Pressure Measurement In Shale

PRESSURE MEASUREMENT IN SHALE

Shale Pressure Measurements Methods

A project by: Naser Soufi 2009

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Foreword The present project was initiated in connection with my work on specialization course “TPG 4520 Drilling Technology”. I would like to express my thanks to my supervisor Professor Pål Skale and PHD student Aminul Islam as they helped me for more sources in this rapport! Finally I would like to thank all my fellow students at the Department of Petroleum Engineering and Applied Geophysics. Mutual encouragement and professional as well as social discussion has truly enriched my time as a student.

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PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------Abstract: Formation pore pressure can be determined with information from several sources. All sources should be utilized during planning, executing and analyzing drilling effort. Reservoir engineers, geologists and geophysicists can make important contributions particularly in regard to stratigraphic correlations. “Shale is a fine grained, clastic mineral, especially quartz and calcite. 1 Shale is the predominant lithology found in petroleum basins. Most of drilling and seismic travel times take place in shale. Mechanically shale remains the least understood rock type because lack of reliable pressure measurements. Pore pressure, together with total stress, defines the “effective stress” which controls the mechanical behavior of rocks in terms of strength and stiffness. Shale is exceedingly variable in all of their properties. This variability further complicates the definition of shale normal compaction curves as shale compaction characteristics vary considerably. Shale is a tight material with a sufficient low permeability. Porosity in shale varies between 50 to 5 % when depth increasing. It’s extremely difficult to estimate and measured the porosity in shale. That’s a challenge for estimation of variation of pore pressure in shale. In over pressured shale’s which contain pressured water, density is lower and porosity is higher then normal. There are several method have been existed to estimate pore pressure in shale since 1950. Many authors have outline procedures for estimating formation (shale) pressure using data obtained from electrical and acoustical surveys. This project has three parts including six chapters for describe and solve the problem. Part one is based on challenge on porosity estimation in shale and how to solve the problem and measurements methods. Part two is based on direct pressure measurements methods, and part three is theoretical indirect methods for measuring pressure based on well data analyzing to distribute the realistic solution with real well data, curve analyzing based on electrical or logical surveys equipment. Thus, we review the most useable methods of shale pressure estimation and fit the real well data to these methods and Simulated and analyses them as it has been shown in Appendixes.

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Content:

Page

Foreword……………………………………………………………….………………….3 Abstract………………………………………………………………………………...….4 Introduction........................................................................ .....................................9

Part I: Challenge of Porosity…………………………………………………….11 Chapter 1: Challenge of Porosity Measurement in Shale …...………12 1. Bases for porosity-based techniques………………………….…………….14  1.1The effective stress concept……………………………………….…..14  1.1.2 Normal Trend………………………………………………………..16  1.2 Determination of shale porosity ……………………………………....17  1.2.1 Porosity determination of shale by using Resistivity ……………17  1.2.2 The Mechanical Module…………………………………………….20  1.3 Estimation of porosity from Wireline logs…………….……………….22  1.3.1 Estimation of porosity from sonic logs…………………………….22  1.3.2 Estimation of porosity from density log……………………………23  1.3.3 Estimation of porosity from Resistivity log using Archie Eq….....25  1.4 Summary and conclusion………………………………………………26

Part II: Direct pressure measurement……………………………………………………………...27 Chapter 2: Direct pressure measurement in formation…………………………….28 2. Direct measurement of permeable pore pressure……….……...……..30  2.1 RFT a briefly review………………………………………….………...30  2.1.1 The RFT Tool…………………………………………..…………...30  2.1.2 Principle of RFT works……………………………..………………30  2.1.3 Application of RFT……………………………..…………………...31  2.1.4 Limitation of RFT…………………………..……………………….32  2.2 Drill Stem Test(DST)…………………………………………...………32  2.2.1 Limitation of the DST……………….……………………………...32  2.3 RFT and estimation of pressure in shale……………….…………....33  2.4 Summary of the pressure determination……………………………..34

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PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------Chapter 3: Direct pressure measurement in Shale………………………………..…35  3.1 Application………………………………………………………………37  3.2 Existing Techniques…………..……………………………………....37  3.2.1 Pore pressure measurement in petroleum industry…...…37  3.3.2 Limitations of this method…………………………………..38  3.3 Basic Principle……………………………………...………………….38  3.3.1Chemical and Temperature effect………………………………..38  3.3.2 Pore pressure excess from wellbore fluid during drilling….…..39  3.3.3 Cement sealing……………………………………………………39  3.4 Measurement methods…………………….…………………..…......40  3.4.1 Short Term Measurement………………………………………...41  3.4.2 Long Term Measurement………………………………………...42  3.5 Challenges…………………………………………………..…………43

Part III: Indirect Pressure Measurement…………………………………………..….…..44 Chapter 4: seismic While Drilling (SWD)……………………………………………….45  4.1 Seismic While Drilling Operation and Application……………..…...47  4.1.1 Planning phase………………………………………………..…...48  4.1.2 System design and Consideration………………………...…..…48  4.1.3 SWD Tool…………………………….…………………….……....50  4.1.4: Process of SWD………………………………………… ….......50  4.1.5 SWD Application………………………………………….......……50  4.2 Drill-Bit Seismic…………………………………………………. ……53  4.2.1 Application……………………………………………………. …..53  4.2.2 Procedure technique………………………………………....…….53  4.2.3 Advantage drill-bit seismic…………………………………… …...55  4.2.4 Limitation drill-bit seismic…………………………………….. …..55  4.3 Vertical Seismic Profiling (VSP)…………………..……… ……..…56  4.3.1 Advantage of VSP-MD…………………………………… …….….56  4.3.2 Limitation of VSP- MD…………………………………… ………...57  4.4 SWD using Swept Impulse Source……………………… …….…..58  4.4.1 Seismic profiling using Swept Impulse Tool (SIT)…….. ……..…59  4.4.2 Advantage of Swept Impulse Tool …………………….. …….….59  4.4.3 Limitations……………………………………………..…… …..….59

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PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------Chapter 5: MWD/LWD………………………………………………………………..… 60  5.1 Measurement while drilling (MWD)…………………………….. ……62  5.1.1 Types of transmitted information…………………………..… ….62  5.1.2 Directional information………………………………………..… ..62  5.1.3 Drilling mechanics information………………………….…….… 63  5.1.4 Formation properties………………………………………….…. 63  5.2 Data transmission methods………….……………………….….. 63  5.2.1 Mud pulse telemetry…………………………………………..  5.2.2 Positive Pulse …………………………………………………  5.2.3 Negative Pulse …………………………………...…………...  5.2.4 Continuous Wave ……………………………………………..

63 64 64 65

 5.3 Electromagnetic telemetry (EM Tool)……………………….…..  5.4 Wired Drill Pipe……………………………………………………  5.5 Retrievable tools…………………………………………………..  5.6 Logging while drilling (LWD) …………………………….……

66 66 67 68

 5.6.1 Available LWD Measurements………………………………  5.7 MWD/LWD Advantages………………………………………….  5.8 MWD/LWD Disadvantages………………………………………

68 70 70

Chapter 6: Miscellanies……………………………………………………………

72

 6.1 Eaton Method………………………………………………………  6.2 Equivalent Method…………………………………………………  6.2.1 Calculation of Overburden Gradient…………………………

74 75 77

 6.3 The Ratio Method …………………………………………………  6.3.1 Isodensity Concept……………………………………………  6.3.2 Establishing isodensity line…………………………………..  6.4 Vertical and Horizontal Models Method…………………………  6.5 Pore Pressure in Over consolidated Shale……………………..  6.6 Compaction Concept Method…………………………………….  6.7 Power Law Relationship Method………………………………... References:........................................................................... .........................

78 79 79 81 83 85 87 91

Appendix A:………………………………………………………………………………

93

Appendix B:………………………………………………………………………………

112

Appendix C:……………………………………………………………………………

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Predication of Pore pressure using Eaton Method

Predication of Pore pressure using equivalent depth method. Predication of Pore pressure using Vertical & Horizontal Methods

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Appendix D:……………………………………………………………………………

129

Appendix E:……………………………………………………………………………

138

Predication of Pore pressure using overconsolidated Pore pressure method

Nomenclature

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List of Figures:

page

Ref.

Fig.1.1 Fig.1.2 Fig.1.3 Fig.1.4 Fig.1.5 Fig.1.6 Fig.1.7 Fig.1.8 Fig.1.9 Fig.2.1 Fig.2.2 Fig.2.3 Fig.2.4 Fig.3.1 Fig.3.2 Fig.3.3 Fig.4.1 Fig.4.2 Fig.4.3 Fig.4.4 Fig.4.5 Fig.4.6 Fig.4.7 Fig.4.8 Fig.4.9 Fig.5.1 Fig.5.2 Fig.5.3 Fig.5.4 Fig.5.5 Fig.5.6 Fig.5.7 Fig.5.8 Fig.6.1 Fig.6.2 Fig.6.3 Fig.6.4 Fig.6.5

[- ] Illustration of Overburden Pore fluid rock grain in deep sediment rocks…15 [- ] Illustration of main stress and direction of force on a sample rock in a deep sediment rocks…………………………………………………………...15 [3] Pressure-Depth shows the relationship between total stress, pore pressure and effective stress……………………………………………..……………...16 [3] Bases for porosity based on pore pressure predication ............................16 [- ] Illustration of Normal Trend Line……………………………………………...17 [4] Cation distribution in Clay particles…………………………………………...18 [8] Shale resistivity…………………………………………………………………..19 [- ] Porosity vs. depth based on Wyllie and Raiga Clemenceaue Methods…....24 [- ] Illustration in variation in estimate of the porosity from a density log using grain densities…………………………………………………………………….25 [9] Modern Multi Tester Tool (RFT, DST,…) from schlumberger ……….….....31 [8] Typical analog pressure record in low permeability formation……………...31 [9] RFT and sampling principle……………………………………………………..32 [7] Estimation of pore pressure in shale based on extra plotting on RFT data in Nile Delta Egypt…………………………………………………………………..34 [10] Option for pore pressure Measurement in Shale…………….….…………..41 [10] Schematic pore pressure measurement system…….………………..……..42 [11] Image of Halliburton Geo Tap……………………………………...…………..42 [12] Rig set up and system design for SWD including boat operations………...50 [12] Sensors on the SWD Tool……………………………………..…….………....51 [ - ] Schematic of SWD process………………………..…………………………....52 [12] SWD Process…………………………………………………………………….53 [14] Illustration of acoustic Radiation Pattern of the Tri-Cone Bit………………..54 [14] Cross correlating the accelerometer signal…………………………………...55 [14] Transfer of the wireline seismic technology to drilling operation……………57 [14] Operation procedures of VSP-WD surveys…………………...………………58 [17] Comparing of VSP&VSP look-ahead done by DNO…………………………58 [20] Positive Mud pulse System……………………………………………………..65 [20] Negative Mud pulse System…………………………………..………………..65 [23] Position of Mud Pulse Telemetry in Drill String………………………...…….65 [20] Continuous wave (Mud Siren) System….……………………………...……..65 [- ] Principle of EM-effects in MWD/LWD………….………………………………67 [23] Image of Wired Drill Pipe………..……...………..……………………………..67 [23] Section view of double-shouldered pin tool joint,……………………..…….68 [-] Principle of the LWD…………………….…………………………………………69 [22] Pore pressure predication based on Eaton method…………………….……75 [ - ] Principle of the Equivalent depth method……………………………………..76 [22] Ratio Method: Principle of the dc-exponent…………………………..………79 [22] Example of a set of isodensity lines……………………………………………80 [22] Shows how to setting isodensity lines in Ratio Method………………...……80

