
ELEVATION(TVD)
2.00
PERFS.DESCRIPTION_1
CORE_SH.PHI_CORE_1 (V/V)
2.65 1.90 0.45 2.71 0.43 1565
FACIESLITH.VALUE_1
1560
1.90
0.01
0.050
0.01
1555
TABLE OF CONTENT GENERALITIES-MUD LOG - WELL LOG
Pages 1 to 86
THE TOOLS
Pages 87 to 224 • • • • • • • • • • • • • • •
CALIPER
91
GAMMA RAY
99
SPONTANEOUS POTENTIAL
107
INDUCTION, LATEROLOG and MICRORESISTIVITY 119 DENSITY-NEUTRON-SONIC
145
NUCLEAR MAGNETIC RESONANCE
189
DIPMETER and BOREHOLE IMAGING
197
PRESSURE MEASUREMENTS
209
Pages 225 to 268 • QUICKLOOK INTERPRETATION • • CROSSPLOTS • • QUANTITATIVE INTERPRETATION
APPENDIX-CHARTS-BIBLIOGRAPHY
Geosciences – Reservoir Engineering
2
225 241 245
Pages 269 to 318
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
INTERPRETATION
MUD LOGGING / WIRELINE LOGGING / LWD/MWD INTRODUCTION As soon as an oil target has been defined by geological and geophysical studies, drilling then determines its precise position and characteristics. The measurements in boreholes correspond to a set of techniques whose purpose is to obtain local information on the formations being drilled, the fluids that they contain and the state of the well; this information can confirm or not the surface studies. The direct information (cuttings, cores, fluid samples) is not always sufficient or of high enough quality, so it may need to be supplemented by a whole series of downhole operations called logging, a term including all the various methods used for carrying out measurements in a borehole:
- WeII Logging (Wireline logging) These are measurements of physical parameters (electrical, acoustic, nuclear etc.) carried out periodically during the halt phases in the drilling, after the drill pipe string has been pulled out. The sondes can be: - lowered into the weII at the end of a cable (general case); - pushed down and then brought back up by the drill pipe string (especially in deviated wells); - pushed to the end of the hole, attached to a cable, and then pulled up by this cable (Coiled Tubing or Pumping Down method) (also for deviated wells). They are carried out in open-hole sections and sometimes (for some of the measurements) in cased hole. - Measurement/Logging While Drilling (MWD- LWD) Both of these types of measurements are carried out during drilling, and yield information obtained via sensors placed on the drill pipe string, close to the drilling tool, which relate to the drilling conditions (drilI pipe string and mud : MWD) and the formations drilled.
3
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
- Mud Logging Its aim is to ensure the weIl site geological monitoring, the behaviour of the weII, while also maintaining the desired drilling conditions. Mud Iogging is carried out during the drilling of the hole and the information is conveyed through the mud or the drill pipe string.
WELL LOGGING and RESERVOIR STUDIES WELL LOG CORRELATION REGIONAL GEOLOGY SEISMICS RESERVOIR GEOMETRY
LARGE SCALE SMALL SCALE GEOLOGICAL RESERVOIR MODEL
DIPMETER TOOLS IMAGING TOOLS
LOG SEQUENCE ANALYSIS CORE ANALYSIS
SEDIMENTOLOGICAL MODEL QUANTITATIVE INTERPRETATION of THE LOGS
Geosciences – Reservoir Engineering
4
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
LOG/SEISMICS CALIBRATION
OBSERVATION SCALES THIN SECTION
CORES
WELL LOG
micron -- mm
mm -- dm
dm -- m TENS_1 11000
LBF
1000
PEF_1 0
B/E
20
DRHO_1 -0.35
BS_1 GR_1 0
GAPI
100
1.95
IDPH_1 0.2
CALI_1 4
IN
G/C3
0.15
RHOB_1 14
DEPTH
IN
METRES
4
OHMM
0.2
OHMM
2.95
NPHI_1 2000 0.45
IMPH_1 14
G/C3
V/V
-0.15
DT_1 2000 140
US/F
40
1510.2
1515
1520
1525
1530
1535
1540
1545
1550
1555
1560
1565
ELECTRONIC MICROSCOPE micron 5
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
1570
GENERALITIES
• Reservoirs and Seals • Reservoir and fluid characteristics • Invasion Phenomenon • Basic Equations • Mud Logging
• Logs Presentation and Quality Control
Geosciences – Reservoir Engineering
6
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
• Wireline Logging operations
SEALS AND RESERVOIRS
G O w
->
Geosciences – Reservoir Engineering
7
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
w w
Geosciences – Reservoir Engineering
8
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Notes
RESERVOIR AND FLUID CHARACTERISTICS
G O w
Original Oil In Place : OOIP ?
->
Geosciences – Reservoir Engineering
9
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
w w
Geosciences – Reservoir Engineering
10
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Notes
VOLUMETRIC ANALYSIS OF A SEDIMENTARY ROCK
MATRIX
DRY CLAY
CEMENT
Bound Water
Respective mineral and fluid volumes in a sedimentary rock 11
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
WATER
OIL / GAS
POROSITY - Φ φ : Porosity : Fraction of the bulk volume occupied by voids Porosity = Ratio of pore volume to total rock volume
Φ=
Vpore Vtotal
Vtotal − Vsolid = Vtotal
Porosity is expressed in % or V/ V or Porosity units (Pu) . In general, reservoirs have porosities ranging from 5 to 35 %. φ < 5%
low porosity
φ > 20 %
good porosity
average porosity
- Primary Porosity : Inherited from deposit of original sediment.
- Secondary Porosity : Due to effects of diagenesis during the burial phase of sediments , dissolutions ( vugs) or due to the existence of fractures in the the rock . Geosciences – Reservoir Engineering
12
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
10% < φ < 20%
Thin section in a sandstone
Thin section in an oolitic limestone
Red color for Porosity
Yellow pale color for Porosity
Thin section in a limestone
Thin section in a bioclastic limestone
Pink color for Porosity
Yellow pale color for Porosity
13
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
POROSITY EXAMPLES
Poor connection between pores
Good connection between pores
( isolated pores ) Geosciences – Reservoir Engineering
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Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
PORE CONNECTION
POROSITY TYPE DEFINITIONS Apparent porosity
Φ •
Vhc Vwb
•
Vt
Vw + Vhc Vt
Φ = [Vw + Vhc] e
•
connected
Vt
Effective porosity – Log Analysis
Φ = [Vpore − Vw associated to the shale] e
Geosciences – Reservoir Engineering
u
=
Vw + Vhc + Vwb Vt
Effective porosity - Petrophysics
Vw Vma
=
Useful porosity
Φ Vsh
a
Vt
15
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
•
Geosciences – Reservoir Engineering
16
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Notes
PERMEABILITY
•
Permeability is the property of a porous formation to let the fluid flow under a certain pressure gradient. It is usually expressed in mDarcy or Darcy .
P1
∆P
P2
Flow rate :
Q=
Q Flow rate
Mobility :
L
µ
Darcy’s Law K: µ: ∆P: A: Q: L:
Rock sample Permeability (Darcy) Fluid Viscosity (cP) Differential Pressure (atm) Cross sectional area (cm2) Flow rate (cm3/s) Rock sample length (cm)
Geosciences – Reservoir Engineering
K
K × A ∆P µ L
=
Q× L A × ∆P
Typically : 0.1 mD < K < 10000 mD K in Darcy = 0.987 10 -12 m2
17
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
•
PERMEABILITY ESTIMATION
•
Horizontal or vertical permeability can be measured on core samples in a laboratory
•
Permeability can be estimated
•
Permeability-thickness Kh can be estimated during a production test ( DST )
Geosciences – Reservoir Engineering
18
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
– using the drawdown or buildup recorded during the pretest of a pressure measurement. – from the effective porosity and irreducible water saturation Swi using empirical formula. – from the Nuclear Magnetic Resonance
FLUID SATURATION It is essential to know the type of fluids present in a reservoir and the proportion of each fluid in the pore volume , ie the fluid saturation . The fluid saturation is defined as the ratio of the fluid volume to the pore volume. It is expressed in % or in V/V fluid
Saturation =
Below a certain depth , pores are no more occupied by air , but by a fluid , generally fresh or salty water. In the case of an hydrocarbon reservoir, pores can be occupied by water with oil and/or gas.
V Vpore
Thin section showing the oil Saturation
In an hydrocarbon zone, it always remain a certain quantity of water trapped between the grains or linked to the grains by capillary presure. This is the irreducible water . The irreducible water saturation may vary from 10 to 35 % 19
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Therefore , one can define a water saturation Sw, an oil saturation So or a gas Saturation Sg.
WATER AND HYDROCARBON SATURATIONS In an hydrocarbon zone
V Sw = w Vpore V + Vhc Sw + Shc = w =1 Vpore Vpore = Vw + Vhc
Shc = 1 − Sw
Shc =
Vhc Vpore Matrix Oil Water
In an oil zone
In a gas zone
Sg = 1 − S w Geosciences – Reservoir Engineering
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Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
So = 1 − S w
RESISTIVITY OF AN NaCl SOLUTION Rw = 0.1 Ohmm
Temp
Salinity = 25 kppm Geosciences – Reservoir Engineering
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Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
= 90 C
RESISTIVITY OF AN NaCl SOLUTION
Rw = 0.1 Ohmm Salinity = 25 kppm
Geosciences – Reservoir Engineering
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Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Temp = 90 C
RESISTIVITY vs CONDUCTIVITY PRINCIPLE OF RESISTIVITY MEASUREMENT In electricity :
U R= I
L
Current I
R U
S
R=
ρ *L S
R = Resistance (Ohm) ρ = Resistivity
Resistance is a function of the geometry of the medium. As this geometry is unknown, one uses the resistivity in well logging
For example Rt = True Formation Resistivity Conductivity C is expressed in Siemens/m or mho/m or in mSiemens/m or mmho/m 23
Geosciences – Reservoir Engineering
1 R 1000 C= R
C=
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Resistivity is called R in well logging, expressed in Ω.m or Ohmm (Symbol ρ is used for the density )
ARCHIE LAW - FORMATION FACTOR F •
A rock sample containing 100 % water (Sw = 1) has a true resistivity Rt, usually called Ro
•
This Resistivity Ro is proportional to the resistivity of the water Rw
Ro1 = FR w1 Porosity φ
•
Ro2 = FR w 2 Porosity φ
The proportionality factor F is called the Formation Resistivity Factor and it is therefore the Ratio of the Resistivity Ro to the water resistivity Rw
Porosity φ1 Geosciences – Reservoir Engineering
Porosity φ2
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Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Ro = FR w
ARCHIE LAW - FORMATION FACTOR F •
The formation factor depends on the lithology and the porosity of the rock :
R F= o Rw
a F= m φ R o1 =
a φ1m
Ro =
Then : ×Rw
R o2 =
Porosity φ1
a ×Rw m φ
a φ m2
×Rw
Porosity φ2
In general , the constant a is close to 1 and the cimentation factor m is close to 2 .
0.81
or
F=
0.62
For Sandstones, in general :
•
For Carbonates, in general, a = 1 and m = 2, but m is variable : 1.3 < m < 2.5
φ2
φ 2.15
-> Geosciences – Reservoir Engineering
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Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
F=
•
ARCHIE LAW - FORMATION FACTOR F
log(F) = log(a ) − m log(φ)
Geosciences – Reservoir Engineering
26
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Formation Resistivity Factor versus Porosity ( Chart Por1 – Schlumberger)
ARCHIE LAW – WATER SATURATION •
A rock sample having a water saturation Sw has a true resistivity Rt Rt varies with the water saturation Sw and it is inversely proportional to Swn , n is the saturation exponent and it is usually close to 2
• •
Rt =
Ro Rw a = × n Φ m Sw n Sw
HC
or
Sw = n
a Rw Φm R t
HC
Water
F*Rw S w1
R t2 =
n Water
Water Saturation Sw1
F*Rw Sw 2
n
Water Saturation Sw2
This is the Archie equation and it is only valid in clean formation ( Vsh = 0 ) Geosciences – Reservoir Engineering
27
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
R t1 =
ARCHIE LAW : WATER SATURATION Estimation of Sw in clean formations
a Rw Sw = n m φ Rt •
Resistivity logs ( Laterolog, Induction)
Î
Rt
• • •
Porosity logs ( Density, Neutron, Sonic, RMN) SP, Resistivity Ratio, Rwa, Water sample Petrophysical measurements in laboratory
Î Î Î
φ Rw a, m, n
Formula only valid for clean formations ( No Shale : Vsh = 0)
Geosciences – Reservoir Engineering
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Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Default values: a = 1, m = 2 , n = 2
VARIATIONS OF RESISTIVITY WITH POROSITY Training exercise on Archie Formula
Rw =
F=
Φ=2%
FF=
Rt =
Φ = 10%
FF =
Rt =
Φ = 25%
FF =
Rt =
a
φ
m
Rt =
a
φm
×
Sw = 100 %
Rw n Sw
Formation water salinity : 30 Kppm Temperature : 70 °C Rw : Coefficients for Archie Formula : a: 1 m: 2 n: 2
->
29
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Sw=100 %
VARIATIONS OF RESISTIVITY WITH Sw Training exercise on Archie Formula
Φ = 25%
FF =
F=
Sw = 10%
Rw =
Rt =
Sw = 50%
Rw =
Rt =
a
φ
Φ = 25%
m
Rt =
a
φ
m
×
Rw n Sw
Formation water salinity : 100 Kppm Temperature : 70 °C Rw :
Rw =
Rt =
Coefficients for Archie Formula : a: 1 m: 2 n: 2
-> Geosciences – Reservoir Engineering
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Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Sw = 100%
VARIATIONS OF RESISTIVITY Example of Variation of Rt with Sw
Example of Variation of Rt (LLD) with Porosity GR_1 0
LLD_1
GAPI 100
0.2
OHMM
PXND_1 2000 0.45
V/V
SWE_1 -0.15 1
V/V
GR_1 0
0
RT_1
GAPI 150
0.2
PHIE_1
OHMM
2000 0.45
V/V
SWE_1 -0.15 1
V/V
0
Limestone – No HC shows
Sandstone : No HC shows below depth xxx
Reservoir Temperature = 50 C
Temperature = 60 C
a = 1 m= 2 n= 2
a = 0,81 m= 2 n= 2
Rw =
Rw =
Formation Water Salinity =
Kppm
Formation Water Salinity : ->
31
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
xxx
ARCHIE LAW – RESISTIVITY INDEX In Petrophysics , the Resistivity Index is the Ratio of the Resistivity of the porous medium having a water saturation Sw to the Resistivity of the porous medium 100 % saturated with brine. 1/ n
R 1 RI = t = n R o Sw
or
Geosciences – Reservoir Engineering
or
⎛ Ro S w = ⎜⎜ ⎝ Rt
⎞ ⎟⎟ ⎠
a Rw Sw = n m φ Rt
32
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
•
INVASION
33
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
INVASION PHENOMENON, ZONES AND ASSOCIATED PARAMETERS
INVASION OF A RESERVOIR DRILLING HORIZONTAL FORMATIONS BY A VERTICAL WELL INVASION OF RESERVOIRS BY THE DRILLING FLUID Damage of porous and permeable formations (reservoirs) is linked to the invasion by the filtered drilling fluid, essentially the mudfiltrate. • The presence of residual hydrocarbon in the flushed zone affects the measurements of resistivity and porosity such as density and neutron logs . MUD
SEAL
SEAL MUD CAKE FLUSHED ZONE
W
Phyd MUD FILTRATE
VIRGIN ZONE
Mud filtrate & Residual HC
PForm MUD FILTRATE
HC & Water
WATER
Invasion Diameter Di ?
Geosciences – Reservoir Engineering
34
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
HC
Mud filtrate & Residual HC
INVASION AND ASSOCIATED PARAMETERS Case of a well drilled with a Water Based Mud SEAL FLUSHED ZONE
RESERVOIR
Transition Zone
VIRGIN ZONE Fluid Saturation Formation Resistivity
Gas zone
Fluid Resistivity Fluid Type
GOC
Fluid Saturation Formation Resistivity
Oil zone
Fluid Resistivity Fluid Type
WOC
Formation Resistivity
Water zone
Fluid Resistivity Fluid Type
35
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Fluid Saturation
INVASION AND ASSOCIATED PARAMETERS Case of a well drilled with a Water Based Mud MUD
RESERVOIR
Φ
Hu
u ,
Rm
ρm
FLUSHED ZONE
K, T, Pf
Gas zone
Transition Zone
Sxo and Sgr Rmc
Sw and Sg
Rxo
Rtr
GOC
Mud Filtrate and Residual Gas (+Irr w)
W , MF, G
Pf
Rtr
Rxo
Oil zone Phyd
Rmf W , MF, O
Sxo Rtr
Rxo
Water zone Hu
Hole Diameter CALI
Rmf Mud Filtrate
Rt Rw
Mud Filtrate and Residual Oil (+Irr w)
WOC
Water and Gas
Sw and So
Sxo and Sor Hu
Rt Rw
Rmf hmc
VIRGIN ZONE
Water and Oil
W , MF
Fluid Resistivity Fluid Type
Fluid Saturation Formation Resistivity Fluid Resistivity Fluid Type
Sw
Fluid Saturation
Rt
Formation Resistivity
Rw ( + Irr w)
Fluid Saturation Formation Resistivity
Water
Fluid Resistivity Fluid Type
Bit Size BS Invasion Diameter Di Invasion Diameter Dj Geosciences – Reservoir Engineering
Sg = 1- Sw
Sgr = 1- Sxo
So = 1- Sw Sor = 1- Sxo
36
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
SEAL
INVASION IN WATER BASED MUD Resistivities and Saturations CLEAN HYDROCARBON BEARING FORMATION (Porosity Φ )
Fluid Resistivity Formation Resistivity
Virgin Zone
Invaded Zone Formation Resistivity
Geosciences – Reservoir Engineering
Rxo =
a
φ
m
×
Rmf S xo
Rt =
n
37
a
φ
m
×
Rw n Sw Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Water Saturation
INVASION IN WATER BASED MUD POROUS and PERMEABLE HYDROCARBON bearing FORMATION
INVASION PROCESS and
Fluid Distribution
Geosciences – Reservoir Engineering
38
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
RESISTIVITY PROFILE
INVASION IN OIL BASED MUD FLUSHED ZONE
OIL BASED MUD
VIRGIN ZONE
HYDROCARBONS
HYDROCARBON ZONE With IRREDUCIBLE
OIL FILTRATE WATER
WATER SATURATION
Sxo = Sw = Swi HYDROCARBONS
TRANSITION ZONE
OIL FILTRATE WATER
Geosciences – Reservoir Engineering
Sxo < 1
OIL FILTRATE
WATER
Sxo < 1
Sw = 1 39
WATER ZONE
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Sxo < Sw
Geosciences – Reservoir Engineering
40
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Notes
MUD LOGGING
Geosciences – Reservoir Engineering
41
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
MUD LOGGING
MUD LOGGING
RIG
INSIDE CABIN (Geological side)
Geosciences – Reservoir Engineering
42
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
MUD LOGGING UNIT
MUD LOGGING OBJECTIVES
ANALYTICAL
OF
and
WELL SITE GEOLOGY
OBSERVATION FACILITIES
DRILLING •
Well follow up
•
Drilling optimization
• UNIT or LABORATORY on RIG SITE • SENSORS on RIG EQUIPMENTS
WELL SAFETY Risk evaluation
• •
• HYDRAULIC LOGGING
Lithology
• GEOLOGICAL LOGGING
Formation Pressure
• HYDROCARBON LOGGING
ARCHIVES •
Final report
Geosciences – Reservoir Engineering
43
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
•
• MECHANICAL LOGGING
MUD LOGGING INSTANTANEOUS PARAMETERS
LAGGED PARAMETERS
• HOOK HEIGHT
GAZ IN MUD HYDROCARBONS : C1 Ö C5
• WEIGHT ON HOOK (WOH)
•
• RPM
•
HYDROGEN SULFIDE (H2S)
•
CO2 (optional)
•
H2 (Optional)
• TORQUE • INJECTION PRESSURE (SPP) • WELL HEAD PRESSURE (ANNULAR
MUD PARAMETERS OUT
PRESSURE)
•
DENSITY
• PUMP STROKES
•
TEMPERATURE
• MUD PIT LEVEL
•
CONDUCTIVITY
•
MUD FLOW OUT
• MUD PARAMETERS IN • DENSITY
•
Lithology (cuttings %)
• CONDUCTIVITY
•
Calcimetry
• MUD FLOW IN
Geosciences – Reservoir Engineering
44
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
FORMATION
• TEMPERATURE
MUD LOGGING
45
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
RECORDED DATA
MUD LOGGING MUD LOG versus WELL LOG
Geosciences – Reservoir Engineering
46
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
WELL LOG
MUD LOG
MUD LOGGING
Geosciences – Reservoir Engineering
47
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
GEOLOGICAL LOG
MUD LOGGING
Geosciences – Reservoir Engineering
48
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
GEOLOGICAL LOG
MUD LOGGING
Geosciences – Reservoir Engineering
49
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
GEOLOGICAL LOG
Geosciences – Reservoir Engineering
50
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Notes
WIRELINE LOGGING
51
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
WIRELINE LOGGING
WELL LOGS : INTRODUCTION Everything began in September 1927 when two French brothers, Conrad and Marcel Schlumberger saw their efforts crowned with success when, in a well at the Pechelbronn field in France, they carried out the first downhole electric log based on the principle of surface resistivity measurements. Since then, the improvement in logging tool technology has lead to a better knowledge of the reservoir characteristics: Lithology, Porosity, Water saturation, fluid types, identification of fractures and helped to decide on the future of a well or a field. TENS_1 11000
LBF
1000
PEF_1 0
B/E
20
DRHO_1 -0.35
14
GR_1 0
GAPI
100
DEPTH
IN
METRES
BS_1 4
IDPH_1 0.2
CALI_1 4
IN
OHMM
0.2
OHMM
G/C3
0.15
2.95
NPHI_1 2000 0.45
IMPH_1 14
G/C3
RHOB_1 1.95
V/V
-0.15
DT_1 2000 140
US/F
40
1510.2
1515
1520
1525
1530
1535
1540
1545
1550
1555
1565
1570
1575
1580
1585.0
CLASSICAL COMPOSITE LOG Geosciences – Reservoir Engineering
BOREHOLE IMAGING LOG 52
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
1560
LOGGING OPERATION ON LAND Tension Measurement
Sheave Cable or wireline
Depth Measurement Kelly Bushing KB
Ground Level GL
Tension Measurement
Drill Floor DF or Rotary Table RT
Cable Drum
Truck and Computer
Measured Depth MD below DF (Deviated well)
Vertical Well Head Tension Measurement Deviated Well Logging tools
53
Geosciences – Reservoir Engineering
J_Delalex_Feb06
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Measured Depth MD below DF (Vertical well)
RIG-UP Drill Floor DF
Tool « Zero » on Drill Floor DF
Rotary Table RT
Rig view and Logging Truck
Ground Level GL
Bottom of the tool
Caliper Calibration
Kelly Bushing KB rotating while drilling Geosciences – Reservoir Engineering
Depth Measurement 54
Head of the tool
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
KB
DEPTH and TENSION MEASUREMENTS
Depth Measurement
Tension Measurement
Cable Drum
55
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Cable
DEPTH - REFERENCES MD - TVD - TVDSS Deviated Well
Offshore
On Land
Kelly Bushing KB
GL
Drill Floor
DF or Rotary Table RT
Ground Level
DF MSL
MSL Mean Sea Level (Reference) TVD
TVD-SS
MD
GL MD
TVD
TVD-SS
RESERVOIR
Geosciences – Reservoir Engineering
56
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
DF
TOOL COMBINATION Dual Laterolog –
Litho-Density-Neutron GR
Microresistivity - GR
Gamma Ray
Gamma Ray
Neutron Dual Laterolog Litho-Density
57
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Microresistivity
TOOL COMBINATION Logging Tool Combination : PEX Platform Express (Schlumberger)
Telemetry
Gamma Ray
Neutron
+ + + + + + + +
Sonic
+ + + +
Resistivity : Laterolog or Induction
Geosciences – Reservoir Engineering
58
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Litho-DensityMicroresistivity
FIELD LOG RESULTS
Geosciences – Reservoir Engineering
59
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
PLATFORM EXPRESS RESULTS (SCHLUMBERGER)
LOGGING TOOL EXAMPLES
SONIC BHC Sonde Caliper
SONIC DSI Sonde
Centralizer
Electronic Cartridge
Geosciences – Reservoir Engineering
60
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Stand-off
LOGGING RUNS Most common Bit Sizes :
26
17.5
12 ¼
8½
6
Most common Casing Sizes :
20
13 3/8
9 5/8
7
5½
Run-1
1
Open Cased Hole Hole
Run-2
Run-1, 2 & 3 spliced
2 Run-1 & 2 spliced
Run-3
Geosciences – Reservoir Engineering
61
3
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Watch for splicing Anomaly !
LOGGING IN DEVIATED OR HORIZONTAL WELLS
Geosciences – Reservoir Engineering
Pump Down
62
Coil Tubing
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
TLC (Tough Logging Conditions)
LOG PRESENTATION
OVERLAP SECTION
CALIBRATIONS AFTER SURVEY
MASTER CALIBRATIONS & CALIBRATIONS BEFORE SURVEY
Geosciences – Reservoir Engineering
LOG HEADER
MAIN LOG ->
REPEAT SECTION
63
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
-> MAIN LOG
LOG QUALITY CONTROL • LOG HEADER (Coordinates, References, Mud data, hole size , Casing, Timing , Temperature, Remarks …) • LOGGING SPEED • SAMPLING RATE • ENVIRONMENTAL EFFECTS • HOLE (Mud, Diameter, Mudcake, Restrictions, Caves) • SHOULDER BEDS • INVASION • REPEAT SECTION AND MAIN LOG • OVERLAP SECTION • TOOL VERIFICATION IN CASING ( Caliper , Sonic ) • CALIBRATIONS • DEPTH MATCHING OF LOGS • TENSION EFFECTS, TOOL STICKING • CHOICE OF TOOLS • REFERENCE VALUES ( SALT , ANHYDRITE, TIGHT FORMATIONS …) Geosciences – Reservoir Engineering
64
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
• ACQUISITION PARAMETERS
LOG HEADER
Geosciences – Reservoir Engineering
65
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
LOG HEADER : Well Info, Casing & Bit Size Data
LOG HEADER
MAXIMUM THERMOMERS (On Tool Head)
Geosciences – Reservoir Engineering
66
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
LOG HEADER : Mud & Temperature Data
LOG HEADER
REMARKS : Mud With Barite ( 210 KG/CM3) File 4 & File 5 with Barite Correction No PEF on Main Log
Geosciences – Reservoir Engineering
67
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
LOG HEADER : Other Services & Remarks
ACQUISITION PARAMETERS TOOL MEASURE POINTS and ACQUISITION PARAMETERS LDL-CNL-GR
Caliper Measure Point
10.4 m
GR Measure Point Neutron Measure Point
Litho-Density Measure Points
Matrix = LIMESTONE ⇒Neutron log NPHI recorded in Limestone Matrix
1.4 m
Tens
Geosciences – Reservoir Engineering
68
1.1 m
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
7.8 m
LOG FIRST READINGS EXAMPLE OF MAIN LOG AT TD FOR LITHO-DENSITY-NEUTRON-GR
FR = First Reading
GR
FR - GR FR - NPHI
FR- CALI
TDL = 5741 m Total Depth Logger
GR
CNT
NPHI 10.4 m 7.8 m
Tension
LDT
RHOB 1.1 m
Tension pick-up
Geosciences – Reservoir Engineering
69
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
FR - RHOB,PEF
LAST READING – CASING OVERLAP SECTION AND CALIPER CHECK IN CASING GR recorded in casing to OVERLAP with previous log section 7" Casing Shoe
Caliper Check in 7 inch Casing Casing Weight = 23 Lb/ft Caliper should read : ID = 6.37 inches
Density log RHOB affected by Cave
Cave below CasingShoe
Geosciences – Reservoir Engineering
70
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
IHV Integrated hole volume ( 0,1 m3)
Caliper and GR in 6" open hole
REPEAT SECTION & MAIN LOG
Geosciences – Reservoir Engineering
REPEAT SECTION (LAE-1)
71
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
MAIN LOG (LAE-1)
REPEAT SECTION & MAIN LOG
Geosciences – Reservoir Engineering
72
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
REPEAT SECTION compared to MAIN LOG For Litho-Density-Neutron-GR log
LOGGING SPEED
Depth (m)
Logging Speed
9m
= 9m/mn = 540m/hr
1 mn
Geosciences – Reservoir Engineering
73
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
= 1800Ft /hr
Geosciences – Reservoir Engineering
74
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
QUALITY CONTROL OF MUD DATA
TENSION EFFECT ON LOGS
Tension effect on GR
LLD, LLS
Effect on Caliper
MSFL Tension increases when the tool gets stuck Geosciences – Reservoir Engineering
75
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Effect on resistivity logs
?
Geosciences – Reservoir Engineering
76
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Notes
TENSION EFFECT ON LOGS Comparison of GR Logs recorded with different tool combinations in the same well ( Upper Section ) InductionSonic – GR- SP
Tension
Density-Neutron – NGL -Caliper
DLL-MSFL GR-SP-Caliper
Tension
Tension
DLL-MSFL GR-SP- Caliper
Tension
77
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Thickness of this upper reservoir ??
TENSION EFFECT ON LOGS Comparison of GR Logs recorded with different tool combinations in the same well ( Lower Section ) Tension
Density-Neutron – NGL -Caliper
Tension
DLL-MSFL GR-SP-Caliper
Tension
DLL-GR-SP(CAL Closed )
Geosciences – Reservoir Engineering
78
Tension
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
InductionSonic – GR- SP
LOG CALIBRATION
Geosciences – Reservoir Engineering
79
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
MASTER CALIBRATION FOR NEUTRON AND LITHO-DENSITY TOOLS
LOG CALIBRATION
Geosciences – Reservoir Engineering
80
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
BEFORE SURVEY CALIBRATION FOR NEUTRON AND LITHO-DENSITY TOOLS
LOG CALIBRATION
Geosciences – Reservoir Engineering
81
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
AFTER SURVEY CALIBRATION FOR NEUTRON AND LITHO-DENSITY TOOLS
CALIBRATIONS Example of Litho-Density calibration
Schlumberger Document
Geosciences – Reservoir Engineering
82
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
recorded with Maxis-500
DEPTH OF INVESTIGATION & VERTICAL RESOLUTION DEPTH of INVESTIGATION and VERTICAL RESOLUTION
Courtesy of S. Boyer
Geosciences – Reservoir Engineering
83
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
OF LOGGING TOOLS
VERTICAL RESOLUTION
MACRO-DEVICES
MICRO-DEVICES
Gamma Ray Neutron Density Sonic Laterologs Inductions
Micro-resistivity
Geosciences – Reservoir Engineering
84
DIPMETER
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
RELATIONS between LAYER THICKNESS and VERTICAL RESOLUTION of the TOOLS
85
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
VERTICAL RESOLUTION
INVOICE WIRELINE LOGGING COSTS (after Schlumberger price list 1994 – US $)
2000m (6000’)
For a minimum and sufficient set of geological logs for a wildcat In standard conditions (mud type, hole diameter, deviation, temperatue, pressure, sample rate) Personnal, equipement and transportation charges are not inclued.
CSU Unit
3000 / Month
Depth charge (min 2000’)
Survey charge (min 1000’)
Neutron Density GR (in combustion)
1.15 * 6000 = 6900 1.25 * 6000 = 7500 0.8 * 6000 = 4800
1.15 * 1500 = 1750 1.25 * 1500 = 1875 0.8 * 1500 = 1200
DLL MLL PS GR
1.1 * 6000 = 6600 1.0 * 6000 = 6000 Free 0.2 * 6000 = 1200
1.1 * 1500 = 1650 1.0 * 1500 = 1500 Free Free
Sonic GR
1.1 * 6000 = 6600 0.2 * 6000 = 1200
1.1 * 3000 = 3300 Free
30000 + 40800
11275
1.4 * 6000 = 8400
1.85 * 3000 = 5550 1.9 * 3000 = 5700
SHDT MSDip FE Quicklook
2.52 * 1500 = 37800 8400
15030
LOGGING
96025 (16825 Measurement)
INTERPRETATION
7500
Geosciences – Reservoir Engineering
86
103525 (16825 Measurement)
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
1500m (4500’)
Logging
Sonic, SHDT
1000m (3000’)
WIRELINE LOGGING
Geosciences – Reservoir Engineering
87
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
THE TOOLS
TOOLS THE TOOLS • CALIPER • GAMMA RAY • SPONTANEOUS POTENTIAL • INDUCTION and RESISTIVITIES • DENSITY – NEUTRON - SONIC
• DIPMETER and FORMATION IMAGING • PRESSURE MEASUREMENTS AND FLUID SAMPLING Geosciences – Reservoir Engineering
88
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
• NUCLEAR MAGNETIC RESONANCE
TOOL NMEMONICS SCHLUMBERGER
BAKER ATLAS
COMMERCIAL DENOMINATIONS OF THE MAIN CONVENTIONNAL LOGGING TOOLS AND TOOL SETS This list is not exhaustive; abbreviations and tool names may be slightly modified Other contractors offer similar services under other denominations Most of the tools may be combined under denominations and regulations proper to each contractor (L for Tool, T for Log ) Please , consult tool catalogues or web sites of service companies for up_to-date informations
89
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
HALLIBURTON
LOGGING TOOLS USED WELL LOGGING PROGRAM for EXPLORATION WELLS GOALS IDENTIFICATION of
RESERVOIRS and SEALS
DETERMINATION of
RESERVOIR CHARACTERISTICS FLUID CHARACTERISTICS
TIME – DEPTH CONVERSION of SEISMICS
LOGGING TOOLS USED CALIPER for caves, fractures and borehole rugosity identification GAMMA RAY for shales and lithology identification SPONTANEOUS POTENTIAL for Water Resistivity computation
RESISTIVITY TOOLS 3 Resistivity tools with different depths of investigation for Rt, Rxo and water saturation computations Laterologs in conductive muds or if Rxo < Rt Inductions in non conductive muds or if Rxo > Rt WIRELINE FORMATION TESTER for fluid identification and pressure measurements
Geosciences – Reservoir Engineering
90
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
LITHOLOGY – POROSITY TOOLS DENSITY, NEUTRON and SONIC
CALIPER MEASUREMENT
Geosciences – Reservoir Engineering
91
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
BOREHOLE DIAMETER MEASUREMENT
CALIPER TYPES LITHO-DENSITY TOOL
FORMATION MICRO-IMAGER
6 Arms Dipmeter, EMI BS
CALI
BS Tool excentered with one arm => 1 Diameter : CALI
Geosciences – Reservoir Engineering
Tool Centered with 4 arms
Tool Centered with 6 arms
=> 2 Diameters : C1 & C2
=> 3 Diameters
92
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
BS
CALIPER OF DENSITY TOOL
CALIPER OF SAD (DIPMETER)
93
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
CALIPER CALIBRATION
CALIPER APPLICATIONS Applications : - Hole Diameter - Hole Volume => Cement Volume - Ovalisation - With Deviation and Azimuth => Hole Profile - Presence of caves - Presence of restrictions ( Swelling Shales )
- Information on Lithology (Mechanical Properties) => Quality Control of the logs Geosciences – Reservoir Engineering
94
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
- Presence of mudcake ( => hmc)
CALIPER LOG AND IHV
Integrated Hole Volume IHV =
Caliper Check in Casing
0.1 m3 between 2 small pips if depth in meters or
CASING 9" 5/8
10 Cuft , if depth in Feet
53.5 LB/F ID = 8.54
BS : 8.5
95
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Caliper
MUDCAKE ET CAVES
Caliper of
Caliper of
MSFL
Density
Caves
Unconsolidated Sandstone
With Caliper of Density Tool ( one arm ) : Mudcake Thickness = hmc = BS – Cali (hmc = 0 , if Cali>BS) Geosciences – Reservoir Engineering
96
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
BS=8.5
HOLE PROFILE & HOLE VOLUME
IHV Integrated Hole Volume
Microresistivity curve of Dipmeter Tool
Caliper 1 Pads 1 & 3
Caliper 2 Pads 2 & 4
DEVIATION
Geosciences – Reservoir Engineering
97
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
AZIMUTH
Geosciences – Reservoir Engineering
98
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Notes
NATURAL RADIOACTIVITY
Geosciences – Reservoir Engineering
99
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
NATURAL RADIOACTIVITY GAMMA RAY
GR - NATURAL RADIOACTIVITY In sedimentary rocks, natural radioactivity comes from the elements issued of the series of Thorium , Uranium and isotope 40 of K.