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PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------Fig.6.6 Fig.6.7

[ - ] Principle of Vertical-Horizontal Methods in deep water depth….……………82 [24] Shows the comparing of the Vertical vs. Horizontal pressure measurements methods on shale………………………………………………………………...83 Fig.6.8 [ - ] Determination of pore pressure in over consolidated Shale…..……………..86 Fig.A1: [ - ] Variation of Sonic travel Time vs. Depth………………………….…………….99 Fig.A2: [ - ] Pore pressure predication using Eaton sonic log method………….………100 Fig.A3: [ - ] Variation of traveltime sonic log vs.depth……………………………………..109 Fig.A4: [ - ] Pore pressure predication using Eaton sonic travel time method…...……..110 Fig.A5: [ - ] Variation of Resistivity Vs. depth………………………………………………111 Fig.A6: [ - ] Pore pressure predication using Eaton Resistivity method…………………112 Fig.B1: [ - ] variation of porosity vs. depth in Norne felt well nr: N6608 10-E-3 H…...…117 Fig.B2: [ - ] Predication of pore pressure using equivalent depth method……………….117 Fig.C1: [ - ] Principle of predication pore pressure in Horizontal & Vertical Methods…..118 Fig.C2: [ - ] Velocity vs. depth…………………………………………………………………126 Fig.C3: [ - ] Pore pressure predication using vertical method……………………………..127 Fig.C4: [ - ] Pore pressure predication using Horizontal method(X=3)…………………...128 Fig.C4: [ - ] Pore pressure predication using Horizontal method(X=2)……..…………….129 Fig.D1: [ - ] sonic travel time vs. depth……………………………………………………….133 Fig.D2: [ - ] Velocity and Normal compaction Curve………………………………………..134 Fig.D3: [ - ] Pore pressure predication using Eaton Method………………………………136 Fig.D4: [ - ] Pore pressure predication using Bower’s method…………………………....137 Fig.D5: [ - ] Pore pressure predication using overcosolidated model…………………....138

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PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------Introduction: An important parameter for well planning is the knowledge about the formation pore pressure. Shale is one of the most important rocks which can be found in all reservoir rocks, often with an abnormally high pore pressure. And also detecting of abnormally high pore pressure is an important task in every drilling program. Overpressure sediments are generally caused by sequence of events where becomes trapped by fault or non- permeable barriers in sediments at depth. In a normally pressured formation the water was forced out by normal increases in overburden pressure. But abnormally pressure is caused by releases of water into the sedimentary pore system, Clay diagenesis, normal compaction and other mechanisms are strongly related. In over pressured shale which contains pressured water, density is lower and porosity is higher then normal. Shale comprises a large proportion of most sedimentary basins and forms the seal and source rocks for many hydrocarbon reservoirs .Shale is a tight material with a sufficient low permeability. Because of their low permeability, there is great interest in using shale as host rocks for waste storage. Porosity in shale varies between 50 to 5 % when depth increasing. It’s extremely difficult to estimate and measured the porosity in shale. That’s a challenge for direct measurement of variation of pore pressure in shale. several method exist to estimate pore pressure in shale since 1950.Many authors have outline procedures for estimating formation (shale) pressure using data obtained from electrical and acoustical surveys. Some others as Eaton, Hubbert, Willis and Mathews have outline procedures for estimating fracture pore pressure. Knowledge of these two parameters (formation & fracture pressure) is important in planning and drilling future wells. In fact one can divided these methods in two categories. Direct pressure measurement and indirect measuring methods. Direct pressure measurement in porous and permeable formation (RFT) has been made for decades. But direct measurement of pore fluid pressure by the modular dynamic test or repeat formation test tools in shale seems to be impossible due to their low permeability. The use of shale compaction curves is thus the basis of several methods of pore fluid pressure estimation, pressure from seismic, wire line and in basin modeling. All these methods require the definition of a normal compaction curve (NCC), or set of normal compaction curves for the shale. These curves are typically empirical, being based on regional experience or using calibration from soil mechanics experiments, but some is based on work in the rock mechanics. The most of these methods based on detection of normal pressure trend comparing with an abnormal trend in formation (especially Shale) to obtain overburden gradient pressure in the pointed depth. Other methods as Seismic While Drilling (SWD), Logging While Drilling (LWD) and vertical Seismic Profiling (VSP) are the new technology for more accuracy of data and well logging for estimation of pore pressure in shale which is used by the most of oil companies. All these used on in indirect pressure measurement. The direct pressure measurement in shale (“MESPOSH”) has been obtained since 2000(?) by some oil companies as Statoil, BP and others! This method considers for two main applications as Long term and short term pressure measurement. Effects of local stress, chemical and temperature on pressure measurement have been obtained. These methods shows the more can be learned about shale, directly by measurement or indirectly by inference, the better our position will be in interpreting and understanding the causes of the instability of pressure variations. This knowledge can lead us to more realistic application of technology and product NTNU | Atumn2009

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PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------development to the problem of controlling of unstable shale. In the petroleum industry, shale causes billions of dollars in losses annually through, for example, pore-pressure-related kicks, blow-outs, and wellbore instability. Shale has a decisive impact on fluid-flow and seismic-wave propagation because of their low permeability and anisotropic microstructure. Thus we review the most of useable pressure estimation and try to present the new methods and fit the real well data to these methods. Simulate and analyses them.

.

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Part I: Challenge of porosity in Shale

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Chapter 1: Challenge of Porosity Measurement in Shale

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Introduction Fluid pressure estimation down well and its accuracy is one of important fact for safe and economical drilling. Standard direct methods of pore pressure determination in shale are impossible because of shale’s low permeability. wireline loges commonly used for estimation of pore pressure in offset wells .A method combining electrical and mechanical models to estimate pore fluid pressures from wireline logs has been developed since 1950s.this methods reduce uncertainty involved in estimating porosity from the logs and includes a simple model of mud rock lithology in the calculation of fluid pressure. Porosity is commonly used to estimate pore pressure. If assume all shale behaved in a homogeneous manner in response to increasing effective stress, this estimation process would be relatively simple. The common inference of overpressure from porosity data from wireline on the assumption that overpressured shale is under compacted relative to its depth of burial is flawed. As we know the shale compaction is strongly dependent on lithology. Thus a combination of detailed rock data and suitable soil mechanics will lead us to an increased ability for estimating pore pressure. Porosity estimation is one of this challenges which knowledge about the quantity of it, leads us to put a big step to pore pressure estimation. In this chapter we try to a benefit description of porosity estimation methods.

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1. Bases for porosity-based techniques  1.1 The effective stress concept Terzaghi stress relationship is basis for pore pressure predication and pore pressure in the simplest form is:

 Z , tot   ob   v  Pp …………………….1.1 Where:  Z, tot   ob : Total stress or Overburden v Pp

: Effective stress : Pores pressure

And porosity can be calculated from:

   i  exp(K  v ) ……………………...1.2  i K v

: Porosity of shale @ depth D : Initial shale porosity @ surface : constant : Effective stress

The total vertical stress (  v ) is derived from overburden which is combined weight of the sediments and contained fluids. The density log or density-sonic transform is used, coupled with an estimate of average sediment density from the top of the logged interval to seabed. Incorrect of average density estimation leads to a systematic error in pore pressure predication in the formation. The magnitude of the two horizontal stress (  h ,  H ) is less well constrained;  h can be most readily estimated from borehole data, while the magnitude of  H is only rarely known. In practice most of engineers use vertical effective stress (  v   v  Pp ) , (also known as overburden or lithostatic pressure Fig.1.3) as a proxy for mean effective stress. hence that, there is a tendency to use vertical effective stress in pore pressure predication.

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If the pore pressure is unknown in the above equation, where dose the magnitude of the effective stress com from? Effective stress (grain to grain contact stress) is the principal driving mechanism for compaction of compressible sediments. The magnitude of the effective stress increase with depth when the pore pressure remains hydrostatic or normal which in turn reduction of porosity (Fig.1.4).porosity can be used, under the right conditions, as a direct indicator of effective stress. With overpressure due to effective dewatering, compaction is slower than expected relative to the depth of burial and normal effective stress. Although the sediments are overpressuered they still retain the correct relationship between porosity and effective stress (Fig.1.3). In this case the rocks are under compaction and they will hold sediments properties, such as porosity and permeability, which are associated with shallower depths of burial. This framework describe the basis for porosity-based pore pressure predication, in which porosity assumed to be controlled slowly by compaction (i.e. no chemical involved) and to reflect the current effective stress of sediment. Theses principles are summarized on (Fig 1.4). Practically during conventional oilfield drilling operations, porosity is not measured directly. Rather porosity values can be obtained from wireline response (e.g. density, sonic, resistivity, neutron log), or a porosity attribute may be used directly, for example velocity data derived from seismic. These methods have good results in low temperature, young, fineNTNU | Atumn2009

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PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------grained sediments, particularly where the lithology remains similar (in composition and grain size) throughout the section drilled, and where an upper shallow section exhibits a recognizable” normal compaction curve”. However porosity based pore pressure predication dos not always deliver satisfactory pore pressure estimation, either because these assumption are not valid, or because there is insufficient data. There are several reasons for failure of the traditional porosity-based methods, especially in older (higher Temperature) basins as shale and where mixed lithologies are found. These solutions are found in:  Calibration using offset wells-essentially introducing a “fudge factor” which will be locally developed.  Maximizing the number of direct pressure measurements  Employing multiple complementary techniques to help understanding the uncertainty. There are several methods employed to obtain porosity in shale based on pore pressure predication (e.g. Eaton Ratio Method an Equivalent Depth Method, etc…)all of these methods are best suited to pore pressure resulting from disequilibrium compaction, and require development of a type curve to characterize the change of porosity with depth, referred to as the “normal compaction curve”. [1]  1.1.2 Normal Trend It is widely known that different lithology compact at different rates, and from contrasting starting porosity. Lithological variability is accounted for by” best fit” of the shallow data, assumed to be normally compacted if the porosity is decreasing with increasing depth. This normal compaction curve is used to compare actual porosity on the curve such that an estimation of effective stress can be made for pore pressure estimation. Alternative to best fit of data include: 



A standard algorithm to describe normal compaction behavior of the same lithology, for example the shale compaction curve of Balawin and Butler (1985) A used-defined porosity depth curve or similar function based on local experience.