K:
SHALES (ILLITES) POTASSIC EVAPORITES POTASSIC FELDSPARS MICAS MINERALS with K (MUD with KCl)
U:
Geosciences – Reservoir Engineering
SHALES (with organic matter) ORGANIC MATTER MINERALS with U
100
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Th : DETRITIC SHALES MINERALS with Th ( Heavy Minerals )
GR AND SPECTRAL GR TOOLS • GR TOOL : Measurement of total radioactivity (GR) , Units = API • SPECTROMETRY GR TOOL : - SPECTRAL GAMMA RAY (SGR) - CORRECTED GAMMA RAY (CGR) Units :
: U + K + Th : K + Th
SGR and CGR in API K in % , Th and U in ppm
In HNGS Sonde ( Schlumberger)
101
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BGO SCINTILLATION DETECTORS
GR - WELLSITE CALIBRATION
Calibration JIG
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GR TOOL
GR - NATURAL RADIOACTIVITY • APPLICATIONS • Bed Boundaries • Geological correlations • Shale content estimation • Type of clays • Presence of radioactive minerals • Depth matching of subsequent logs
103
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• Correlation with cased hole logs
Examples of GR log and Spectral GR log GR
CGR
SGR
TH
U
K
GR_1 0
GAPI
BS_1 4
IN
100
IMPH_1
DEPTH 14 METRES
0.2
14
0.2
4
IN
OHMM
2000
IDPH_1
CALI_1
OHMM
DT_1 2000 140
US/F
40
1525
1575
Geosciences – Reservoir Engineering
104
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1550
SPECTRAL GR - Crossplot Th-K Th-K CP-19
K
(Schlumberger)
105
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Well Log Interpretation – PDVSA – January 2007
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Th
ESTIMATION OF SHALE CONTENT FROM GR GRmax GR log
Estimation of VSH
GR min
from GR log
GR
GR - GR min
GRmax - GRmin
GR VSH = GR GR Geosciences – Reservoir Engineering
- GR max
- GR
min
min 106
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Anomaly of radioactivity
SP
SPONTANEOUS POTENTIAL
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SP
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Notes
SPONTANEOUS POTENTIAL • PRINCIPLE OF MEASUREMENT Measurement of a difference of potentiel between 2 electrodes, one on the tool in the well and one at surface . It is linked mainly to - The contrast between the formation water salinity and the mudfiltrate salinity ( Liquid-Junction Potential Ej) -The contrast between the formation water salinity and the mud salinity ( Membrane Potential Em through shale) - The shale content of the formation It is expressed in milliVolt and can only be recorded in water based mud. The Electrokinetic potential Ec may be negligeable in formation with reasonable permeability
– – – – –
Detection of permeable layers Determination of bed boundaries Log correlation Evaluation of Rw Estimation of shale content in reservoirs 109
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• MAIN APPLICATIONS
NORMAL SP AND INVERSE SP
Negative SP or Normal SP
Positive SP or Inverse SP
Rmf > Rw
Rmf < Rw
Shale Baseline
Interface ShaleReservoir
SP log
Static SP
Interface Flushed zone – Virgin Zone
Rmfe E C = E M + E J = - K log Rwe Geosciences – Reservoir Engineering
SSP = E C ( + E K )
K = f(Temp)
K = 61+.133∗ T (°F) K = 65+.240∗T (°C)
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Borehole
SP EXAMPLES mV SP Scale
Shale baseline SHALE
mV
GR
SSP<0
SHALE SSP = mV
SHALE
Positive or Inverse SP
SHALE Pseudo-SP =PSP = mV
SHALE
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SSP <0
Negative or Normal SP
Effect of Rmf/Rw on SP
Geosciences – Reservoir Engineering
Effect of Shale and Hydrocarbon on SP
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MAIN PARAMETERS AFFECTING SP
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EXAMPLE OF SP LOG
DETERMINATION OF Rw FROM SP • Check validity of mudfiltrate resistivity measurement in log header • Identify shale layers • Draw SP shale baseline • Estimate maximum SP deflection in front of each reservoir : SSP • Estimate Reservoir temperature ( Chart Gen-6 ) • Determine Rmf at reservoir temperature (Chart Gen-9) • Determine Rmfe/Rwe ratio from SSP at reservoir temperature (Chart SP-1) • Determine Rmfe from Rmf at reservoir T° (Compute or use chart SP-2) • Determine Rwe (Chart SP-1)
Rmfe SSP = - K log Rwe Geosciences – Reservoir Engineering
K = 61+.133∗ T (°F) K = 65+.240∗T (°C)
Well Log Interpretation – PDVSA – January 2007
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• Determine Rw (Chart SP-2)
ESTIMATION OF SHALE CONTENT FROM SP
Estimation of VSH SP log SSP
from SP log
Static SP
PSP
Pseudo SP
SP Shale Baseline
VSH
Geosciences – Reservoir Engineering
SP
=1−α =1−
PSP SSP - PSP = SSP SSP 115
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SSP - PSP
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Notes
RESISTIVITY MEASUREMENTS
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RESISTIVITY LOGGING Rt, Rxo
RESISTIVITY MEASUREMENTS
• • • •
Detect the presence of hydrocarbon in the reservoirs (Water-HC Contact ) Determine the resistivities Rt and Rxo and estimate the invasion diameter Di Determine the hydrocarbon saturation in the virgin zone ( Shc = 1-Sw ) Determine the residual hydrocarbon saturation in the flushed zone ( Shr = 1-Sxo )
•
But be careful, because … – The formation resistivity varies also with the formation porosity – The true resistivity Rt depends also on the resistivity Rw of the water in the reservoirs, which is also function of the water salinity and the formation temperature.
Rw a Rt = m × n φ Sw Geosciences – Reservoir Engineering
R xo
118
a R mf = m× n φ S xo Well Log Interpretation – PDVSA – January 2007
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OBJECTIVES: The standard measurements of formation deep , shallow and micro resistivities or the multiple depth of investigation Laterolog or Induction logs are used to :
INDUCTION
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INDUCTION
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Notes
INDUCTION TOOLS AND LOGS •
INDUCTION TOOLS and Associated INDUCTION LOGS :
– – – – – – – •
Early Tools (1952…) : IES => ILD, SN Induction Tool IRT (1959 ) (6FF40) => ILD , LL8, SP Dual Induction Tool DIT(1962) => ILD, ILM, SFL, SP Phasor Induction Tool DITE => IDPH, IMPH, SFL , SP Array Induction Tool AIT (1992) => AH90, 60, 30, 20, 10” , SP (Schlumberger) HDIL => 120, 90, 60, 30, 20, 10” Investigation and 3DEX(Rv-Rh) (Baker Atlas) HRAI-X => 120, 90, 60, 30, 20, 10” Investigation (Halliburton LS )
Obtention of Deep Resistivities ( ILD, 90 or 120” Induction log ) and Intermediate ( ILM , SFL, AIT logs 60, 30,20,10 ) in the following cases :
•
Best conditions for Induction :
– Low or not too high formation Resistivities – Fresh water based mud and formation containing salty water – High ratio Rxo/Rt ( Rxo > 2 * Rt )
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– Drilling with Oil based Mud (OBM) – Drilling with fresh or low salinity water based mud (WBM) – Drilling with air or foam
INDUCTION-SFL PRINCIPLE Induction Principle (2 Coils)
SFL Principle Spherically Focused log
Gi = Geometrical Factor of Zone i
Ca = Gm * Cm + Gxo * Cxo + Gt * Ct Geosciences – Reservoir Engineering
Ci = Conductivity of Zone i ( mmho/m) 122
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(Water based mud only )
ARRAY INDUCTION SONDE AND LOG 28 Array signals
Borehole correction
Software focusing
Computed Products
Receiver Electronics
R1
8 arrays 2 frequencies R2
20 30
R3
60
R4 R5 Transmitter
90
R6 R7 R8
Transmitter Electronics
Schlumberger document
123
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R & X signals
10
HDIL INDUCTION LOG
HDIL Log Example
Rxo Rt
20
Di
30 60 90 120
Baker Atlas document Geosciences – Reservoir Engineering
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10
LATEROLOG
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LATEROLOG
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Notes
•
LATEROLOG TOOLS and LOGS – Early Devices : Normal and Lateral, LL3, LL7 – Dual Laterolog (DLT) => LLDeep , LLShallow – Azimuthal Laterolog ARI => LLD, LLS, LLHR , Images – HDLL : High resolution and multiple depths of investigation ( Baker Atlas) – Obtention of Deep Resistivity (LLD) and Intermediate resistivity (LLS) of the formations in the case of wells drilled with water based mud ( WBM)
•
Applications : – Determination of the Water–Hydrocarbon contact (Rt Rxo Overlay) – In combination with the microresistivities and after environmental correction, determination of Rt and Di – Computation of Sw and Shc
•
Best results are obtained – If the ratio Rxo / Rt is low ( Rxo < 2 * Rt ) – If the formations have high resistivity
•
Limitations : – Only used in water based mud 127
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LATEROLOG TOOLS AND APPLICATIONS
BASIC NORMAL & LATERAL RESISTIVITY MEASUREMENTS
Geosciences – Reservoir Engineering
LATERAL
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NORMAL
LATEROLOG TOOL SCHEMA OF THE DUAL LATEROLOG TOOL LLs
LLd
A2
A’2
Schlumberger Tool
Ji = Pseudo-Geometrical Factor of zone i
Ra = Jm * Rm + Jmc * Rmc + Jxo * Rxo + Jt * Rt Geosciences – Reservoir Engineering
Ri = Resistivity of zone i ( mmho/m)
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A1 M2 M1 A0 M’1 M’2 A’1
ARI – AZIMUTHAL RESISTIVITY IMAGER LLd and deep azimuthal resistivity
LLs and azimuthal electrical standoff
A2
A’2 Schlumberger Tool
ELECTRODES CONFIGURATION Geosciences – Reservoir Engineering
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A1 M2 M1 A0 M’1 M’2 A’1
MICRORESISTIVITY
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MICRORESISTIVITIES
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Notes
MICRORESISTIVITY MEASUREMENTS •
TOOLS AND LOGS – – – – –
•
Proximity log MICROLOG or MINILOG MICROLATEROLOG Tool SRT Tool , combined with the DLT PEX Tool
=> PL (Obsolete) => MINV, MNOR (Micro-Inverse and Micro-Normal ) (Schlumberger (obsolete) , Baker Atlas) => Log MLL => log MSFL (Micro-Spherically Focused Log ) ( Schlumberger, HLS) => log MCFL (Micro-Circumferential Focused Log ) ( Schlumberger)
APPLICATIONS – Obtention of the Resistivity Rxo of the flushed zone : –
Rxo = MSFL or MLL or MCFL corrected for mudcake effect (Thickness hmc and Resistivity ) Identification of Water-Hydrocarbon contact ( Rt-Rxo Overlay technique) Estimation of residual hydrocarbon saturation Shr Detection of permeable zones ( Microlog) Detection of fractures
– – – –
•
Limitations : – Measurements only available in wells drilled with water based mud
•
Logs very sensitive to bad holes ( caves, rugosity ) 133
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Rmc
MICRORESISTIVITY MEASUREMENT : MSFL MICRO-SFL SCHEMA SRS (Old Tool) (4 arms )
Mud
A1
Mudcake
M0 A0 Monitor Electrodes Monitor Voltage
Schlumberger document Geosciences – Reservoir Engineering
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Measure Voltage
MICRORESISTIVITY MEASUREMENT : MCFL Tool combining Litho-Density and Microresistivity
HRMS : High Resolution Mechanical Sonde
• • • •
LS – Long Spacing Detector (Densité) SS – Short Spacing Detector (Densité) BS – Back Scatter Detector (Densité) MCFL – Micro-cylindrical focused Log.
Hinge Joints
Schlumberger
135
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Hinge Joints
MICRORESISTIVITY MEASUREMENTS MICROLOG and PROXIMITY LOG
MNOR
MINV
COMPARISON OF CURRENT LINES Geosciences – Reservoir Engineering
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MICROLATEROLOG and MICROLOG
DLL-MSFL LOG EXAMPLE 20000 2000
20
20000 10000
High resistivities in Tight formations
137
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Well Log Interpretation – PDVSA – January 2007
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INVASION PROFILE => Reservoir
DLL-MSFL-MICROLOG EXAMPLE Use of Microlog for accurate reservoir identification
MNOR MINV
Separation MNOR_MINV => Permeable Zone
GR
SP
Geosciences – Reservoir Engineering
LLD-LLS-MSFL Separation ? INVASION PROFILE ? => Reservoir ??
High resistivities in Tight formations
138
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Mudcake
DLL-MSFL Geosciences – Reservoir Engineering
Array Induction Log 139
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Comparison : DLL-MSFL and Array Induction
Geosciences – Reservoir Engineering
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ARI - AZIMUTHAL RESISTIVITY IMAGER
CHOICE OF RESISTIVITY TOOLS Rmf > 2*Rw Rxo > 2*Rt
Fresh Water
Rxo
Based
Rxo
Mud
Rxo/Rt > 2
Rt
Rt
If Sw = 1
Î INDUCTION + MSFL or MLL
Saline Water
Rt
Based Mud
Rxo/Rt < 2
Î LATEROLOG Rxo
+MSFL or MLL
Rxo
141
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Rt
Rmf < 2* Rw Rxo < 2* Rt
CHOICE OF RESISTIVITY TOOLS
(Rxo) Rt
Rt
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Î INDUCTION
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(Rxo)
Oil Based Mud
CHOICE OF RESISTIVITY TOOLS: LATEROLOG OR INDUCTION Case of Water based Mud
30
INDUCTION LOG PREFERRED ABOVE APPROPRIATE RW CURVE
Porosity (%)
20
RW = 1 Ω - M
LATEROLOG PREFERED 10
Schlumberger document
RW = 0.01 Ω - M
0 .5
.7
1.
2.
3.
5.
10.
20.
30.
Rmf / Rw Geosciences – Reservoir Engineering
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RW = 0.1 Ω - M
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Notes
POROSITY-LITHOLOGY MEASUREMENTS
POROSITY-LITHOLOGY MEASUREMENTS
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DENSITY – NEUTRON – SONIC NUCLEAR MAGNETIC RESONANCE
POROSITY-LITHOLOGY MEASUREMENTS
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DENSITY LOGGING
DENSITY TOOL PRINCIPLE PRINCIPLE OF DENSITY MEASUREMENT : Gamma Rays emitted by a Cesium 137 radioactive source located in the Density tool enter in collision with electrons surrounding the atoms of the formation and loose energy. These GR are counted after interactions on 2 detectors situated on the Density tool above the source . The tool is pushed against the formation by a caliper arm and the two detectors are in close contact with the formation. From these count rates, the electronic density the formation can be obtained. ρ = ρ * 2 Z el
ρ
el
and then the bulk density ρb of
ρ b = 1.0704 * ρ el − .1883
A
b
(Z : Atomic Number, A : Atomic Weight ; 2Z/A close to 1)
For quality control, the density correction ∆ρb which is applied to the ρb log is also displayed. Since 1980 , the Litho-Density tool provides also a Photoelectric Absorption Factor curve Pe. 147
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The mudcake effect is compensated by the measurements on both detectors.
LITHO-DENSITY TOOL Invaded Zone
Virgin Zone
Mud cake
γRay
D
Far Detector Measure Point
D
137Cs
Source
S
HRMS : High Resolution Mechanical Sonde (Recent) • • • •
Litho-Density Tool
LS – Long Spacing Detector (Density) SS – Short Spacing Detector (Density) BS – Back Scatter Detector (Density) MCFL – Micro-cylindrical focused Log. Schlumberger Document
Density Tools and Logs FDC : Formation Density Compensated => Logs RHOB et DRHO LDT : Litho-Density Tool (> 1980)
Geosciences – Reservoir Engineering
=> Logs RHOB , DRHO et PEF 148
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Near Detector
DENSITY AND PEF MEASUREMENTS 2 different energy windows
SOURCE Low Energy Window High Energy Window DENSITY Information
DETECTORS ENERGY LOSS ABSORPTION (Photoelectric Effect) 149
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PEF & DENSITY Information
GR of known Energy
DENSITY AND PEF VALUES Photoelectric Absorption Factor
⎛Z⎞ Pef = ⎜ ⎟ ⎝ 10 ⎠
3,6
Density
PEF is function of the lithology and the values are little affected by the fluids ( See chart PEF – RHOB) => Warning : Pef is very sensitive to the presence of Barite , therefore it might be reading too high and be wrong
ρ b = (1 − Φ u )ρ ma + Φ u ρ f .
For clean formations , without shale ( Vsh = 0 )
Density varies with Lithology, Porosity, Fluid density
PEF (barn/e)
Limestone (CaCO3)
5.1 (5.1 –> 4.4)
2.71 g/cm3
Dolomite (CaCO3, MgCO3)
3.1 (3.1 –> 2.7)
2.85 g/cm3
Sandstone ( SiO2)
1.8 (1.8 –> 1.6)
2.65 g/cm3
Salt (NaCl)
4.7
2.04 g/cm3
Anhydrite (CaSO4)
5.1
2.98 g/cm3
Pyrite (FeS2)
17
4.99 g/cm3
Barite (BaSO4)
267
4.09 g/cm3
Geosciences – Reservoir Engineering
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Density ρma
MINERAL
(Schlumberger document )
151
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DENSITY CORRECTION
DENSITY AND PEF LOGS : LITHO-DENSITY LOG
BIT SIZE
RHOB DRHO PEF
(LDL – CNL Schlumberger Log Example )
Density and PEF are very sensitive to presence of caves Equivalent for Baker Atlas => ZDL Tool => ZDEN ( Bulk Density) and ZCOR ( Density Correction) Equivalent for Halliburton => SSDL Tool Geosciences – Reservoir Engineering
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CALIPER
ESTIMATION OF POROSITY FROM DENSITY LOG Vt = 1
For clean formations , without shale ( Vsh = 0 )
Φu
ρ b = (1 − Φ u )ρ ma + Φ u ρ f . ρb
: Density log
ρma Φu
1-Φu
Φ U(D) =
ρ ma − ρ b ρ ma − ρ f
Lithology
Density ρma
: Matrix density
Limestone (CaCO3)
2.71 g/cm3
Dolomite (CaCO3, MgCO3)
2.85 g/cm3
: Formation Porosity
Sandstone ( SiO2)
2.65 g/cm3
( PHID ou DPHI )
Φu
In Water zone
ρf = ρ
In Hydrocarbon zone
ρf = Sxo * ρ
MF
Mud Filtrate Density
mf
+(
Φu
1- Sxo ) * ρhc HC
ρmf = 1 + 0.7 * P
MF
P = Salinity ( kppm) *10-3 153
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mf
POROSITY FROM DENSITY LOG Determination of Porosity from the Density log
ρfl = 1.0
In the case of Clean formation ( Vsh = 0 )
Porosity
and in Water Zone Porosity = 25 %
Φ U(D) = Sandstone line Porosity = 14 %
ρ ma − ρ b ρ ma − ρ f
Mud Filtrate Density
ρmf = 1 + 0.7 * P ρma = 2.65 g/cc
ρb = 2.42 g/cc
Example 1 :
(Schlumberger Chart )
Example 2 :
Limestone formation
Sandstone formation
ρb = 2.31 g/cm3
ρb = 2.42 g/cm3
ρma = 2.71 g/cm3 ( Calcite )
ρma = 2.65 g/cm3( Quartz )
ρf = 1.1 g/cm3 ( Salt mud)
ρf = 1.0 g/cm3 ( Fresh mud)
Formation porosity = 25 p.u Geosciences – Reservoir Engineering
P = Salinity ( kppm) *10-3
Formation porosity = 14 p.u
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RHOB
PEF versus RHOB ρ
b
Pef
(Schlumberger Chart )
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Porosity
VOLUMETRIC PHOTOELECTRIC ABSORPTION FACTOR Combination of RHOB and PEF
U = Pe * ρ el = Pe * (
ρ b + 0.1883 ). 1.0704
Used in Multimineral log Interpretation
Lithology
Uma ( barn/cm3)
Log response similar to RHOB :
Limestone (CaCO3)
13.8
U = (1 − Φ u )U ma + Φ u U f .
Dolomite (CaCO3, MgCO3)
9.0
Sandstone ( SiO2)
4.78
Fluid
Uf ( barn/cm3)
Fresh Water ( H2O)
0.398
Salty Water ( 120 Kppm )
0.85
Oil ( 0.85 g/cm3)
0.136
In Water zone
Uf = U
In Hydrocarbon zone
Uf = Sxo * U
Geosciences – Reservoir Engineering
mf
mf
156
+(
1- Sxo ) * Uhc Well Log Interpretation – PDVSA – January 2007
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U = Volumetric Photoelectric Absorption Factor ( Barn/cm3)
POROSITY-LITHOLOGY MEASUREMENTS
Geosciences – Reservoir Engineering
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NEUTRON LOGGING
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Notes
NEUTRON TOOL PRINCIPLE PRINCIPLE High energy Neutrons are emitted from an Am-Be chemical radioactive source into the formation. After collisions with atoms, neutrons loose energy. They are mainly slowed down by Hydrogen atoms which have the same mass. Neutrons having reached an epithermal or a thermal energy level are counted on 2 detectors situated on the neutron tool above the source.
In a clean fresh water bearing limestone, which is the reference matrix for neutron calibration, the Neutron Porosity Hydrogen Index NPHI recorded in Limestone Matrix corresponds to the porosity of the Limestone. (Master Calibration Pit in Houston ) In the case of different lithology ( Sandstone or Dolomite ) or type of fluid (Salty water , Oil or Gas ) , a correction will have to be applied to the NPHI log to obtain the formation porosity.
Geosciences – Reservoir Engineering
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The Hydrogen Index HI which represents the amount of Hydrogen atoms in the formation is derived from the ratio of the neutron counts on both detectors.
NEUTRON TOOL Invaded Zone
Virgin Zone
Mud cake
Example of Compensated Neutron Tool CNT (Schlumberger)
Far Detector (25’’) Measure Point Near Detector (15’’)
Tool Excentraliser
Geosciences – Reservoir Engineering
Am - Be Neutron Source
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Neutron path
NEUTRON TOOLS AND LOGS Schlumberger Tools and Logs : SNP : Sidewall Neutron Porosity Tool (obsolete) - Epithermal Neutrons => Log in API Units CNT : Compensated Neutron Tool - Thermal Neutrons => Logs NPHI Neutron Porosity Hydrogen Index or TNPH Thermal Neutron Porosity Hydrogen ( Index ) in % or V/V or Porosity Units Pu - No Chemical source but Neutrons generated by Minitron - Epithermal & Thermal Neutrons => Log APLC and SIGMA ( Capture crossection) Equivalent for Baker Atlas => CN Tool => CNCF ( Field Normalized Compensated Neutron Porosity) 161
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APS : Accelerometer Porosity Sonde (> 1990)
NEUTRON SLOWING DOWN AND CAPTURE PROCESS FAST NEUTRON
Emission of High energy Neutrons =>
E = 4 à 6 MeV
SLOWING DOWN
THERMAL NEUTRONS DIFFUSION
E = 0.1 à 100 eV
E = 0.025 eV
NEUTRON CAPTURE
γ Geosciences – Reservoir Engineering
γ
γ 162
=> Emission of Gamma Rays
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
EPITHERMAL NEUTRONS SLOWING DOWN
NEUTRON CALIBRATION Installation of Neutron Source in the Tool
Before Survey Calibration of Neutron Tool
Source Container
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Calibration Jig
FACTORS AFFECTING NEUTRON MEASUREMENTS Linked to Recording - Time Constant - Logging Speed - Dead Time – Detector - Bed Thickness
Linked to the Borehole Environment - Mud Salinity and Density (Presence of Barite) - Mud Filtrate Salinity - Hole Diameter - Tool Standoff - Presence of mudcake - Presence of casing - Invasion Diameter - Pressure and Temperature Geosciences – Reservoir Engineering
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- Drilling fluid type (WBM, OBM)
NEUTRON LOG EXAMPLE ( Schlumberger) Units : % ou PU (0-100) ou V/V (0 --1)
Neutron Log is affected by caves
Cave NPHI
Caliper
Neutron Log corrected for Hole size during acquisition process. (Hole Correction : CALI)
Acquisition parameters
NPHI recorded in OPEN Hole BHS = Borehole Status = OPEN
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Neutron log NPHI recorded in Limestone Matrix MATR = LIMEstone
NEUTRON LOG EXAMPLE (Baker Atlas)
Bulk Density ZDEN
Neutron Porosity CNCF
DPIL Induction log
Neutron Log corrected for Hole size during acquisition process. (Hole Correction : CALI)
Log recorded in Venezuela Geosciences – Reservoir Engineering
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Neutron log NPHI recorded in Sandstone Matrix MATR = SANDSTONE
ESTIMATION OF POROSITY FROM NEUTRON LOG For clean formations , without shale ( Vsh = 0 )
Φ N = (1 − Φ u )Φ Nma + Φ u Φ Nfl : Neutron log
ΦNma
: Neutron matrix
ΦNfl
: Neutron fluid
Φu
: Formation Porosity
Φ N − Φ Nma Φ Nfl − Φ Nma
MINERAL
Φ
Limestone (CaCO3)
0.00
Dolomite (CaCO3, MgCO3)
0.03 (0.01 for TNPH)
Sandstone ( SiO2) Salt (NaCl) Anhydrite (CaSO4)
Nma
- 0.02 - 0.03 - 0.02
In Water zone
ΦNfl
In Hydrocarbon zone
ΦNfl = Sxo * ΦNmf + ( 1- Sxo ) * ΦNhc
= ΦNmf
Mud Filtrate Neutron response
Hydrocarbon Neutron response
ρmf = 1 + 0.7 * P P = Salinity ( kppm) *10-3
ΦNmf = ρ
mf
(V/V)
( 1- P )
If
ρ
hc
< 0.25
=>
ΦNhc = 2.2 * ρ
If
ρ
hc
>= 0.25
=>
ΦNhc = 0.3 + ρ
hc
167
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hc
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
ΦN
Φ u(N) =
FORMATION POROSITY FROM NEUTRON LOG SS + Water
TNPH 250 kppm
Porosity
LS + Water
Determination of Porosity from Neutron Log NPHI or TNPH, recorded in Limestone matrix
TNPH 0 kppm
NPHI
Porosity = 24 p.u. DOLOMITE + Water
TNPH 0 kppm
Porosity = 22.5 p.u.
Example 1 :
NPHI
Sandstone formation with a water salinity of 20 kppm NPHIcor = 18 p.u. in limestone lithology True porosity = 22.5 p.u
Example 2 : Sandstone formation with a water salinity of 250 kppm TNPHcor = 18 p.u. in limestone lithology Corrected NPHI or TNPH
True porosity = 24.0 p.u
(Schlumberger Chart) Geosciences – Reservoir Engineering
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TNPH 250 kppm
APS CONFIGURATION Sensors and Measurements
Curves and products
Electronic neutron source Minitron
Near-array epithermal ratio porosity Hydrogen index measurement
Near epithermal detector Count Rate
Epithermal slowing-down time Standoff determination
Array epithermal Count Rate Time Distribution
Near-far ratio Lithology indicator Stand-alone gas indicator (in clean formations)
Far epithermal detector Count Rate
(Schlumberger) Geosciences – Reservoir Engineering
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Thermal neutron decay rate Formation capture cross section (sigma) of invaded zone
Array thermal Count Rate Time Distribution
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Notes
POROSITY-LITHOLOGY MEASUREMENTS
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SONIC LOGGING
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Notes
SONIC PRINCIPLE • SONIC PRINCIPLE Sonic logging tools emits from a transducer T1 a compressionnal sound wave in the borehole. The sound travels through the mud and the formation and reaches 2 receivers R1 and R3 generally spaced 2 feet apart and situated at a distance of 5 and 3 feet from the transducer. The slowness DT expressed in µs/ft corresponds to the time it takes for the sound to travel through one foot of formation. It is the inverse of the velocity of the compressionnal sound wave.
The borehole compensated sonic BHC for sonde tilt is obtained by doing a second measurement from another transducer T2 to another pair of receivers R4 and R2 situated very close to the previous ones, and by taking the average the 2 measurements . From the processing of the 8 waveforms recorded from 8 receivers on an array sonic or a dipole sonic , the DT shear slowness and the Shear velocity can also be obtained. 173
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It is obtained by the difference in the arrival times of the sound wave at the two receivers.
SONIC DT MEASUREMENT (BHC) Shema of the BoreHole Compensated Sonic BHC
(T R − T R ) + (T2 R 4 − T2 R 2 ) ∆t = 1 1 1 3 4 µs/ft
T2
Compensation for sonde tilt
T1R1 – T1R3 T1R1 R1 R2
Threshold detection
2ft
T1R3
R3 5ft
R4
To
3ft
To
Time in µs
Velocity( m / s ) =
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304800 ∆t µs/ft Well Log Interpretation – PDVSA – January 2007
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T1
SONIC BHC LOG
ITT Integrated
Tension
ITT
Transit Time in ms
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Sonic DT
SONIC LOG QUALITY CONTROL FACTORS AFFECTING THE SONIC LOG Cycle Skipping
• Linked to detection • Cycle skips ( Weak signal ) • Noise • Stretch
Noise Detection
• Linked to Formations • Undercompacted shales • Unconsolidated sandstone • Formations with high porosity • Formation with gas
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• Linked to travel path of sound wave • Caves • Damaged borehole and borehole rugosity
SONIC LOG QUALITY CONTROL EXAMPLE OF SONIC LOG WITH ANOMALIES DT
Caliper Cycle Skip or Noise
Watch also for errors when splicing subsequent logging runs !
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Sonic Logs must always be checked and eventually edited before use !
SONIC LOG QUALITY CONTROL TT1, 2, 3, 4
DT (BHC)
Noise on TT3 => DT bad
EXAMPLE OF BAD SONIC LOG
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DT (Bad)
Display of IndividualTtransit Times TT’s helps identification of bad zones
SONIC LOGGING TOOLS ARRAY Mode DTCO, DTSM
Dipole Transducer
12 ft 10 ft 10 ft
U_Dipole Monopole P
DDBHC
DDBHC
DDBHC
DDBHC
3-5 ft
5-7 ft
8-10 ft
10-12 ft
DT
DTL
DTLN
DTLF
DT2
DTCO, DTSM, Monopole ST
L_Dipole
DTST
Borehole Compensated
Array SONIC
Sonic BHC (3-5ft)
SDT
Geosciences – Reservoir Engineering
DT1
Dipole SONIC (Schlumberger)
179
DSI
(Schlumberger)
Well Log Interpretation – PDVSA – January 2007
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8 ft
Slow ( Soft ) Formation
Fast ( Hard ) Formation
Compressional Monopole
Compressional Monopole
Flexural Wave from
P & Stoneley waves
P & Refracted Shear waves
Dipole Transducer
DSI
DSI
DSI
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MONOPOLE - DIPOLE SONIC MODES
DIPOLE STC PROCESSING
8 Waveforms From 8 receivers Poisson Ratio
DSI
DTS
DTC
DTS
STC Slowness - Time Processing DSI
DTc & DTs Results
DTS Projection Plane
DSI
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Coherence
SLOWNESS EVALUATION DSI Log
Compressional DT : Dt or DTCO or LSDT
Monopole Compressionnal and Monople Stoneley
DTST = DT Stoneley
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DTSM = DT shear (Refracted )
SONIC APPLICATIONS • APPLICATIONS • DT is an essential measurement for the geophysicist : • Sound velocity in the geological formations • Time–depth relationship (Time = f(Depth) and Time-Depth conversion • Comparison of Log and Seismic data • Determination of the porosity of reservoirs • Determination of lithology ( DT combined with Density or Neutron; DTc vs DTs)
• Anisotropy, main stresses from Cross-Dipole Sonic measurements. • Facture identification from Stoney waves • In cased hole, DTc (from WF) or CBL for cement evaluation ( Cement Bond Log )
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• Combining Density, DTc and DTs , rock mechanical properties can be derived (Rock Strength, Earth Stress, Rock Failure) and used for Sanding prediction, Hydraulic fracture height, Wellbore stability .
STONELEY WAVEFORM APPLICATION FRACTURE IDENTIFICATION IN OPEN HOLE
Chevrons patterns on Stoneley Variable Density Log (VDL) due to presence of Fracture
Fracture
STONELEY WAVE FROM DSI Geosciences – Reservoir Engineering
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Stoney reflection coefficent
POROSITY FROM SONIC
∆t p = (1 − Φu) ⋅ ∆t ma + Φu ⋅ ∆t f
( Time Averaged)
Φ u(S) =
In the case of Clean formation ( Vsh = 0 )
∆t − ∆t ma 1 × ∆t f − ∆t ma Bcp
1 < Bcp< 1.6
( Φu 1 1 − Φu ) = + ∆t ∆t ma ∆t f ∆t - ∆t ma Φ u(S_RH) = K × ∆t 2
Raymer, Hunt & Gartner Formula ( Field Observation) Simplified RHG Formula
Sonic ∆tcma ( µs/ft)
Lithology
Compaction factor
K = 0,625
Fluid
Sonic ∆tfl ( µs/ft)
Limestone (CaCO3)
49
Water
189 (180-200)
Dolomite (CaCO3, MgCO3)
44
Oil
200-220
Sandstone ( SiO2)
56
Gas
> 250 ( -> 500)
185
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Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Wyllie Formula
POROSITY FROM SONIC PHIS Wyllie = ( DT - Dtma ) / ( DTfl - Dtma ) x ( 1/Bcp )
Determination of Porosity from the Sonic log
PHIS RH* = K * ( DT - Dtma ) / DT
In the case of Clean formation ( Vsh = 0 )
(Schlumberger Chart Por-3)
Sandstones Limestones Dolomites
Sonic Velocity ft/s 18000 - 19500 21000 - 23000 23000 - 26000
∆ Tma µs/ft 55,6 51,3 47,6 43,5 43,5 38,5
Sonic Velocity m/s 5486 - 5944 6401 - 7010 7010 - 7925
∆ Tma µs/m 182,3 - 168,2 156,2 - 142,6 142,6 - 126,2
20000 14925
50,0 67,0
6096 4549
164,0 219,8
Anhydrite Salt Geosciences – Reservoir Engineering
186
Example : DT = 76 µs/ft ( 249 µs/m ) SVma = 18000 ft/s ( 5486 m/s ) Sandstone Thus Porosity = 15 % by time average or 18% by field observation method) * RH = Raymer-Hunt
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Bcp
• Compressionnal and Shear Waves • Compressionnal Waves (P) • Shear Waves (S)
Dtp, Vp Dts, Vs
• OTHER WAVES • Pseudo-Raylegh Waves • Stoneley Waves • Direct propagation in the mud
VPR VSt Vf
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ACOUSTIC WAVES
ROCK MECHANICAL PROPERTIES 4 K+ µ µ 2 2 3 Shear velocity : Vs = Compressionnal velocity : Vp = ρb ρb ELASTIC CONSTANTS AND RELATION WITH Vp and Vs
• Bulk Modulus
• Young’s Modulus
• Poisson’s Ratio
Geosciences – Reservoir Engineering
µ = ρ b Vs2 4 ⎞ ⎛ K = ρ b ⎜ Vp2 − Vs2 ⎟ 3 ⎠ ⎝ ρ b Vs2 3Vp2 − 4Vs2 9Kµ E= E= Vp2 − Vs2 3K + µ 2 2 1 ⎛⎜ Vp − 2Vs ⎞⎟ 3K - 2µ ν= ν= 2 ⎜⎝ Vp2 − Vs2 ⎟⎠ 2(3K + µ)
(
188
)
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
• Shear Modulus
POROSITY-LITHOLOGY MEASUREMENTS
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NUCLEAR MAGNETIC RESONANCE LOGGING
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© 2006 ENSPM Formation Industrie - IFP Training
Notes
NMR MEASUREMENT PRINCIPLE Tool principle and measurements: Spin excitation at resonance frequency of the protons (mainly H nuclei) under an electro-magnetic field.
Computed Parameters T1 Longitudinal Relaxation Time (ms) Identification of hydrocarbon fluids in non-wetting phase
D Fluid Diffusivity It helps to differentiate gas phase and liquid phase. The tool response is mainly influenced by the pore size distribution and the type of fluids (independently of the lithology). The data are directly comparable to core measurements. Geosciences – Reservoir Engineering
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T2 Transversal Relaxation Time (ms) - (T2lm : logarithmic mean of T2) This rate of the decay of transverse magnetization depends on the ratio surface/volume of the pores Rapid decay time for small pores and slow decay time for large pores.
NMR TOOL AND PRINCIPLE CMR TOOL
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(Schlumberger)
NMR RESULTS Results : The tool responds mainly to the quantity of Hydrogen atoms present in the fluids. It allows : - the evaluation of the - Total Porosity - Effective Porosity, - Irreducible water volume (or "Capillary Bound Water" BVI), - Free Fluid volume (FFI), - Clay Bound water volume The pore size distribution is derived through various T2 cut offs.
K = a⎜ ⎟ ×⎜ ⎟ ⎝ 10 ⎠ ⎝ BVI ⎠
SDR Schlumberger
(b=4,c=2)
K = a × PHI b × T2 lm
c
- the determination of the type of Hydrocarbons (Gas/Oil identification). Geosciences – Reservoir Engineering
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- the evaluation of the permeability of the formation through various relationships such as : 4 2 ⎛ PHI ⎞ ⎛ FFI ⎞ Timur Coates Law
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NMR TOOL AND PRINCIPLE
NMR LOG EXAMPLE Permeability
NMR Signal
195
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Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Porosity
NMR MODEL NMR POROSITY MODEL MATRIX
DRY CLAY
CLAY BOUND WATER
CAPILLARY BOUND WATER
MOBILE WATER
HYDROCARBON
Vt
Total Porosity Irreducible Water
Vw_sh
Viw
Total Porosity =
Effective Porosity =
Geosciences – Reservoir Engineering
Free Fluids
Vw Effective Porosity
Vhc
Vw_sh + Viw + Vw + Vhc Vt Viw + Vw + Vhc Vt 196
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Bound Water
DIPMETER AND BOREHOLE IMAGING
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© 2006 ENSPM Formation Industrie - IFP Training
DIPMETER AND BOREHOLE IMAGING
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© 2006 ENSPM Formation Industrie - IFP Training
Notes
DIPMETER TOOLS
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© 2006 ENSPM Formation Industrie - IFP Training
STRATIGRAPHIC HIGH RESOLUTION DIPMETER TOOL
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DIPMETER LOG
ELECTRICAL AND ACOUSTIC IMAGING TOOLS Formation Micro-Imager Tool
Ultra-Sonic Borehole Imager ( UBI)
Schlumberger Document
Schlumberger Document
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Acoustic Transducer
BOREHOLE IMAGING FROM FMS TOOL
FORMATION MICRO SCANNER
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Images from 2 pads
BOREHOLE IMAGING
FORMATION MICRO IMAGER Dips from FMI Images 4 pad images
Schlumberger Document
203
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© 2006 ENSPM Formation Industrie - IFP Training
Sinusoid
Dips
BOREHOLE IMAGING RESULTS FMI
Image
ARI
Image
UBI
Image
Formation Micro-Imager Tool
Formation Micro-resistivity
Azimuthal Resistivity
Ultra-Sonic Borehole
Imager
Imager
Imager
Geosciences – Reservoir Engineering
Schlumberger Document
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Comparison between images from FMI, ARI and UBI
BOREHOLE IMAGING
Image from the Formation Micro-Imager tool
Bioturbation
Root Traces
Schlumberger Document
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Bioturbation and Root traces
BOREHOLE IMAGING Fossils Debris
Image from the Formation Micro-Imager tool
Intramoldic Porosity Vuggy Porosity
PinPoint Porosity
Schlumberger Document
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Intramoldic and vuggy porosity
BOREHOLE IMAGING
Image from the Formation Micro-Imager tool
Moldic Porosity
Schlumberger Document
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in a Dolostone
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© 2006 ENSPM Formation Industrie - IFP Training
Notes
PRESSURE MEASUREMENTS AND FLUID SAMPLING
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© 2006 ENSPM Formation Industrie - IFP Training
PRESSURE MEASUREMENTS AND FLUID SAMPLING
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Notes
PRESSURE MEASUREMENTS AND FLUID SAMPLING GOALS
• Measurement of Formation Pressure • Estimation of Reservoir Permeability - Permeability from Drawdown - Permeability from Build-up (Horner plot) • Determination of fluid contacts • Evaluation of Pressure Gradients and Fluid Densities
• PVT Analysis
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• Sampling of Formation Fluids
PRESSURE MEASUREMENTS AND FLUID SAMPLING TOOLS Open Hole :
• Repeat Formation Tester RFT (Schlumberger) Open Hole / Cased Hole – 1 Probe - 2 Samples OLD
• Sampling Formation Tester SFT (Halliburton Logging Services) • Formation MultiTester FMT (Baker Atlas)
• Modular Formation Dynamic Tester MDT ( 3 probes - multi samples) and Slim Hole Repeat Formation Tester SRFT
(Schlumberger)
• Reservoir Description Tool RDT (Halliburton LS) • Reservoir Characterisation Instrument RCI ( Baker Atlas)
Cased Hole : Cased Hole Dynamic Tester CHDT ( Schlumberger)
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RECENT
RFT and MDT
Modular Dynamic Formation Tester
(Document Schlumberger)
213
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Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Repeat Formation Tester
OPERATION DU MDT MDT tool retracted
MDT tool set
Crystal Quartz Gauge
Crystal Quartz Gauge
Isolation valve
Isolation valve
Strain gauge
Equalizing valve
Pretest
Strain gauge
Pretest
Resistivity cell
Resistivity cell Backupshoe
Backupshoe
Invaded zone
Probe
Virgin zone
Invaded zone
Virgin zone
Packer
(from Schlumberger Document )
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Equalizing valve
MDT : PRESSURE GAUGES
(Document Schlumberger)
215
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© 2006 ENSPM Formation Industrie - IFP Training
Crystal Quartz Gauge
Strain Gauge
MDT : Pressure Test Records Pressure Record with SGP gauge
Pressure Record with SGP and HP gauges HPGP
Time
SGP
HPGP
Hydrostatic Pressure after
Formation Pressure
Time SGP Strain gauge pressure
Pressure Buidup
Formation Pressure
SGP
Drawdown
Hydrostatic Pressure before
Pressure Buidup
Drawdown
Hydrostatic Pressure before
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Pretest
RFT : Pressure Plot vs Time Example of Medium Permeability Formation RFT Pressure test record PLOT : HP Pressure Versus TIME
Formation Pressure
Hydrostatic Pressure before test
Hydrostatic Pressure After test Pressure Buidup
Drawdown
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Pretest
Pressure profiles according to permeability HIGH PERMEABILITY
MEDIUM PERMEABILITY
LOW PERMEABILITY
Pressure Buidup with slow pressure stabilisation
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Pressure Buidup with fast pressure stabilisation
Permeability estimation from drawdown
PF1
P1
t1
K=
t2
C * 4388 * q * µ DP
PF2
K = Permeability µ = Fluid Viscosity
DP = P1 – PF1 (psi)
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Q = Flow rate (cm3/s)
Pressure gradients and fluid density True Vertical Depth
Formation Pressure
FLUID DENSITY =
PRESSURE GRADIENT (PSI/Ft) 0.433
FLUID DENSITY =
PRESSURE GRADIENT (PSI/M) 1.422
(WEC Algérie 1979)
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Hydrostatic Pressure
Pressure measurements and fluid sampling Possible MDT Configurations
(Document Schlumberger)
221
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Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Dual Packer Module
Pressure measurements and fluid sampling Optical Fluid Analyser
Pumpout Module
(Document Schlumberger)
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Flow Control Module
LWD
223
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ADN - CDR
(Schlumberger)
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
LOGGING WHILE DRILLING
LWD
RAB : Resistivity at the Bit
Geosteering Tool (Schlumberger)
Geosciences – Reservoir Engineering
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ISonic
LOG INTERPRETATION
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LOG INTERPRETATION
QUICKLOOK
QUICKLOOK
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LOG INTERPRETATION
LOG INTERPRETATION FLOW CHART DATA QUALITY CONTROL RESERVOIR/NON RESERVOIR IDENTIFICATION TIGHT FORMATIONS
SHALES
Marls
Sandy Shales
Clean Reservoirs
Shaly Reservoirs
Rt / Rxo Comparison
PS - GR SP Shale Base Line
Water Bearing zone
Quantitative Interpretation
Hydrocarbon bearing zone
Rt Rw = Rxo Rmf
Rw
Rw
Sw
Rw
N / D Comparison Checking
POROSITY 2
Rw = Rt.Φu Rmf = Rxo.Φu2 Geosciences – Reservoir Engineering
POROSITY
LITHOLOGY LITHOLOGY + FLUID SATURATION 227
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Pure Shales
RESERVOIR
QUICK-LOOK METHOD The Quick-Look method is a rapid interpretation method which is commonly used on the well site for a preliminary interpretation of the log : identification of shales and tight formations, determination of the reservoir characteristics. It is based on the use of a minimum set of conventional logs recorded in open hole and on certain assumptions : The logs used are : GR, Density and Neutron, a deep resistivity log and a micro-resistivity log for Rxo. Caliper which is usually run with these tools is also used, and also SP if it exists. Other data (Spectral Gamma Ray, Pef, Sonic ...) are also welcome if recorded! The following points are assumed : clean reservoirs, reservoirs containing formation water with a constant salinity, parameters m and n equal to 2 in the Archie resistivity formula, and the empirical relationship Sxo= Sw1/5. The main steps of the Quick-Look method are :
u
2
The limited amount of logs used does not enable log interpretation of complex lithology formations.In case of shaly reservoirs, the Quick-Look method gives altered conclusions, and only a quantitative interpretation can give satisfactory results. But the examination of these logs using this method enables a rapid log quality control.It may also be used before making a quantitative interpretation, and for a log sequence analysis, in conjunction with the cross-plot technique.
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• Reservoir delimitation, by identification of shale layers, tight formations and porous and permeable formations. • Rdeep and Rxo overlay in order to determine the hydrocarbon/water contact, and to estimate the Rw and Sw values by using a "5/8 logarithmic scale". This scale corresponds to the relationship between Sw and the Rt/Rxo ratio, which is obtained by the simplification of the Archie formulae which are applied to the flushed and the virgin zones. • Overlay of the Density and Neutron curves in order to determine the porosity of the reservoirs, and the type of lithology and the fluids contained in the pores. This visual analysis of the data may be related to the interpretation of the corresponding 2D crossplot. When these two curves are plotted in a "limestone L compatible scale", the porosity value ΦDLS computed from the density pb (in assuming a clean water bearing limestone reservoir) may be read directly on the Neutron porosity scale and thus corresponds to ΦNLS The distance between the two curves at a certain depth corresponds to the location on the cross plot of the corresponding point relating to the limestone curve. The reading of the porosity value on the Neutron porosity scale in the middle of the separation between the two curves corresponds to the ma ma iso-porosity curve of the Density-Neutron crossplot, the equation of which is : Φ = Φ N + Φ D
"QUICK LOOK " INTERPRETATION - OBJECTIVES •
Delimitation of reservoirs
•
Determination of Water – Hydrocarbon contacts (WOC / WGC)
•
Determination of formation water Resistivity ( Rw)
•
Identification of eventual Gas-Oil contact in HC zones
•
Determination of the lithology
•
Estimation of porosity in the different reservoir intervals
•
Estimation of the water and hydrocarbon saturations in the HC
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zones
"QUICK LOOK " INTERPRETATION - ASSUMPTIONS HYPOTHESES - ASSUMPTIONS – Reservoirs – Water wet – Water salinity is constant in a reservoir – Well drilled with water based mud – Mud filtrate salinity is constant over the processed interval – Formations are clean (No shale content : Vsh = 0)
– Saturation Formula = Archie Formula
– Relation between Sxo and Sw : Sxo = Sw1/5 – Density – Neutron are limestone or sandstone compatible – Resistivity scales are logarithmic
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– Saturation exponent n = 2
QUICKLOOK SEQUENCE 1/2 Non Reservoir identification Identification of Shales (Verification of D-N scales for matrix compatibility ) Identification of Tight formations Identification of Specific lithology (Salt , Anh , Coal , …) Reservoir identification
In water zone Determination of Rw from SP Determination of Rw using the resistivity Rt/Rxo Ratio Determination of Lithology and Quicklook Porosity from Density-Neutron Determination of Rwa from Rt and apparent D-N porosity Determination of Rmfa from Rxo and apparent D-N porosity Geosciences – Reservoir Engineering
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Determination of WOC in a reservoir using the Resistivity Overlay technique (Rt-Rxo)
QUICKLOOK SEQUENCE 2/2 In HC zone Quicklook Water saturation using the SW 5/8 ruler technique Identification of Gas-Oil contact , using D-N In Oil zone Determination of Lithology and Quicklook porosity Computation of Sw and Shc, Sxo and Shr In Gas zone Determination of Lithology and Quicklook porosity Computation of Sw and Shc , Sxo and Shr
Determination of the shale parameters Other Crossplots (D-S, N-S, PE-RHOB, K-TH …) Geosciences – Reservoir Engineering
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Crossplots Density-Neutron : Verification of lithology and porosity for the points in water, oil and gas zones .
QUICKLOOK : NON-RESERVOIR IDENTIFICATION Case of well drilled with water based mud and Rt and Rxo available “Reservoir identification <= ELIMINATION of Shales, Tight Formations, Salt, Anh, Coal..” Identification of Shales ( Log values here below are general average values) First : Verification of D-N scales for matrix compatibility Caliper : Caves GR : High values ( > 70 ) Deep, Shallow, and Microresistivity low ( < 20 ) and close to each other Neutron values : High ( > 30 % ) N-D separation higher than N-D separation observed in Dolomite (6 Divisions with RHOB-NPHI) SP (Shale baseline)
Caliper : close to BS GR : Low values ( < 30 ) Deep, Shallow, and Microresistivity high ( > 200 ) and close to each other Density, Neutron , Sonic : close to Matrix reference values: φNma, ρma, DTma Neutron low ( < 5% ) , Sonic low ( < 60 ) , Density High ( > 2.60) SP flat , similar to SP in Shale
Identification of Specific Lithologies (Salt , Anh ) Caliper : Close to BS , but caving can be observed in Salt GR : Low values ( < 30 ) Deep, Shallow, and Microresistivity high ( > 500 ) and close to each other Density-Neutron- Sonic : see reference values 233
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Identification of Tight formations ( not fractured)
DETERMINATION OF THE WOC : OVERLAY TECHNIQUE COMPARISON of Rt and Rxo logs – WATER ZONE :
Rt Rw = Rxo Rmf
LogRt − log Rxo = log Rw − LogRmf = Cons tan t
• Sw = 1 => Ratio Rw/Rmf = Rt/Rxo = Constant • Rt and Rxo are parallel and Rt can therefore be overlaid on Rxo over a significative interval
HYDROCARBON ZONE :
• Quick approximate estimation of Sw with 5/8 ruler −8 Rt Rw Sw 15 Rw ( )= = Sw 5 Rxo Rmf Sw Rmf
Rt Rw Sxo n ( ) = Rxo Rmf Sw
LogRt − log Rxo = log Rw − LogRmf − 8 / 5 log Sw 8 S [−Lo 5
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• Rt on the right of Rxo after overlay of Rt on Rxo in the water zone
QUICKLOOK INTERPRETATION : WOC and Sw Identification of the WOC using the quicklook overlay technique and Estimation of Sw with the Sw ruler exponent 5/8 RMLL ~ Rxo
RIND ~ RT 100 on shifted Rt
Sw~10%
Read Sw at intersection with Rxo : Sw ~ 50 %
2
1
5
20
10
50
100
Place « 100 » on shifted Rt
Hydrocarbon Zone
2
1
5
20
10
50
100
Rt Shifted to overlay Rxo in water zone
Water Zone
Sw Ruler exponent 1
2
1
5
20
10
22
11
50
55
100
10 10
20 20
50 50
100 100
Sw Ruler exponent 5/8
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WOC
QUICKLOOK INTERPRETATION : WOC and Sw Identification of the WOC using the quicklook overlay technique and Estimation of Sw with the Sw Ruler Exponent 5/8 Construction of the Sw ruler exponent 5/8
Step 2 : L = length * 1.6 ( 1.6 =8/5)
length
Step 1 : Sw Ruler exponent 1
2
1
5
2
1
20
10
5
50
100
20
10
50
100
Sw Ruler exponent 5/8 Example
1 2
10 20 50 10
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5
Step 3 : Graduation of the stretched scale
DETERMINATION OF HC TYPE, LITHOLOGY, POROSITY •
VERIFICATION OF D-N SCALES FOR MATRIX COMPATIBILITY (Limestone or Sandstone)
•
CLEAN WATER ZONE LITHOLOGY : Respective position of Density-Neutron curves ; confirmation with PEF, if available and valid. POROSITY : Reading on the Neutron scale of the value corresponding to the middle of the D-N separation
–
LITHOLOGY : (assumption) similar to lithology in water zone; Crosscheck with PEF
–
HYDROCARBON : Comparison N - D separation with DN separation observed in water zone => Identification of GOC
–
POROSITY : Reading on the Neutron scale of the value corresponding to the middle in OIL zone or to the quarter on the density side for GAS zone of the D-N separation
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CLEAN HYDROCARBON ZONE
•
QUICKLOOK LITHOLOGY AND POROSITY DENSITY – NEUTRON COMPATIBLE SCALES D-N Limestone compatible scales
D-N Sandstone compatible scales
D-N Sandstone Semi-Compatible scales (Algeria)
Resistivities LLD-MSFL
Neutron recorded in Limestone Matrix
Neutron recorded in Sandstone Matrix
Neutron recorded in Limestone Matrix
Rt - Rxo
GR-CALI SP
N_LS = 0 D = 2.70
SP_1 -100
MV
0
BS_1 12
IN
GR_1 0
GAPI
22
DEPTH1.95
100
FEET
1.95
CALI_1 12
IN
RHOB_1 G/C3
2.95
N_SS = 0 D = 2.65 1.90
2.95 1.9
NPHI_1 22
0.45
V/V
RHOB_1 G/C3
N_LS = 0 D = 2.60
2.90 1.85
RHOB_1
2.9 1.85
G/C3
NPHI_SS_1 -0.15 0.45
V/V
2.85
LLD_1
2.85 0.2
NPHI_1 -0.15 0.45
V/V
OHMM
2000
MSFL_1 -0.15 0.2
OHMM
2000
6200
SS
OIL
LLD
MSFL
RHOB NPHI
RHOB
RHOB NPHI
NPHI
W
WOC
Overlay D-N in Sandstone with Water or Oil
Quicklook Porosity : 25-27 % (Middle of the separation)
Quicklook Porosity : Quicklook Porosity : 25-27 % 25-27 % after adding 4% (Middle of the separation) to apparent Porosity
MATRIX = LIME Geosciences – Reservoir Engineering
Overlay D-N in Sandstone with Water or Oil RHOB Shifted 2 divisions
2 to 3 divisions Separation in Sandstone
MATRIX = SAND
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Quicklook Evaluation In Water and Oil zone only
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6250
GR-D-N-S TOOL RESPONSE GAMMA RAY - DENSITY NEUTRON – SONIC TOOL RESPONSE in most common geological formations Density-Neutron scales are Limestone compatible NPHI
RHOB GR
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DT
QUICK LOOK METHOD ON LOG EXAMPLE DRHO_1
MNOR_1 20
OHMM
0
-0.75
0
1.95
OHMM
SP_1 -50
LLD_1
MV
50
GR_1 0
GAPI
0.2
METRES
0.2
IN
OHMM
OHMM
2000 0.45
0.25
0.2
OHMM
V/V
Example of logs showing clearly the fluid contatcs
2.95
-0.15
DT_1 2000 136
MSFL_1 16
G/CC
NPHI_1
LLS_1
DEPTH 100
CALI_1 6
G/CC
RHOB_1
MINV_1 20
US/F
16
DT_1 2000 140
US/F
40
2313.0
2325
NPHI
DT
2350
Resistivities
2375
MSFL
2390.0
Geosciences – Reservoir Engineering
LLD
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Density-Neutron-Sonic
CROSS-PLOTS
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CROSS-PLOTS TECHNIQUES
CROSS-PLOT TECHNIQUE CROSS PLOT TECHNIQUE The cross plot technique is a way to represent the log responses in a two-dimensional space, in which the depth is generally (but not necessarily) lost. Each axis of the diagrams used may be a standard log parameter (Neutron, Density, Sonic Pef...), or a combination of two log parameters (Th/K, M,N,P, pmaa, Atmaa...). A third and also a forth dimension may be added (Z-plot), as a projection of the data on the two dimensional space, by using a code for these parameters, for example a color or an index of GR, instead of simply a point. The most common diagrams used are lithology-porosity cross plots, which enable the determination of the lithology and the porosity of the formations. But other parameters may be used to help determinate the characteristics of the formation water (Rw...), of the shales, or to recognize the presence of particular types of minerals. LTHOLOGY - POROSITY ESTIMATION Clean water bearing formations Theoretical lithology-porosity tool responses are plotted on the conventional lithology-porosity diagrams for standard clean water bearing formations (sandstone, limestone, dolomite), or for certain minerals contained in or which form typical formations, which are commonly encountered during the drilling of sedimentary formations.
In a single matrix, clean and water bearing formation, one cross-plot is usually sufficient (Neutron - Density). In complex lithologies, more than two tools are necessary to achieve the interpretation and more than one of these-cross plots are used. The Pef parameter, which is independant of fluids, and spectral Gamma Ray parameters (Potassium, Thorium and Uranium) are a great help in matrix determination. • The axes of the M-N, M-P or N-P plots are combinations of two standard log parameters. These parameters are quite independant from the porosity value : all points corresponding to formations with the same matrix are located on one point only.
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• The main cross plots used combine the values of two logs (Neutron-Density, Neutron-Sonic, Sonic-Density), and enable the determination of the matrix and the porosity of the corresponding formations.