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PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------Once the normal compaction curve is defined, the pore pressure predication involves comparison between observed porosity (and rather the attribute which is reflecting changing porosity, such as interval velocity or wireline density) and the normal compaction curve. The comparison is made at the depth of interest when using current methods (e.g. Eaton Method and etc...) or comparison of the same porosity value on the normal compaction curve using Equivalent Depth Method .both method assume that the compaction is mechanical, and both can provide pore pressure estimation when the origin of overpressure is under compaction and the sediments are young and low temperature. 1

1.2 Determination of shale porosity  1.2.1 Porosity determination of shale by using Resistivity For determine porosity in shale from resistivity we need to define relationship between formation factor (F) and shale porosity. According to Archie (1942) formation factor define by:

Ro ……………………….………………….....1.3 Rw Where: R o : Resistivity of saturated rock F

R w : Resistivity of the fluid saturating the rock And formation factor relate with formation porosity. Archie developed an empirical relationship (Eq.1.4) which is widely used. Table 1.1 summarized the usual values assumed by “a” and “m” for several types of rocks. a F  m ................................................................1.4  Where : a : Formation factor constant Φ : Porosity m : Cementation factor Formation factor equation has never been proposed for shale, which reservoirs engineers have little interest in. only for shaly sand has been developed by Waxman and Smits in earlier 1968. However they cannot be applied to represent Shale behavior. One of the reasons is that clay particles are under pore pressure conditions is shaly sands. The clay platelets therefore behave approximately as colloids (Fig.1.6) and they are associated to bound water and free water as the dual-water model emphasizes [clavier et al, 1977]. NTNU | Atumn2009

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Equation 0.81 2 1 F 2  0.62 F  2.15  1 F  2,1to 3, 0  F

Application Sand Compacted formation, Chalks Sucrosic Rocks Olicastic Rocks

Table 1.1: usual formation factor expression [Schlumberger, 1987] It’s assumed that a single fluid type could be in compacting smectite shale named “bound water”. There fore a new formation factor relationship must introduce to represent the electrical behavior of Shale. Perez-Rosales (1975) based on mathematical model for electrical conductivity which has been provided by Fricke (1924), improved this new introduction and defined the following relationship between formation factor and porosity:

F

Ro 3   …………………………1.5 Rw 2

This expression of the formation factor derived from Fricke’s work could be used in this form if shale could be actually assimilated to a suspension of a nonconductive solids sphere in a conductive fluid. This is not the case, however; and Eq.5.5 must be modified to represent the geometry of clay platelets and their high concentration in the “suspension.” PereRosales (1975) adapted Fricke’s work to porous media and obtained:

F

Ro 1   1 M  …………………………….1.6   r Rw

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Where:

R o : Resistivity of the system R w : Resistivity of the fluid M : Geometrical factor Φ : Porosity Φ r : Residual Porosity

“M” accounts for departures from the ideal spherical shape of the individual particles, and “Φ r ” is the part of the porosity that does not participate effectively in electrical conduction. 1 In shale the saturating fluid is bound water, and the Eq.5.6 becomes:

F

R Sh 1   1  1.85  …………………………..1.7   0.1 Rw

Where:

R Sh Rw M Φ Φr

: Resistivity of Shale : Resistivity of bound water : (1.85=Geometrical factor by Perez-Rosales) : Porosity : (0.1 =satisfactory for sand)

But none of the earlier approaches is representative of shale pore-water. This research argues that the bound water provides the electrical path in shale.this relation has been developed by Clavier (1977) as below: By rearranging Eq.1.6 eventually yields shale porosity: R w   T   …………………………………………….1.8

Where:

R w : Resistivity of bound water β : Constant =297.6 T : Temperature ( o F)

And porosity of shale: M   r  (F  1) …………………………………1.9  Sh  M  (F  1) And by using numerical value suggested by Perez-Rosales (1975):

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PRESSURE MEASUREMENT IN SHALE ---------------------------------------------------------------------------------------------------------------- Sh 

1.75  0.1  F ……………………………………1.10 0.85  F

Thus shale porosity can be estimated from single shale resistivity measurement, and the approximate knowledge of formation temperature. But represented method has several limitations.

Limitation:  

It is assumed that the Perez-Rosales (1975) Eq. provides a reliable description of the conductivity of porous media and that it can be adapted to shale. The data presented by Clavier (1977) for sodium clay are assumed to be representative, and applicable to overpressure shale environments. But Kaiser (1984) has shown that the sodium is the preferred interlayer cation with increasing temperature.

 1.2.2 The Mechanical Module As we have written before for mechanical module we need Terzaghi stress relationship which is basis for pore pressure predication and pore pressure in the simplest form is:

 Z , tot   ob   v  Pp The compaction can be described by the second factor “Void ratio” which is defined as:  ……………………………………………..1.11 e 1  Where: e : Void ratio : Porosity  Using the shale porosity estimates provided by the resistivity module, this equation can be used to evaluate the associated effective vertical stress:

v  10 Where: v

eei Cc

………………………………………1.12

: Effective stress

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PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------Cc e

ei

: Average Constant Compression index : Void ratio : Void ratio corresponded to v =1 psi

C c and e i are experimental data needed for this purpose were taken from a borehole stability study performed in the north Sea by Despax(1988) and this numbers for shale are to:

e i =3.84

C c = -1.1 Thus Eq. 1.12 becomes:

v  10

e3.84 1.1

……………………1.13

Thus at the end we can estimate pore pressure by reforming Eq.1.1 such:

Pp   ov   v …………………....1.14 The summarize of whole steps is drown below:

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1.3 Estimation of porosity from Wireline logs:  1.3.1 Estimation of porosity from sonic logs The sonic logging tool measured the sound wave transit time in a vertical direction in the borehole. The porosity of the formation can be obtained from well logs such as sonic and density. Their responses depend on formation porosity, fluid and matrix density. A commonly used linear relationship for estimating porosity based on acoustic measurement was published by Wyllie (1956) as follow:

1  1    …………………………………..1.15  p  fl m Where:

Ʋp

:

Ʋm Ʋfl

formation velocity

:

:

Matrix velocity fluid velocity

And in terms of transit times as:

t  t fl  (1  )t m ……………………….….……1.16 And porosity estimation in shale can be calculated from: t  t m  sh  ……………………………..….…….1.17 t fl  t m  t  t m …………………………………..1.18  sh  1.268 t  200 Where: Formation transit travel time ([

s s ] or [ ]) ft m

Δt

:

Δt m

: Matrix transit travel time (for Shale :Δt m = 47

Δt fl

:

Fluid transit travel time (Δt fl = 68, 8

Φsh

:

Shale porosity

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s s or Δt m = 14, 32 ) ft m

s s or Δt fl = 226 ) ft m

[ 4]

24

[ 4]

PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------In the other hand Raiga-Clemenceau suggested other equation based on empirical study of a very large dataset as follow:

 t    1  m   t 

1 x

………………………………..…1.19

Where: x

:

an exponent specific to the matrix lithology.

In (Fig.1.8) shows the comparing of these two methods for estimation of porosity!

 1.3.2 Estimation of porosity from density log. The density tools measures the strength of the diffused gamma rays. The number of electron in atoms is approximately proportional to their density. Thus collisions are therefore more numerous the denser the material. Gamma ray attenuation is directly depends on formation bulk density. If the density of the matrix is known, porosity can be calculated from:

 b  (1  ) m     fl ……1.20 Where: density

ρb

:

ρm

:

ρfl

:

measured bulk Matrix density fluid density

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PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------And porosity for shale formation can be calculated from:

 sh 

m  b ………………..……….1.21  m   fl

However the blind use of density log to estimate porosity in shale has a large amount of uncertainty associated with it, as the matrix density of shale can vary over large range. Typically density range estimation for shale is between 2.65 g g [ ] and 2.70 [ ]. 3 cm cm 3 Shale is also a blanket term used to describe a very large range of quartz contents in rock (typically <40 %).this also has heavily effects the grain density of samples. (Fig 1.9) shows the variation in estimate of porosity from a density log using grain densities of g g 2.40[ ] and 2.70 [ ]. 3 cm cm 3

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PRESSURE MEASUREMENT IN SHALE ---------------------------------------------------------------------------------------------------------------- 1.3.3 Estimation of porosity from Resistivity log using Archie Eq. : Porosity estimation from Resistivity log can be done by using the Archie Eq. (Rider, 1996) as follow:

 R S    t  Rw  a

2 w

Where:

1 m

  ………………………………1.22 

Rt

: Formation resistivity

Rw

: Pore water

Sw

: Water saturation

a

: Lithology constant

m

: Lithology constant

The number of parameters that have to be estimated using this technique aid the reduction in accuracy of any porosity estimates that it produces. The neutron log measures the hydrogen index of the rock surrounding the borehole. This can be quickly transferred into the porosity of the sand stones and carbonates, but the bounds water in clay structure gives an anomalously high estimate of shale porosity (Rider, 1996). Since the amount of bound water in clays is variable, any estimate of shale porosity using the neutron log is liable to be inaccurate.

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1.4 Summary and conclusion The model developed in this study comprises two modules. An electrical module and a mechanical module. It is able to provide effective vertical stress estimates in shale using resistivity measurements and formation temperature. The equations necessary to the interpretation were derived analytically, until calibration was needed to adjust the ideal model to the real environment. This approach provides the user with better control and the possibility to calibrate the model rapidly in new environments. If any of these methods are used with care and large numbers of calibration samples are available, they can provide fairly accurate estimates of porosity. Wireline log analysis is still one of the major methods employed to estimate pore pressure. It is used to create models of pressure in offset wells during the planning of drilling programs. Many methods of pore pressure estimation, such as that from Resistivity, Sonic and Density logs, require many assumptions about the rock properties, and so, unless copious of calibration data has been produced, the accurate estimation of porosity from wireline logs is difficult.