DENSITY-NEUTRON CROSS-PLOT Example of D-N crossplot in Shaly-Sand sequence
0.4
0
2.00 2870
0.35
2.10
FDC*-CNL* ρf = 1.0
0 621 734 0
0.45 2650 1.90 2710 0.43
2.00
RHOB
0.450
0.400
0.350
0.300
0.250
0.200
0.150
0.100
0.050
0.000
-0.050
Filter:
1.90
2.10
WIRE_1.RHOB_1 (G/CM3)
0.3
2.20
2.20 0.25
2.30
2.30
0.2
2.40
2.40
0.15 0.1
2.50
2.50
0.05
2.60
2.60
0
2.70
2.70
2.80
2.80
2.90
2.90
0.450
0.400
0.350
0.300
0.250
0.200
0.150
0.100
0.000
0.050
3.00 -0.050
3.00
WIRE_1.NPHI_1 (V/V) 0
150 Color: WIRE_1.SGR_1
F
ti
1.90
0 341 341 0
0
0
0.450
0.400
0.350
0.300
0.250
0.200
0.150
0.100
0.050
0.000
-0.050
Example of D-N crossplot in carbonate serie
2.65 1.90 0.45 2.71 0.43 0.4
2.00
2.00 2.87
0.35
2.10
2.10 2.20
0.25
2.30
0.2
2.40
2.40
0.15 0.1
2.50
2.50
0.05
2.60
2.60
0
0.450
0.400
0.350
0.300
0.250
3.00 0.200
2.90
3.00 0.150
2.80
2.90
0.100
2.70
2.80
0.050
2.70
WIRE_1.NPHI_1 (V/V) 0
120 Color: Maximum of WIRE_1.GR_1
unctions:
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2.30
-0.050
NPHI
2.20
0.000
WIRE_1.RHOB_1 (G/C3)
0.3
LITHOLOGY AND POROSITY : CROSS-PLOTS MAIN CROSS PLOTS with GAS and SHALE EFFECTS
DT
AS
RHOB
RHOB
C
SH
GAS
G
C
GA S AL E
C
A
SH
A
B
SH
B
AL E
A
AL E
B
NPHI
Point A
Water bearing limestone, slightly dolomitic, with Φ = 15% (looks like a sandstone with Φ = 10% on cross plot SONIC - DENSITY)
Point B
Water bearing dolomitic sandstone, wtih Φ = 8% (looks like a limestone with Φ = 10% on cross plot SONIC - DENSITY)
Point C
Gas bearing sandstone with Φ = 30% (looks like a water bearing sandstone with Φ = 35% on cross plot SONIC – DENSITY)
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DT
NPHI
QUANTITATIVE LOG INTERPRETATION
QUANTITATIVE LOG
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INTERPRETATION
QUANTITATIVE INTERPRETATION STEPS 1) COMPUTATION of Rt and Rxo • Environmental Corrections Deep Resistivities Shallow Resistivities
Borehole effect (mud) Mud cake effect
• Computation Rlog = J Di .Rxo + (1 – J Di ).Rt 3 equations ÅÆ
3 tools
2) COMPUTATION of Rw • SP • Clean Water bearing Formations • Quick-Look Rw / Rmf = Rt / Rxo • Archie Rw = Rt / F 3) Vsh SHALINESS COMPUTATION Shale indicators Vshi
• Reservoir determination • Comparison of Rt and Rxo • Comparison of Neutron and Density logs 5) QUANTITATIVE INTERPRETATION • n equations with n unknowns (Knowledge of matrix and hydrocarbon) • n equations with p unknowns (n > p) (Knowledge of mineral model) 6) COHERENCE CONTROL of DATA and RESULTS Geosciences – Reservoir Engineering
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4) QUALITATIVE INTERPRETATION
QUANTITATIVE INTERPRETATION Determination of Rt, Rxo, Di
DIL *Dual InductionSFL *Spherically Focused Resistivity Log
Dual Laterolog-Rxo Device
DIL - SFL
(
)
R = J ∗ R + 1− J ∗R cor Di Di xo t
Induction :
(
247
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)
= G ∗C + 1−G ∗C C cor Di xo Di t Well Log Interpretation – PDVSA – January 2007
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LLD – LLS - Rxo
Resistivity :
(Examples)
RW DETERMINATION Rw Determination - Spontaneous Potential
⎛ Rmfe ⎞ SSP = −K log ⎜ ⎟ ⎝ Rwe ⎠ K = 61+.133 ∗ T ( °F ) K = 65+.240 ∗ T ( °C )
- Resistivity Ratio method , in a clean water bearing zone ( Sw =1 )
Rw Rt Rt = ⇒ Rw = Rmf ∗ Rmf Rxo Rxo
Rw a = Rt ∗
Φm a
- Other method : Pickett plot
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- Archie Formula in a clean water bearing zone (Sw = 1)
DETERMINATION OF Rw FROM SP • Check validity of mudfiltrate resistivity measurement in log header • Identify shale layers • Draw SP shale baseline • Estimate maximum SP deflection in front of each reservoir : SSP • Estimate Reservoir temperature ( Chart Gen-6 ) • Determine Rmf at reservoir temperature (Chart Gen-9) • Determine Rmfe/Rwe ratio from SSP at reservoir temperature (Chart SP-1) • Determine Rmfe from Rmf at reservoir T° (Compute from Rmf or use chart SP-2) • Determine Rw (Chart SP-2)
SSP = - K log
Rmfe Rwe
K = 61+.133∗ T (°F) K = 65+.240∗T (°C)
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• Determine Rwe (Chart SP-1)
RW DETERMINATION USING Pickett PLOT • Representation of Resistivity Rt versus Porosity in logarithmic scale • Iso-Saturation Sw lines aRw = 0.1710 DETERMIN.PHIE_1 vs. CORENV.RT_1 Crossplot
1
Sw = 1
0 384 406 22
1
0
0
10000
1000
100
10
1
0.1
Well: DLG1 DEPTH 2490 - 2552 metres Filter:
a Rw × φ m Sw n log(Rt ) = log(aRw) - mlog(Φ ) Rt =
Sw = 1 & Porosity = 1 =>
o R
aRw= 0.1710
e lin ; =
0.1
m =2 Rw = 0.211 Ohmm
CORENV.RT_1 (OHMM) 0
0.01 10000
1000
1
0.1
0.01
100
0.1
10
0 1
a = .81
150 Color: Maximum of WIRE_1.SGR_1
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w
% 0 1 = % w 0 S 2 = 2 % w = 0 S 4 m ; = 2 w 7 % 0 S 0 1 6 7 = % 0.1 0 w 8 = S = w w R S a* ; % 0
S
DETERMIN.PHIE_1 (V/V)
Rt = aRw
ESTIMATION OF SHALE CONTENT : VSH Estimation of VSH
(
VSH = Min VSH
- Gamma Ray
i
)
- Neutron
GR VSH = GR GR
- GR max
- GR
Φ N VSH = N Φ Nsh
min
min
- Spontaneous Potential
- Density- Neutron
Density X’
PSP VSH = 1 − SP SSP
VSH
DN
=
L
X' L X' A
A
- Resistivities
- Density- Sonic
Rsh VSH = Rt Rt
Density
Rsh VSH = Rxo Rxo
VSH
DS
=
X' L X' A
X’ L A
Sonic
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Neutron
ESTIMATION OF SHALE CONTENT : VSH-GR GRmax
Estimation of VSH with GR
GR log
GR min
GR
GR - GR min
GRmax - GRmin
GR VSH = GR GR Geosciences – Reservoir Engineering
- GR max
- GR
min
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Anomaly of radioactivity
ESTIMATION OF SHALE CONTENT : VSH-SP
Estimation of VSH with SP SP log SSP
Static SP
PSP
Pseudo SP
SP Shale Baseline
VSH
SP
=1−α =1−
PSP SSP - PSP = SSP SSP 253
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SSP - PSP
ESTIMATION OF SHALE CONTENT : VSH-DN FLUID POINT WIRE_1.RHOB_1 vs. WIRE_1.NPHI_1 Crossplot RHOmf, PHINmf
1.00 CCUT COAL
1.20
VSH_DN IN WATER ZONE
1.78
Estimation of VSH-DN Using Density-Neutron ( In a water zone )
ISO-Shale 1.78 LINE CONTENT (VSH = 50%)
L
X'
0.45 2650 0.432710 0.4 2870
1.98
1.98
0.35
2.37
0.15 0.1
2.56
VSH_dn = X'L / X' A
A
0.3 0.25 0.2
2.17
2.17
SHALE POINT 2.37 RHOsh, PHINsh 2.56 VSH = 100%
SH
0.05 0 MA
1.000
0.905
0.809
0.714
0.618
0.523
0.427
0.332
0.236
0.141
-0.050
2.75
VSH = 75%
VSH = 50%
VSH = 25% 2.95
DENSITY-NEUTRON Crossplot
1.59
0.045
WIRE_1.RHOB_1 (G/C3)
1.39
1.59
2.75
0
1.00
1.39
MATRIX POINT RHOma, PHINma VSH = 0%
0 997 997 0
2.95
WIRE_1.NPHI_1 (V/V) 0
150 Color: WIRE_1.GR_1
Functions: mm_cp1c mm_cp1c_p
: Por. & Lith determ. from RHOB & CNL, fresh mud. : Pmaa from RHOB & CNL logs for fresh muds
Example 1 Example 2 P = 10 - 6 * Salinity (ppm)…………..Salinity = 10 kppm……….Salinity = 200 kppm RHOmf = 1 + 0.7 P…………………..P = ,01…………………….P = ,2 PHINmf * (1 - P)……………………...RHOmf = 1,007…………..RHOmf = 1,14 PHINmf = 0,996 PHINmf = 0,91 Geosciences – Reservoir Engineering
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1.20
0
1.000
0.905
0.809
VSH = 0% 0.714
0.618
0.523
0.427
0.332
0.236
0.141
0.045
-0.050
Well: DLG1 2450 - 2602 METRES Filter:
ESTIMATION OF SHALE CONTENT : VSH-DN WIRE_1.RHOB_1 vs. WIRE_1.NPHI_1 Crossplot
0.00
FLUID POINT RHOhc, PHINhc
0.30 0.59
0
0 734 734 0
0
1.000
0.905
0.809
0.714
0.618
0.523
0.427
0.332
0.236
0.141
0.045
-0.050
Well: DLG1 Range: Intervals Filter:
0.00
DENSITY-NEUTRON Crossplot
0.30
DETERMINATION OF VSH
0.59
IN OIL ZONE
0.89
0.89
1.18 CCUT COAL
1.18
1.48
1.48
VSH_dn = X'L / X' A
X'
1.77 0.45 2650 2710 0.43 0.4 2870 0.35
2.06 0.3 0.25
1.000
0.905
0.809
0.714
0.618
0.523
0.236
2.65
SHALE POINT RHOsh, PHINsh
L 0.045
-0.050
2.95
MATRIX POINT RHOma, PHINma
0 MA
0.427
2.65
2.36
SH
0.332
2.36
2.06
A
0.2 0.15 0.1 0.05
2.95
WIRE_1.NPHI_1 (V/V) 0
150 Color: WIRE_1.GR_1
Functions: mm_cp1c mm_cp1c_p
: Por. & Lith determ. from RHOB & CNL, fresh mud. : Pmaa from RHOB & CNL logs for fresh muds
RHOhc = x PHINhc = 2.2 * RHOhc if RHOhc <= 0.25 PHINhc = 0.3 + RHOhc if RHOhc >= 0.25 RHOhc PHINhc
Geosciences – Reservoir Engineering
0.1 0.22
0.2 0.44
0.3 0.6
0.4 0.7
0.5 0.8
0.6 0.9
255
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1.77
0.141
WIRE_1.RHOB_1 (G/C3)
VSH_DN IN OIL ZONE
ESTIMATION OF SHALE CONTENT : VSH-DN WIRE_1.RHOB_1 vs. WIRE_1.NPHI_1 Crossplot
0.00
FLUID POINT RHOhc, PHINhc
0.30
VSH_DN IN GAS ZONE
0.89
0.45 2650 2710 0.43 0.4 2870 0.35
0
DETERMINATION OF VSH_DN
0.59
IN GAS ZONE
2.06
A
0.3 0.25 0.2 0.15 0.1 0.05
2.36 SH
SHALE POINT RHOsh , PHINsh
0 MA
2.65
WIRE_1.NPHI_1 (V/V) 0
150 Color: WIRE_1.GR_1
Functions: mm_cp1c mm_cp1c_p
: Por. & Lith determ. from RHOB & CNL, fresh mud. : Pmaa from RHOB & CNL logs for fresh muds
RHOhc = x PHINhc = 2.2 * RHOhc if RHOhc <= 0.25 PHINhc = 0.3 + RHOhc if RHOhc >= 0.25 RHOhc PHINhc
Geosciences – Reservoir Engineering
0.1 0.22
0.2 0.44
0.3 0.6
0.4 0.7
0.5 0.8
0.6 0.9
256
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1.000
0.905
0.809
0.714
0.618
0.523
0.427
0.332
0.236
2.95 0.141
-0.050
2.95
0.30
1.77
L
2.06
2.65
MATRIX POINT RHOma, PHINma
DENSITY-NEUTRON Crossplot
1.48
VSH_dn = X'L / X' A
1.77
2.36
0.00
1.18
X'
1.48
0 734 734 0
0.89
1.18 CCUT COAL
0.045
WIRE_1.RHOB_1 (G/C3)
0.59
0
1.000
0.905
0.809
0.714
0.618
0.523
0.427
0.332
0.236
0.141
0.045
-0.050
Well: DLG1 Range: Intervals Filter:
ESTIMATION OF EFFECTIVE POROSITY : PHIE WIRE_1.RHOB_1 vs. WIRE_1.NPHI_1 Crossplot FLUID POINT
1.00 CCUT COAL
X'
2.37
0
2.17
A
0.15 0.1
2.56
2.37
SH
SHALE POINT PHIE = 0%
0.05 0 MA
2.56 2.75
1.000
0.905
0.809
0.714
0.618
0.523
0.332
0.236
0.141
0.045
-0.050
L : VSH = 30 %
MATRIX POINT for X' PHIE = 0%
( Case of a water zone )
2870
0.3 0.25 0.2
0.427
WIRE_1.RHOB_1 (G/C3)
0.35
PHIE = PHI(X’) * ( 1 – Vsh )
1.78
ISO-POROSITY LINE through 1.98 Point L
0.45 2650 0.432710 0.4
2.17
Density-Neutron
1.59
X' : X'A = LA / (1-VSH)
1.78
2.95
From VSH_Min and
1.39
1.59
2.75
Estimation of PHIE
1.20
PHI 1.98 (X') = 27 %
MATRIX LINE for X'
DENSITY-NEUTRON Crossplot
1.00
Shaly Water bearing Sandstone
1.39
PHIE = PHI(X') * (1-VSH) = 27 * ( 1- 0.3) = 19 %
0 997 997 0
2.95
WIRE_1.NPHI_1 (V/V)
0
150 Color: WIRE_1.GR_1
Functions: mm_cp1c mm_cp1c_p
: Por. & Lith determ. from RHOB & CNL, fresh mud. : Pmaa from RHOB & CNL logs for fresh muds
257
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1.20
0
1.000
0.905
0.809
0.714
PHIE =100%
0.618
0.523
0.427
0.332
0.236
0.141
0.045
-0.050
Well: DLG1 2450 - 2602 METRES Filter:
HYDROCARBON CORRECTION Φ -Φ Nhc ) ∆Φ = − A × Φ × S × ( Nmf N hr Φ Nmf ∆ρ = −1.07 × Φ × S × (C × ρ − C ×ρ ) b hr mf mf hc hc with ΦShr = 0,3 , P = 0 et ρmf = 1
FDC*-CNL* ρf = 1.0
∆ρb
Φ Nmf = ρ mf (1 − P) Φ Nhc = ρ hc + 0.3, ifρ hc > 0.25 Φ Nhc = 2.2× ρ hc, ifρ hc < 0.25
0,7 0,6 0,5 0,4
∆ΦN
P = Salinity ( kppm ) x 10 – 3
0,3 0,25
0,2
0,15
0,1
ρhc
ρ b = (1 − Φ u )* ρ ma + Φ u (Sxo * ρ mf + Shr * ρ hc ) 0.45 2650 0.432710 0.4
1.98 0.3 0.25
2.37
0.15 0.1
2.56
SH
2.56
0.05 0 MA
1.000
0.905
0.809
0.714
0.618
0.523
0.427
0.332
0.236
2.75
0.141
-0.050
2.95
2.17
0.2
2.37
2.95
WIRE_1.NPHI_1 (V/V) 0
150 Color: WIRE_1.GR_1
Functions:
Geosciences – Reservoir Engineering
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2.17
2.75
1.98
2870
0.35
0.045
WIRE_1.RHOB_
Points in gas zones
ESTIMATION OF Sw Estimation of Sw in clean formation Archie Formula :
Sw = n
aRw φ m Rt
Estimation of Sw in shaly formation
⎡V (1−V2sh ) φ m / 2 ⎤ 1 ⎥ S wn / 2 = ⎢ sh + Rt ⎢ Rsh aRw ⎥ ⎣ ⎦
Geosciences – Reservoir Engineering
259
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Example of Poupon formula ( Indonesia) :
METHODS
DETERMINISTIC APPROACH : - SHALY SAND
DUAL WATER METHOD OPTIMISTIC APPROACH Geosciences – Reservoir Engineering
260
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- COMPLEX LITHOLOGY
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261
Well Log Interpretation – PDVSA – January 2007
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SHALY SAND METHOD (1/2)
Geosciences – Reservoir Engineering
262
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
SHALY SAND METHOD (2/2)
Geosciences – Reservoir Engineering
263
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
COMPLEX LITHOLOGY METHOD (1/2)
Geosciences – Reservoir Engineering
264
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
COMPLEX LITHOLOGY METHOD (2/2)
DUAL WATER MODEL
265
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Well Log Interpretation – PDVSA – January 2007
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PASS 2
PASS 1
DUAL WATER MODEL Ro Rt
SwT = X + (X 2 +
si Rwb > Rw
Rw ) RtΦT 2
Swb = Vshmin
Sw = CYBERLOOK
Geosciences – Reservoir Engineering
si Rwb < Rw
SwT − Swb 1− Swb
Φe = ΦT (1 – Swb)
266
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SwT =
QUANTITATIVE INTERPRETATION : OPTIMISTIC APPROACH GENERAL INVERSION METHOD COMPUTER PROCESSED RESULTS
(GLOBAL Example) PROGRAMS : - GLOBAL - ELAN
Geosciences – Reservoir Engineering
267
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- MULTIMIN
QUANTITATIVE INTERPRETATION : OPTIMISTIC APPROACH GENERAL INVERSION METHOD
Geosciences – Reservoir Engineering
268
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Reconstructed Logs (GLOBAL Example)
CHARTS
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269
Well Log Interpretation – PDVSA – January 2007
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APPENDIX MAIN CHARTS FOR LOG INTERPRETATION
ESTIMATION OF FORMATION TEMPERATURE
Geosciences – Reservoir Engineering
270
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Gen-6
Geosciences – Reservoir Engineering
271
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
CONVERSIONS (1/2)
Geosciences – Reservoir Engineering
272
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
CONVERSIONS (2/2)
Water Resistivity and Water Salinity
Geosciences – Reservoir Engineering
273
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Gen-9
Water Resistivity and Water Salinity
Geosciences – Reservoir Engineering
274
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Gen-9
Rwe from SSP SP-1
(Schlumberger) Geosciences – Reservoir Engineering
275
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Rwe
Rwe from SSP
(Schlumberger)
Geosciences – Reservoir Engineering
276
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
SP-1
Rw versus Rwe ( SP-2) ( DegF) SP-2
(Schlumberger)
Geosciences – Reservoir Engineering
277
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
DEGF
Rw versus Rwe ( SP-2m) ( DegC) SP-2m
(Schlumberger)
Geosciences – Reservoir Engineering
278
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
DEGC
Main Logging Tool Response in Sedimentary Minerals
Geosciences – Reservoir Engineering
279
Well Log Interpretation – PDVSA – January 2007
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MAIN LOGGING TOOL RESPONSE in Sedimentary Minerals (1/2)
Main Logging Tool Response in Sedimentary Minerals
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280
Well Log Interpretation – PDVSA – January 2007
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MAIN LOGGING TOOL RESPONSE in Sedimentary Minerals (2/2)
Porosity from DENSITY LOG ρfl = 1.0
Determination of Porosity from Density Log
Sandstone line Porosity = 14 %
(Schlumberger)
Example 2 :
Example 1 :
Sandstone formation
Limestone formation ρb = 2.31 g/cm3 in limestone lithology ρma = 2.71 g/cm3 ( Calcite )
ρb = 2.42 g/cm3 in limestone lithology ρma = 2.65 g/cm3( Quartz ) ρf = 1.0 g/cm3 ( Fresh mud)
ρf = 1.1 g/cm3 ( Salt mud)
Formation porosity = 14 p.u
Formation porosity = 25 p.u
281
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ρb = 2.42 g/cc
ρma = 2.65 g/cc
Porosity from NEUTRON Log
TNPH 250 kppm
TNPH 0 kppm
Determination of Porosity from Neutron Log
NPHI
Porosity = 24 p.u.
TNPH 0 kppm
Porosity = 22.5 p.u.
Example 1 :
NPHI
Sandstone formation with a formation salinity of 20 kppm NPHIcor = 18 p.u. in limestone lithology True porosity = 22.5 p.u
Example 2 : Sandstone formation with a formation salinity of 250 kppm TNPHcor = 18 p.u. in limestone lithology True porosity = 24.0 p.u (Schlumberger) Geosciences – Reservoir Engineering
282
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TNPH 250 kppm
Porosity from SONIC Log PHIS Wyllie = ( DT - Dtma ) / ( DTfl - Dtma ) x ( 1/Bcp )
PHIS RH* = K * ( DT - Dtma ) / DT
Determination of Porosity from Sonic Log
(Schlumberger Chart Por-3)
Sandstones Limestones Dolomites
Sonic Velocity ft/s 18000 - 19500 21000 - 23000 23000 - 26000
∆ Tma µs/ft 55,6 51,3 47,6 43,5 43,5 38,5
Sonic Velocity m/s 5486 - 5944 6401 - 7010 7010 - 7925
∆ Tma µs/m 182,3 - 168,2 156,2 - 142,6 142,6 - 126,2
20000 14925
50,0 67,0
6096 4549
164,0 219,8
Example : DT = 76 µs/ft ( 249 µs/m ) SVma = 18000 ft/s ( 5486 m/s ) Sandstone Thus Porosity = 15 % by time average or 18% by field observation method) * RH = Raymer-Hunt
Anhydrite Salt Geosciences – Reservoir Engineering
283
Well Log Interpretation – PDVSA – January 2007
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Bcp
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284
Well Log Interpretation – PDVSA – January 2007
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Notes
SPECTRAL GR NGS - CHART Th-K Th-K CP-19
K
(Schlumberger)
285
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Th
SPECTRAL GR NGS - CHART PEF-K, PEF-Th/K PEF-K CP-18 PEF
K
PEF-Th/K
PEF
Th/K
Geosciences – Reservoir Engineering
286
(Schlumberger)
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
CP-18
Density-Neutron Crossplot ( NPHI) 1/2 RHOB-NPHI CP-1c Rhofl = 1.0
NPHI
287
Geosciences – Reservoir Engineering
(Schlumberger)
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
RHOB
Density-Neutron Crossplot ( NPHI) 2/2 RHOB-NPHI CP-1d Rhofl = 1.1
NPHI
Geosciences – Reservoir Engineering
288
(Schlumberger)
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
RHOB
Density-Neutron Crossplot ( TNPH) 1/2 RHOB-TNPH CP-1e Rhofl = 1.0
TNPH
289
Geosciences – Reservoir Engineering
(Schlumberger)
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
RHOB
Density-Neutron Crossplot ( TNPH) 2/2 RHOB-TNPH CP-1f Rhofl = 1.19
TNPH
Geosciences – Reservoir Engineering
290
(Schlumberger)
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
RHOB
Sonic-Neutron Crossplot 1/2 DT-NPHI CP-2b
NPHI (Schlumberger)
291
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
DT
Sonic-Neutron Crossplot 2/2 DT-TNPH CP-2c
TNPH (Schlumberger)
Geosciences – Reservoir Engineering
292
Well Log Interpretation – PDVSA – January 2007
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DT
Density-Sonic Crossplot RHOB-DT CP-7
DT (Schlumberger)
Geosciences – Reservoir Engineering
293
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Rhofl = 1.0
RHOB
M versus N M-N
(Schlumberger)
Geosciences – Reservoir Engineering
294
Well Log Interpretation – PDVSA – January 2007
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CP-8
PEF versus RHOB PEF-RHOB CP-16
RHOB (Schlumberger)
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295
Well Log Interpretation – PDVSA – January 2007
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Rhofl = 1.0
PEF
PEF versus RHOB PEF-RHOB CP-17
RHOB (Schlumberger)
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296
Well Log Interpretation – PDVSA – January 2007
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Rhofl = 1.1
PEF
(Schlumberger)
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
GR - ENVIRONMENTAL CORRECTION
(Schlumberger)
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
GR - ENVIRONMENTAL CORRECTION
(Schlumberger)
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
NEUTRON - ENVIRONMENTAL CORRECTION
(Schlumberger) Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
NEUTRON - ENVIRONMENTAL CORRECTION
(Schlumberger)
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
NEUTRON - ENVIRONMENTAL CORRECTION
(Schlumberger)
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
NEUTRON - ENVIRONMENTAL CORRECTION
(Schlumberger)
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
INDUCTION - ENVIRONMENTAL CORRECTION
INDUCTION - ENVIRONMENTAL CORRECTION Dual Induction
(Schlumberger) Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Rcor-4a
DLT - ENVIRONMENTAL CORRECTION DLT ( D/E) Centered
LLD
Rcor-2b
(Schlumberger)
305
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Well Log Interpretation – PDVSA – January 2007
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LLS
DLT - ENVIRONMENTAL CORRECTION DLT ( D/E) Eccentered LLD
Rcor-2c
(Schlumberger)
Geosciences – Reservoir Engineering
306
Well Log Interpretation – PDVSA – January 2007
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LLS
MLL – PL - ENVIRONMENTAL CORRECTION MLL - PL Rxo-2 MLL
(Schlumberger)
307
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Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
PL
MSFL - ENVIRONMENTAL CORRECTION MLL - PL Rxo-3 MSFL Version III
(Schlumberger)
Geosciences – Reservoir Engineering
308
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
MSFL Slim Hole
Chart Rt-Rxo-Di for LLD-LLS-Rxo ( Rint – 9b) DLL-Rxo Rint-9b
LLD/LLS
309
Geosciences – Reservoir Engineering
(Schlumberger)
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
LLD/Rxo
Chart Rt-Rxo-Di for DIL-SFL ( Rint – 9b) DIL-SFL Rint-2c
ILM/ILD
Geosciences – Reservoir Engineering
310
(Schlumberger)
Well Log Interpretation – PDVSA – January 2007
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SFL/ILD
FORMULA : Density-Neutron-Sonic - 1/4 Density, Neutron , Sonic Tool responses Clean Water bearing formations
U = Pe * ρ el = Pe * (
ρ b = (1 − Φ u )ρ ma + Φ u ρ f
ρ b + 0.1883 ) 1.0704
U = Volumetric Photoelectric Absorption Factor ( Barn/cm3)
Φ N = (1 − Φ u )Φ Nma + Φ u Φ Nfl
Mud Filtrate Parameters
∆t p = (1 − Φu) ⋅ ∆t ma + Φu ⋅ ∆t f
P = Salinity ( kppm ) x 10 – 3
U = (1 − Φ u )U ma + Φ u U f .
ρ mf = 1 + 0.7 P
Φ Nmf = ρ mf (1 − P)
Clean Hydrocarbon bearing formations
ρ b = (1 − Φ u )ρ ma + Φ u [Sxo * ρ mf + (1 − Sxo) * ρ hc ]
Φ N = (1 − Φ u )Φ Nma + Φ u [Sxo * Φ Nmf + (1 − Sxo) * Φ Nhc ] − ∆Φ NExc
ρ b = (1 − Φ u − Vsh )ρ ma + Vsh * ρ sh + Φ u ρ f Φ N = (1 − Φ u − Vsh )Φ Nma + Vsh * Φ Nsh + Φ u Φ Nfl ∆t p = (1 − Φu − Vsh ) ⋅ ∆t ma + Vsh * ∆t sh + Φu ⋅ ∆t f Shaly Hydrocarbon bearing formations
ρ b = (1 − Φ u − Vsh )ρ ma + Vsh * ρ sh + Φ u [Sxo * ρ mf + (1 − Sxo) * ρ hc ] Φ N = (1 − Φ u − Vsh )Φ Nma + Vsh * Φ Nsh + Φ u [Sxo * Φ Nmf + (1 − Sxo) * Φ Nhc ] − ∆Φ NExc 311
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Shaly Water bearing formations
FORMULA: Porosities – HC Correction – 2/4 POROSITIES Porosity from Density, Neutron, Sonic in clean Water bearing formations :
Φ u (D) =
ρ ma − ρ b ρ ma − ρ f
Φ u(N) =
Φ N − Φ Nma Φ Nfl − Φ Nma
Φ u(S) =
Φ
+Φ 2
ma D
Φu =
[ ma = Limestone matrix ( ρma = 2.71 ,
( Raymer-Hunt-Gartner )
Gas bearing formations
Water or Oil bearing formations
Φu =
2
( Wyllie )
Apparent Density-Neutron Porosity in clean formations : ma N
(1 − Φu ) + Φ u 1 = ∆t ∆t ma ∆t f
∆t − ∆t ma 1 × ∆t f − ∆t ma Bcp
φNma = 0)
ma 3Φ ma D + ΦN 4
or
Φu =
ma 7 Φ ma D + 2Φ N 9
]
HYDROCARBON CORRECTION Hydrocarbon correction on Density and Neutron
Mud Filtrate Parameters P = Salinity ( kppm ) x 10 – 3
ρ b_cor_hc = ρ b - ∆ρ b
ρ mf = 1 + 0.7 P
Φ N_cor_hc = Φ N − ∆Φ N
Φ - Φ Nhc ∆Φ N = − A × Φ × Shr × ( Nmf ) Φ Nmf
Hydrocarbon Parameters
Φ Nhc = 2.2× ρ hc, ifρ hc < 0.25 and Φ Nhc = ρ hc + 0.3, ifρ hc ≥ 0.25
A = f ( excavation factor) 1 < A < 1.3
or
312
[
Φ Nhc = 9ρ hc 0.15 + 0.2(0.9 − ρ hc ) 2
C hc = 1.15
]
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Φ Nmf = ρ mf (1 − P)
∆ρ = −1.07 × Φ × Shr × (C × ρ − C ×ρ ) b mf mf hc hc
Geosciences – Reservoir Engineering
C mf = 1.11 − 0.15P
FORMULA : VSH – Shale Correction – 3/4
(
VSH = Min VSH
Estimation of VSH : GR
VSH = GR GR VSH
- Spontaneous Potential
SP
VSH
- Resistivities
=1−
Rt
=b
max
- GR
min
i
)
( Deterministic Approach )
min
PSP SSP
Rsh Rt
or
VSH
Rt
=b
Rsh (Rlim - Rt ) Rt (Rlim - Rsh)
Density X ’
L A
Φ N VSH = N Φ Nsh
- Neutron
- Density- Neutron
VSH
- Density- Sonic
VSH
DN DS
=
X' L X' A
=
X' L X' A
Neutr on
or
or
Φ − RΦ Φ N D Dmin with R= DN Φ − RΦ Φ Nsh Dsh Nmin Φ −Φ S D VSH = DS Φ −Φ Ssh Dsh =
VSH
Shale Correction on D- N- S Φ Ncor = Φ N − VshΦ Nsh
ΦScor = ΦS − VshΦSsh
Φ Dcor = Φ D − VshΦ Dsh
Apparent Density-Neutron Porosity in shaly formations :
Φu =
ma 7 Φ ma Dcor + 2Φ Ncor 9
ma = Limestone matrix ( ρma = 2.71 ,
313
Geosciences – Reservoir Engineering
φNma = 0)
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
- Gamma Ray
- GR
FORMULA: Water Saturations - 4/4 WATER SATURATION EQUATIONS Archie Formula
aR Sw = n m w φ Rt
FR aR Rt = n w = m wn Sw φ Sw
or
Shaly formation (Laminated Shales)
or
F=
a
φm
1 Vsh (1 − Vsh )φ m n = + Sw Rt Rsh aRw
Shaly formation (Dispersed Shales) Simandoux Formula
φm n 1 Vsh = Sw + Sw Rt Rsh aRw
Hossin Formula
1 Vsh2 φ m n = + Sw Rt Rsh aRw
Poupon Formula
⎡V (1−V2sh ) φ m / 2 ⎤ 1 ⎥ S wn / 2 = ⎢ sh + Rt ⎢ Rsh aRw ⎥ ⎣ ⎦
Juhasz Formula
1 φTmSnwT = Rt aR w
Geosciences – Reservoir Engineering
1 φm n = Sw Rt aRw
⎡ BQ vn ⎤ ⎥ ⎢1 + ⎣ SwT ⎦
V 1 φm / 2 n / 2 = sh + Sw Rt R sh aR w
Doll Formula
Simandoux-De Witte
with
314
or
V 1 φm n = sh Sw + Sw R t R sh aR w
V ⎡ Cw φ m / 2 ⎤ n / 2 (1− sh ) 2 + Ct = ⎢ Csh Vsh ⎥ Sw a ⎦⎥ ⎣⎢
Qvn =
V sh φ sh
φT
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Clean formation :
Bibliography 1/3 Selected References on Well Logging GENERAL DOCUMENTS (Tools - Interpretation ) Chambre Syndicale de la Recherche et de la Production du Pétrole et du Gaz Naturel – Comité des Techniciens - Editions Technip. Interprétation rapide sur chantier des diagraphies différées en trou ouvert (1975). Chambre Syndicale de la Recherche et de la Production du Pétrole et du Gaz Naturel – Editions Technip. Contrôle des sondages : Diagraphies instantanées - Catalogue de cas types (1979). Chambre Syndicale de la Recherche et de la Production du Pétrole et du Gaz Naturel – Editions Technip. Wireline Logging Tool Catalog (1986). BASSIOUNI Z. (1994) Theory, Measurement, and Interpretation of Well Logs - SPE Textbook Series Vol. 4 BATEMAN R.M. (1985) Log Quality Control - Reidel Open Hole Log Analysis and Formation Evaluation - Reidel Cased Hole Log Analysis and Reservoir Performance Monitoring - Reidel
BOYER S. (1998) Well Logging / Diagraphies Différées (CD - ROM pour Macintosh/PC) – IFP School, Editions Technip CHAPELLIER D. (1987) - Diagraphies appliquées à l'Hydrologie - Lavoisier Tec & Doc DESBRANDES R. Théorie et interprétation des diagraphies (1968) - Publication de l'Institut Français du Pétrole - Editions Technip. * Les Diagraphies dans les sondages (1982) - Editions Technip Paris.
315
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
BOYER S., ANDRIEUX P. et MICHAUT B. (1993) Principes physiques de fonctionnement des outils de diagraphies - Revue Géologue de l'UFG N° 99
Bibliography 2/3 Selected References on Well Logging DEWAN J. (1983) - Essentials of Modern Open Hole Log Interpretation DOVETON J.H. (1986) - Log Analysis of subsurface Geology (Concepts and Computer Methods) - John Wiley & Sons HEARST and NELSON (1985) - Well Logging for Petrophysical Properties - Mc Graw, Hill Book Company HILCHIE D.W. (1979) Old Electrical Log Interpretation (1979) Advanced Well Logging Interpretation (2nd Edition) (1989) HOSSIN A. (1983) - Manuel de Diagraphies Différées : Appareils et Interprétation – Cours ENSPM (not published) HURST A., LOVELL M.A. and MORTON A.C. (1990) Geological Applications of Wireline Logs – Geological Society KERZNER M. (1986) - Image Processing Well Log Analysis - IHRDC MARI J.L., COPPENS F., GAVIN Ph. et WICQUART E. (1992) Traitement des Diagraphies acoustiques (Full Waveform Data Processing, 1994) - Editions Technip
SERRA O. (1979 et 1985) - Diagraphies Différées - Bases de l'interprétation – Bulletin des Centres de Recherche Exploration Production Elf Aquitaine - Pau. * Volume 1 : Acquisition des données (1979). * Volume 2 : Interprétation (1985). THEYS Ph. (1991) - Log Data Acquisition and Quality Control - Editions Techn
Geosciences – Reservoir Engineering
316
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
SCHLUMBERGER (1989) - Schlumberger Educational Services. Log Interpretation Principles /Applications Cased Hole Log Interpretation Principles /Applications
Bibliography 3/3 Selected References on Well Logging WELL LOGGING and SEDIMENTOLOGY SERRA O. (1979 et 1985) - Diagraphies Différées - Bases de l'interprétation – Bulletin des Centres de Recherche Exploration Production Elf Aquitaine - Pau. * Volume 2 : Interprétation (1985).
WELL LOGGING : Acoustics and seismics BOYER S. et MARI J.L. (1994) - Sismique et Diagraphies - Editions Technip. MARI J.L. et COPPENS F. (1989) - La sismique de puits (Seismic Well Surveying, 1991) - Editions Technip
JOURNALS The Log Analyst (Revue de la SPWLA) SPWLA Transactions & SAID Transactions Technical Review (Schlumberger)
SPE Monograph Series Vol. 9 : Well Logging Tome 1 (JORDENJ.R. and CAMPBELL F.L.) Vol 10 : Well Logging Tome 2 (JORDENJ.R. and CAMPBELL F.L.) Vol. 14 : Production Logging (HILCHIEA.D.) SPWLA Reprint Volume Pulsed Neutron (1976), Gamma Ray, Neutron, Density (1978), Acoustic Logging (1978) Geothermal Interpretation Handbook (1982), Shaly Sand (1983) ...
Geosciences – Reservoir Engineering
317
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
SPE Reprint Series Open Hole Well Logging N° 21 (1986) & Production Logging N° 27 Vol 1 (1989)
Geosciences – Reservoir Engineering
318
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Notes
LBF
1000
PEF_1 0
B/E
20
DRHO_1 -0.35
BS_1 IN
14
GAPI
100
1.95
DEPTH
GR_1 0
METRES
4
G/C3
IDPH_1 0.2
CALI_1 4
G/C3
0.15
RHOB_1
OHMM
NPHI_1 2000 0.45
V/V
IMPH_1
IN
14
0.2
OHMM
2.95
-0.15
DT_1 2000 140
US/F
1000
1000
100
100
10
10
1
1
40
1510.2
1515
CORE_SH.K_CORE_1 (MD)
1520
1535
1540
WELL LOG INTERPRETATION
1550
0.1
0.01
0.01
1560
0.050
0.000
1555
0.1
0.100
1545
0.200
1530
0.150
1525
CORE_SH.PHI_CORE_1 (V/V) 1565
0
9 Color: Maximum of FACIES_EZT.EF2ANDEXT_1
1570
Petrofisica Registros Electricos
RHO_MAA_1
K_CORE_1
3 0.01
MD
PHI_CORE_1
1000
0.2 SWE_1
V/V
CALCI_3MN_1
0 100
VOL_UWAT_1
0
0
0
0
0
0
0
0
0
0
GR_1
0
GAPI
1000 1
K_EZT_1
100 0.01
MD
V/V
0 0.2
SWE_1
1000 1
V/V
V/V
01
PHIE_1
0 0.2
V/V
0 PHIE_1
0.4 2.00 Geosciences – Reservoir Engineering 2.87 0.35 2.10 ENSPM Formation Industrie - IFP Training
2.00
OHMM
00
V/V V/V
EF_EZT_1
10
PAY_1 0 3 RESERVOIR_1 0 1.7
0
VSH_1
10
METRES
METRES
RT_1
3 0.01
DEPTH
G/C3
DENS_CORE_1
2.5
CORE_NO_1 SHOWS_1
2.5
PERFS.DESCRIPTION_1
FACIESLITH.VALUE_1
J. DELALEX
2.65 1.90 0.45 2.71 0.43
1.90
ELEVATION(TVD)
-0
Wells:
SAND_1 0 1.2
-1090
2.10
1515
-1091
0.3
WIRE_1.RHOB_1 (G/C3)
2.20
2.20
Call_Sup
0.25 -1095
2.30 2.40
-1096
1525
2.40
0.15
-1100
0.1
2.50
1520
2.30
0.2
2.50 1530
0.05
2.60
2.60 0
-1105 1535
2.70
2.70
2.80
2.80
2.90
2.90
3.00
3.00
Call_Inf
1540
0.450
0.400
0.350
0.300
0.250
0.200
0.150
0.100
PDVSA - EFAI LA TAHONA 120 January 15 – 19 2007 Color: Maximum of WIRE_1.GR_1
0.050
0.000
-0.050
1545
-1115
1550 -1118
WIRE_1.NPHI_1 (V/V)
0
Geosciences-Reservoir Engineering
1555
Well Log Interpretation – PDVSA – January 2007
© 2007 ENSPM Formation Industrie - IFP Training
-1110
FOREWORD
This document does not constitute in itself a written course on “ Well Log Interpretation ” , « Petrofisica Registros Electricos ». lt is a written support for short course of J.Delalex of ENSPM Formation Industrie - IFP Training, presented in LA TAHONA, Venezuela to participants of PDVSA – EFAI from 15th to 19th January 2007. Thanks to the contribution of S.Boyer of ENSPM - IFP School and B.Michaut of ENSPM Formation Industrie - IFP Training . It was built by assembling various documents from different origins; most of the diagrams and drawings presented and not identified, are taken from Schlumberger documents or from the ENSPM course documents of the authors. Other documents come from brochures , web site information or released field cases. The document is presented as a synthesis of key points, where the participants may add their own comments in following the course. Some parts of these pages have been left blank to be filled in by the participants, in order to help them become more efficient. Other pages have been left blank intentionally for their personal notes. The charts the most used in conventional log interpretation are presented in the appendix section. Several practical applications will be made under the supervision of the instructor and will enable the participants to understand and assimilate the well log interpretation.
Note to participants : As this present document is the very first complete reviewed version of the course in powerpoint format , you may find possible typing errors on the figures, in the text or in the equations . I will be very grateful if you could forward them to me and this will help me to make the course more professionnal . Jacques Delalex Jacques.delalex @enspmfi.com January 2007
Geosciences-Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2007 ENSPM Formation Industrie - IFP Training
For more information, the participants are invited to consult the bibliography included at the end of this booklet.
TENS_1 11000
LBF
1000
PEF_1 0
B/E
20
DRHO_1 -0.35
BS_1
GAPI
100
1.95
DEPTH
14
GR_1 0
G/C3
IDPH_1 0.2
0.15
2000 0.45
V/V
IMPH_1
IN
14
0.2
1000
1000
100
100
10
10
1
1
2.95
NPHI_1
OHMM
CALI_1 4
G/C3
RHOB_1
IN
METRES
4
-0.15
DT_1
OHMM
2000 140
US/F
40
1510.2
CORE_SH.K_CORE_1 (MD)
1515
1520
WELL LOG INTERPRETATION
1525
1530
1535
1540
0.1
0.1
1545
Petrofisica Registros Electricos
1550
0.200
0.150
0.100
0.000
0
0
0
0
0
0
0
0
0
0
-0
GAPI
1000
K_EZT_1
100 0.01
MD
0.2
SWE_1
1000 1
0 0.2
SWE_1
1000 1
V/V
0 100
VOL_UWAT_1
V/V
V/V PHIE_1
V/V
0 0.2
V/V
0
0
PHIE_1
01
V/V
9
VSH_1
00
V/V
EF_EZT_1
10
3
RESERVOIR_1 0 1.7
0 10
SAND_1 0 1.2
-1090
1515
Geosciences – Reservoir Engineering 2.30 ENSPM Formation Industrie - IFP Training
0.25 0.2
1520
-1095
-1096
2.40
0.15
-1091
Call_Sup
1525
0.1
2.50
2.50
0.05
2.60
-1100
2.60
1530
0
2.70
2.70
-1105 1535
2.80 2.90
2.80 PDVSA - EFAI 2.90 LA TAHONA 3.00 January 15 – 19 2007
Call_Inf
1540
0.450
0.350
0.300
0.250
0.200
0.150
0.100
0.050
0.000
-0.050
3.00
0.400
-1110
1545
-1115
1550
WIRE_1.NPHI_1 (V/V) 0
-1118
120 Color: Maximum of WIRE_1.GR_1
1555
1
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
WIRE_1.RHOB_1 (G/C3)
0
MD OHMM
METRES
METRES
3 0.01
J. DELALEX 2.20
2.20
2.40
3 0.01
Wells:RT_1
GR_1
2.10
0.3
2.30
G/C3 DENS_CORE_1
2.87
0.35
1570
2.10
2.5 2.5
CALCI_3MN_1 Color:PHI_CORE_1 Maximum of FACIES_EZT.EF2ANDEXT_1 PAY_1
K_CORE_1
DEPTH
2.00
0 RHO_MAA_1
CORE_NO_1 SHOWS_1
0.4
ELEVATION(TVD)
2.00
PERFS.DESCRIPTION_1
CORE_SH.PHI_CORE_1 (V/V)
2.65 1.90 0.45 2.71 0.43 1565
FACIESLITH.VALUE_1
1560
1.90
0.01
0.050
0.01
1555
TABLE OF CONTENT GENERALITIES-MUD LOG - WELL LOG
Pages 1 to 86
THE TOOLS
Pages 87 to 224 • • • • • • • • • • • • • • •
CALIPER
91
GAMMA RAY
99
SPONTANEOUS POTENTIAL
107
INDUCTION, LATEROLOG and MICRORESISTIVITY 119 DENSITY-NEUTRON-SONIC
145
NUCLEAR MAGNETIC RESONANCE
189
DIPMETER and BOREHOLE IMAGING
197
PRESSURE MEASUREMENTS
209
Pages 225 to 268 • QUICKLOOK INTERPRETATION • • CROSSPLOTS • • QUANTITATIVE INTERPRETATION
APPENDIX-CHARTS-BIBLIOGRAPHY
Geosciences – Reservoir Engineering
2
225 241 245
Pages 269 to 318
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
INTERPRETATION
MUD LOGGING / WIRELINE LOGGING / LWD/MWD INTRODUCTION As soon as an oil target has been defined by geological and geophysical studies, drilling then determines its precise position and characteristics. The measurements in boreholes correspond to a set of techniques whose purpose is to obtain local information on the formations being drilled, the fluids that they contain and the state of the well; this information can confirm or not the surface studies. The direct information (cuttings, cores, fluid samples) is not always sufficient or of high enough quality, so it may need to be supplemented by a whole series of downhole operations called logging, a term including all the various methods used for carrying out measurements in a borehole:
- WeII Logging (Wireline logging) These are measurements of physical parameters (electrical, acoustic, nuclear etc.) carried out periodically during the halt phases in the drilling, after the drill pipe string has been pulled out. The sondes can be: - lowered into the weII at the end of a cable (general case); - pushed down and then brought back up by the drill pipe string (especially in deviated wells); - pushed to the end of the hole, attached to a cable, and then pulled up by this cable (Coiled Tubing or Pumping Down method) (also for deviated wells). They are carried out in open-hole sections and sometimes (for some of the measurements) in cased hole. - Measurement/Logging While Drilling (MWD- LWD) Both of these types of measurements are carried out during drilling, and yield information obtained via sensors placed on the drill pipe string, close to the drilling tool, which relate to the drilling conditions (drilI pipe string and mud : MWD) and the formations drilled.
3
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
- Mud Logging Its aim is to ensure the weIl site geological monitoring, the behaviour of the weII, while also maintaining the desired drilling conditions. Mud Iogging is carried out during the drilling of the hole and the information is conveyed through the mud or the drill pipe string.
WELL LOGGING and RESERVOIR STUDIES WELL LOG CORRELATION REGIONAL GEOLOGY SEISMICS RESERVOIR GEOMETRY
LARGE SCALE SMALL SCALE GEOLOGICAL RESERVOIR MODEL
DIPMETER TOOLS IMAGING TOOLS
LOG SEQUENCE ANALYSIS CORE ANALYSIS
SEDIMENTOLOGICAL MODEL QUANTITATIVE INTERPRETATION of THE LOGS
Geosciences – Reservoir Engineering
4
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
LOG/SEISMICS CALIBRATION
OBSERVATION SCALES THIN SECTION
CORES
WELL LOG
micron -- mm
mm -- dm
dm -- m TENS_1 11000
LBF
1000
PEF_1 0
B/E
20
DRHO_1 -0.35
BS_1 GR_1 0
GAPI
100
1.95
IDPH_1 0.2
CALI_1 4
IN
G/C3
0.15
RHOB_1 14
DEPTH
IN
METRES
4
OHMM
0.2
OHMM
2.95
NPHI_1 2000 0.45
IMPH_1 14
G/C3
V/V
-0.15
DT_1 2000 140
US/F
40
1510.2
1515
1520
1525
1530
1535
1540
1545
1550
1555
1560
1565
ELECTRONIC MICROSCOPE micron 5
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
1570
GENERALITIES
• Reservoirs and Seals • Reservoir and fluid characteristics • Invasion Phenomenon • Basic Equations • Mud Logging
• Logs Presentation and Quality Control
Geosciences – Reservoir Engineering
6
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
• Wireline Logging operations
SEALS AND RESERVOIRS
G O w
->
Geosciences – Reservoir Engineering
7
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
w w
Geosciences – Reservoir Engineering
8
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Notes
RESERVOIR AND FLUID CHARACTERISTICS
G O w
Original Oil In Place : OOIP ?
->
Geosciences – Reservoir Engineering
9
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
w w
Geosciences – Reservoir Engineering
10
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Notes
VOLUMETRIC ANALYSIS OF A SEDIMENTARY ROCK
MATRIX
DRY CLAY
CEMENT
Bound Water
Respective mineral and fluid volumes in a sedimentary rock 11
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
WATER
OIL / GAS
POROSITY - Φ φ : Porosity : Fraction of the bulk volume occupied by voids Porosity = Ratio of pore volume to total rock volume
Φ=
Vpore Vtotal
Vtotal − Vsolid = Vtotal
Porosity is expressed in % or V/ V or Porosity units (Pu) . In general, reservoirs have porosities ranging from 5 to 35 %. φ < 5%
low porosity
φ > 20 %
good porosity
average porosity
- Primary Porosity : Inherited from deposit of original sediment.
- Secondary Porosity : Due to effects of diagenesis during the burial phase of sediments , dissolutions ( vugs) or due to the existence of fractures in the the rock . Geosciences – Reservoir Engineering
12
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
10% < φ < 20%
Thin section in a sandstone
Thin section in an oolitic limestone
Red color for Porosity
Yellow pale color for Porosity
Thin section in a limestone
Thin section in a bioclastic limestone
Pink color for Porosity
Yellow pale color for Porosity
13
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
POROSITY EXAMPLES
Poor connection between pores
Good connection between pores
( isolated pores ) Geosciences – Reservoir Engineering
14
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
PORE CONNECTION
POROSITY TYPE DEFINITIONS Apparent porosity
Φ •
Vhc Vwb
•
Vt
Vw + Vhc Vt
Φ = [Vw + Vhc] e
•
connected
Vt
Effective porosity – Log Analysis
Φ = [Vpore − Vw associated to the shale] e
Geosciences – Reservoir Engineering
u
=
Vw + Vhc + Vwb Vt
Effective porosity - Petrophysics
Vw Vma
=
Useful porosity
Φ Vsh
a
Vt
15
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
•
Geosciences – Reservoir Engineering
16
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Notes
PERMEABILITY
•
Permeability is the property of a porous formation to let the fluid flow under a certain pressure gradient. It is usually expressed in mDarcy or Darcy .
P1
∆P
P2
Flow rate :
Q=
Q Flow rate
Mobility :
L
µ
Darcy’s Law K: µ: ∆P: A: Q: L:
Rock sample Permeability (Darcy) Fluid Viscosity (cP) Differential Pressure (atm) Cross sectional area (cm2) Flow rate (cm3/s) Rock sample length (cm)
Geosciences – Reservoir Engineering
K
K × A ∆P µ L
=
Q× L A × ∆P
Typically : 0.1 mD < K < 10000 mD K in Darcy = 0.987 10 -12 m2
17
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
•
PERMEABILITY ESTIMATION
•
Horizontal or vertical permeability can be measured on core samples in a laboratory
•
Permeability can be estimated
•
Permeability-thickness Kh can be estimated during a production test ( DST )
Geosciences – Reservoir Engineering
18
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
– using the drawdown or buildup recorded during the pretest of a pressure measurement. – from the effective porosity and irreducible water saturation Swi using empirical formula. – from the Nuclear Magnetic Resonance
FLUID SATURATION It is essential to know the type of fluids present in a reservoir and the proportion of each fluid in the pore volume , ie the fluid saturation . The fluid saturation is defined as the ratio of the fluid volume to the pore volume. It is expressed in % or in V/V fluid
Saturation =
Below a certain depth , pores are no more occupied by air , but by a fluid , generally fresh or salty water. In the case of an hydrocarbon reservoir, pores can be occupied by water with oil and/or gas.
V Vpore
Thin section showing the oil Saturation
In an hydrocarbon zone, it always remain a certain quantity of water trapped between the grains or linked to the grains by capillary presure. This is the irreducible water . The irreducible water saturation may vary from 10 to 35 % 19
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Therefore , one can define a water saturation Sw, an oil saturation So or a gas Saturation Sg.
WATER AND HYDROCARBON SATURATIONS In an hydrocarbon zone
V Sw = w Vpore V + Vhc Sw + Shc = w =1 Vpore Vpore = Vw + Vhc
Shc = 1 − Sw
Shc =
Vhc Vpore Matrix Oil Water
In an oil zone
In a gas zone
Sg = 1 − S w Geosciences – Reservoir Engineering
20
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
So = 1 − S w
RESISTIVITY OF AN NaCl SOLUTION Rw = 0.1 Ohmm
Temp
Salinity = 25 kppm Geosciences – Reservoir Engineering
21
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
= 90 C
RESISTIVITY OF AN NaCl SOLUTION
Rw = 0.1 Ohmm Salinity = 25 kppm
Geosciences – Reservoir Engineering
22
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Temp = 90 C
RESISTIVITY vs CONDUCTIVITY PRINCIPLE OF RESISTIVITY MEASUREMENT In electricity :
U R= I
L
Current I
R U
S
R=
ρ *L S
R = Resistance (Ohm) ρ = Resistivity
Resistance is a function of the geometry of the medium. As this geometry is unknown, one uses the resistivity in well logging
For example Rt = True Formation Resistivity Conductivity C is expressed in Siemens/m or mho/m or in mSiemens/m or mmho/m 23
Geosciences – Reservoir Engineering
1 R 1000 C= R
C=
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Resistivity is called R in well logging, expressed in Ω.m or Ohmm (Symbol ρ is used for the density )
ARCHIE LAW - FORMATION FACTOR F •
A rock sample containing 100 % water (Sw = 1) has a true resistivity Rt, usually called Ro
•
This Resistivity Ro is proportional to the resistivity of the water Rw
Ro1 = FR w1 Porosity φ
•
Ro2 = FR w 2 Porosity φ
The proportionality factor F is called the Formation Resistivity Factor and it is therefore the Ratio of the Resistivity Ro to the water resistivity Rw
Porosity φ1 Geosciences – Reservoir Engineering
Porosity φ2
24
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Ro = FR w
ARCHIE LAW - FORMATION FACTOR F •
The formation factor depends on the lithology and the porosity of the rock :
R F= o Rw
a F= m φ R o1 =
a φ1m
Ro =
Then : ×Rw
R o2 =
Porosity φ1
a ×Rw m φ
a φ m2
×Rw
Porosity φ2
In general , the constant a is close to 1 and the cimentation factor m is close to 2 .
0.81
or
F=
0.62
For Sandstones, in general :
•
For Carbonates, in general, a = 1 and m = 2, but m is variable : 1.3 < m < 2.5
φ2
φ 2.15
-> Geosciences – Reservoir Engineering
25
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
F=
•
ARCHIE LAW - FORMATION FACTOR F
log(F) = log(a ) − m log(φ)
Geosciences – Reservoir Engineering
26
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Formation Resistivity Factor versus Porosity ( Chart Por1 – Schlumberger)
ARCHIE LAW – WATER SATURATION •
A rock sample having a water saturation Sw has a true resistivity Rt Rt varies with the water saturation Sw and it is inversely proportional to Swn , n is the saturation exponent and it is usually close to 2
• •
Rt =
Ro Rw a = × n Φ m Sw n Sw
HC
or
Sw = n
a Rw Φm R t
HC
Water
F*Rw S w1
R t2 =
n Water
Water Saturation Sw1
F*Rw Sw 2
n
Water Saturation Sw2
This is the Archie equation and it is only valid in clean formation ( Vsh = 0 ) Geosciences – Reservoir Engineering
27
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
R t1 =
ARCHIE LAW : WATER SATURATION Estimation of Sw in clean formations
a Rw Sw = n m φ Rt •
Resistivity logs ( Laterolog, Induction)
Î
Rt
• • •
Porosity logs ( Density, Neutron, Sonic, RMN) SP, Resistivity Ratio, Rwa, Water sample Petrophysical measurements in laboratory
Î Î Î
φ Rw a, m, n
Formula only valid for clean formations ( No Shale : Vsh = 0)
Geosciences – Reservoir Engineering
28
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Default values: a = 1, m = 2 , n = 2
VARIATIONS OF RESISTIVITY WITH POROSITY Training exercise on Archie Formula
Rw =
F=
Φ=2%
FF=
Rt =
Φ = 10%
FF =
Rt =
Φ = 25%
FF =
Rt =
a
φ
m
Rt =
a
φm
×
Sw = 100 %
Rw n Sw
Formation water salinity : 30 Kppm Temperature : 70 °C Rw : Coefficients for Archie Formula : a: 1 m: 2 n: 2
->
29
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Sw=100 %
VARIATIONS OF RESISTIVITY WITH Sw Training exercise on Archie Formula
Φ = 25%
FF =
F=
Sw = 10%
Rw =
Rt =
Sw = 50%
Rw =
Rt =
a
φ
Φ = 25%
m
Rt =
a
φ
m
×
Rw n Sw
Formation water salinity : 100 Kppm Temperature : 70 °C Rw :
Rw =
Rt =
Coefficients for Archie Formula : a: 1 m: 2 n: 2
-> Geosciences – Reservoir Engineering
30
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Sw = 100%
VARIATIONS OF RESISTIVITY Example of Variation of Rt with Sw
Example of Variation of Rt (LLD) with Porosity GR_1 0
LLD_1
GAPI 100
0.2
OHMM
PXND_1 2000 0.45
V/V
SWE_1 -0.15 1
V/V
GR_1 0
0
RT_1
GAPI 150
0.2
PHIE_1
OHMM
2000 0.45
V/V
SWE_1 -0.15 1
V/V
0
Limestone – No HC shows
Sandstone : No HC shows below depth xxx
Reservoir Temperature = 50 C
Temperature = 60 C
a = 1 m= 2 n= 2
a = 0,81 m= 2 n= 2
Rw =
Rw =
Formation Water Salinity =
Kppm
Formation Water Salinity : ->
31
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
xxx
ARCHIE LAW – RESISTIVITY INDEX In Petrophysics , the Resistivity Index is the Ratio of the Resistivity of the porous medium having a water saturation Sw to the Resistivity of the porous medium 100 % saturated with brine. 1/ n
R 1 RI = t = n R o Sw
or
Geosciences – Reservoir Engineering
or
⎛ Ro S w = ⎜⎜ ⎝ Rt
⎞ ⎟⎟ ⎠
a Rw Sw = n m φ Rt
32
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
•
INVASION
33
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
INVASION PHENOMENON, ZONES AND ASSOCIATED PARAMETERS
INVASION OF A RESERVOIR DRILLING HORIZONTAL FORMATIONS BY A VERTICAL WELL INVASION OF RESERVOIRS BY THE DRILLING FLUID Damage of porous and permeable formations (reservoirs) is linked to the invasion by the filtered drilling fluid, essentially the mudfiltrate. • The presence of residual hydrocarbon in the flushed zone affects the measurements of resistivity and porosity such as density and neutron logs . MUD
SEAL
SEAL MUD CAKE FLUSHED ZONE
W
Phyd MUD FILTRATE
VIRGIN ZONE
Mud filtrate & Residual HC
PForm MUD FILTRATE
HC & Water
WATER
Invasion Diameter Di ?
Geosciences – Reservoir Engineering
34
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
HC
Mud filtrate & Residual HC
INVASION AND ASSOCIATED PARAMETERS Case of a well drilled with a Water Based Mud SEAL FLUSHED ZONE
RESERVOIR
Transition Zone
VIRGIN ZONE Fluid Saturation Formation Resistivity
Gas zone
Fluid Resistivity Fluid Type
GOC
Fluid Saturation Formation Resistivity
Oil zone
Fluid Resistivity Fluid Type
WOC
Formation Resistivity
Water zone
Fluid Resistivity Fluid Type
35
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Fluid Saturation
INVASION AND ASSOCIATED PARAMETERS Case of a well drilled with a Water Based Mud MUD
RESERVOIR
Φ
Hu
u ,
Rm
ρm
FLUSHED ZONE
K, T, Pf
Gas zone
Transition Zone
Sxo and Sgr Rmc
Sw and Sg
Rxo
Rtr
GOC
Mud Filtrate and Residual Gas (+Irr w)
W , MF, G
Pf
Rtr
Rxo
Oil zone Phyd
Rmf W , MF, O
Sxo Rtr
Rxo
Water zone Hu
Hole Diameter CALI
Rmf Mud Filtrate
Rt Rw
Mud Filtrate and Residual Oil (+Irr w)
WOC
Water and Gas
Sw and So
Sxo and Sor Hu
Rt Rw
Rmf hmc
VIRGIN ZONE
Water and Oil
W , MF
Fluid Resistivity Fluid Type
Fluid Saturation Formation Resistivity Fluid Resistivity Fluid Type
Sw
Fluid Saturation
Rt
Formation Resistivity
Rw ( + Irr w)
Fluid Saturation Formation Resistivity
Water
Fluid Resistivity Fluid Type
Bit Size BS Invasion Diameter Di Invasion Diameter Dj Geosciences – Reservoir Engineering
Sg = 1- Sw
Sgr = 1- Sxo
So = 1- Sw Sor = 1- Sxo
36
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
SEAL
INVASION IN WATER BASED MUD Resistivities and Saturations CLEAN HYDROCARBON BEARING FORMATION (Porosity Φ )
Fluid Resistivity Formation Resistivity
Virgin Zone
Invaded Zone Formation Resistivity
Geosciences – Reservoir Engineering
Rxo =
a
φ
m
×
Rmf S xo
Rt =
n
37
a
φ
m
×
Rw n Sw Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Water Saturation
INVASION IN WATER BASED MUD POROUS and PERMEABLE HYDROCARBON bearing FORMATION
INVASION PROCESS and
Fluid Distribution
Geosciences – Reservoir Engineering
38
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
RESISTIVITY PROFILE
INVASION IN OIL BASED MUD FLUSHED ZONE
OIL BASED MUD
VIRGIN ZONE
HYDROCARBONS
HYDROCARBON ZONE With IRREDUCIBLE
OIL FILTRATE WATER
WATER SATURATION
Sxo = Sw = Swi HYDROCARBONS
TRANSITION ZONE
OIL FILTRATE WATER
Geosciences – Reservoir Engineering
Sxo < 1
OIL FILTRATE
WATER
Sxo < 1
Sw = 1 39
WATER ZONE
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Sxo < Sw
Geosciences – Reservoir Engineering
40
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Notes
MUD LOGGING
Geosciences – Reservoir Engineering
41
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
MUD LOGGING
MUD LOGGING
RIG
INSIDE CABIN (Geological side)
Geosciences – Reservoir Engineering
42
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
MUD LOGGING UNIT
MUD LOGGING OBJECTIVES
ANALYTICAL
OF
and
WELL SITE GEOLOGY
OBSERVATION FACILITIES
DRILLING •
Well follow up
•
Drilling optimization
• UNIT or LABORATORY on RIG SITE • SENSORS on RIG EQUIPMENTS
WELL SAFETY Risk evaluation
• •
• HYDRAULIC LOGGING
Lithology
• GEOLOGICAL LOGGING
Formation Pressure
• HYDROCARBON LOGGING
ARCHIVES •
Final report
Geosciences – Reservoir Engineering
43
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
•
• MECHANICAL LOGGING
MUD LOGGING INSTANTANEOUS PARAMETERS
LAGGED PARAMETERS
• HOOK HEIGHT
GAZ IN MUD HYDROCARBONS : C1 Ö C5
• WEIGHT ON HOOK (WOH)
•
• RPM
•
HYDROGEN SULFIDE (H2S)
•
CO2 (optional)
•
H2 (Optional)
• TORQUE • INJECTION PRESSURE (SPP) • WELL HEAD PRESSURE (ANNULAR
MUD PARAMETERS OUT
PRESSURE)
•
DENSITY
• PUMP STROKES
•
TEMPERATURE
• MUD PIT LEVEL
•
CONDUCTIVITY
•
MUD FLOW OUT
• MUD PARAMETERS IN • DENSITY
•
Lithology (cuttings %)
• CONDUCTIVITY
•
Calcimetry
• MUD FLOW IN
Geosciences – Reservoir Engineering
44
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
FORMATION
• TEMPERATURE
MUD LOGGING
45
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
RECORDED DATA
MUD LOGGING MUD LOG versus WELL LOG
Geosciences – Reservoir Engineering
46
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
WELL LOG
MUD LOG
MUD LOGGING
Geosciences – Reservoir Engineering
47
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
GEOLOGICAL LOG
MUD LOGGING
Geosciences – Reservoir Engineering
48
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
GEOLOGICAL LOG
MUD LOGGING
Geosciences – Reservoir Engineering
49
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
GEOLOGICAL LOG
Geosciences – Reservoir Engineering
50
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Notes
WIRELINE LOGGING
51
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
WIRELINE LOGGING
WELL LOGS : INTRODUCTION Everything began in September 1927 when two French brothers, Conrad and Marcel Schlumberger saw their efforts crowned with success when, in a well at the Pechelbronn field in France, they carried out the first downhole electric log based on the principle of surface resistivity measurements. Since then, the improvement in logging tool technology has lead to a better knowledge of the reservoir characteristics: Lithology, Porosity, Water saturation, fluid types, identification of fractures and helped to decide on the future of a well or a field. TENS_1 11000
LBF
1000
PEF_1 0
B/E
20
DRHO_1 -0.35
14
GR_1 0
GAPI
100
DEPTH
IN
METRES
BS_1 4
IDPH_1 0.2
CALI_1 4
IN
OHMM
0.2
OHMM
G/C3
0.15
2.95
NPHI_1 2000 0.45
IMPH_1 14
G/C3
RHOB_1 1.95
V/V
-0.15
DT_1 2000 140
US/F
40
1510.2
1515
1520
1525
1530
1535
1540
1545
1550
1555
1565
1570
1575
1580
1585.0
CLASSICAL COMPOSITE LOG Geosciences – Reservoir Engineering
BOREHOLE IMAGING LOG 52
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
1560
LOGGING OPERATION ON LAND Tension Measurement
Sheave Cable or wireline
Depth Measurement Kelly Bushing KB
Ground Level GL
Tension Measurement
Drill Floor DF or Rotary Table RT
Cable Drum
Truck and Computer
Measured Depth MD below DF (Deviated well)
Vertical Well Head Tension Measurement Deviated Well Logging tools
53
Geosciences – Reservoir Engineering
J_Delalex_Feb06
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Measured Depth MD below DF (Vertical well)
RIG-UP Drill Floor DF
Tool « Zero » on Drill Floor DF
Rotary Table RT
Rig view and Logging Truck
Ground Level GL
Bottom of the tool
Caliper Calibration
Kelly Bushing KB rotating while drilling Geosciences – Reservoir Engineering
Depth Measurement 54
Head of the tool
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
KB
DEPTH and TENSION MEASUREMENTS
Depth Measurement
Tension Measurement
Cable Drum
55
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Cable
DEPTH - REFERENCES MD - TVD - TVDSS Deviated Well
Offshore
On Land
Kelly Bushing KB
GL
Drill Floor
DF or Rotary Table RT
Ground Level
DF MSL
MSL Mean Sea Level (Reference) TVD
TVD-SS
MD
GL MD
TVD
TVD-SS
RESERVOIR
Geosciences – Reservoir Engineering
56
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
DF
TOOL COMBINATION Dual Laterolog –
Litho-Density-Neutron GR
Microresistivity - GR
Gamma Ray
Gamma Ray
Neutron Dual Laterolog Litho-Density
57
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Microresistivity
TOOL COMBINATION Logging Tool Combination : PEX Platform Express (Schlumberger)
Telemetry
Gamma Ray
Neutron
+ + + + + + + +
Sonic
+ + + +
Resistivity : Laterolog or Induction
Geosciences – Reservoir Engineering
58
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Litho-DensityMicroresistivity
FIELD LOG RESULTS
Geosciences – Reservoir Engineering
59
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
PLATFORM EXPRESS RESULTS (SCHLUMBERGER)
LOGGING TOOL EXAMPLES
SONIC BHC Sonde Caliper
SONIC DSI Sonde
Centralizer
Electronic Cartridge
Geosciences – Reservoir Engineering
60
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Stand-off
LOGGING RUNS Most common Bit Sizes :
26
17.5
12 ¼
8½
6
Most common Casing Sizes :
20
13 3/8
9 5/8
7
5½
Run-1
1
Open Cased Hole Hole
Run-2
Run-1, 2 & 3 spliced
2 Run-1 & 2 spliced
Run-3
Geosciences – Reservoir Engineering
61
3
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Watch for splicing Anomaly !
LOGGING IN DEVIATED OR HORIZONTAL WELLS
Geosciences – Reservoir Engineering
Pump Down
62
Coil Tubing
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
TLC (Tough Logging Conditions)
LOG PRESENTATION
OVERLAP SECTION
CALIBRATIONS AFTER SURVEY
MASTER CALIBRATIONS & CALIBRATIONS BEFORE SURVEY
Geosciences – Reservoir Engineering
LOG HEADER
MAIN LOG ->
REPEAT SECTION
63
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
-> MAIN LOG
LOG QUALITY CONTROL • LOG HEADER (Coordinates, References, Mud data, hole size , Casing, Timing , Temperature, Remarks …) • LOGGING SPEED • SAMPLING RATE • ENVIRONMENTAL EFFECTS • HOLE (Mud, Diameter, Mudcake, Restrictions, Caves) • SHOULDER BEDS • INVASION • REPEAT SECTION AND MAIN LOG • OVERLAP SECTION • TOOL VERIFICATION IN CASING ( Caliper , Sonic ) • CALIBRATIONS • DEPTH MATCHING OF LOGS • TENSION EFFECTS, TOOL STICKING • CHOICE OF TOOLS • REFERENCE VALUES ( SALT , ANHYDRITE, TIGHT FORMATIONS …) Geosciences – Reservoir Engineering
64
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
• ACQUISITION PARAMETERS
LOG HEADER
Geosciences – Reservoir Engineering
65
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
LOG HEADER : Well Info, Casing & Bit Size Data
LOG HEADER
MAXIMUM THERMOMERS (On Tool Head)
Geosciences – Reservoir Engineering
66
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
LOG HEADER : Mud & Temperature Data
LOG HEADER
REMARKS : Mud With Barite ( 210 KG/CM3) File 4 & File 5 with Barite Correction No PEF on Main Log
Geosciences – Reservoir Engineering
67
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
LOG HEADER : Other Services & Remarks
ACQUISITION PARAMETERS TOOL MEASURE POINTS and ACQUISITION PARAMETERS LDL-CNL-GR
Caliper Measure Point
10.4 m
GR Measure Point Neutron Measure Point
Litho-Density Measure Points
Matrix = LIMESTONE ⇒Neutron log NPHI recorded in Limestone Matrix
1.4 m
Tens
Geosciences – Reservoir Engineering
68
1.1 m
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
7.8 m
LOG FIRST READINGS EXAMPLE OF MAIN LOG AT TD FOR LITHO-DENSITY-NEUTRON-GR
FR = First Reading
GR
FR - GR FR - NPHI
FR- CALI
TDL = 5741 m Total Depth Logger
GR
CNT
NPHI 10.4 m 7.8 m
Tension
LDT
RHOB 1.1 m
Tension pick-up
Geosciences – Reservoir Engineering
69
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
FR - RHOB,PEF
LAST READING – CASING OVERLAP SECTION AND CALIPER CHECK IN CASING GR recorded in casing to OVERLAP with previous log section 7" Casing Shoe
Caliper Check in 7 inch Casing Casing Weight = 23 Lb/ft Caliper should read : ID = 6.37 inches
Density log RHOB affected by Cave
Cave below CasingShoe
Geosciences – Reservoir Engineering
70
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
IHV Integrated hole volume ( 0,1 m3)
Caliper and GR in 6" open hole
REPEAT SECTION & MAIN LOG
Geosciences – Reservoir Engineering
REPEAT SECTION (LAE-1)
71
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
MAIN LOG (LAE-1)
REPEAT SECTION & MAIN LOG
Geosciences – Reservoir Engineering
72
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
REPEAT SECTION compared to MAIN LOG For Litho-Density-Neutron-GR log
LOGGING SPEED
Depth (m)
Logging Speed
9m
= 9m/mn = 540m/hr
1 mn
Geosciences – Reservoir Engineering
73
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
= 1800Ft /hr
Geosciences – Reservoir Engineering
74
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
QUALITY CONTROL OF MUD DATA
TENSION EFFECT ON LOGS
Tension effect on GR
LLD, LLS
Effect on Caliper
MSFL Tension increases when the tool gets stuck Geosciences – Reservoir Engineering
75
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Effect on resistivity logs
?
Geosciences – Reservoir Engineering
76
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Notes
TENSION EFFECT ON LOGS Comparison of GR Logs recorded with different tool combinations in the same well ( Upper Section ) InductionSonic – GR- SP
Tension
Density-Neutron – NGL -Caliper
DLL-MSFL GR-SP-Caliper
Tension
Tension
DLL-MSFL GR-SP- Caliper
Tension
77
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Thickness of this upper reservoir ??