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Part II: Direct pressure measurement

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Chapter 2: Direct Pressure Measurement Methods in Formation

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Introduction: The Repeat Formation Test (RFT) and Drill Stem Test (DST) are an open hole wire line instrument primarily used for measuring vertical pressure distribution in reservoir, as well as for recovering formation fluid samples. The point by point reservoir pressure measurement technique is to used to determine the gradient of both hydrostatic pressure of mud column in the bore hole before the tool is set or after the tools is retracted, and the formation pressure when the tool is set.RFT & DST also are a device capable of providing an estimate of formation permeability through the interpretation of pretest pressure data recorded during downward and build -up. The idea with any relation between RFT and shale pressure measurement may be able to use this test for shale which is among to permeable lags! And by measuring pressure on these lags my we can estimate formation pressure in shale too. An example for this situation is deep water Sandston reservoirs which commonly observed to be isolated with shale dominated sequences. Pore pressure profiles through such sequences are based on both direct measurements in the reservoirs, and estimation based on porosity and shale properties in to non-reservoirs section. In this chapter a briefly review of the most useable direct pressure measurement and it will be tried to obtain relation between these two kinds of pressure measurements to estimate pore pressure in shale!

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2. Direct measurement of permeable pore pressure: The most direct pore pressure measurements are made on porous and permeable formations! Two main methods are Repeat Formation Test (RFT) and Drill Stem Test (DST) which briefly have been present in this chapter.

2.1 RFT a briefly review:  2.1.1 The RFT Tool: The repeat formation test tool has been designed to:  

Measure Formation Test Collect Reservoir Fluid Samples.

Depth accuracy can be controlled by correlated a Gamma Ray curve or an SP curve with the Open Hole loges. when the tool is set, a packer moves out one side, and back up pistons move out on the opposite side, as seen in(Fig.2.1) the body of the tool is held away from the borehole wall to reduce the chances of the differential sticking.

 2.1.2 Principle of RFT works: When the tool is set, the pressure rises slightly because of the compression of mud cake by the packer. Probe piston retracts and the pressure drops due to the resulting flow line volume expansion and communication with the formation. When the piston stops, the pressure build up again because the packer is still continuing to compress the mud cake until the tool is fully set. Next the pressure drops as the first 10 cc pretest piston binges moving at a constant rate. This time denoted as t 0 . After about 15 seconds the first pretest piston reaches the end of its travel. At this time t 1 , the second piston begins moving at rate of 2, 5 times faster than the first piston movement, consequently the pressure drops further. When both pressure chambers are full, at time t 2 , the pressure builds up towards a final pressure. NTNU | Atumn2009

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PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------The running times used for pressure analyses, Δt, is counted starting at t 2 .analyses of the build-up curve may yield permeability and reservoir pressure as with conventional drill stem and production pressure tests. Finally, after the tool is retracted, the mud column pressure is again measured. Fig.2.2 shows the RFT pretest and sampling Principle. A typical pressure recording is shown in Fig.2.3 which shows both analog and digital pressure curves as standard log penetration.

 2.1.3 Application of RFT Besides the retrieval of formation fluid samples and measurement of the formation pressure, the RFT has found many applications in the field of reservoir engineering:   

In exploration wells in unproduced fields In development wells

In exploration wells in unproduced fields it’s known that formation pressures must conform to gravity capillary equilibrium establishing over time. Thus the conduct of the RFT survey and the interpretation of the data is governed by the concentration that the formation pressures lie on straight-line fluid gradients and the main objective of this testing is to delineate this gradient. NTNU | Atumn2009

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In development wells, the observed formation pressures may already affect by either partial depletion or possibility water injection. Thus the new development well is used as an observation location at which the current state of the reservoir can be measured on a vertically distributed basis. The measured pressure profile reflects the response of the reservoir to production/injection and it is axiomatic that the pressure information may not be interpretated in terms of reservoir structure and fluid distribution with out knowledge of the production which has taken place. Reservoir simulation may often be the only possibility approach to interpret RFT data on a fieldwide basis. [ 6 ]  2.1.4 Limitation of RFT 



The RFT tools provide accurate, definitive data on formation pore pressure. However, the formation pressure data can only be obtained from permeable layers, such as reservoir sandstones or limestones. This formation may contain pressures which bear no resemblance to the pore pressure in the overlaying and underlaying formations, and such their application is restricted to the formation sampled. In HPHT wells the RFT tool should be considered for use prior to performing potentially problematic drilling operations, such as coring, in order to fine tune the required med density and minimize the risk of swab or surge problems. [5]

2.2 Drill Stem Test(DST) DST is a method of the testing formation pressure and fluid. A drill stem with a packer is run and set just above the zone to be tested. The packer is set and a DST valve is opened to allow the reservoir to communicate with the inside of the drillstem which is run either empty or with a small calculated cushion. The drill stem is run with several pressure gauges. The purpose of the pressure gauges is to record the downhole pressure during the sequence of flow and shut in periods that comprise the DST. The pressures recorded during the test are used to calculate reservoir characteristics such as formation pressure, permeability, skin damage and productivity index. Analysis of the pressure build up from shut in leads to accurate determination of the formation pore pressure. The second shut-in period is used for determining the final shut-in reservoir pressure. The actual static reservoir pressure is determined from Horner analyses of the DST pressure data.  2.2.1: Limitation of the DST Data from drill stem tests enable accurate determination of the reservoir pressure. However, the pressure data can only be obtained from permeable formations that exhibit sufficient hydrocarbon reservoir potential to warrant the expense of the DST. As with RFT pressure data, the reservoir pressure calculated from the DST may, or may not be the same as the pore pressure in the adjacent formations. [5] NTNU | Atumn2009

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2.3 RFT and estimation of pressure in shale As we know RFT is used for direct pressure measurement in permeable layers. In shale as an impermeable layer we can not used RFT or we get any data from RFT tools during passing shale layers. But in some case we take RFT data to estimate Formation pressure in shale! In some case we have two permeable layers upper and downer the shale layers and with using RFT data from this permeate layers with continuing sketch of these points we may estimate pore pressure in shale! But this gives a big uncertainty to us and for solve this problem and decreasing uncertainty we can use other SWD tools as VSP data with RFT data. (Fig. 2.4) shows a principle of this method which have been done already in Nile Delta in Egypt by Mann & Mackenzie (1990).

However direct data (RFT, MDT, FMT, DST) in the shale as impermeability’s layers, are too low to take samples; therefore, overpressures in shale can be calculated from using pressures recorded in isolated sands or just use pressures in isolated sands directly to establish regional shale pressure gradients.

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2.4 Summary of the pressure determination When collecting pore pressure data for a new well, it imperative to label the data points according to source used to measure or calculated them. Hence that the data may come from mud logging, LWD or RFT and DST sources. Obviously the RFT and DST pressure data are the most definitive and have the least uncertainty associated with them. Mud program and casing seat selection can therefore be based on RFT and DST pore pressure values. While the RFT and DST data provide definitive values of pore pressure for the well, the direct measurements are only possible in permeable formations and are obtained after the well is drilled. They are also not applicable to the surrounding, largely impermeable, shale sections where the majority of the overpressure is developed. Estimation and calculating of pore pressure from mud logging, wireline and drilling log data are restricted slowly to the Shale sections. Establishing a normal compaction trendline is important when calculating pore pressure from log derived shale properties. Among the several of the available well logs, sonic log data is considered to be the most accurate, as it is largely unaffected by borehole size, formation temperature and pore water salinity.

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Chapter 3 Direct measure Pressure in Shale :( MESPOSH)

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Introduction: Direct pore pressure in shale is one of the greatest progressive step changes in development of pore pressure determination ahead of the drilling bit. The lack of direct pore pressure measurement is preventing improvement of borehole stability assessment and seismic interpretation. This method not yet done in the petroleum industry, it is documented that long term pore pressure measurement in shale is feasible with existing equipment. The review indicates that short term measurement of pore pressure is not possible with current technology. It seems new equipment and technology must be developed. Guidelines for such development have been established but this technique may have a considerable cost. Thus it’s proposed to lunch a JIP on pore pressure measurement in shale, so evaluate of main influencing factor on pore pressure measurement in shale has been performed. Therefore the pore pressure effect of local stress concentrations around a hole needs to be dissipated; and such dissipation for a pore pressure sensor placed at the wall of a standard well may takes a long time (weeks or month!).For short terms application a small size hole may be necessary to get a measurement with in a reasonable time for a drilling operation. The major task for measuring of pore pressure is identified as Zonal isolation. We know that the permeability of a sealing cement may be one magnitude or higher than shale without disturbing the measurement too much. However the major concern still is avoiding channeling or micro annulus. Sensors at various levels are recommended to verify proper sealing. A principal challenge for long term measurement is to develop suitable procedures for installing the instruments. The main objective is to develop a system for reliable and economical pore pressure measurement in shale and to verify the system by a field trial. On long term the pore pressure measurement in shale is a starting point for predication of the pore pressure a head of the drilling bit. Most of drilling and seismic travel time takes place in shale and it is dominating sealing material for hydrocarbon reservoirs. Understanding the shale behavior is necessary for reducing cost of drilling, reliable interpretation of seismic and for assessment of the interaction between the reservoir and surroundings rocks. The roles of Pore pressure in shale may describe as: 1. Pore pressure has a direct impact on drilling safety and further exploration, in over pressure zones. 2. Pore pressure is important as total stress to determine effective stress. The effective stress controls the mechanical behavior of geomaterial as strength and stiffness. Both stability of well bore and seismic velocity are realization of this mechanical behavior. 3. Pore pressure controls hydraulic gradient, which controls fluid flow in a basin. This issue is very important and it’s strange that there aren’t any reports of direct measurement of pore pressure on shale in the petroleum industry. Thus pore pressure in shale is one of the last items on the list of primary mechanical parameters. Thus “It’s time to do something about It.” to enable progress for hole stability assessment, seismic interpretation and fluid flow models. NTNU | Atumn2009

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3.1 Application: Several applications for MESPOSH are: ► First application of direct pressure measurement in shale is calibrating the existing indirect methods. Thus various geological settings should be investigated and depth variation should be checked. So long term measurement techniques are sufficient for this kind of application. It is considered the most simple and reliable approach. ► Measurement in exploration and appraisal wells to speed up the learning curve in new areas and thereby create added value to drilling and exploration risking ►If short terms equipment become available, it would open up for application in exploration and appraisal wells to speed up the learning curve in new areas and so create large values in terms of more efficient drilling and reduced exploration uncertainty. ►there is additional application of MESPOSH which is when shale is near or within reservoirs with serves depletion, for instance HPHT fields. Production related pore pressure changes in such zones are important for drilling in depleted reservoir and also for new technologies such as 4D survey in combination with aeromechanical modeling. ►Tight reservoir

3.2 Existing Techniques:  3.2.1 Pore pressure measurement in petroleum industry: Direct measurement of pore pressure in oil industry is made in permeable reservoir zones and this pressure is called reservoir pressure. This method is done during drilling or in a completed well. During drilling the pore pressure is observed by pore pressure equilibration or transients in a sealed part of the borehole. In a completed well pressure sensors measured the fluid pressure continuously, either with in production tubing or direct contact with formation. Periods with production stop gives a measure of the reservoir pressure (no draw down). Pore pressure in shale is estimated currently by following methods:     

As a part of basin modeling. By calibration of seismic velocity. By calibration of electrical loges. From pore pressure measurement in permeable layers with in the shale sediment. Observation of inflow during drilling. [10 ]

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PRESSURE MEASUREMENT IN SHALE ---------------------------------------------------------------------------------------------------------------- 3.3.2 Limitations of this method:    

Method 1 is a prognosis in need of verification. Methods 2&3 have a problem with the basis for the correlation. Too few data points in method 4. Method 5 suffers from the low permeability of the shale. [10 ]

Pore pressure measurement in clay is a common activity in foundation design and geotechnics pressure measurements. Normally this is done on long term basis by dedicated borehole with one or more pressure sensors in contact with clay and with hydraulic isolation a long the well. Also short term measurement with small piezoelectric penetrated into clay is used.