TENSION EFFECT ON LOGS Comparison of GR Logs recorded with different tool combinations in the same well ( Lower Section ) Tension
Density-Neutron – NGL -Caliper
Tension
DLL-MSFL GR-SP-Caliper
Tension
DLL-GR-SP(CAL Closed )
Geosciences – Reservoir Engineering
78
Tension
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
InductionSonic – GR- SP
LOG CALIBRATION
Geosciences – Reservoir Engineering
79
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
MASTER CALIBRATION FOR NEUTRON AND LITHO-DENSITY TOOLS
LOG CALIBRATION
Geosciences – Reservoir Engineering
80
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
BEFORE SURVEY CALIBRATION FOR NEUTRON AND LITHO-DENSITY TOOLS
LOG CALIBRATION
Geosciences – Reservoir Engineering
81
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
AFTER SURVEY CALIBRATION FOR NEUTRON AND LITHO-DENSITY TOOLS
CALIBRATIONS Example of Litho-Density calibration
Schlumberger Document
Geosciences – Reservoir Engineering
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recorded with Maxis-500
DEPTH OF INVESTIGATION & VERTICAL RESOLUTION DEPTH of INVESTIGATION and VERTICAL RESOLUTION
Courtesy of S. Boyer
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OF LOGGING TOOLS
VERTICAL RESOLUTION
MACRO-DEVICES
MICRO-DEVICES
Gamma Ray Neutron Density Sonic Laterologs Inductions
Micro-resistivity
Geosciences – Reservoir Engineering
84
DIPMETER
Well Log Interpretation – PDVSA – January 2007
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RELATIONS between LAYER THICKNESS and VERTICAL RESOLUTION of the TOOLS
85
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VERTICAL RESOLUTION
INVOICE WIRELINE LOGGING COSTS (after Schlumberger price list 1994 – US $)
2000m (6000’)
For a minimum and sufficient set of geological logs for a wildcat In standard conditions (mud type, hole diameter, deviation, temperatue, pressure, sample rate) Personnal, equipement and transportation charges are not inclued.
CSU Unit
3000 / Month
Depth charge (min 2000’)
Survey charge (min 1000’)
Neutron Density GR (in combustion)
1.15 * 6000 = 6900 1.25 * 6000 = 7500 0.8 * 6000 = 4800
1.15 * 1500 = 1750 1.25 * 1500 = 1875 0.8 * 1500 = 1200
DLL MLL PS GR
1.1 * 6000 = 6600 1.0 * 6000 = 6000 Free 0.2 * 6000 = 1200
1.1 * 1500 = 1650 1.0 * 1500 = 1500 Free Free
Sonic GR
1.1 * 6000 = 6600 0.2 * 6000 = 1200
1.1 * 3000 = 3300 Free
30000 + 40800
11275
1.4 * 6000 = 8400
1.85 * 3000 = 5550 1.9 * 3000 = 5700
SHDT MSDip FE Quicklook
2.52 * 1500 = 37800 8400
15030
LOGGING
96025 (16825 Measurement)
INTERPRETATION
7500
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103525 (16825 Measurement)
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© 2006 ENSPM Formation Industrie - IFP Training
1500m (4500’)
Logging
Sonic, SHDT
1000m (3000’)
WIRELINE LOGGING
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THE TOOLS
TOOLS THE TOOLS • CALIPER • GAMMA RAY • SPONTANEOUS POTENTIAL • INDUCTION and RESISTIVITIES • DENSITY – NEUTRON - SONIC
• DIPMETER and FORMATION IMAGING • PRESSURE MEASUREMENTS AND FLUID SAMPLING Geosciences – Reservoir Engineering
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• NUCLEAR MAGNETIC RESONANCE
TOOL NMEMONICS SCHLUMBERGER
BAKER ATLAS
COMMERCIAL DENOMINATIONS OF THE MAIN CONVENTIONNAL LOGGING TOOLS AND TOOL SETS This list is not exhaustive; abbreviations and tool names may be slightly modified Other contractors offer similar services under other denominations Most of the tools may be combined under denominations and regulations proper to each contractor (L for Tool, T for Log ) Please , consult tool catalogues or web sites of service companies for up_to-date informations
89
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HALLIBURTON
LOGGING TOOLS USED WELL LOGGING PROGRAM for EXPLORATION WELLS GOALS IDENTIFICATION of
RESERVOIRS and SEALS
DETERMINATION of
RESERVOIR CHARACTERISTICS FLUID CHARACTERISTICS
TIME – DEPTH CONVERSION of SEISMICS
LOGGING TOOLS USED CALIPER for caves, fractures and borehole rugosity identification GAMMA RAY for shales and lithology identification SPONTANEOUS POTENTIAL for Water Resistivity computation
RESISTIVITY TOOLS 3 Resistivity tools with different depths of investigation for Rt, Rxo and water saturation computations Laterologs in conductive muds or if Rxo < Rt Inductions in non conductive muds or if Rxo > Rt WIRELINE FORMATION TESTER for fluid identification and pressure measurements
Geosciences – Reservoir Engineering
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LITHOLOGY – POROSITY TOOLS DENSITY, NEUTRON and SONIC
CALIPER MEASUREMENT
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BOREHOLE DIAMETER MEASUREMENT
CALIPER TYPES LITHO-DENSITY TOOL
FORMATION MICRO-IMAGER
6 Arms Dipmeter, EMI BS
CALI
BS Tool excentered with one arm => 1 Diameter : CALI
Geosciences – Reservoir Engineering
Tool Centered with 4 arms
Tool Centered with 6 arms
=> 2 Diameters : C1 & C2
=> 3 Diameters
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BS
CALIPER OF DENSITY TOOL
CALIPER OF SAD (DIPMETER)
93
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CALIPER CALIBRATION
CALIPER APPLICATIONS Applications : - Hole Diameter - Hole Volume => Cement Volume - Ovalisation - With Deviation and Azimuth => Hole Profile - Presence of caves - Presence of restrictions ( Swelling Shales )
- Information on Lithology (Mechanical Properties) => Quality Control of the logs Geosciences – Reservoir Engineering
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- Presence of mudcake ( => hmc)
CALIPER LOG AND IHV
Integrated Hole Volume IHV =
Caliper Check in Casing
0.1 m3 between 2 small pips if depth in meters or
CASING 9" 5/8
10 Cuft , if depth in Feet
53.5 LB/F ID = 8.54
BS : 8.5
95
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© 2006 ENSPM Formation Industrie - IFP Training
Caliper
MUDCAKE ET CAVES
Caliper of
Caliper of
MSFL
Density
Caves
Unconsolidated Sandstone
With Caliper of Density Tool ( one arm ) : Mudcake Thickness = hmc = BS – Cali (hmc = 0 , if Cali>BS) Geosciences – Reservoir Engineering
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BS=8.5
HOLE PROFILE & HOLE VOLUME
IHV Integrated Hole Volume
Microresistivity curve of Dipmeter Tool
Caliper 1 Pads 1 & 3
Caliper 2 Pads 2 & 4
DEVIATION
Geosciences – Reservoir Engineering
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AZIMUTH
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Notes
NATURAL RADIOACTIVITY
Geosciences – Reservoir Engineering
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NATURAL RADIOACTIVITY GAMMA RAY
GR - NATURAL RADIOACTIVITY In sedimentary rocks, natural radioactivity comes from the elements issued of the series of Thorium , Uranium and isotope 40 of K.
K:
SHALES (ILLITES) POTASSIC EVAPORITES POTASSIC FELDSPARS MICAS MINERALS with K (MUD with KCl)
U:
Geosciences – Reservoir Engineering
SHALES (with organic matter) ORGANIC MATTER MINERALS with U
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Th : DETRITIC SHALES MINERALS with Th ( Heavy Minerals )
GR AND SPECTRAL GR TOOLS • GR TOOL : Measurement of total radioactivity (GR) , Units = API • SPECTROMETRY GR TOOL : - SPECTRAL GAMMA RAY (SGR) - CORRECTED GAMMA RAY (CGR) Units :
: U + K + Th : K + Th
SGR and CGR in API K in % , Th and U in ppm
In HNGS Sonde ( Schlumberger)
101
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BGO SCINTILLATION DETECTORS
GR - WELLSITE CALIBRATION
Calibration JIG
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GR TOOL
GR - NATURAL RADIOACTIVITY • APPLICATIONS • Bed Boundaries • Geological correlations • Shale content estimation • Type of clays • Presence of radioactive minerals • Depth matching of subsequent logs
103
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• Correlation with cased hole logs
Examples of GR log and Spectral GR log GR
CGR
SGR
TH
U
K
GR_1 0
GAPI
BS_1 4
IN
100
IMPH_1
DEPTH 14 METRES
0.2
14
0.2
4
IN
OHMM
2000
IDPH_1
CALI_1
OHMM
DT_1 2000 140
US/F
40
1525
1575
Geosciences – Reservoir Engineering
104
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1550
SPECTRAL GR - Crossplot Th-K Th-K CP-19
K
(Schlumberger)
105
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Th
ESTIMATION OF SHALE CONTENT FROM GR GRmax GR log
Estimation of VSH
GR min
from GR log
GR
GR - GR min
GRmax - GRmin
GR VSH = GR GR Geosciences – Reservoir Engineering
- GR max
- GR
min
min 106
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Anomaly of radioactivity
SP
SPONTANEOUS POTENTIAL
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SP
Geosciences – Reservoir Engineering
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Notes
SPONTANEOUS POTENTIAL • PRINCIPLE OF MEASUREMENT Measurement of a difference of potentiel between 2 electrodes, one on the tool in the well and one at surface . It is linked mainly to - The contrast between the formation water salinity and the mudfiltrate salinity ( Liquid-Junction Potential Ej) -The contrast between the formation water salinity and the mud salinity ( Membrane Potential Em through shale) - The shale content of the formation It is expressed in milliVolt and can only be recorded in water based mud. The Electrokinetic potential Ec may be negligeable in formation with reasonable permeability
– – – – –
Detection of permeable layers Determination of bed boundaries Log correlation Evaluation of Rw Estimation of shale content in reservoirs 109
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• MAIN APPLICATIONS
NORMAL SP AND INVERSE SP
Negative SP or Normal SP
Positive SP or Inverse SP
Rmf > Rw
Rmf < Rw
Shale Baseline
Interface ShaleReservoir
SP log
Static SP
Interface Flushed zone – Virgin Zone
Rmfe E C = E M + E J = - K log Rwe Geosciences – Reservoir Engineering
SSP = E C ( + E K )
K = f(Temp)
K = 61+.133∗ T (°F) K = 65+.240∗T (°C)
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Borehole
SP EXAMPLES mV SP Scale
Shale baseline SHALE
mV
GR
SSP<0
SHALE SSP = mV
SHALE
Positive or Inverse SP
SHALE Pseudo-SP =PSP = mV
SHALE
Geosciences – Reservoir Engineering
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SSP <0
Negative or Normal SP
Effect of Rmf/Rw on SP
Geosciences – Reservoir Engineering
Effect of Shale and Hydrocarbon on SP
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MAIN PARAMETERS AFFECTING SP
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EXAMPLE OF SP LOG
DETERMINATION OF Rw FROM SP • Check validity of mudfiltrate resistivity measurement in log header • Identify shale layers • Draw SP shale baseline • Estimate maximum SP deflection in front of each reservoir : SSP • Estimate Reservoir temperature ( Chart Gen-6 ) • Determine Rmf at reservoir temperature (Chart Gen-9) • Determine Rmfe/Rwe ratio from SSP at reservoir temperature (Chart SP-1) • Determine Rmfe from Rmf at reservoir T° (Compute or use chart SP-2) • Determine Rwe (Chart SP-1)
Rmfe SSP = - K log Rwe Geosciences – Reservoir Engineering
K = 61+.133∗ T (°F) K = 65+.240∗T (°C)
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
• Determine Rw (Chart SP-2)
ESTIMATION OF SHALE CONTENT FROM SP
Estimation of VSH SP log SSP
from SP log
Static SP
PSP
Pseudo SP
SP Shale Baseline
VSH
Geosciences – Reservoir Engineering
SP
=1−α =1−
PSP SSP - PSP = SSP SSP 115
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SSP - PSP
Geosciences – Reservoir Engineering
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Notes
RESISTIVITY MEASUREMENTS
Geosciences – Reservoir Engineering
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RESISTIVITY LOGGING Rt, Rxo
RESISTIVITY MEASUREMENTS
• • • •
Detect the presence of hydrocarbon in the reservoirs (Water-HC Contact ) Determine the resistivities Rt and Rxo and estimate the invasion diameter Di Determine the hydrocarbon saturation in the virgin zone ( Shc = 1-Sw ) Determine the residual hydrocarbon saturation in the flushed zone ( Shr = 1-Sxo )
•
But be careful, because … – The formation resistivity varies also with the formation porosity – The true resistivity Rt depends also on the resistivity Rw of the water in the reservoirs, which is also function of the water salinity and the formation temperature.
Rw a Rt = m × n φ Sw Geosciences – Reservoir Engineering
R xo
118
a R mf = m× n φ S xo Well Log Interpretation – PDVSA – January 2007
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OBJECTIVES: The standard measurements of formation deep , shallow and micro resistivities or the multiple depth of investigation Laterolog or Induction logs are used to :
INDUCTION
Geosciences – Reservoir Engineering
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INDUCTION
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Notes
INDUCTION TOOLS AND LOGS •
INDUCTION TOOLS and Associated INDUCTION LOGS :
– – – – – – – •
Early Tools (1952…) : IES => ILD, SN Induction Tool IRT (1959 ) (6FF40) => ILD , LL8, SP Dual Induction Tool DIT(1962) => ILD, ILM, SFL, SP Phasor Induction Tool DITE => IDPH, IMPH, SFL , SP Array Induction Tool AIT (1992) => AH90, 60, 30, 20, 10” , SP (Schlumberger) HDIL => 120, 90, 60, 30, 20, 10” Investigation and 3DEX(Rv-Rh) (Baker Atlas) HRAI-X => 120, 90, 60, 30, 20, 10” Investigation (Halliburton LS )
Obtention of Deep Resistivities ( ILD, 90 or 120” Induction log ) and Intermediate ( ILM , SFL, AIT logs 60, 30,20,10 ) in the following cases :
•
Best conditions for Induction :
– Low or not too high formation Resistivities – Fresh water based mud and formation containing salty water – High ratio Rxo/Rt ( Rxo > 2 * Rt )
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– Drilling with Oil based Mud (OBM) – Drilling with fresh or low salinity water based mud (WBM) – Drilling with air or foam
INDUCTION-SFL PRINCIPLE Induction Principle (2 Coils)
SFL Principle Spherically Focused log
Gi = Geometrical Factor of Zone i
Ca = Gm * Cm + Gxo * Cxo + Gt * Ct Geosciences – Reservoir Engineering
Ci = Conductivity of Zone i ( mmho/m) 122
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(Water based mud only )
ARRAY INDUCTION SONDE AND LOG 28 Array signals
Borehole correction
Software focusing
Computed Products
Receiver Electronics
R1
8 arrays 2 frequencies R2
20 30
R3
60
R4 R5 Transmitter
90
R6 R7 R8
Transmitter Electronics
Schlumberger document
123
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© 2006 ENSPM Formation Industrie - IFP Training
R & X signals
10
HDIL INDUCTION LOG
HDIL Log Example
Rxo Rt
20
Di
30 60 90 120
Baker Atlas document Geosciences – Reservoir Engineering
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10
LATEROLOG
Geosciences – Reservoir Engineering
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LATEROLOG
Geosciences – Reservoir Engineering
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Notes
•
LATEROLOG TOOLS and LOGS – Early Devices : Normal and Lateral, LL3, LL7 – Dual Laterolog (DLT) => LLDeep , LLShallow – Azimuthal Laterolog ARI => LLD, LLS, LLHR , Images – HDLL : High resolution and multiple depths of investigation ( Baker Atlas) – Obtention of Deep Resistivity (LLD) and Intermediate resistivity (LLS) of the formations in the case of wells drilled with water based mud ( WBM)
•
Applications : – Determination of the Water–Hydrocarbon contact (Rt Rxo Overlay) – In combination with the microresistivities and after environmental correction, determination of Rt and Di – Computation of Sw and Shc
•
Best results are obtained – If the ratio Rxo / Rt is low ( Rxo < 2 * Rt ) – If the formations have high resistivity
•
Limitations : – Only used in water based mud 127
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LATEROLOG TOOLS AND APPLICATIONS
BASIC NORMAL & LATERAL RESISTIVITY MEASUREMENTS
Geosciences – Reservoir Engineering
LATERAL
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NORMAL
LATEROLOG TOOL SCHEMA OF THE DUAL LATEROLOG TOOL LLs
LLd
A2
A’2
Schlumberger Tool
Ji = Pseudo-Geometrical Factor of zone i
Ra = Jm * Rm + Jmc * Rmc + Jxo * Rxo + Jt * Rt Geosciences – Reservoir Engineering
Ri = Resistivity of zone i ( mmho/m)
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A1 M2 M1 A0 M’1 M’2 A’1
ARI – AZIMUTHAL RESISTIVITY IMAGER LLd and deep azimuthal resistivity
LLs and azimuthal electrical standoff
A2
A’2 Schlumberger Tool
ELECTRODES CONFIGURATION Geosciences – Reservoir Engineering
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A1 M2 M1 A0 M’1 M’2 A’1
MICRORESISTIVITY
Geosciences – Reservoir Engineering
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MICRORESISTIVITIES
Geosciences – Reservoir Engineering
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Notes
MICRORESISTIVITY MEASUREMENTS •
TOOLS AND LOGS – – – – –
•
Proximity log MICROLOG or MINILOG MICROLATEROLOG Tool SRT Tool , combined with the DLT PEX Tool
=> PL (Obsolete) => MINV, MNOR (Micro-Inverse and Micro-Normal ) (Schlumberger (obsolete) , Baker Atlas) => Log MLL => log MSFL (Micro-Spherically Focused Log ) ( Schlumberger, HLS) => log MCFL (Micro-Circumferential Focused Log ) ( Schlumberger)
APPLICATIONS – Obtention of the Resistivity Rxo of the flushed zone : –
Rxo = MSFL or MLL or MCFL corrected for mudcake effect (Thickness hmc and Resistivity ) Identification of Water-Hydrocarbon contact ( Rt-Rxo Overlay technique) Estimation of residual hydrocarbon saturation Shr Detection of permeable zones ( Microlog) Detection of fractures
– – – –
•
Limitations : – Measurements only available in wells drilled with water based mud
•
Logs very sensitive to bad holes ( caves, rugosity ) 133
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Rmc
MICRORESISTIVITY MEASUREMENT : MSFL MICRO-SFL SCHEMA SRS (Old Tool) (4 arms )
Mud
A1
Mudcake
M0 A0 Monitor Electrodes Monitor Voltage
Schlumberger document Geosciences – Reservoir Engineering
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Measure Voltage
MICRORESISTIVITY MEASUREMENT : MCFL Tool combining Litho-Density and Microresistivity
HRMS : High Resolution Mechanical Sonde
• • • •
LS – Long Spacing Detector (Densité) SS – Short Spacing Detector (Densité) BS – Back Scatter Detector (Densité) MCFL – Micro-cylindrical focused Log.
Hinge Joints
Schlumberger
135
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Hinge Joints
MICRORESISTIVITY MEASUREMENTS MICROLOG and PROXIMITY LOG
MNOR
MINV
COMPARISON OF CURRENT LINES Geosciences – Reservoir Engineering
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MICROLATEROLOG and MICROLOG
DLL-MSFL LOG EXAMPLE 20000 2000
20
20000 10000
High resistivities in Tight formations
137
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Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
INVASION PROFILE => Reservoir
DLL-MSFL-MICROLOG EXAMPLE Use of Microlog for accurate reservoir identification
MNOR MINV
Separation MNOR_MINV => Permeable Zone
GR
SP
Geosciences – Reservoir Engineering
LLD-LLS-MSFL Separation ? INVASION PROFILE ? => Reservoir ??
High resistivities in Tight formations
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Mudcake
DLL-MSFL Geosciences – Reservoir Engineering
Array Induction Log 139
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© 2006 ENSPM Formation Industrie - IFP Training
Comparison : DLL-MSFL and Array Induction
Geosciences – Reservoir Engineering
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ARI - AZIMUTHAL RESISTIVITY IMAGER
CHOICE OF RESISTIVITY TOOLS Rmf > 2*Rw Rxo > 2*Rt
Fresh Water
Rxo
Based
Rxo
Mud
Rxo/Rt > 2
Rt
Rt
If Sw = 1
Î INDUCTION + MSFL or MLL
Saline Water
Rt
Based Mud
Rxo/Rt < 2
Î LATEROLOG Rxo
+MSFL or MLL
Rxo
141
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Rt
Rmf < 2* Rw Rxo < 2* Rt
CHOICE OF RESISTIVITY TOOLS
(Rxo) Rt
Rt
Geosciences – Reservoir Engineering
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Î INDUCTION
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© 2006 ENSPM Formation Industrie - IFP Training
(Rxo)
Oil Based Mud
CHOICE OF RESISTIVITY TOOLS: LATEROLOG OR INDUCTION Case of Water based Mud
30
INDUCTION LOG PREFERRED ABOVE APPROPRIATE RW CURVE
Porosity (%)
20
RW = 1 Ω - M
LATEROLOG PREFERED 10
Schlumberger document
RW = 0.01 Ω - M
0 .5
.7
1.
2.
3.
5.
10.
20.
30.
Rmf / Rw Geosciences – Reservoir Engineering
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RW = 0.1 Ω - M
Geosciences – Reservoir Engineering
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Notes
POROSITY-LITHOLOGY MEASUREMENTS
POROSITY-LITHOLOGY MEASUREMENTS
Geosciences – Reservoir Engineering
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DENSITY – NEUTRON – SONIC NUCLEAR MAGNETIC RESONANCE
POROSITY-LITHOLOGY MEASUREMENTS
Geosciences – Reservoir Engineering
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DENSITY LOGGING
DENSITY TOOL PRINCIPLE PRINCIPLE OF DENSITY MEASUREMENT : Gamma Rays emitted by a Cesium 137 radioactive source located in the Density tool enter in collision with electrons surrounding the atoms of the formation and loose energy. These GR are counted after interactions on 2 detectors situated on the Density tool above the source . The tool is pushed against the formation by a caliper arm and the two detectors are in close contact with the formation. From these count rates, the electronic density the formation can be obtained. ρ = ρ * 2 Z el
ρ
el
and then the bulk density ρb of
ρ b = 1.0704 * ρ el − .1883
A
b
(Z : Atomic Number, A : Atomic Weight ; 2Z/A close to 1)
For quality control, the density correction ∆ρb which is applied to the ρb log is also displayed. Since 1980 , the Litho-Density tool provides also a Photoelectric Absorption Factor curve Pe. 147
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Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
The mudcake effect is compensated by the measurements on both detectors.
LITHO-DENSITY TOOL Invaded Zone
Virgin Zone
Mud cake
γRay
D
Far Detector Measure Point
D
137Cs
Source
S
HRMS : High Resolution Mechanical Sonde (Recent) • • • •
Litho-Density Tool
LS – Long Spacing Detector (Density) SS – Short Spacing Detector (Density) BS – Back Scatter Detector (Density) MCFL – Micro-cylindrical focused Log. Schlumberger Document
Density Tools and Logs FDC : Formation Density Compensated => Logs RHOB et DRHO LDT : Litho-Density Tool (> 1980)
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=> Logs RHOB , DRHO et PEF 148
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Near Detector
DENSITY AND PEF MEASUREMENTS 2 different energy windows
SOURCE Low Energy Window High Energy Window DENSITY Information
DETECTORS ENERGY LOSS ABSORPTION (Photoelectric Effect) 149
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PEF & DENSITY Information
GR of known Energy
DENSITY AND PEF VALUES Photoelectric Absorption Factor
⎛Z⎞ Pef = ⎜ ⎟ ⎝ 10 ⎠
3,6
Density
PEF is function of the lithology and the values are little affected by the fluids ( See chart PEF – RHOB) => Warning : Pef is very sensitive to the presence of Barite , therefore it might be reading too high and be wrong
ρ b = (1 − Φ u )ρ ma + Φ u ρ f .
For clean formations , without shale ( Vsh = 0 )
Density varies with Lithology, Porosity, Fluid density
PEF (barn/e)
Limestone (CaCO3)
5.1 (5.1 –> 4.4)
2.71 g/cm3
Dolomite (CaCO3, MgCO3)
3.1 (3.1 –> 2.7)
2.85 g/cm3
Sandstone ( SiO2)
1.8 (1.8 –> 1.6)
2.65 g/cm3
Salt (NaCl)
4.7
2.04 g/cm3
Anhydrite (CaSO4)
5.1
2.98 g/cm3
Pyrite (FeS2)
17
4.99 g/cm3
Barite (BaSO4)
267
4.09 g/cm3
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Density ρma
MINERAL
(Schlumberger document )
151
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DENSITY CORRECTION
DENSITY AND PEF LOGS : LITHO-DENSITY LOG
BIT SIZE
RHOB DRHO PEF
(LDL – CNL Schlumberger Log Example )
Density and PEF are very sensitive to presence of caves Equivalent for Baker Atlas => ZDL Tool => ZDEN ( Bulk Density) and ZCOR ( Density Correction) Equivalent for Halliburton => SSDL Tool Geosciences – Reservoir Engineering
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CALIPER
ESTIMATION OF POROSITY FROM DENSITY LOG Vt = 1
For clean formations , without shale ( Vsh = 0 )
Φu
ρ b = (1 − Φ u )ρ ma + Φ u ρ f . ρb
: Density log
ρma Φu
1-Φu
Φ U(D) =
ρ ma − ρ b ρ ma − ρ f
Lithology
Density ρma
: Matrix density
Limestone (CaCO3)
2.71 g/cm3
Dolomite (CaCO3, MgCO3)
2.85 g/cm3
: Formation Porosity
Sandstone ( SiO2)
2.65 g/cm3
( PHID ou DPHI )
Φu
In Water zone
ρf = ρ
In Hydrocarbon zone
ρf = Sxo * ρ
MF
Mud Filtrate Density
mf
+(
Φu
1- Sxo ) * ρhc HC
ρmf = 1 + 0.7 * P
MF
P = Salinity ( kppm) *10-3 153
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mf
POROSITY FROM DENSITY LOG Determination of Porosity from the Density log
ρfl = 1.0
In the case of Clean formation ( Vsh = 0 )
Porosity
and in Water Zone Porosity = 25 %
Φ U(D) = Sandstone line Porosity = 14 %
ρ ma − ρ b ρ ma − ρ f
Mud Filtrate Density
ρmf = 1 + 0.7 * P ρma = 2.65 g/cc
ρb = 2.42 g/cc
Example 1 :
(Schlumberger Chart )
Example 2 :
Limestone formation
Sandstone formation
ρb = 2.31 g/cm3
ρb = 2.42 g/cm3
ρma = 2.71 g/cm3 ( Calcite )
ρma = 2.65 g/cm3( Quartz )
ρf = 1.1 g/cm3 ( Salt mud)
ρf = 1.0 g/cm3 ( Fresh mud)
Formation porosity = 25 p.u Geosciences – Reservoir Engineering
P = Salinity ( kppm) *10-3
Formation porosity = 14 p.u
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RHOB
PEF versus RHOB ρ
b
Pef
(Schlumberger Chart )
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Porosity
VOLUMETRIC PHOTOELECTRIC ABSORPTION FACTOR Combination of RHOB and PEF
U = Pe * ρ el = Pe * (
ρ b + 0.1883 ). 1.0704
Used in Multimineral log Interpretation
Lithology
Uma ( barn/cm3)
Log response similar to RHOB :
Limestone (CaCO3)
13.8
U = (1 − Φ u )U ma + Φ u U f .
Dolomite (CaCO3, MgCO3)
9.0
Sandstone ( SiO2)
4.78
Fluid
Uf ( barn/cm3)
Fresh Water ( H2O)
0.398
Salty Water ( 120 Kppm )
0.85
Oil ( 0.85 g/cm3)
0.136
In Water zone
Uf = U
In Hydrocarbon zone
Uf = Sxo * U
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mf
mf
156
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U = Volumetric Photoelectric Absorption Factor ( Barn/cm3)
POROSITY-LITHOLOGY MEASUREMENTS
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NEUTRON LOGGING
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Notes
NEUTRON TOOL PRINCIPLE PRINCIPLE High energy Neutrons are emitted from an Am-Be chemical radioactive source into the formation. After collisions with atoms, neutrons loose energy. They are mainly slowed down by Hydrogen atoms which have the same mass. Neutrons having reached an epithermal or a thermal energy level are counted on 2 detectors situated on the neutron tool above the source.
In a clean fresh water bearing limestone, which is the reference matrix for neutron calibration, the Neutron Porosity Hydrogen Index NPHI recorded in Limestone Matrix corresponds to the porosity of the Limestone. (Master Calibration Pit in Houston ) In the case of different lithology ( Sandstone or Dolomite ) or type of fluid (Salty water , Oil or Gas ) , a correction will have to be applied to the NPHI log to obtain the formation porosity.
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The Hydrogen Index HI which represents the amount of Hydrogen atoms in the formation is derived from the ratio of the neutron counts on both detectors.
NEUTRON TOOL Invaded Zone
Virgin Zone
Mud cake
Example of Compensated Neutron Tool CNT (Schlumberger)
Far Detector (25’’) Measure Point Near Detector (15’’)
Tool Excentraliser
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Am - Be Neutron Source
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Neutron path
NEUTRON TOOLS AND LOGS Schlumberger Tools and Logs : SNP : Sidewall Neutron Porosity Tool (obsolete) - Epithermal Neutrons => Log in API Units CNT : Compensated Neutron Tool - Thermal Neutrons => Logs NPHI Neutron Porosity Hydrogen Index or TNPH Thermal Neutron Porosity Hydrogen ( Index ) in % or V/V or Porosity Units Pu - No Chemical source but Neutrons generated by Minitron - Epithermal & Thermal Neutrons => Log APLC and SIGMA ( Capture crossection) Equivalent for Baker Atlas => CN Tool => CNCF ( Field Normalized Compensated Neutron Porosity) 161
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APS : Accelerometer Porosity Sonde (> 1990)
NEUTRON SLOWING DOWN AND CAPTURE PROCESS FAST NEUTRON
Emission of High energy Neutrons =>
E = 4 à 6 MeV
SLOWING DOWN
THERMAL NEUTRONS DIFFUSION
E = 0.1 à 100 eV
E = 0.025 eV
NEUTRON CAPTURE
γ Geosciences – Reservoir Engineering
γ
γ 162
=> Emission of Gamma Rays
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EPITHERMAL NEUTRONS SLOWING DOWN
NEUTRON CALIBRATION Installation of Neutron Source in the Tool
Before Survey Calibration of Neutron Tool
Source Container
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Calibration Jig
FACTORS AFFECTING NEUTRON MEASUREMENTS Linked to Recording - Time Constant - Logging Speed - Dead Time – Detector - Bed Thickness
Linked to the Borehole Environment - Mud Salinity and Density (Presence of Barite) - Mud Filtrate Salinity - Hole Diameter - Tool Standoff - Presence of mudcake - Presence of casing - Invasion Diameter - Pressure and Temperature Geosciences – Reservoir Engineering
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- Drilling fluid type (WBM, OBM)
NEUTRON LOG EXAMPLE ( Schlumberger) Units : % ou PU (0-100) ou V/V (0 --1)
Neutron Log is affected by caves
Cave NPHI
Caliper
Neutron Log corrected for Hole size during acquisition process. (Hole Correction : CALI)
Acquisition parameters
NPHI recorded in OPEN Hole BHS = Borehole Status = OPEN
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Neutron log NPHI recorded in Limestone Matrix MATR = LIMEstone
NEUTRON LOG EXAMPLE (Baker Atlas)
Bulk Density ZDEN
Neutron Porosity CNCF
DPIL Induction log
Neutron Log corrected for Hole size during acquisition process. (Hole Correction : CALI)
Log recorded in Venezuela Geosciences – Reservoir Engineering
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Neutron log NPHI recorded in Sandstone Matrix MATR = SANDSTONE
ESTIMATION OF POROSITY FROM NEUTRON LOG For clean formations , without shale ( Vsh = 0 )
Φ N = (1 − Φ u )Φ Nma + Φ u Φ Nfl : Neutron log
ΦNma
: Neutron matrix
ΦNfl
: Neutron fluid
Φu
: Formation Porosity
Φ N − Φ Nma Φ Nfl − Φ Nma
MINERAL
Φ
Limestone (CaCO3)
0.00
Dolomite (CaCO3, MgCO3)
0.03 (0.01 for TNPH)
Sandstone ( SiO2) Salt (NaCl) Anhydrite (CaSO4)
Nma
- 0.02 - 0.03 - 0.02
In Water zone
ΦNfl
In Hydrocarbon zone
ΦNfl = Sxo * ΦNmf + ( 1- Sxo ) * ΦNhc
= ΦNmf
Mud Filtrate Neutron response
Hydrocarbon Neutron response
ρmf = 1 + 0.7 * P P = Salinity ( kppm) *10-3
ΦNmf = ρ
mf
(V/V)
( 1- P )
If
ρ
hc
< 0.25
=>
ΦNhc = 2.2 * ρ
If
ρ
hc
>= 0.25
=>
ΦNhc = 0.3 + ρ
hc
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hc
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ΦN
Φ u(N) =
FORMATION POROSITY FROM NEUTRON LOG SS + Water
TNPH 250 kppm
Porosity
LS + Water
Determination of Porosity from Neutron Log NPHI or TNPH, recorded in Limestone matrix
TNPH 0 kppm
NPHI
Porosity = 24 p.u. DOLOMITE + Water
TNPH 0 kppm
Porosity = 22.5 p.u.
Example 1 :
NPHI
Sandstone formation with a water salinity of 20 kppm NPHIcor = 18 p.u. in limestone lithology True porosity = 22.5 p.u
Example 2 : Sandstone formation with a water salinity of 250 kppm TNPHcor = 18 p.u. in limestone lithology Corrected NPHI or TNPH
True porosity = 24.0 p.u
(Schlumberger Chart) Geosciences – Reservoir Engineering
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TNPH 250 kppm
APS CONFIGURATION Sensors and Measurements
Curves and products
Electronic neutron source Minitron
Near-array epithermal ratio porosity Hydrogen index measurement
Near epithermal detector Count Rate
Epithermal slowing-down time Standoff determination
Array epithermal Count Rate Time Distribution
Near-far ratio Lithology indicator Stand-alone gas indicator (in clean formations)
Far epithermal detector Count Rate
(Schlumberger) Geosciences – Reservoir Engineering
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Thermal neutron decay rate Formation capture cross section (sigma) of invaded zone
Array thermal Count Rate Time Distribution
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Notes
POROSITY-LITHOLOGY MEASUREMENTS
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SONIC LOGGING
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Notes
SONIC PRINCIPLE • SONIC PRINCIPLE Sonic logging tools emits from a transducer T1 a compressionnal sound wave in the borehole. The sound travels through the mud and the formation and reaches 2 receivers R1 and R3 generally spaced 2 feet apart and situated at a distance of 5 and 3 feet from the transducer. The slowness DT expressed in µs/ft corresponds to the time it takes for the sound to travel through one foot of formation. It is the inverse of the velocity of the compressionnal sound wave.
The borehole compensated sonic BHC for sonde tilt is obtained by doing a second measurement from another transducer T2 to another pair of receivers R4 and R2 situated very close to the previous ones, and by taking the average the 2 measurements . From the processing of the 8 waveforms recorded from 8 receivers on an array sonic or a dipole sonic , the DT shear slowness and the Shear velocity can also be obtained. 173
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It is obtained by the difference in the arrival times of the sound wave at the two receivers.
SONIC DT MEASUREMENT (BHC) Shema of the BoreHole Compensated Sonic BHC
(T R − T R ) + (T2 R 4 − T2 R 2 ) ∆t = 1 1 1 3 4 µs/ft
T2
Compensation for sonde tilt
T1R1 – T1R3 T1R1 R1 R2
Threshold detection
2ft
T1R3
R3 5ft
R4
To
3ft
To
Time in µs
Velocity( m / s ) =
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T1
SONIC BHC LOG
ITT Integrated
Tension
ITT
Transit Time in ms
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Sonic DT
SONIC LOG QUALITY CONTROL FACTORS AFFECTING THE SONIC LOG Cycle Skipping
• Linked to detection • Cycle skips ( Weak signal ) • Noise • Stretch
Noise Detection
• Linked to Formations • Undercompacted shales • Unconsolidated sandstone • Formations with high porosity • Formation with gas
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• Linked to travel path of sound wave • Caves • Damaged borehole and borehole rugosity
SONIC LOG QUALITY CONTROL EXAMPLE OF SONIC LOG WITH ANOMALIES DT
Caliper Cycle Skip or Noise
Watch also for errors when splicing subsequent logging runs !
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Sonic Logs must always be checked and eventually edited before use !
SONIC LOG QUALITY CONTROL TT1, 2, 3, 4
DT (BHC)
Noise on TT3 => DT bad
EXAMPLE OF BAD SONIC LOG
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DT (Bad)
Display of IndividualTtransit Times TT’s helps identification of bad zones
SONIC LOGGING TOOLS ARRAY Mode DTCO, DTSM
Dipole Transducer
12 ft 10 ft 10 ft
U_Dipole Monopole P
DDBHC
DDBHC
DDBHC
DDBHC
3-5 ft
5-7 ft
8-10 ft
10-12 ft
DT
DTL
DTLN
DTLF
DT2
DTCO, DTSM, Monopole ST
L_Dipole
DTST
Borehole Compensated
Array SONIC
Sonic BHC (3-5ft)
SDT
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DT1
Dipole SONIC (Schlumberger)
179
DSI
(Schlumberger)
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8 ft
Slow ( Soft ) Formation
Fast ( Hard ) Formation
Compressional Monopole
Compressional Monopole
Flexural Wave from
P & Stoneley waves
P & Refracted Shear waves
Dipole Transducer
DSI
DSI
DSI
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MONOPOLE - DIPOLE SONIC MODES
DIPOLE STC PROCESSING
8 Waveforms From 8 receivers Poisson Ratio
DSI
DTS
DTC
DTS
STC Slowness - Time Processing DSI
DTc & DTs Results
DTS Projection Plane
DSI
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Coherence
SLOWNESS EVALUATION DSI Log
Compressional DT : Dt or DTCO or LSDT
Monopole Compressionnal and Monople Stoneley
DTST = DT Stoneley
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DTSM = DT shear (Refracted )
SONIC APPLICATIONS • APPLICATIONS • DT is an essential measurement for the geophysicist : • Sound velocity in the geological formations • Time–depth relationship (Time = f(Depth) and Time-Depth conversion • Comparison of Log and Seismic data • Determination of the porosity of reservoirs • Determination of lithology ( DT combined with Density or Neutron; DTc vs DTs)
• Anisotropy, main stresses from Cross-Dipole Sonic measurements. • Facture identification from Stoney waves • In cased hole, DTc (from WF) or CBL for cement evaluation ( Cement Bond Log )
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• Combining Density, DTc and DTs , rock mechanical properties can be derived (Rock Strength, Earth Stress, Rock Failure) and used for Sanding prediction, Hydraulic fracture height, Wellbore stability .
STONELEY WAVEFORM APPLICATION FRACTURE IDENTIFICATION IN OPEN HOLE
Chevrons patterns on Stoneley Variable Density Log (VDL) due to presence of Fracture
Fracture
STONELEY WAVE FROM DSI Geosciences – Reservoir Engineering
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Stoney reflection coefficent
POROSITY FROM SONIC
∆t p = (1 − Φu) ⋅ ∆t ma + Φu ⋅ ∆t f
( Time Averaged)
Φ u(S) =
In the case of Clean formation ( Vsh = 0 )
∆t − ∆t ma 1 × ∆t f − ∆t ma Bcp
1 < Bcp< 1.6
( Φu 1 1 − Φu ) = + ∆t ∆t ma ∆t f ∆t - ∆t ma Φ u(S_RH) = K × ∆t 2
Raymer, Hunt & Gartner Formula ( Field Observation) Simplified RHG Formula
Sonic ∆tcma ( µs/ft)
Lithology
Compaction factor
K = 0,625
Fluid
Sonic ∆tfl ( µs/ft)
Limestone (CaCO3)
49
Water
189 (180-200)
Dolomite (CaCO3, MgCO3)
44
Oil
200-220
Sandstone ( SiO2)
56
Gas
> 250 ( -> 500)
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Wyllie Formula
POROSITY FROM SONIC PHIS Wyllie = ( DT - Dtma ) / ( DTfl - Dtma ) x ( 1/Bcp )
Determination of Porosity from the Sonic log
PHIS RH* = K * ( DT - Dtma ) / DT
In the case of Clean formation ( Vsh = 0 )
(Schlumberger Chart Por-3)
Sandstones Limestones Dolomites
Sonic Velocity ft/s 18000 - 19500 21000 - 23000 23000 - 26000
∆ Tma µs/ft 55,6 51,3 47,6 43,5 43,5 38,5
Sonic Velocity m/s 5486 - 5944 6401 - 7010 7010 - 7925
∆ Tma µs/m 182,3 - 168,2 156,2 - 142,6 142,6 - 126,2
20000 14925
50,0 67,0
6096 4549
164,0 219,8
Anhydrite Salt Geosciences – Reservoir Engineering
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Example : DT = 76 µs/ft ( 249 µs/m ) SVma = 18000 ft/s ( 5486 m/s ) Sandstone Thus Porosity = 15 % by time average or 18% by field observation method) * RH = Raymer-Hunt
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Bcp
• Compressionnal and Shear Waves • Compressionnal Waves (P) • Shear Waves (S)
Dtp, Vp Dts, Vs
• OTHER WAVES • Pseudo-Raylegh Waves • Stoneley Waves • Direct propagation in the mud
VPR VSt Vf
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ACOUSTIC WAVES
ROCK MECHANICAL PROPERTIES 4 K+ µ µ 2 2 3 Shear velocity : Vs = Compressionnal velocity : Vp = ρb ρb ELASTIC CONSTANTS AND RELATION WITH Vp and Vs
• Bulk Modulus
• Young’s Modulus
• Poisson’s Ratio
Geosciences – Reservoir Engineering
µ = ρ b Vs2 4 ⎞ ⎛ K = ρ b ⎜ Vp2 − Vs2 ⎟ 3 ⎠ ⎝ ρ b Vs2 3Vp2 − 4Vs2 9Kµ E= E= Vp2 − Vs2 3K + µ 2 2 1 ⎛⎜ Vp − 2Vs ⎞⎟ 3K - 2µ ν= ν= 2 ⎜⎝ Vp2 − Vs2 ⎟⎠ 2(3K + µ)
(
188
)
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• Shear Modulus
POROSITY-LITHOLOGY MEASUREMENTS
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NUCLEAR MAGNETIC RESONANCE LOGGING
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Notes
NMR MEASUREMENT PRINCIPLE Tool principle and measurements: Spin excitation at resonance frequency of the protons (mainly H nuclei) under an electro-magnetic field.
Computed Parameters T1 Longitudinal Relaxation Time (ms) Identification of hydrocarbon fluids in non-wetting phase
D Fluid Diffusivity It helps to differentiate gas phase and liquid phase. The tool response is mainly influenced by the pore size distribution and the type of fluids (independently of the lithology). The data are directly comparable to core measurements. Geosciences – Reservoir Engineering
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T2 Transversal Relaxation Time (ms) - (T2lm : logarithmic mean of T2) This rate of the decay of transverse magnetization depends on the ratio surface/volume of the pores Rapid decay time for small pores and slow decay time for large pores.
NMR TOOL AND PRINCIPLE CMR TOOL
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(Schlumberger)
NMR RESULTS Results : The tool responds mainly to the quantity of Hydrogen atoms present in the fluids. It allows : - the evaluation of the - Total Porosity - Effective Porosity, - Irreducible water volume (or "Capillary Bound Water" BVI), - Free Fluid volume (FFI), - Clay Bound water volume The pore size distribution is derived through various T2 cut offs.
K = a⎜ ⎟ ×⎜ ⎟ ⎝ 10 ⎠ ⎝ BVI ⎠
SDR Schlumberger
(b=4,c=2)
K = a × PHI b × T2 lm
c
- the determination of the type of Hydrocarbons (Gas/Oil identification). Geosciences – Reservoir Engineering
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- the evaluation of the permeability of the formation through various relationships such as : 4 2 ⎛ PHI ⎞ ⎛ FFI ⎞ Timur Coates Law
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NMR TOOL AND PRINCIPLE
NMR LOG EXAMPLE Permeability
NMR Signal
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Porosity
NMR MODEL NMR POROSITY MODEL MATRIX
DRY CLAY
CLAY BOUND WATER
CAPILLARY BOUND WATER
MOBILE WATER
HYDROCARBON
Vt
Total Porosity Irreducible Water
Vw_sh
Viw
Total Porosity =
Effective Porosity =
Geosciences – Reservoir Engineering
Free Fluids
Vw Effective Porosity
Vhc
Vw_sh + Viw + Vw + Vhc Vt Viw + Vw + Vhc Vt 196
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Bound Water
DIPMETER AND BOREHOLE IMAGING
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DIPMETER AND BOREHOLE IMAGING
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Notes
DIPMETER TOOLS
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STRATIGRAPHIC HIGH RESOLUTION DIPMETER TOOL
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DIPMETER LOG
ELECTRICAL AND ACOUSTIC IMAGING TOOLS Formation Micro-Imager Tool
Ultra-Sonic Borehole Imager ( UBI)
Schlumberger Document
Schlumberger Document
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Acoustic Transducer
BOREHOLE IMAGING FROM FMS TOOL
FORMATION MICRO SCANNER
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Images from 2 pads
BOREHOLE IMAGING
FORMATION MICRO IMAGER Dips from FMI Images 4 pad images
Schlumberger Document
203
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Sinusoid
Dips
BOREHOLE IMAGING RESULTS FMI
Image
ARI
Image
UBI
Image
Formation Micro-Imager Tool
Formation Micro-resistivity
Azimuthal Resistivity
Ultra-Sonic Borehole
Imager
Imager
Imager
Geosciences – Reservoir Engineering
Schlumberger Document
204
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Comparison between images from FMI, ARI and UBI
BOREHOLE IMAGING
Image from the Formation Micro-Imager tool
Bioturbation
Root Traces
Schlumberger Document
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Bioturbation and Root traces
BOREHOLE IMAGING Fossils Debris
Image from the Formation Micro-Imager tool
Intramoldic Porosity Vuggy Porosity
PinPoint Porosity
Schlumberger Document
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Intramoldic and vuggy porosity
BOREHOLE IMAGING
Image from the Formation Micro-Imager tool
Moldic Porosity
Schlumberger Document
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in a Dolostone
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208
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Notes
PRESSURE MEASUREMENTS AND FLUID SAMPLING
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PRESSURE MEASUREMENTS AND FLUID SAMPLING
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Notes
PRESSURE MEASUREMENTS AND FLUID SAMPLING GOALS
• Measurement of Formation Pressure • Estimation of Reservoir Permeability - Permeability from Drawdown - Permeability from Build-up (Horner plot) • Determination of fluid contacts • Evaluation of Pressure Gradients and Fluid Densities
• PVT Analysis
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• Sampling of Formation Fluids
PRESSURE MEASUREMENTS AND FLUID SAMPLING TOOLS Open Hole :
• Repeat Formation Tester RFT (Schlumberger) Open Hole / Cased Hole – 1 Probe - 2 Samples OLD
• Sampling Formation Tester SFT (Halliburton Logging Services) • Formation MultiTester FMT (Baker Atlas)
• Modular Formation Dynamic Tester MDT ( 3 probes - multi samples) and Slim Hole Repeat Formation Tester SRFT
(Schlumberger)
• Reservoir Description Tool RDT (Halliburton LS) • Reservoir Characterisation Instrument RCI ( Baker Atlas)
Cased Hole : Cased Hole Dynamic Tester CHDT ( Schlumberger)
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RECENT
RFT and MDT
Modular Dynamic Formation Tester
(Document Schlumberger)
213
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Repeat Formation Tester
OPERATION DU MDT MDT tool retracted
MDT tool set
Crystal Quartz Gauge
Crystal Quartz Gauge
Isolation valve
Isolation valve
Strain gauge
Equalizing valve
Pretest
Strain gauge
Pretest
Resistivity cell
Resistivity cell Backupshoe
Backupshoe
Invaded zone
Probe
Virgin zone
Invaded zone
Virgin zone
Packer
(from Schlumberger Document )
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Equalizing valve
MDT : PRESSURE GAUGES
(Document Schlumberger)
215
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Crystal Quartz Gauge
Strain Gauge
MDT : Pressure Test Records Pressure Record with SGP gauge
Pressure Record with SGP and HP gauges HPGP
Time
SGP
HPGP
Hydrostatic Pressure after
Formation Pressure
Time SGP Strain gauge pressure
Pressure Buidup
Formation Pressure
SGP
Drawdown
Hydrostatic Pressure before
Pressure Buidup
Drawdown
Hydrostatic Pressure before
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Pretest
RFT : Pressure Plot vs Time Example of Medium Permeability Formation RFT Pressure test record PLOT : HP Pressure Versus TIME
Formation Pressure
Hydrostatic Pressure before test
Hydrostatic Pressure After test Pressure Buidup
Drawdown
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Pretest
Pressure profiles according to permeability HIGH PERMEABILITY
MEDIUM PERMEABILITY
LOW PERMEABILITY
Pressure Buidup with slow pressure stabilisation
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Pressure Buidup with fast pressure stabilisation
Permeability estimation from drawdown
PF1
P1
t1
K=
t2
C * 4388 * q * µ DP
PF2
K = Permeability µ = Fluid Viscosity
DP = P1 – PF1 (psi)
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Q = Flow rate (cm3/s)
Pressure gradients and fluid density True Vertical Depth
Formation Pressure
FLUID DENSITY =
PRESSURE GRADIENT (PSI/Ft) 0.433
FLUID DENSITY =
PRESSURE GRADIENT (PSI/M) 1.422
(WEC Algérie 1979)
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Hydrostatic Pressure
Pressure measurements and fluid sampling Possible MDT Configurations
(Document Schlumberger)
221
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Dual Packer Module
Pressure measurements and fluid sampling Optical Fluid Analyser
Pumpout Module
(Document Schlumberger)
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222
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Flow Control Module
LWD
223
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ADN - CDR
(Schlumberger)
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LOGGING WHILE DRILLING
LWD
RAB : Resistivity at the Bit
Geosteering Tool (Schlumberger)
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ISonic
LOG INTERPRETATION
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LOG INTERPRETATION
QUICKLOOK
QUICKLOOK
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LOG INTERPRETATION
LOG INTERPRETATION FLOW CHART DATA QUALITY CONTROL RESERVOIR/NON RESERVOIR IDENTIFICATION TIGHT FORMATIONS
SHALES
Marls
Sandy Shales
Clean Reservoirs
Shaly Reservoirs
Rt / Rxo Comparison
PS - GR SP Shale Base Line
Water Bearing zone
Quantitative Interpretation
Hydrocarbon bearing zone
Rt Rw = Rxo Rmf
Rw
Rw
Sw
Rw
N / D Comparison Checking
POROSITY 2
Rw = Rt.Φu Rmf = Rxo.Φu2 Geosciences – Reservoir Engineering
POROSITY
LITHOLOGY LITHOLOGY + FLUID SATURATION 227
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Pure Shales
RESERVOIR
QUICK-LOOK METHOD The Quick-Look method is a rapid interpretation method which is commonly used on the well site for a preliminary interpretation of the log : identification of shales and tight formations, determination of the reservoir characteristics. It is based on the use of a minimum set of conventional logs recorded in open hole and on certain assumptions : The logs used are : GR, Density and Neutron, a deep resistivity log and a micro-resistivity log for Rxo. Caliper which is usually run with these tools is also used, and also SP if it exists. Other data (Spectral Gamma Ray, Pef, Sonic ...) are also welcome if recorded! The following points are assumed : clean reservoirs, reservoirs containing formation water with a constant salinity, parameters m and n equal to 2 in the Archie resistivity formula, and the empirical relationship Sxo= Sw1/5. The main steps of the Quick-Look method are :
u
2
The limited amount of logs used does not enable log interpretation of complex lithology formations.In case of shaly reservoirs, the Quick-Look method gives altered conclusions, and only a quantitative interpretation can give satisfactory results. But the examination of these logs using this method enables a rapid log quality control.It may also be used before making a quantitative interpretation, and for a log sequence analysis, in conjunction with the cross-plot technique.
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• Reservoir delimitation, by identification of shale layers, tight formations and porous and permeable formations. • Rdeep and Rxo overlay in order to determine the hydrocarbon/water contact, and to estimate the Rw and Sw values by using a "5/8 logarithmic scale". This scale corresponds to the relationship between Sw and the Rt/Rxo ratio, which is obtained by the simplification of the Archie formulae which are applied to the flushed and the virgin zones. • Overlay of the Density and Neutron curves in order to determine the porosity of the reservoirs, and the type of lithology and the fluids contained in the pores. This visual analysis of the data may be related to the interpretation of the corresponding 2D crossplot. When these two curves are plotted in a "limestone L compatible scale", the porosity value ΦDLS computed from the density pb (in assuming a clean water bearing limestone reservoir) may be read directly on the Neutron porosity scale and thus corresponds to ΦNLS The distance between the two curves at a certain depth corresponds to the location on the cross plot of the corresponding point relating to the limestone curve. The reading of the porosity value on the Neutron porosity scale in the middle of the separation between the two curves corresponds to the ma ma iso-porosity curve of the Density-Neutron crossplot, the equation of which is : Φ = Φ N + Φ D
"QUICK LOOK " INTERPRETATION - OBJECTIVES •
Delimitation of reservoirs
•
Determination of Water – Hydrocarbon contacts (WOC / WGC)
•
Determination of formation water Resistivity ( Rw)
•
Identification of eventual Gas-Oil contact in HC zones
•
Determination of the lithology
•
Estimation of porosity in the different reservoir intervals
•
Estimation of the water and hydrocarbon saturations in the HC
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zones
"QUICK LOOK " INTERPRETATION - ASSUMPTIONS HYPOTHESES - ASSUMPTIONS – Reservoirs – Water wet – Water salinity is constant in a reservoir – Well drilled with water based mud – Mud filtrate salinity is constant over the processed interval – Formations are clean (No shale content : Vsh = 0)
– Saturation Formula = Archie Formula
– Relation between Sxo and Sw : Sxo = Sw1/5 – Density – Neutron are limestone or sandstone compatible – Resistivity scales are logarithmic
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– Saturation exponent n = 2
QUICKLOOK SEQUENCE 1/2 Non Reservoir identification Identification of Shales (Verification of D-N scales for matrix compatibility ) Identification of Tight formations Identification of Specific lithology (Salt , Anh , Coal , …) Reservoir identification
In water zone Determination of Rw from SP Determination of Rw using the resistivity Rt/Rxo Ratio Determination of Lithology and Quicklook Porosity from Density-Neutron Determination of Rwa from Rt and apparent D-N porosity Determination of Rmfa from Rxo and apparent D-N porosity Geosciences – Reservoir Engineering
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Determination of WOC in a reservoir using the Resistivity Overlay technique (Rt-Rxo)
QUICKLOOK SEQUENCE 2/2 In HC zone Quicklook Water saturation using the SW 5/8 ruler technique Identification of Gas-Oil contact , using D-N In Oil zone Determination of Lithology and Quicklook porosity Computation of Sw and Shc, Sxo and Shr In Gas zone Determination of Lithology and Quicklook porosity Computation of Sw and Shc , Sxo and Shr
Determination of the shale parameters Other Crossplots (D-S, N-S, PE-RHOB, K-TH …) Geosciences – Reservoir Engineering
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Crossplots Density-Neutron : Verification of lithology and porosity for the points in water, oil and gas zones .
QUICKLOOK : NON-RESERVOIR IDENTIFICATION Case of well drilled with water based mud and Rt and Rxo available “Reservoir identification <= ELIMINATION of Shales, Tight Formations, Salt, Anh, Coal..” Identification of Shales ( Log values here below are general average values) First : Verification of D-N scales for matrix compatibility Caliper : Caves GR : High values ( > 70 ) Deep, Shallow, and Microresistivity low ( < 20 ) and close to each other Neutron values : High ( > 30 % ) N-D separation higher than N-D separation observed in Dolomite (6 Divisions with RHOB-NPHI) SP (Shale baseline)
Caliper : close to BS GR : Low values ( < 30 ) Deep, Shallow, and Microresistivity high ( > 200 ) and close to each other Density, Neutron , Sonic : close to Matrix reference values: φNma, ρma, DTma Neutron low ( < 5% ) , Sonic low ( < 60 ) , Density High ( > 2.60) SP flat , similar to SP in Shale
Identification of Specific Lithologies (Salt , Anh ) Caliper : Close to BS , but caving can be observed in Salt GR : Low values ( < 30 ) Deep, Shallow, and Microresistivity high ( > 500 ) and close to each other Density-Neutron- Sonic : see reference values 233
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Identification of Tight formations ( not fractured)
DETERMINATION OF THE WOC : OVERLAY TECHNIQUE COMPARISON of Rt and Rxo logs – WATER ZONE :
Rt Rw = Rxo Rmf
LogRt − log Rxo = log Rw − LogRmf = Cons tan t
• Sw = 1 => Ratio Rw/Rmf = Rt/Rxo = Constant • Rt and Rxo are parallel and Rt can therefore be overlaid on Rxo over a significative interval
HYDROCARBON ZONE :
• Quick approximate estimation of Sw with 5/8 ruler −8 Rt Rw Sw 15 Rw ( )= = Sw 5 Rxo Rmf Sw Rmf
Rt Rw Sxo n ( ) = Rxo Rmf Sw
LogRt − log Rxo = log Rw − LogRmf − 8 / 5 log Sw 8 S [−Lo 5
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• Rt on the right of Rxo after overlay of Rt on Rxo in the water zone
QUICKLOOK INTERPRETATION : WOC and Sw Identification of the WOC using the quicklook overlay technique and Estimation of Sw with the Sw ruler exponent 5/8 RMLL ~ Rxo
RIND ~ RT 100 on shifted Rt
Sw~10%
Read Sw at intersection with Rxo : Sw ~ 50 %
2
1
5
20
10
50
100
Place « 100 » on shifted Rt
Hydrocarbon Zone
2
1
5
20
10
50
100
Rt Shifted to overlay Rxo in water zone
Water Zone
Sw Ruler exponent 1
2
1
5
20
10
22
11
50
55
100
10 10
20 20
50 50
100 100
Sw Ruler exponent 5/8
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WOC
QUICKLOOK INTERPRETATION : WOC and Sw Identification of the WOC using the quicklook overlay technique and Estimation of Sw with the Sw Ruler Exponent 5/8 Construction of the Sw ruler exponent 5/8
Step 2 : L = length * 1.6 ( 1.6 =8/5)
length
Step 1 : Sw Ruler exponent 1
2
1
5
2
1
20
10
5
50
100
20
10
50
100
Sw Ruler exponent 5/8 Example
1 2
10 20 50 10
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5
Step 3 : Graduation of the stretched scale
DETERMINATION OF HC TYPE, LITHOLOGY, POROSITY •
VERIFICATION OF D-N SCALES FOR MATRIX COMPATIBILITY (Limestone or Sandstone)
•
CLEAN WATER ZONE LITHOLOGY : Respective position of Density-Neutron curves ; confirmation with PEF, if available and valid. POROSITY : Reading on the Neutron scale of the value corresponding to the middle of the D-N separation
–
LITHOLOGY : (assumption) similar to lithology in water zone; Crosscheck with PEF
–
HYDROCARBON : Comparison N - D separation with DN separation observed in water zone => Identification of GOC
–
POROSITY : Reading on the Neutron scale of the value corresponding to the middle in OIL zone or to the quarter on the density side for GAS zone of the D-N separation
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CLEAN HYDROCARBON ZONE
•
QUICKLOOK LITHOLOGY AND POROSITY DENSITY – NEUTRON COMPATIBLE SCALES D-N Limestone compatible scales
D-N Sandstone compatible scales
D-N Sandstone Semi-Compatible scales (Algeria)
Resistivities LLD-MSFL
Neutron recorded in Limestone Matrix
Neutron recorded in Sandstone Matrix
Neutron recorded in Limestone Matrix
Rt - Rxo
GR-CALI SP
N_LS = 0 D = 2.70
SP_1 -100
MV
0
BS_1 12
IN
GR_1 0
GAPI
22
DEPTH1.95
100
FEET
1.95
CALI_1 12
IN
RHOB_1 G/C3
2.95
N_SS = 0 D = 2.65 1.90
2.95 1.9
NPHI_1 22
0.45
V/V
RHOB_1 G/C3
N_LS = 0 D = 2.60
2.90 1.85
RHOB_1
2.9 1.85
G/C3
NPHI_SS_1 -0.15 0.45
V/V
2.85
LLD_1
2.85 0.2
NPHI_1 -0.15 0.45
V/V
OHMM
2000
MSFL_1 -0.15 0.2
OHMM
2000
6200
SS
OIL
LLD
MSFL
RHOB NPHI
RHOB
RHOB NPHI
NPHI
W
WOC
Overlay D-N in Sandstone with Water or Oil
Quicklook Porosity : 25-27 % (Middle of the separation)
Quicklook Porosity : Quicklook Porosity : 25-27 % 25-27 % after adding 4% (Middle of the separation) to apparent Porosity
MATRIX = LIME Geosciences – Reservoir Engineering
Overlay D-N in Sandstone with Water or Oil RHOB Shifted 2 divisions
2 to 3 divisions Separation in Sandstone
MATRIX = SAND
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6250
GR-D-N-S TOOL RESPONSE GAMMA RAY - DENSITY NEUTRON – SONIC TOOL RESPONSE in most common geological formations Density-Neutron scales are Limestone compatible NPHI
RHOB GR
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DT
QUICK LOOK METHOD ON LOG EXAMPLE DRHO_1
MNOR_1 20
OHMM
0
-0.75
0
1.95
OHMM
SP_1 -50
LLD_1
MV
50
GR_1 0
GAPI
0.2
METRES
0.2
IN
OHMM
OHMM
2000 0.45
0.25
0.2
OHMM
V/V
Example of logs showing clearly the fluid contatcs
2.95
-0.15
DT_1 2000 136
MSFL_1 16
G/CC
NPHI_1
LLS_1
DEPTH 100
CALI_1 6
G/CC
RHOB_1
MINV_1 20
US/F
16
DT_1 2000 140
US/F
40
2313.0
2325
NPHI
DT
2350
Resistivities
2375
MSFL
2390.0
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LLD
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Density-Neutron-Sonic
CROSS-PLOTS
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CROSS-PLOTS TECHNIQUES
CROSS-PLOT TECHNIQUE CROSS PLOT TECHNIQUE The cross plot technique is a way to represent the log responses in a two-dimensional space, in which the depth is generally (but not necessarily) lost. Each axis of the diagrams used may be a standard log parameter (Neutron, Density, Sonic Pef...), or a combination of two log parameters (Th/K, M,N,P, pmaa, Atmaa...). A third and also a forth dimension may be added (Z-plot), as a projection of the data on the two dimensional space, by using a code for these parameters, for example a color or an index of GR, instead of simply a point. The most common diagrams used are lithology-porosity cross plots, which enable the determination of the lithology and the porosity of the formations. But other parameters may be used to help determinate the characteristics of the formation water (Rw...), of the shales, or to recognize the presence of particular types of minerals. LTHOLOGY - POROSITY ESTIMATION Clean water bearing formations Theoretical lithology-porosity tool responses are plotted on the conventional lithology-porosity diagrams for standard clean water bearing formations (sandstone, limestone, dolomite), or for certain minerals contained in or which form typical formations, which are commonly encountered during the drilling of sedimentary formations.
In a single matrix, clean and water bearing formation, one cross-plot is usually sufficient (Neutron - Density). In complex lithologies, more than two tools are necessary to achieve the interpretation and more than one of these-cross plots are used. The Pef parameter, which is independant of fluids, and spectral Gamma Ray parameters (Potassium, Thorium and Uranium) are a great help in matrix determination. • The axes of the M-N, M-P or N-P plots are combinations of two standard log parameters. These parameters are quite independant from the porosity value : all points corresponding to formations with the same matrix are located on one point only.
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• The main cross plots used combine the values of two logs (Neutron-Density, Neutron-Sonic, Sonic-Density), and enable the determination of the matrix and the porosity of the corresponding formations.