3.3 Basic Principle: General:

To obtain pore pressure in shale three requirements must be in place:   

A pressure sensor communicating with the pore fluid of the shale. Eliminate or manage the disturbance from installing the sensor. Eliminate or manage disturbance during the measurement.

The disturbance from installation of the sensor may have the following sources:    

Concentration of local stress from penetration or drilling of a hole Chemical and Temperature effect from the wellbore fluid during drilling Pore pressure excess from wellbore fluid during drilling Cement Sealing

Unintended pressure communication is the main source of disturbance during the measurement of pore pressure. A typical problem of this kind is insufficient cement seal along the wellbore. Heating and water absorption during hardening of cement are other possibility disturbance during drilling. Temperature variations due to the production flow also may disturb the measurement, if the sensor is placed in a producer.  3.3.1 Chemical and Temperature effect: Assuming dissipation’s effect of local stress also accounts for temperature and chemical effects in the wellbore during drilling time. Thus fluid chemistry and fluid temperature (if it’s possible) should be designed to minimize this effect. However, the temperature effect of the production flow is more severe concern for long term measurement in the producing well. If flow and flow temperature are constant, the effect of the pore pressure will reduce with increasing time. But in reality the temperature effect will vary. This disturbance needs to be managed by combination of modeling and temperature measurement. As temperature is an issue in both producing and non produces wells, pore pressure measurement should always be accompanied by measurement of temperature. NTNU | Atumn2009

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 3.3.2 Pore pressure excess from wellbore fluid during drilling: In drilling with WBM (water based mud) dissipation of pressure during drilling in shale is possible. Such dissipation would give excess pore pressure relative to the in situ pore pressure. This effect may be significant. Time exposure is more important than the hole size. For a week time demonstration which is not uncommon for a well section, effect on borehole wall takes longer to dissipate then the local stress concentrations. Influence depth also becomes significant for one week time demonstration. Error handling:

  

Eliminate the effect by waiting until the effect is dissipated (may takes months). Effect managing by modeling the transient pressure as in well testing, must also include the effect of local stress concentration. Minimizing effect by short demonstrated time or rapid penetration, particularly relevant for short term measurement.

Thus, using of OBM (oil based mud) may be an alternative to avoid excess pore pressure during drilling well. But it must be ensure that the capillary effect of oil based mud does not prevent contact between the pore pressure sensor and formation. [10 ]  3.3.3 Cement sealing: Traditionally the cement which sealing a pore pressure sensor should has permeability equal or less than formation. Vaughan in (1969) indicated that the permeability of the cement in a geotechnical piozometer string may be string significantly lager than the permeability of clay without disturbing the pore pressure measurement too much. [10 ] Pore pressure measurement due to cemented annulus communication depends on the following factors: ► Cement-shale relative permeability ► Geometric relationship between two flow areas:  Flow area of the cemented annulus outside the well.  Flow area between pore pressure sensor and shale formation. Parameters which control this flow area are annulus radiuses (inside and outside) and length of pore pressure zones. Practically results confirm that cement’s permeability may be larger then shale’s permeability without giving a considerable error. In the large contact area between shale and sensor, this error is less than 1% even cement’s permeability is 300 times bigger than shale’s permeability. NTNU | Atumn2009

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PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------This means that the nominal cement permeability as used today is enough for reasonable pore pressure measurement in shale. But the main problem here is associated channel in cement. Such channels may appear from bad cementing job or long term effects from a micro annulus created by shrinkage during cement hardening. Such channeling is probably not uncommon. Installation of pore pressure sensor in different parts of drilling levels for evaluating of the possible errors from cement seal should be helpful.

3.4 Measurement methods: Overview Generally Short term and long term measurements are two methods for measuring pore pressure in shale from existing pore pressure measurement methods. An overview of the options based on this distinction is given in Fig 3.1 and Fig.3.2 Schematic illustration of the options.

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 3.4.1 Short Term Measurement: Short term measurement is mad by drill string during drilling time or by wireline in open or closed hole. Sidewall pore pressure is greatly affected by local stress and by fluid pressure unless OBM is used. For more accuracy it’s possible to drive the in situ pore pressure from early time development of the sidewall based on a dissipation model. Use of OBM may improve such measurement if the test penetrates a bit into the formation. The accuracy of this method is low and even worth while to check out as similar equipment already exists for application in permeable zones. In this method drill string must stop (avoid of drillstring movement). For fixed drilling’s units are no problem but its need to be addressed when drilling is on a flouting unit. The most reliable short term NTNU | Atumn2009

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PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------measurement will be in penetration of small hole with a function similar to the piozoprobe in geochemical application. Such penetration could be mad laterally through the bore hole wall or axially at the bottom of the hole. As we discussed before a dissipation time of minutes or a couple of hours could be sufficient for dissipation of the local stress if the hole diameter is not more then 5 mm. [10 ] The effect of well bore pressure would not be concern in this case. Clay allows penetration with out drilling thus clay is an ensure sealing. In Shale both drilling and sealing device would be required .drill string movement during measurement would be concern for this option and for borehole wall measurement. The most realistic option for short term measurement may be a compromise between a sidewall device and a deep penetration test. That means a semi deep penetration being practically possible with disturbance manageable by means of transient modeling. At the qualification stage a short term method should in any case be verified by more reliable long term measurement. [10 ]  3.4.2 Long Term Measurement: 

Dedicated well/Sidetrack

The most robust and accurate example of long term pressure measurement is pore pressure measuring in a deviated or sidetrack borehole. Existing equipment may be used. An open hole well is the simplest solution. A string and sensors may be used and conventional cement sealing would normally be sufficient. If the sensor is surrounded by cementing, in many cases it would not be a problem. An alternative for that is to place sensor inside the casing. The sensor must be sealed with packers inside the casing and by the same time communicate with the formation, for inside through perforations. Sensors at several levels to confirm sealing are recommended. 

Abandoned well/sidetrack

An abandoned producing well or sidetrack may be utilized for pore pressure measurement. With respect to cost this is an alternative option and it still avoids conflict with other functions. But the long term integrity of the sealing cement is a particular concern in this case. It may also necessary to address some formalities with respect to final abandonment. A sensor inside the casing would be the most straight forward measurement which it would be sealed internally by packers and communicating with the outside formation through perforations. Inside the casing combination with cement seal can be used and in this case sensors at different levels would be available to verify the seals. Putting sensor outside the casing and then plug the casing is the other measurement option to drill through the casing. Schlumberger’s Cased Hole Dynamic tester or similar may be applied. Signal transfer through the casing appears to be missing for this option and its need for equipment development is thereby likely. NTNU | Atumn2009

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New producer/sidetrack

The possibility of measurement at a site of current interest would be increase if we use a new producer in stead of an abandoned well. It would allow design from scratch but it also introduces conflicts with other functions. The conflicts may be limitation of space, barrier requirements and restriction on signal transfer. In addition, the temperature effect of the time from drilling to production is sufficient to allow a pore pressure measurement before the production is started. Also in this case the main options are to place the sensor inside or outside of casing. Both options are applicable with current equipment.

3.5 Challenges: 1. A principal challenge for Long Term measurement is to develop suitable procedures for installing the instruments. 2. Short Term measurement of pore pressure is dependent on technology development. An attempt to describe the most important elements of such development is given in section 3.4.1of these elements is small diameter drilling. 3. Another technology which should be considered to get sidewall penetration for short term pore pressure measurement is the existing rotary sidewall coring method. For both short term and long term application it is advisable to collect the standard log used for pore pressure interpretation to calibrate the existing indirect methods.

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Part III: Indirect Pressure Measurement

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Chapter 4: Seismic While Drilling (SWD)

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Introduction Geophysical methods in combine with other tools, can predict the reservoir pressure in many cases. Overpressure shale can act as good reservoir seals, but can also cause drilling difficulties, particularly in maintaining safety margin for drilling mud weight. Geophysical techniques are based on the impact of reservoir pressure on the seismic velocities (primarily Compressional waves).Many studies have demonstrated the effectiveness of geophysical methods for pore pressure predication. One of the first of these studies has been published on earlier 1968 by Pennebaker. However Geophysicists published geopressure (Dutta, 1987) that include major geophysics-related methods for pore pressure predication (See table 4). The new technology improvement of 3D seismic and more recently 4D seismic, it has become possible to make pore pressure predications more reliable and create threedimensional pressure profiles. Seismic while drilling (SWD) is the seismic techniques operated while the drilling is lowered in the borehole, during effective drilling or while connecting drill pipes. In the past 24years (1986-20009) ,the drill- bit SWD technique practiced by the industry utilized the acoustic energy radiated by the Tri-Cone bit to provide the real time information during drilling by providing time-to-depth and lookahead information. Another emerging technique which is being used mainly by Schlumberger since 2000 is Vertical Seismic Profile While Drilling (WSP-WD), which consists in recording the seismic signal generated by a surface seismic source on seismic sensors integrated inside the downhole borehole assembly (BHA). In this chapter it has been tried to give a present day picture of the SWD techniques briefly.

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PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------SWD can be subdivided on several methods as below which we tried to describe each method briefly: 12345-

Drill Bit Seismic Vertical Seismic Profiling While Drilling (VSP-WD) SWD using Swept Impulse Source Coil Tubing SWD New Concepts for SWD

4.1 Seismic While Drilling Operation and Application Even thought the SWD tool is coupled to BHA like a standard tool but its operation and set up is far from standard. For making this service as a powerful drilling decision tool, a proper planning ahead and a proper understanding of the full potential of the data will be necessary. SWD has the potential of the producing a real time update to the geological model. It offers improved resolution and more accuracy of depth conversion. Its flexibility of source / receiver positioning several other geophysical applications will be possible (i.e. salt flank & fault plane). SWD service has the potential of becoming a key drilling decision tool. Uncertainties in data quality coupled with surface seismic limitations leads to risk management process. This needs to a good understanding of workflow of seismic processing and reservoir properties to minimize time for data preparations prior to evaluation and decisions. SWD can be done in two path method: 

Normal ray path (source on surface and receivers in the borehole “BHA” i.e. Halliburton model)



Reveres ray path (source in the hole and receivers on surface)

SWD needs a quiet environment and for performing this quiet environment standard drilling activities must be stopped including mud pumps! This will be done during the stand changing! A stand change takes some time (2-10 minutes) which is enough for 3 to5 shots to be fired! It’s however too short time to reposition the source with current technology. The source position is an alternative for future! But its location can be either on rig or seabed or a boat connected source. Vertical Seismic Profiling (VSP) is a technology which makes better the surface seismic resolutions. It is great risk to do drilling campaign based on only surface seismic but VSP reduces these risks! In VSP data will be available in time before reservoir zone is approached. As the earlier data is available the bigger impact the data will have on the risk reduction. Getting the VSP data and availability on time due drilling is the important issue for the SWD solution.