DENSITY-NEUTRON CROSS-PLOT Example of D-N crossplot in Shaly-Sand sequence
0.4
0
2.00 2870
0.35
2.10
FDC*-CNL* ρf = 1.0
0 621 734 0
0.45 2650 1.90 2710 0.43
2.00
RHOB
0.450
0.400
0.350
0.300
0.250
0.200
0.150
0.100
0.050
0.000
-0.050
Filter:
1.90
2.10
WIRE_1.RHOB_1 (G/CM3)
0.3
2.20
2.20 0.25
2.30
2.30
0.2
2.40
2.40
0.15 0.1
2.50
2.50
0.05
2.60
2.60
0
2.70
2.70
2.80
2.80
2.90
2.90
0.450
0.400
0.350
0.300
0.250
0.200
0.150
0.100
0.000
0.050
3.00 -0.050
3.00
WIRE_1.NPHI_1 (V/V) 0
150 Color: WIRE_1.SGR_1
F
ti
1.90
0 341 341 0
0
0
0.450
0.400
0.350
0.300
0.250
0.200
0.150
0.100
0.050
0.000
-0.050
Example of D-N crossplot in carbonate serie
2.65 1.90 0.45 2.71 0.43 0.4
2.00
2.00 2.87
0.35
2.10
2.10 2.20
0.25
2.30
0.2
2.40
2.40
0.15 0.1
2.50
2.50
0.05
2.60
2.60
0
0.450
0.400
0.350
0.300
0.250
3.00 0.200
2.90
3.00 0.150
2.80
2.90
0.100
2.70
2.80
0.050
2.70
WIRE_1.NPHI_1 (V/V) 0
120 Color: Maximum of WIRE_1.GR_1
unctions:
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2.30
-0.050
NPHI
2.20
0.000
WIRE_1.RHOB_1 (G/C3)
0.3
LITHOLOGY AND POROSITY : CROSS-PLOTS MAIN CROSS PLOTS with GAS and SHALE EFFECTS
DT
AS
RHOB
RHOB
C
SH
GAS
G
C
GA S AL E
C
A
SH
A
B
SH
B
AL E
A
AL E
B
NPHI
Point A
Water bearing limestone, slightly dolomitic, with Φ = 15% (looks like a sandstone with Φ = 10% on cross plot SONIC - DENSITY)
Point B
Water bearing dolomitic sandstone, wtih Φ = 8% (looks like a limestone with Φ = 10% on cross plot SONIC - DENSITY)
Point C
Gas bearing sandstone with Φ = 30% (looks like a water bearing sandstone with Φ = 35% on cross plot SONIC – DENSITY)
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DT
NPHI
QUANTITATIVE LOG INTERPRETATION
QUANTITATIVE LOG
245
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INTERPRETATION
QUANTITATIVE INTERPRETATION STEPS 1) COMPUTATION of Rt and Rxo • Environmental Corrections Deep Resistivities Shallow Resistivities
Borehole effect (mud) Mud cake effect
• Computation Rlog = J Di .Rxo + (1 – J Di ).Rt 3 equations ÅÆ
3 tools
2) COMPUTATION of Rw • SP • Clean Water bearing Formations • Quick-Look Rw / Rmf = Rt / Rxo • Archie Rw = Rt / F 3) Vsh SHALINESS COMPUTATION Shale indicators Vshi
• Reservoir determination • Comparison of Rt and Rxo • Comparison of Neutron and Density logs 5) QUANTITATIVE INTERPRETATION • n equations with n unknowns (Knowledge of matrix and hydrocarbon) • n equations with p unknowns (n > p) (Knowledge of mineral model) 6) COHERENCE CONTROL of DATA and RESULTS Geosciences – Reservoir Engineering
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4) QUALITATIVE INTERPRETATION
QUANTITATIVE INTERPRETATION Determination of Rt, Rxo, Di
DIL *Dual InductionSFL *Spherically Focused Resistivity Log
Dual Laterolog-Rxo Device
DIL - SFL
(
)
R = J ∗ R + 1− J ∗R cor Di Di xo t
Induction :
(
247
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)
= G ∗C + 1−G ∗C C cor Di xo Di t Well Log Interpretation – PDVSA – January 2007
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LLD – LLS - Rxo
Resistivity :
(Examples)
RW DETERMINATION Rw Determination - Spontaneous Potential
⎛ Rmfe ⎞ SSP = −K log ⎜ ⎟ ⎝ Rwe ⎠ K = 61+.133 ∗ T ( °F ) K = 65+.240 ∗ T ( °C )
- Resistivity Ratio method , in a clean water bearing zone ( Sw =1 )
Rw Rt Rt = ⇒ Rw = Rmf ∗ Rmf Rxo Rxo
Rw a = Rt ∗
Φm a
- Other method : Pickett plot
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- Archie Formula in a clean water bearing zone (Sw = 1)
DETERMINATION OF Rw FROM SP • Check validity of mudfiltrate resistivity measurement in log header • Identify shale layers • Draw SP shale baseline • Estimate maximum SP deflection in front of each reservoir : SSP • Estimate Reservoir temperature ( Chart Gen-6 ) • Determine Rmf at reservoir temperature (Chart Gen-9) • Determine Rmfe/Rwe ratio from SSP at reservoir temperature (Chart SP-1) • Determine Rmfe from Rmf at reservoir T° (Compute from Rmf or use chart SP-2) • Determine Rw (Chart SP-2)
SSP = - K log
Rmfe Rwe
K = 61+.133∗ T (°F) K = 65+.240∗T (°C)
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• Determine Rwe (Chart SP-1)
RW DETERMINATION USING Pickett PLOT • Representation of Resistivity Rt versus Porosity in logarithmic scale • Iso-Saturation Sw lines aRw = 0.1710 DETERMIN.PHIE_1 vs. CORENV.RT_1 Crossplot
1
Sw = 1
0 384 406 22
1
0
0
10000
1000
100
10
1
0.1
Well: DLG1 DEPTH 2490 - 2552 metres Filter:
a Rw × φ m Sw n log(Rt ) = log(aRw) - mlog(Φ ) Rt =
Sw = 1 & Porosity = 1 =>
o R
aRw= 0.1710
e lin ; =
0.1
m =2 Rw = 0.211 Ohmm
CORENV.RT_1 (OHMM) 0
0.01 10000
1000
1
0.1
0.01
100
0.1
10
0 1
a = .81
150 Color: Maximum of WIRE_1.SGR_1
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
w
% 0 1 = % w 0 S 2 = 2 % w = 0 S 4 m ; = 2 w 7 % 0 S 0 1 6 7 = % 0.1 0 w 8 = S = w w R S a* ; % 0
S
DETERMIN.PHIE_1 (V/V)
Rt = aRw
ESTIMATION OF SHALE CONTENT : VSH Estimation of VSH
(
VSH = Min VSH
- Gamma Ray
i
)
- Neutron
GR VSH = GR GR
- GR max
- GR
Φ N VSH = N Φ Nsh
min
min
- Spontaneous Potential
- Density- Neutron
Density X’
PSP VSH = 1 − SP SSP
VSH
DN
=
L
X' L X' A
A
- Resistivities
- Density- Sonic
Rsh VSH = Rt Rt
Density
Rsh VSH = Rxo Rxo
VSH
DS
=
X' L X' A
X’ L A
Sonic
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Neutron
ESTIMATION OF SHALE CONTENT : VSH-GR GRmax
Estimation of VSH with GR
GR log
GR min
GR
GR - GR min
GRmax - GRmin
GR VSH = GR GR Geosciences – Reservoir Engineering
- GR max
- GR
min
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Anomaly of radioactivity
ESTIMATION OF SHALE CONTENT : VSH-SP
Estimation of VSH with SP SP log SSP
Static SP
PSP
Pseudo SP
SP Shale Baseline
VSH
SP
=1−α =1−
PSP SSP - PSP = SSP SSP 253
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SSP - PSP
ESTIMATION OF SHALE CONTENT : VSH-DN FLUID POINT WIRE_1.RHOB_1 vs. WIRE_1.NPHI_1 Crossplot RHOmf, PHINmf
1.00 CCUT COAL
1.20
VSH_DN IN WATER ZONE
1.78
Estimation of VSH-DN Using Density-Neutron ( In a water zone )
ISO-Shale 1.78 LINE CONTENT (VSH = 50%)
L
X'
0.45 2650 0.432710 0.4 2870
1.98
1.98
0.35
2.37
0.15 0.1
2.56
VSH_dn = X'L / X' A
A
0.3 0.25 0.2
2.17
2.17
SHALE POINT 2.37 RHOsh, PHINsh 2.56 VSH = 100%
SH
0.05 0 MA
1.000
0.905
0.809
0.714
0.618
0.523
0.427
0.332
0.236
0.141
-0.050
2.75
VSH = 75%
VSH = 50%
VSH = 25% 2.95
DENSITY-NEUTRON Crossplot
1.59
0.045
WIRE_1.RHOB_1 (G/C3)
1.39
1.59
2.75
0
1.00
1.39
MATRIX POINT RHOma, PHINma VSH = 0%
0 997 997 0
2.95
WIRE_1.NPHI_1 (V/V) 0
150 Color: WIRE_1.GR_1
Functions: mm_cp1c mm_cp1c_p
: Por. & Lith determ. from RHOB & CNL, fresh mud. : Pmaa from RHOB & CNL logs for fresh muds
Example 1 Example 2 P = 10 - 6 * Salinity (ppm)…………..Salinity = 10 kppm……….Salinity = 200 kppm RHOmf = 1 + 0.7 P…………………..P = ,01…………………….P = ,2 PHINmf * (1 - P)……………………...RHOmf = 1,007…………..RHOmf = 1,14 PHINmf = 0,996 PHINmf = 0,91 Geosciences – Reservoir Engineering
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1.20
0
1.000
0.905
0.809
VSH = 0% 0.714
0.618
0.523
0.427
0.332
0.236
0.141
0.045
-0.050
Well: DLG1 2450 - 2602 METRES Filter:
ESTIMATION OF SHALE CONTENT : VSH-DN WIRE_1.RHOB_1 vs. WIRE_1.NPHI_1 Crossplot
0.00
FLUID POINT RHOhc, PHINhc
0.30 0.59
0
0 734 734 0
0
1.000
0.905
0.809
0.714
0.618
0.523
0.427
0.332
0.236
0.141
0.045
-0.050
Well: DLG1 Range: Intervals Filter:
0.00
DENSITY-NEUTRON Crossplot
0.30
DETERMINATION OF VSH
0.59
IN OIL ZONE
0.89
0.89
1.18 CCUT COAL
1.18
1.48
1.48
VSH_dn = X'L / X' A
X'
1.77 0.45 2650 2710 0.43 0.4 2870 0.35
2.06 0.3 0.25
1.000
0.905
0.809
0.714
0.618
0.523
0.236
2.65
SHALE POINT RHOsh, PHINsh
L 0.045
-0.050
2.95
MATRIX POINT RHOma, PHINma
0 MA
0.427
2.65
2.36
SH
0.332
2.36
2.06
A
0.2 0.15 0.1 0.05
2.95
WIRE_1.NPHI_1 (V/V) 0
150 Color: WIRE_1.GR_1
Functions: mm_cp1c mm_cp1c_p
: Por. & Lith determ. from RHOB & CNL, fresh mud. : Pmaa from RHOB & CNL logs for fresh muds
RHOhc = x PHINhc = 2.2 * RHOhc if RHOhc <= 0.25 PHINhc = 0.3 + RHOhc if RHOhc >= 0.25 RHOhc PHINhc
Geosciences – Reservoir Engineering
0.1 0.22
0.2 0.44
0.3 0.6
0.4 0.7
0.5 0.8
0.6 0.9
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1.77
0.141
WIRE_1.RHOB_1 (G/C3)
VSH_DN IN OIL ZONE
ESTIMATION OF SHALE CONTENT : VSH-DN WIRE_1.RHOB_1 vs. WIRE_1.NPHI_1 Crossplot
0.00
FLUID POINT RHOhc, PHINhc
0.30
VSH_DN IN GAS ZONE
0.89
0.45 2650 2710 0.43 0.4 2870 0.35
0
DETERMINATION OF VSH_DN
0.59
IN GAS ZONE
2.06
A
0.3 0.25 0.2 0.15 0.1 0.05
2.36 SH
SHALE POINT RHOsh , PHINsh
0 MA
2.65
WIRE_1.NPHI_1 (V/V) 0
150 Color: WIRE_1.GR_1
Functions: mm_cp1c mm_cp1c_p
: Por. & Lith determ. from RHOB & CNL, fresh mud. : Pmaa from RHOB & CNL logs for fresh muds
RHOhc = x PHINhc = 2.2 * RHOhc if RHOhc <= 0.25 PHINhc = 0.3 + RHOhc if RHOhc >= 0.25 RHOhc PHINhc
Geosciences – Reservoir Engineering
0.1 0.22
0.2 0.44
0.3 0.6
0.4 0.7
0.5 0.8
0.6 0.9
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1.000
0.905
0.809
0.714
0.618
0.523
0.427
0.332
0.236
2.95 0.141
-0.050
2.95
0.30
1.77
L
2.06
2.65
MATRIX POINT RHOma, PHINma
DENSITY-NEUTRON Crossplot
1.48
VSH_dn = X'L / X' A
1.77
2.36
0.00
1.18
X'
1.48
0 734 734 0
0.89
1.18 CCUT COAL
0.045
WIRE_1.RHOB_1 (G/C3)
0.59
0
1.000
0.905
0.809
0.714
0.618
0.523
0.427
0.332
0.236
0.141
0.045
-0.050
Well: DLG1 Range: Intervals Filter:
ESTIMATION OF EFFECTIVE POROSITY : PHIE WIRE_1.RHOB_1 vs. WIRE_1.NPHI_1 Crossplot FLUID POINT
1.00 CCUT COAL
X'
2.37
0
2.17
A
0.15 0.1
2.56
2.37
SH
SHALE POINT PHIE = 0%
0.05 0 MA
2.56 2.75
1.000
0.905
0.809
0.714
0.618
0.523
0.332
0.236
0.141
0.045
-0.050
L : VSH = 30 %
MATRIX POINT for X' PHIE = 0%
( Case of a water zone )
2870
0.3 0.25 0.2
0.427
WIRE_1.RHOB_1 (G/C3)
0.35
PHIE = PHI(X’) * ( 1 – Vsh )
1.78
ISO-POROSITY LINE through 1.98 Point L
0.45 2650 0.432710 0.4
2.17
Density-Neutron
1.59
X' : X'A = LA / (1-VSH)
1.78
2.95
From VSH_Min and
1.39
1.59
2.75
Estimation of PHIE
1.20
PHI 1.98 (X') = 27 %
MATRIX LINE for X'
DENSITY-NEUTRON Crossplot
1.00
Shaly Water bearing Sandstone
1.39
PHIE = PHI(X') * (1-VSH) = 27 * ( 1- 0.3) = 19 %
0 997 997 0
2.95
WIRE_1.NPHI_1 (V/V)
0
150 Color: WIRE_1.GR_1
Functions: mm_cp1c mm_cp1c_p
: Por. & Lith determ. from RHOB & CNL, fresh mud. : Pmaa from RHOB & CNL logs for fresh muds
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1.20
0
1.000
0.905
0.809
0.714
PHIE =100%
0.618
0.523
0.427
0.332
0.236
0.141
0.045
-0.050
Well: DLG1 2450 - 2602 METRES Filter:
HYDROCARBON CORRECTION Φ -Φ Nhc ) ∆Φ = − A × Φ × S × ( Nmf N hr Φ Nmf ∆ρ = −1.07 × Φ × S × (C × ρ − C ×ρ ) b hr mf mf hc hc with ΦShr = 0,3 , P = 0 et ρmf = 1
FDC*-CNL* ρf = 1.0
∆ρb
Φ Nmf = ρ mf (1 − P) Φ Nhc = ρ hc + 0.3, ifρ hc > 0.25 Φ Nhc = 2.2× ρ hc, ifρ hc < 0.25
0,7 0,6 0,5 0,4
∆ΦN
P = Salinity ( kppm ) x 10 – 3
0,3 0,25
0,2
0,15
0,1
ρhc
ρ b = (1 − Φ u )* ρ ma + Φ u (Sxo * ρ mf + Shr * ρ hc ) 0.45 2650 0.432710 0.4
1.98 0.3 0.25
2.37
0.15 0.1
2.56
SH
2.56
0.05 0 MA
1.000
0.905
0.809
0.714
0.618
0.523
0.427
0.332
0.236
2.75
0.141
-0.050
2.95
2.17
0.2
2.37
2.95
WIRE_1.NPHI_1 (V/V) 0
150 Color: WIRE_1.GR_1
Functions:
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2.17
2.75
1.98
2870
0.35
0.045
WIRE_1.RHOB_
Points in gas zones
ESTIMATION OF Sw Estimation of Sw in clean formation Archie Formula :
Sw = n
aRw φ m Rt
Estimation of Sw in shaly formation
⎡V (1−V2sh ) φ m / 2 ⎤ 1 ⎥ S wn / 2 = ⎢ sh + Rt ⎢ Rsh aRw ⎥ ⎣ ⎦
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Example of Poupon formula ( Indonesia) :
METHODS
DETERMINISTIC APPROACH : - SHALY SAND
DUAL WATER METHOD OPTIMISTIC APPROACH Geosciences – Reservoir Engineering
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- COMPLEX LITHOLOGY
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© 2006 ENSPM Formation Industrie - IFP Training
SHALY SAND METHOD (1/2)
Geosciences – Reservoir Engineering
262
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© 2006 ENSPM Formation Industrie - IFP Training
SHALY SAND METHOD (2/2)
Geosciences – Reservoir Engineering
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© 2006 ENSPM Formation Industrie - IFP Training
COMPLEX LITHOLOGY METHOD (1/2)
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© 2006 ENSPM Formation Industrie - IFP Training
COMPLEX LITHOLOGY METHOD (2/2)
DUAL WATER MODEL
265
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PASS 2
PASS 1
DUAL WATER MODEL Ro Rt
SwT = X + (X 2 +
si Rwb > Rw
Rw ) RtΦT 2
Swb = Vshmin
Sw = CYBERLOOK
Geosciences – Reservoir Engineering
si Rwb < Rw
SwT − Swb 1− Swb
Φe = ΦT (1 – Swb)
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SwT =
QUANTITATIVE INTERPRETATION : OPTIMISTIC APPROACH GENERAL INVERSION METHOD COMPUTER PROCESSED RESULTS
(GLOBAL Example) PROGRAMS : - GLOBAL - ELAN
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- MULTIMIN
QUANTITATIVE INTERPRETATION : OPTIMISTIC APPROACH GENERAL INVERSION METHOD
Geosciences – Reservoir Engineering
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Reconstructed Logs (GLOBAL Example)
CHARTS
Geosciences – Reservoir Engineering
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APPENDIX MAIN CHARTS FOR LOG INTERPRETATION
ESTIMATION OF FORMATION TEMPERATURE
Geosciences – Reservoir Engineering
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Gen-6
Geosciences – Reservoir Engineering
271
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
CONVERSIONS (1/2)
Geosciences – Reservoir Engineering
272
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
CONVERSIONS (2/2)
Water Resistivity and Water Salinity
Geosciences – Reservoir Engineering
273
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© 2006 ENSPM Formation Industrie - IFP Training
Gen-9
Water Resistivity and Water Salinity
Geosciences – Reservoir Engineering
274
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Gen-9
Rwe from SSP SP-1
(Schlumberger) Geosciences – Reservoir Engineering
275
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Rwe
Rwe from SSP
(Schlumberger)
Geosciences – Reservoir Engineering
276
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
SP-1
Rw versus Rwe ( SP-2) ( DegF) SP-2
(Schlumberger)
Geosciences – Reservoir Engineering
277
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
DEGF
Rw versus Rwe ( SP-2m) ( DegC) SP-2m
(Schlumberger)
Geosciences – Reservoir Engineering
278
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
DEGC
Main Logging Tool Response in Sedimentary Minerals
Geosciences – Reservoir Engineering
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Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
MAIN LOGGING TOOL RESPONSE in Sedimentary Minerals (1/2)
Main Logging Tool Response in Sedimentary Minerals
Geosciences – Reservoir Engineering
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MAIN LOGGING TOOL RESPONSE in Sedimentary Minerals (2/2)
Porosity from DENSITY LOG ρfl = 1.0
Determination of Porosity from Density Log
Sandstone line Porosity = 14 %
(Schlumberger)
Example 2 :
Example 1 :
Sandstone formation
Limestone formation ρb = 2.31 g/cm3 in limestone lithology ρma = 2.71 g/cm3 ( Calcite )
ρb = 2.42 g/cm3 in limestone lithology ρma = 2.65 g/cm3( Quartz ) ρf = 1.0 g/cm3 ( Fresh mud)
ρf = 1.1 g/cm3 ( Salt mud)
Formation porosity = 14 p.u
Formation porosity = 25 p.u
281
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ρb = 2.42 g/cc
ρma = 2.65 g/cc
Porosity from NEUTRON Log
TNPH 250 kppm
TNPH 0 kppm
Determination of Porosity from Neutron Log
NPHI
Porosity = 24 p.u.
TNPH 0 kppm
Porosity = 22.5 p.u.
Example 1 :
NPHI
Sandstone formation with a formation salinity of 20 kppm NPHIcor = 18 p.u. in limestone lithology True porosity = 22.5 p.u
Example 2 : Sandstone formation with a formation salinity of 250 kppm TNPHcor = 18 p.u. in limestone lithology True porosity = 24.0 p.u (Schlumberger) Geosciences – Reservoir Engineering
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TNPH 250 kppm
Porosity from SONIC Log PHIS Wyllie = ( DT - Dtma ) / ( DTfl - Dtma ) x ( 1/Bcp )
PHIS RH* = K * ( DT - Dtma ) / DT
Determination of Porosity from Sonic Log
(Schlumberger Chart Por-3)
Sandstones Limestones Dolomites
Sonic Velocity ft/s 18000 - 19500 21000 - 23000 23000 - 26000
∆ Tma µs/ft 55,6 51,3 47,6 43,5 43,5 38,5
Sonic Velocity m/s 5486 - 5944 6401 - 7010 7010 - 7925
∆ Tma µs/m 182,3 - 168,2 156,2 - 142,6 142,6 - 126,2
20000 14925
50,0 67,0
6096 4549
164,0 219,8
Example : DT = 76 µs/ft ( 249 µs/m ) SVma = 18000 ft/s ( 5486 m/s ) Sandstone Thus Porosity = 15 % by time average or 18% by field observation method) * RH = Raymer-Hunt
Anhydrite Salt Geosciences – Reservoir Engineering
283
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© 2006 ENSPM Formation Industrie - IFP Training
Bcp
Geosciences – Reservoir Engineering
284
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Notes
SPECTRAL GR NGS - CHART Th-K Th-K CP-19
K
(Schlumberger)
285
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Th
SPECTRAL GR NGS - CHART PEF-K, PEF-Th/K PEF-K CP-18 PEF
K
PEF-Th/K
PEF
Th/K
Geosciences – Reservoir Engineering
286
(Schlumberger)
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
CP-18
Density-Neutron Crossplot ( NPHI) 1/2 RHOB-NPHI CP-1c Rhofl = 1.0
NPHI
287
Geosciences – Reservoir Engineering
(Schlumberger)
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
RHOB
Density-Neutron Crossplot ( NPHI) 2/2 RHOB-NPHI CP-1d Rhofl = 1.1
NPHI
Geosciences – Reservoir Engineering
288
(Schlumberger)
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
RHOB
Density-Neutron Crossplot ( TNPH) 1/2 RHOB-TNPH CP-1e Rhofl = 1.0
TNPH
289
Geosciences – Reservoir Engineering
(Schlumberger)
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
RHOB
Density-Neutron Crossplot ( TNPH) 2/2 RHOB-TNPH CP-1f Rhofl = 1.19
TNPH
Geosciences – Reservoir Engineering
290
(Schlumberger)
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
RHOB
Sonic-Neutron Crossplot 1/2 DT-NPHI CP-2b
NPHI (Schlumberger)
291
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
DT
Sonic-Neutron Crossplot 2/2 DT-TNPH CP-2c
TNPH (Schlumberger)
Geosciences – Reservoir Engineering
292
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
DT
Density-Sonic Crossplot RHOB-DT CP-7
DT (Schlumberger)
Geosciences – Reservoir Engineering
293
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Rhofl = 1.0
RHOB
M versus N M-N
(Schlumberger)
Geosciences – Reservoir Engineering
294
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
CP-8
PEF versus RHOB PEF-RHOB CP-16
RHOB (Schlumberger)
Geosciences – Reservoir Engineering
295
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Rhofl = 1.0
PEF
PEF versus RHOB PEF-RHOB CP-17
RHOB (Schlumberger)
Geosciences – Reservoir Engineering
296
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Rhofl = 1.1
PEF
(Schlumberger)
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
GR - ENVIRONMENTAL CORRECTION
(Schlumberger)
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
GR - ENVIRONMENTAL CORRECTION
(Schlumberger)
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
NEUTRON - ENVIRONMENTAL CORRECTION
(Schlumberger) Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
NEUTRON - ENVIRONMENTAL CORRECTION
(Schlumberger)
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
NEUTRON - ENVIRONMENTAL CORRECTION
(Schlumberger)
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
NEUTRON - ENVIRONMENTAL CORRECTION
(Schlumberger)
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
INDUCTION - ENVIRONMENTAL CORRECTION
INDUCTION - ENVIRONMENTAL CORRECTION Dual Induction
(Schlumberger) Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Rcor-4a
DLT - ENVIRONMENTAL CORRECTION DLT ( D/E) Centered
LLD
Rcor-2b
(Schlumberger)
305
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
LLS
DLT - ENVIRONMENTAL CORRECTION DLT ( D/E) Eccentered LLD
Rcor-2c
(Schlumberger)
Geosciences – Reservoir Engineering
306
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
LLS
MLL – PL - ENVIRONMENTAL CORRECTION MLL - PL Rxo-2 MLL
(Schlumberger)
307
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
PL
MSFL - ENVIRONMENTAL CORRECTION MLL - PL Rxo-3 MSFL Version III
(Schlumberger)
Geosciences – Reservoir Engineering
308
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
MSFL Slim Hole
Chart Rt-Rxo-Di for LLD-LLS-Rxo ( Rint – 9b) DLL-Rxo Rint-9b
LLD/LLS
309
Geosciences – Reservoir Engineering
(Schlumberger)
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
LLD/Rxo
Chart Rt-Rxo-Di for DIL-SFL ( Rint – 9b) DIL-SFL Rint-2c
ILM/ILD
Geosciences – Reservoir Engineering
310
(Schlumberger)
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
SFL/ILD
FORMULA : Density-Neutron-Sonic - 1/4 Density, Neutron , Sonic Tool responses Clean Water bearing formations
U = Pe * ρ el = Pe * (
ρ b = (1 − Φ u )ρ ma + Φ u ρ f
ρ b + 0.1883 ) 1.0704
U = Volumetric Photoelectric Absorption Factor ( Barn/cm3)
Φ N = (1 − Φ u )Φ Nma + Φ u Φ Nfl
Mud Filtrate Parameters
∆t p = (1 − Φu) ⋅ ∆t ma + Φu ⋅ ∆t f
P = Salinity ( kppm ) x 10 – 3
U = (1 − Φ u )U ma + Φ u U f .
ρ mf = 1 + 0.7 P
Φ Nmf = ρ mf (1 − P)
Clean Hydrocarbon bearing formations
ρ b = (1 − Φ u )ρ ma + Φ u [Sxo * ρ mf + (1 − Sxo) * ρ hc ]
Φ N = (1 − Φ u )Φ Nma + Φ u [Sxo * Φ Nmf + (1 − Sxo) * Φ Nhc ] − ∆Φ NExc
ρ b = (1 − Φ u − Vsh )ρ ma + Vsh * ρ sh + Φ u ρ f Φ N = (1 − Φ u − Vsh )Φ Nma + Vsh * Φ Nsh + Φ u Φ Nfl ∆t p = (1 − Φu − Vsh ) ⋅ ∆t ma + Vsh * ∆t sh + Φu ⋅ ∆t f Shaly Hydrocarbon bearing formations
ρ b = (1 − Φ u − Vsh )ρ ma + Vsh * ρ sh + Φ u [Sxo * ρ mf + (1 − Sxo) * ρ hc ] Φ N = (1 − Φ u − Vsh )Φ Nma + Vsh * Φ Nsh + Φ u [Sxo * Φ Nmf + (1 − Sxo) * Φ Nhc ] − ∆Φ NExc 311
Geosciences – Reservoir Engineering
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Shaly Water bearing formations
FORMULA: Porosities – HC Correction – 2/4 POROSITIES Porosity from Density, Neutron, Sonic in clean Water bearing formations :
Φ u (D) =
ρ ma − ρ b ρ ma − ρ f
Φ u(N) =
Φ N − Φ Nma Φ Nfl − Φ Nma
Φ u(S) =
Φ
+Φ 2
ma D
Φu =
[ ma = Limestone matrix ( ρma = 2.71 ,
( Raymer-Hunt-Gartner )
Gas bearing formations
Water or Oil bearing formations
Φu =
2
( Wyllie )
Apparent Density-Neutron Porosity in clean formations : ma N
(1 − Φu ) + Φ u 1 = ∆t ∆t ma ∆t f
∆t − ∆t ma 1 × ∆t f − ∆t ma Bcp
φNma = 0)
ma 3Φ ma D + ΦN 4
or
Φu =
ma 7 Φ ma D + 2Φ N 9
]
HYDROCARBON CORRECTION Hydrocarbon correction on Density and Neutron
Mud Filtrate Parameters P = Salinity ( kppm ) x 10 – 3
ρ b_cor_hc = ρ b - ∆ρ b
ρ mf = 1 + 0.7 P
Φ N_cor_hc = Φ N − ∆Φ N
Φ - Φ Nhc ∆Φ N = − A × Φ × Shr × ( Nmf ) Φ Nmf
Hydrocarbon Parameters
Φ Nhc = 2.2× ρ hc, ifρ hc < 0.25 and Φ Nhc = ρ hc + 0.3, ifρ hc ≥ 0.25
A = f ( excavation factor) 1 < A < 1.3
or
312
[
Φ Nhc = 9ρ hc 0.15 + 0.2(0.9 − ρ hc ) 2
C hc = 1.15
]
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Φ Nmf = ρ mf (1 − P)
∆ρ = −1.07 × Φ × Shr × (C × ρ − C ×ρ ) b mf mf hc hc
Geosciences – Reservoir Engineering
C mf = 1.11 − 0.15P
FORMULA : VSH – Shale Correction – 3/4
(
VSH = Min VSH
Estimation of VSH : GR
VSH = GR GR VSH
- Spontaneous Potential
SP
VSH
- Resistivities
=1−
Rt
=b
max
- GR
min
i
)
( Deterministic Approach )
min
PSP SSP
Rsh Rt
or
VSH
Rt
=b
Rsh (Rlim - Rt ) Rt (Rlim - Rsh)
Density X ’
L A
Φ N VSH = N Φ Nsh
- Neutron
- Density- Neutron
VSH
- Density- Sonic
VSH
DN DS
=
X' L X' A
=
X' L X' A
Neutr on
or
or
Φ − RΦ Φ N D Dmin with R= DN Φ − RΦ Φ Nsh Dsh Nmin Φ −Φ S D VSH = DS Φ −Φ Ssh Dsh =
VSH
Shale Correction on D- N- S Φ Ncor = Φ N − VshΦ Nsh
ΦScor = ΦS − VshΦSsh
Φ Dcor = Φ D − VshΦ Dsh
Apparent Density-Neutron Porosity in shaly formations :
Φu =
ma 7 Φ ma Dcor + 2Φ Ncor 9
ma = Limestone matrix ( ρma = 2.71 ,
313
Geosciences – Reservoir Engineering
φNma = 0)
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
- Gamma Ray
- GR
FORMULA: Water Saturations - 4/4 WATER SATURATION EQUATIONS Archie Formula
aR Sw = n m w φ Rt
FR aR Rt = n w = m wn Sw φ Sw
or
Shaly formation (Laminated Shales)
or
F=
a
φm
1 Vsh (1 − Vsh )φ m n = + Sw Rt Rsh aRw
Shaly formation (Dispersed Shales) Simandoux Formula
φm n 1 Vsh = Sw + Sw Rt Rsh aRw
Hossin Formula
1 Vsh2 φ m n = + Sw Rt Rsh aRw
Poupon Formula
⎡V (1−V2sh ) φ m / 2 ⎤ 1 ⎥ S wn / 2 = ⎢ sh + Rt ⎢ Rsh aRw ⎥ ⎣ ⎦
Juhasz Formula
1 φTmSnwT = Rt aR w
Geosciences – Reservoir Engineering
1 φm n = Sw Rt aRw
⎡ BQ vn ⎤ ⎥ ⎢1 + ⎣ SwT ⎦
V 1 φm / 2 n / 2 = sh + Sw Rt R sh aR w
Doll Formula
Simandoux-De Witte
with
314
or
V 1 φm n = sh Sw + Sw R t R sh aR w
V ⎡ Cw φ m / 2 ⎤ n / 2 (1− sh ) 2 + Ct = ⎢ Csh Vsh ⎥ Sw a ⎦⎥ ⎣⎢
Qvn =
V sh φ sh
φT
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Clean formation :
Bibliography 1/3 Selected References on Well Logging GENERAL DOCUMENTS (Tools - Interpretation ) Chambre Syndicale de la Recherche et de la Production du Pétrole et du Gaz Naturel – Comité des Techniciens - Editions Technip. Interprétation rapide sur chantier des diagraphies différées en trou ouvert (1975). Chambre Syndicale de la Recherche et de la Production du Pétrole et du Gaz Naturel – Editions Technip. Contrôle des sondages : Diagraphies instantanées - Catalogue de cas types (1979). Chambre Syndicale de la Recherche et de la Production du Pétrole et du Gaz Naturel – Editions Technip. Wireline Logging Tool Catalog (1986). BASSIOUNI Z. (1994) Theory, Measurement, and Interpretation of Well Logs - SPE Textbook Series Vol. 4 BATEMAN R.M. (1985) Log Quality Control - Reidel Open Hole Log Analysis and Formation Evaluation - Reidel Cased Hole Log Analysis and Reservoir Performance Monitoring - Reidel
BOYER S. (1998) Well Logging / Diagraphies Différées (CD - ROM pour Macintosh/PC) – IFP School, Editions Technip CHAPELLIER D. (1987) - Diagraphies appliquées à l'Hydrologie - Lavoisier Tec & Doc DESBRANDES R. Théorie et interprétation des diagraphies (1968) - Publication de l'Institut Français du Pétrole - Editions Technip. * Les Diagraphies dans les sondages (1982) - Editions Technip Paris.
315
Geosciences – Reservoir Engineering
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© 2006 ENSPM Formation Industrie - IFP Training
BOYER S., ANDRIEUX P. et MICHAUT B. (1993) Principes physiques de fonctionnement des outils de diagraphies - Revue Géologue de l'UFG N° 99
Bibliography 2/3 Selected References on Well Logging DEWAN J. (1983) - Essentials of Modern Open Hole Log Interpretation DOVETON J.H. (1986) - Log Analysis of subsurface Geology (Concepts and Computer Methods) - John Wiley & Sons HEARST and NELSON (1985) - Well Logging for Petrophysical Properties - Mc Graw, Hill Book Company HILCHIE D.W. (1979) Old Electrical Log Interpretation (1979) Advanced Well Logging Interpretation (2nd Edition) (1989) HOSSIN A. (1983) - Manuel de Diagraphies Différées : Appareils et Interprétation – Cours ENSPM (not published) HURST A., LOVELL M.A. and MORTON A.C. (1990) Geological Applications of Wireline Logs – Geological Society KERZNER M. (1986) - Image Processing Well Log Analysis - IHRDC MARI J.L., COPPENS F., GAVIN Ph. et WICQUART E. (1992) Traitement des Diagraphies acoustiques (Full Waveform Data Processing, 1994) - Editions Technip
SERRA O. (1979 et 1985) - Diagraphies Différées - Bases de l'interprétation – Bulletin des Centres de Recherche Exploration Production Elf Aquitaine - Pau. * Volume 1 : Acquisition des données (1979). * Volume 2 : Interprétation (1985). THEYS Ph. (1991) - Log Data Acquisition and Quality Control - Editions Techn
Geosciences – Reservoir Engineering
316
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
SCHLUMBERGER (1989) - Schlumberger Educational Services. Log Interpretation Principles /Applications Cased Hole Log Interpretation Principles /Applications
Bibliography 3/3 Selected References on Well Logging WELL LOGGING and SEDIMENTOLOGY SERRA O. (1979 et 1985) - Diagraphies Différées - Bases de l'interprétation – Bulletin des Centres de Recherche Exploration Production Elf Aquitaine - Pau. * Volume 2 : Interprétation (1985).
WELL LOGGING : Acoustics and seismics BOYER S. et MARI J.L. (1994) - Sismique et Diagraphies - Editions Technip. MARI J.L. et COPPENS F. (1989) - La sismique de puits (Seismic Well Surveying, 1991) - Editions Technip
JOURNALS The Log Analyst (Revue de la SPWLA) SPWLA Transactions & SAID Transactions Technical Review (Schlumberger)
SPE Monograph Series Vol. 9 : Well Logging Tome 1 (JORDENJ.R. and CAMPBELL F.L.) Vol 10 : Well Logging Tome 2 (JORDENJ.R. and CAMPBELL F.L.) Vol. 14 : Production Logging (HILCHIEA.D.) SPWLA Reprint Volume Pulsed Neutron (1976), Gamma Ray, Neutron, Density (1978), Acoustic Logging (1978) Geothermal Interpretation Handbook (1982), Shaly Sand (1983) ...
Geosciences – Reservoir Engineering
317
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
SPE Reprint Series Open Hole Well Logging N° 21 (1986) & Production Logging N° 27 Vol 1 (1989)
Geosciences – Reservoir Engineering
318
Well Log Interpretation – PDVSA – January 2007
© 2006 ENSPM Formation Industrie - IFP Training
Notes
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