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PRESSURE MEASUREMENT IN SHALE ---------------------------------------------------------------------------------------------------------------- 4.1.1 Planning phase Design of the SWD is one of the first step for successfully utilize its full potential. This could be as follow: [12 ]  Planning      

Ray trace modeling Real time processing Acquisition density Site survey Rig setup Drilling personal training

 Operation   

Source handling Network/application performance Decision making process/resources

 4.1.2 System design and Consideration SWD contains:     

main surface computer surface control box seismic source controllers seismic sources down hole tool

Seismic sources and controllers are standard. (Fig.4.1) shows the main system design. In order to design a borehole seismic survey to meet specific target objectives, it is necessary to model the seismic response of the earth near the borehole. A perfect design process would take into consideration all available data, including but not limited to: A. geological structure and stratigraphy B. characteristic surface seismic waveforms C. The local P&S-velosity fields, including well VSP data and seismic processing and migration velocity cubes. D. Local and area well information, including multi-pole sonic and density logs.

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PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------While many SWD projects include well path-on seismic mapping objectives, it is becoming increasing desirable to perform wave form processing of SWD data in order to image and detect certain targets ahead of the projected well path. In order to support these design objectives, it is necessary to model wave fields and amplitude distributions in 3D using wave-front ray tracing and finite different modeling tools. These tools have been specifically designed for the borehole to include all aspects of borehole and source geometries while accounting for diffractions, anisotropy, and converted waves. [12 ]

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PRESSURE MEASUREMENT IN SHALE ---------------------------------------------------------------------------------------------------------------- 4.1.3 SWD Tool The SWD tool contains 4 geophones, 8 accelerometers of which 4 are external and 4 internal and 4 hydrophones that can be configured and mounted for operation in any of the three principal axes. 12 of the sensors are exposed to the borehole annulus. [12 ] The sensors are mounted such that they are passively coupled to the surface and structure of the interest in the well, and they are robust enough to withstand the viberation, temperature and pressure conditions that the tool will experience while drilling. The geophones and the external accelerometer are coupled with the collar. The hydrophones are exposed to the well fluid. The sensors are designed to withstand temperature up to 165ºC and pressures of 25,000psi in all directions. Fig.4.2 shows sensor positions on SWD tools.

 4.1.4: Process of SWD The system direct measurement of seismic travel times from surface to the survey locations along the well bore. Data are used to track the bits on the original surface seismic images used to plan the well. In addition section of the stocked waveforms used for check-shut and in certain circumstances can also provide a limited image many hundreds feet a head of the bit. The information gathered will be used to steer the well, set casing points, and avoid drilling hazard. The tool has a processor and memory and receives its seismic energy from a surface seismic source an air gun array located on either the rig or source vessel offshore or a viberator or dynamite shot on land. After acquisition, the signals are stored and processed, and check-shot data and quality indicators are transmitted uphole in real time by mud-pulse telemetry. The time –depth data are used to position the well on the seismic map, and waveforms can now also be sent uphole in real time. All of the raw recorded waveforms are stored in memory for processing after the tool gets back to the surface. One of the key advantages of the tool is that it dose not interfere with the drilling process, and it doesn’t require any extra rig time. Fig.4.3 & Fig. 4.4 show schematic of SWD process in a simple way.

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 4.1.5 SWD Application    

Sub-Seismic fault imaging Overpressure detection Reducing Rig-Time It can be often only way to collect data in much deviated wells or the wells with stability issues while wire line tool are difficult or noneconomical to run.

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4.2 Drill-Bit Seismic Two types of Drill-Bit Seismic:

 A. conventional Drill-Bit Seismic

The drill bit seismic method delivers seismic time-to-depth and look ahead seismic images of the formation ahead of the bit. It does this in real-time, allowing timely input to the drilling process. The data and images are available at the well site, or can be transmitted back to town. Only surface sensors are used to acquire the data, avoiding the high costs and potential risks associated with downhole tools. No rig time is required, and the technique does not interfere with the drilling process. [13]

 4.2.1 Application: The information obtained from drill bit seismic surveys can be used for a number of applications, some of which are listed below: 1. 2. 3. 4. 5. 6.

Locating on the Bit. Look Ahead Imaging Casing/Coring Point Selection. Pore Pressure at the Bit. Pore Pressure Ahead of the Bit. Depth-to-Hazard Prediction.

 4.2.2 Procedure technique The basic concept behind drill bit seismic is very simple. It uses the acoustic energy radiated by a working drill bit to determine the seismic time-todepth as the well is being drilled. The energy needs for drilling is supplied to the bit by rotation of the drillstring, if a rollercone bit is used; this rotation causes the cones to roll over the bottom of the hole. As the cones roll over, the teeth penetrate and dig the formation, destroying the rock. As each tooth indents the formation it applies an axial force to the bottom of the hole, and an equal and opposite force to the drillstring. The succession of axial impacts as the bit drills radiates compressional or P-waves into the NTNU | Atumn2009

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PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------formation, and causes axial vibrations to travel up the drillstring. A working rollercone bit acts as a dipole source for P-waves radiating energy upwards towards the surface, and downwards ahead of the bit (FIG4.5). At the surface geophones, hydrophones, or a combination of both are used to detect the P-waves. Sensors, such as accelerometers, placed near the top of the drillstring (on the swivel or top drive) detect the axial vibrations traveling up the drillpipe. Although the bit generated signal can be detected, it is continuous in nature. Since the fundamental drill bit seismic measurement is time-to-depth, timing information must be extracted. In general, the energy propagating through the formation travels more slowly than the axial vibrations in the drillstring. The seismic sensor signal therefore contains a time shifted version of the drillstring sensor signal. Correlating the drillstring sensor signal with the seismic sensor signals, a technique patented by Elf in1985, helps to determine this difference in travel time ΔT re (see FIG.4.6). Once ΔT re is known, if the time taken for the axial vibrations to travel along the drillstring, ΔT ds can be determined, the absolute travel time from bit to surface, and, ΔT f can be calculated. The time-to-depth is calculated using the direct radiation from the drill bit. The energy that propagates downwards ahead of the bit is often reflected back to the surface by impedance changes in the formation. This energy can also be detected, and processed to produce a seismic image of the formation ahead of the bit. When used in combination with the surface seismic, such “look ahead” images allow the approach to critical horizons to be monitored as drilling progresses. The above explanation is rather simplistic. In practice there are significant difficulties that must be overcome before useful information can be obtained. [14 ]

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PRESSURE MEASUREMENT IN SHALE ---------------------------------------------------------------------------------------------------------------- B. Drill-Bit Seismic with Shock Absorber and EMWD First time it has been used by drillers in order to collect downhole data by IFP, a France company in 1991 with an MWD field test in eastern France Gaz De France well. They used real-time field evaluation of the seismic signal generated by Drill-Bit. as result, the first minutes of drill-bit seismic data correlated either by the downhole accelerometer or by the top of drillstring accelerometer did not show a big differences, as both correlated records were altered by a high level of drillstring multiples. The main improvement obtained by correlation with the downhole accelerometer was a higher frequency content. IFP field geophysics’ felt that it would be desirable to introduce a mechanical decoupling device above the drill bit and downhole sensor, in order to reduce the generation of the drillstring multiples and all sorts of associated secondary seismic source effects related to presence of the drillstring. This kind of damping element is well known by the drillers as a “shock Absorber” and had been developed by the drilling equipment manufactures during the period 1950-1985. the concept was quite feasible because drill-bit vibrations are powerful enough to generate long range seismic signal from the bit to the surface .the signal to noise ratio improved after using shock sub despite the fact that the presence of shock sub reduced the peak amplitude up to 80 %. [14 ]

 4.2.3 Advantage drill-bit seismic The drill bit seismic techniques provides useful real-time information. When used in conjunction with other information it can help to:

      

Locating the bit on the seismic section Optimizing casing and coring points Reducing the number of casing Pore pressure estimating at the bit Predication of pore pressure ahead of the bit Predication of the depth to drilling hazard No more rig-time activities and risks and more drilling operation costs.

 4.2.4 Limitation drill-bit seismic  In soft rocks and large depth (above 18,000 ft) and in horizontal wells this technology is unreliable!  In high deviated wells it cannot be used.  It can only work reliably when drilling with rollercone Bit. Not with PDC Bits.

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4.3 Vertical Seismic Profiling While Drilling (VSP-WD) VSP-MD is a transfer of wireline borehole seismic to drilling operations for drilling and real time operations benefits(Fig.4.7). VSP-MD is almost identical to wireline service using the same surface source and downhole sensors. The main difrence is ,there is no directe cable connection between tool and surface. This technique use a downhole sensor in connection with BHA which receives seismic energy from sources which is coming from a source vessel (rig or boat).The source is fired while making the drill string connection or drilling and mud circulation stopped, to prevent the effect of drilling noises on data acquisition process. The seismic energy can be produce by a source as air-gun on offshore or dynamite on onshore and receives by VSP-WD tool. This tool can collect both the directed and reflected seismic signals. The VSP-MD tool can store a raw fullwaveform data in the downhole memoray storage which culd be sendback later during tripping of the bit. Seismic signals are recorded both directly from the source and reflected from formations to be imaged.these signals are stored in tool memory for later processing. Immediately after obtainning the data,downhole processing determines the check-shot time. A complet procedure of the tool is shown in Fig. 4.8 . The real-time relationship is used to locate the bit on the surface seismic image and this enables to forward drilling decision. Only the most important data will be transferred uphole, the rest data will be stored in donwnhole tool memory. When the drill string is pull out of the hole, waveform data can be downloaded from tool memory and then send them to a processing center for VSP image processing. This technique depends on the geometry of the well and the source location. Vertical wells with zero offset sources are best fitted for this method.  4.3.1 Advantage of VSP-MD  In horizontal wells VSP-WD seems is the only alternative for more well instability and security. 

It places the bit on the seismic map or section. An important result of correction of the seismic down to bit position is that the seismic uncertainty ahead of the bit is reduced. Uncertainty will be reduced from 700 m to 10 m.

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



While coring operations well can be drilled very close to the interface where the core is needed. This eliminates a large amount of unnecessary hole that needs to be drilled. Thus avoiding reduced or missed core data and saving time as well as money. Large saving can be realized using VSP- WD service. It saved cost of running wire line VSP which was not a preferred option due drilling.



since the bit can be seen on the seismic map in real time the driller can drill the well very close to events seen on the seismic map and place the casing very close to where they ideally should be set.



It allows early predication of potential pore pressure anomalies and it can efficiently assist salt proximity surveys.

 4.3.2 Limitation of VSP- MD 

It’s claimed that it provides look – ahead imaging, however the range and accuracy of this capability is still not accurately known.



Mud pulse telemetry of processed velocity is planned but not presently commercial. The biggest limitation of VSP-WD services is to ensure a good mechanical coupling of the VSP seismic sensor with the borehole and high precision required on downhole clock



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4.4 SWD using Swept Impulse Source Seismic profiling using impulse hydraulic tool is the new method in SWD techniques. The tool has capability of generating a broadband seismic signal at bit due drilling. This method overcomes the limitation of Drill-Bit Seismic technique. For example can be used in soft formation and inclined holes with PDC bits. This method provides real -time reverse seismic profile while drilling and high resolution look a head imaging while drilling (Fig4.9). It can be used in both vertical and deviated wells by using its independent compression and share wave source. It also helps to give early warning of gas kicks. Seismic profiling and imaging could be taken out without stopping normal drilling operation and without a downhole motor. This method was tested successfully by Baker Hughes.

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PRESSURE MEASUREMENT IN SHALE ---------------------------------------------------------------------------------------------------------------- 4.4.1 Seismic profiling using Swept Impulse Tool (SIT) Different test shows that the hydraulic pulse tool has good signal propagation to the surface over a depth of 2700 ft. This method will be available on both vertical and deviated wells. The tool produces a strong shear wave while drilling but when drilling is stopping, it will be not generated any share waves. This ability allows profiling of both P- Waves and S-waves velocities with direct application to pore gas detection. A little free gas presentation at the bit will immediately eliminate the seismic signal to give early warning of gas kick. The Swept Impulse Source incorporates a hydraulic pulse valve. It consists of a mechanism which varies the duration in between two pulses. Sweeping the cycle rate allows Seismic profiling and high resolution look ahead imaging while drilling using a technique similar to swept impact seismic profiling.

 4.4.2 Advantage of Swept Impulse Tool        

True real-time seismic while drilling Reverse vertical seismic profiling for depth correction Pore-pressure detection High-resolution look ahead imaging due drilling Independent compression and shear wave source Early warning gas kick detection Vertical or inclined wells Cross-well surveys

 4.4.3 Limitations:     

Communication between different personnel groups in a drilling process. Bad weather and big water wave limited gun operations The EX-rating of the cables and its layout Drilling time increasing is high risk for SWD Operation(example from 19 to 43 days) High cost in special deviated wells

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Chapter 5: MWD/LWD

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PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------Introduction: MWD/LWD is a system which we can get a wide variety of directional steering, formation evaluation, geosteering and drilling efficiency applications. These measured while drilling data are in real time and recorded modes at the well site and can be transmitted directly to office-based computer systems. In addition, the MWD data can be available anywhere in the world in real time due to a secure internet connection. MWD/LWD design allows the tool string to be configured with virtually any combination of sensors to meet specific application and BHA design requirements. Three different real-time telemetry systems (positive mud pulse, negative mud pulse and electromagnetic) are available to make dependable real-time data under a wide range of drilling conditions and with type of drilling fluid. Real-time data transmission is supplemented by recording data in downhole memory for retrieval after each bit run. The suck, vibration and heat of downhole drilling environment make survival of any electronic instrument difficult. MWD provides geometrical information on the position and helps to drill the well safely and efficiently. Measure While Drilling (MWD) is measuring and getting of directional data form wellbore, pressure in the wellbore and drilling dynamics measurement such as vibration and shock. But Logging While Drilling (LWD) is logging of the properties of the formation and reservoir fluids while drilling and before drilling fluids invade the formation, similar to open-hole, wire line logs. The most frequently used measurements include Gama Ray, Resistivity, Density, Porosity, Acoustic travel time and Formation pore pressure. In this paper we discuses MWD/LWD briefly related to pressure predication and detection in formation and shale.

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PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------5.1 Measurement while drilling (MWD): MWD is a system to make drilling measurements and transmit data to the surface while drilling the well. MWD tools are as part of BHA. The tools are either contained inside a drill collar (sonde type) or are built into the collars themselves. The measurements of GR, directional survey, tool face, pressure in borehole, temperature, vibration, shock, torque etc can be taken by MWD. Some advanced MWD tools can even measure formation pressure and take formation samples. The MWD also provides the telemetry for operating rotary steering tools (RST). The measured results can be stored in MWD tools and the results transmit digitally to surface using mud pulsar telemetry or other advanced technology. MWD systems have the capability of receiving control commands which can be sent by turning on and off mud pumps or by changing the rotation speed of drill pipe or by other advanced telemetry technology such as wired pipe.

 5.1.1 Types of transmitted information: 

5.1.2 Directional information

Taking directional surveys in real time is one of MWD tools capabilities. MWD tools are generally capable of taking directional surveys in real time. Accelerometers and magnetometers to measure the inclination and azimuth of the wellbore at certain location can be used by these tools, and then they transmit data to the surface. A series of surveys at some intervals of the well bore (anywhere from every 30 ft (i.e. 10 m) to every 500 ft can be calculated. MWD tools are extremely complex pieces of high- tech electronics. This information from MWD allows operators company to prove that their well does not cross into areas that they are not authorized to drill. However, they are not generally used on vertical wells, due to the cost of MWD systems.’’ Instead, the wells are surveyed after drilling through the use of Multishot Surveying Tools lowered into the drillstring on slickline or wireline.” [ 22] Directional Drilling is the primary use of real-time surveys. Because the Driller must know where the well is going and he must steer the well towards target zone. MWD tools also generally provide tool face measurements to aid in directional drilling using downhole mud motors with bent subs or bent housings.

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5.1.3 Drilling mechanics information

MWD tools can also provide information about the conditions at the drill bit. This may include:      

Rotational speed of the drillstring Smoothness of that rotation Type and severity of any vibration downhole Downhole temperature Torque and Weight on Bit, measured near the drill bit Mud flow volume

Use of this information can allow the operator to drill the well more efficiently, and to ensure that the MWD tool and any other downhole tools, such as Mud Motors, Rotary Steerable Systems, and LWD tools, are operated within their technical specifications to prevent tool failure. This information also is valuable to Geologists responsible for the well information about the formation which is being drilled. [18] 

5.1.4 Formation properties

Many of MWD tools can take formation properties measurements. At surface this measured data can converted to loges as same as wireline logging. The MWD tool allows these measurements to be taken and evaluated while the well is being drilled. This information makes it possible to perform Geosteering, or Directional Drilling based on measured formation properties, rather than simply drilling into a target. “Most MWD tools contain an internal Gamma Ray sensor to measure natural Gamma Ray values. This is because these sensors are compact, inexpensive, reliable, and can take measurements through unmodified drill collars. Other measurements often require separate Logging While Drilling tools, which communicate with the MWD tools downhole through internal wires. [18] 5.2 Data transmission methods:  5.2.1 Mud pulse telemetry This method is most used method for transmitting data from measurement tools in the borehole up to surface on rig. Due drilling time, mud will be pumped from surface down through drill string and of course through the measurement and logging tools (MWD/LWD), then through the drill bit and back to the surface through the ring-room between the drill string and formation. The increasing in number of measurements puts a higher demand on data transmission speed. Mud pulse telemetry is limited with regard to bandwidth and can only 10-48 bits pr/sec data transmission. To maximize the real-time value from the advanced measurements we will need kilo-bps capacity. The newly introduced wire drillpipe can obtained this capacity. This test has been done by several companies in North Sea.

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PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------This technology is available in three varieties:   

Positive Pulse Negative Pulse Continuous Wave

 5.2.2 Positive Pulse This system causes a periodic, partial restriction of the drilling fluid inside the MWD collar. The speed of transmission is between 4000 - 5000 ft/sec in the drilling fluid. The positive pulse system is low cost when compared to hardwire systems, and no special rig modifications are necessary. It has the added advantage because it is not affected by LCM. The system does have a slow data rate and is limited to a digital encoding scheme. This type of system is used by Eastman-Teleco, Smith Datadril, Speery- Sun and Western Atlas. [ 20]

 5.2.3 Negative Pulse Negative pulse tools briefly open and close the valve to release mud from inside the drillpipe out to the annulus. This produces a decrease in pressure that can be seen at surface. Line codes are used to represent the digital information in form of pulses. [ 20]

Fig.5.3: Position of Mud Pulse Telemetry in Drill String.

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PRESSURE MEASUREMENT IN SHALE ---------------------------------------------------------------------------------------------------------------- 5.2.4 Continuous Wave This system uses a slotted disk and creates a frequency modulation of the carrier wave. The speed of transmission is between 4000-5000 ft/sec in the drilling fluid. This type of pulsing system requires no major modification to the rig and is a lower cost system compared to hardwire systems. This siren system has a higher data rate compared to the positive and negative pulsars, and because of this more sensors are possible. The main drawbacks of the mud siren are the slotted disk is prone to plugging by LCM, there is no transmission with the pumps off, and the system has a low signal to noise ratio. This system is used by [ 20 ] Schlumberger/Anadrill.

Mud pulse telemetry is unusable in underbalanced drilling. This is because of reduction of mud density (a compressible gas) injected to the mud. This causes high signal attenuation which drastically reduces the ability of the mud to transmit pulsed data. It is necessary to use other methods such as electromagnetic waves propagation through the formation or weird drill pipe telemetry, than mud pulse telemetry in this situation. The offering bandwidth in Current mud pulse telemetry technology is up to 40 bps (bits per second).The data rate drops with increasing depth of the wellbore is typically as low as (1.5 - 3.0) bps, at the depth of 35,000 ft 40,000 ft (10668 m - 12192 m). Communication between surface and downhole is done via changes to drilling parameters, i.e. change of the drill string’s rotation speed or flow rate of mud. Changing in the drilling parameters in order to send information can require interruption of the drilling process, which is unfavorable due to the fact that it causes non-productive time. 5.3 Electromagnetic telemetry (EM Tool): EM-MWD uses low-frequency electromagnetic waves to transmit downhole measured data in real time to the surface during conventional and underbalanced horizontal and directional drilling operations. EM telemetry transmits information through the formation to a surface antenna, where it is received and sent to a data acquisition system to be decoded and processed. This system generally offers data rates of up to 10 bps. In addition, many of these tools are also capable of receiving data from the surface in the same way, while mud pulse-based tools rely on changes in the drilling parameters. Operators using EM-MWD are able to drill and survey wells independent of rig hydraulics. Bit pressure drop, flow rates, drilling fluid and losses to the formation are transparent to the technology.

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These capabilities equate to substantial savings in drilling time and total project cost. However, it generally falls short when drilling exceptionally deep wells and the signal can lose strength rapidly in certain types of formations, becoming undetectable at only a few thousand feet of depth. Receivers have to be placed over a wide area, and this limits their use offshore. This system is used by Geoservices.

5.4 Wired Drill Pipe: Wired drill pipe systems are developing by several oilfield companies. These systems use electrical wires built into every component of the drillstring, which carry electrical signals directly to the surface. Wired pipe telemetry systems, however, can provide a bandwidth of up to 57,600 bits/sec and can transmit data from downhole tools to surface at high update rates. Real-time transmission of information is not affected by depth, formation resistivity, fluid properties or flow rates.

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PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------One of the newest wired pipe networks is The IntelliServ which offering data rates upwards 1M bit/s and become commercial in 2006. This system has been used and tested by some of oil companies as BP America, Statoil Hydro, INTEQ, and Schlumberger presented three success stories using this system, both onshore and offshore, at the March, 2008 SPE/IADC Drilling Conference in Orlando, Florida.

5.5 Retrievable tools: MWD tools may be semi-permanently mounted in a drill collar (only removable at servicing facilities), or they may be self-contained and wireline retrievable. Retrievable tools, sometimes known as Slim Tools, and they can be retrieved and replaced by using wireline in the drill string. This usually allows the tools to replace much faster in case of failure, also in case of stacking of drillstring; it allows the tool to be recovered. Retrievable tools must be much smaller, usually about 2 inches or less in diameter, and their length may be 20 feet or more. The small size is necessary for the tool to fit through the drillstring; however, it also limits the tool's capabilities. For example, slim tools are not capable of sending data at the same rates as collar mounted tools, and they are also more limited in their ability to communicate with and supply electrical power to other LWD tools. Collar-mounted tools, also known as Fat Tools, cannot generally be removed from their drill collar at the well site. If the tool fails, the entire drillstring must be pulled out of the hole to replace it. However, without the need to fit through the drillstring, the tool can be larger and more capable. The ability to retrieve the tool via wireline is often useful. For example, if the drillstring becomes stuck in the hole, then retrieving the tool via wireline will save a substantial amount of money compared to leaving it in the hole with the stuck portion of the drillstring. However, there are some limitations on the process.

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PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------5.6 Logging while drilling (LWD) LWD is a technique of transporting well logging tools into downhole of the well as part of the BHA. The combination of LWD tools and MWD system transmit partial or complete measurement results to the surface via a drilling mud pulser or other improved techniques, while LWD tools are still in the borehole, which is called "Real Time Data". Real-time data from LWD services let us make timely, informed decisions, reducing time and costs. Complete measurement results can be downloaded from LWD tools after they are pulled out of hole, which is called "Memory Data". LWD data will be collected during drilling operations. Collecting and processing data due drilling operations eliminate the requisition of drilling assembly to insert a wireline logging tool. LWD technology was developed originally as an enhancement to the earlier MWD technology to completely or partially replace wireline logging operation. Developing of the technology in the past decades, LWD widely is used for drilling (including geosteering), formation evaluation (especially for real time and high angle wells). By LWD drilling process will be controlled better and be allowed performance optimization and minimizing down time. Scope services dramatically improve drilling performance, opening a new era in data excellence. Increase the rate of penetration, improve wellbore stability and hole quality, and optimize well placement for maximum production faster. [ 23]

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PRESSURE MEASUREMENT IN SHALE ---------------------------------------------------------------------------------------------------------------- 5.6.1 Available LWD Measurements: LWD technology was originally developed to partial or complete replace wireline logging. Over the years, majority of the measurements have been made available in LWD. Certain new measurements are also development in LWD only. The following is an incomplete list of available measurement in LWD technology. [ 23]  Natural Gamma Ray (GR) 

Total Gamma Ray

  

Spectral Gamma Ray Azimuthal Gamma Ray Gamma ray close to drill bit.

 Density and Photoelectric Index  Neutron Porosity  Borehole Caliper  

Ultra sonic azimuthal caliper. Density Caliper

 Resistivity (ohm-m)   

Attenuation and phase shift resistivity at different transmitter spacing and frequencies. Resistivity at the drill bit. Deep directional resistivity

 Sonic  

Compression Slowness(Δtc) Shear Slowness (Δts)

 Borehole Images  

Density Borehole Image Resistivity Borehole Image

 Formation Tester and Sampler  

Formation Pressure Formation Fluid Sample

 Nuclear Magnetic Resonance (NMR)  Seismic While Drilling (SWD)  

Drill bit-SWD VSP-WD (Vertical Seismic Profile While Drilling

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PRESSURE MEASUREMENT IN SHALE ---------------------------------------------------------------------------------------------------------------- 5.7 MWD/LWD Advantages: The advantages of MWD/LWD can be described in three areas:  Directional Control Using multiple accelerometers and magnetometers, MWD surveys make much more accuracy in location of drill bit in the well. Reduction in survey downtime and reduce of risk in differentially sticking of the drill string.  Formation Evaluation Real time logging results in quick evaluation of formation data and this results to fast, accurate correlation decisions. Information can be gained before significant hole deterioration takes place, prior to significant filtrate invasion, and the hole is logged and information gained before the possible loss of the hole. This real time information can eliminate top hole wireline log runs, and with the real time pore pressure information can eliminate planned casing string.  Drilling safety and Optimization This information provide by MWD allows for make drilling efficiency and improved bit performance by indicating formation changes. The information allows for improved pore pressure evaluation, highlighting the safety aspects of MWD

 5.8 MWD/LWD Disadvantages: 

Inclinations errors by:  Movement of MWD tools  Misalignment of MWD collar in the borehole  Misalignment of accelerometer  Temperature fluctuations



Azimuthally errors:    

Wrong positioning of the magnetic parts Problem with LWD power Wrong estimation of collar mass Collar Hot Spots problem

Micro-Resistivity imaging and fluid sampling can’t be done by LWD tools.

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Chapter 6 Miscellanies

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Introduction: The accurate predication of pore pressure in shale has become almost essential to the drilling of deep wells with higher then normal pore pressure. Shale pressure can be the major factor affecting the success of drilling operations. Unfortunately, shale pressure can be very difficult to quantify precisely where unusual or abnormal pressure exists. If pressure is not properly evaluated, it can lead to drilling problems such as lost circulation, blowouts, hole instability, and excessive costs. Thus drilling costs and problems can be reduced substantially by the early recognition of abnormally high pore pressures. In this chapter we try to present the most world wide used for estimation pressure in shale which has capability for an abnormal pressure in formation. Some of these methods are:  Eaton Method  Equivalent depth method  Ratios Method  Vertical and Horizontal Methods  Compaction Concept Method  Power Law Method

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PRESSURE MEASUREMENT IN SHALE -----------------------------------------------------------------------------------------------------------------

6.1 Eaton Method The Eaton Method is typically applied to seismic or acoustic velocity data, and resistivity data. The procedure is to examine the porosity vs. depth data and to make a ratio comparison between the value recorded and the expected value if the pore pressures where hydrostatic, i.e. plotted on the normal compaction curve. Application: 

Interval velocity



d-exponent



Resistivity/Conductivity



Sonic log



Shale density



Density log

Principles: Relationship between the observed parameter & normal parameter ratio and formation pressure depends on change

in

overburden

pressure.

Eaton

in

1972

established the following empirical relationship from real Data: Ppore  Povb  (Povb

1.5

 R sh ,a  Pp ,n )  R sh ,n

  …………………...6.1 Eaton(1972)  

With more experimental data and performing of his studies he published his result in 1975 as following formulas: 1.2

Ppore  Povb  (Povb

R  Pp ,n ) a  Rn

  ……………………..6.2 Resistivity 

Ppore  Povb  (Povb

 t  Pp ,n ) n  t a

  ……….……………..6.3 Sonic 

Ppore  Povb  (Povb

d  Pp ,n ) c.a  d c.n

  

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3

1.2

…………….......…6.4 dc-exponent

76

PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------where R a , R n , t a , t n , d a and d c.n are

Resistivity (ohm) ,Sonic transit time

(μsec/ft or (μsec /m) and dc-exponents for normal and actual case. “This method is empirically derived. It assumes that a normal trend can be defined and that the pore pressure at any point can be related to the ratio between actual and normal indicator value.

6.2 Equivalent Method The method of equivalent depth is based on the assumption that the same shale with equal physical properties at different depths will have equal effective stress. Applications: Interval velocities exponent, shale density, Resistivity, Conductivity, Sonic, Density loges

and

any

direct

or

indirect

measurements of clay porosity.

Principle: Every point A in an under compacted clay is associated with a normally compacted point B The compaction at point A is identical to that at point B (Fig. 6.2) The depth of point B, Z B is called the equivalent depth, or some times the isolation depth. The fluid contained within the pores of clay A has been subjected to all geostic loads in the course of burial from Z B to Z A .

We know that: Povb    Ppore …………………..……………….….6.2.1  B  Povb,B  Ppore,B ……………….………….. ……. 6.2.2

B  A With knowing the overburden pressure at A ( Povb,A ), the pore pressure at A ( Ppore,A ) can be calculated. NTNU | Atumn2009

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PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------Ppore ,A  Povb,A   B …………………………….. 6.2.3

Then by eliminating  A and  B : Ppore,A  Ppore,B  Povb,A  Povb,B  ……………..….6.2.4

It is necessary to correct all parameter values for temperature, especially when the resistivity data are used as a geophysical property to identify equivalent depths. Example: ZA=3500 m, ZB=2500m, G p ,n = 1, 06 G ovb,n = 2, 20 at depth B & 2, 26 at depth A Ppore ,B 

ZB 3500 kg  1,06   1, ,06  265 2 10 10 cm

ZB kg  2,20  550 10 cm 2 Z kg  A  2,26  791 2 10 cm

Povb,B  Povb,A

Ppore,A  Ppore,B  Povb,A  Povb,B   Ppore,A  265  (791  550)  506

kg cm 2

The formula to be used at the well site, when the overburden gradient is known, is:

 Eq ,A  G ovb,A 

ZB (G ovb,B   Eq ,B ) ………….……..6.2.5 ZA

 Eq ,A : Equilibrium density at A  Eq ,B : Equilibrium density at B

ZA:

Equivalent depth

ZB:

Depth of the under compacted Clay

G ovb,B : Overburden gradient at A G ovb,A : Overburden gradient at B

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PRESSURE MEASUREMENT IN SHALE ---------------------------------------------------------------------------------------------------------------- 6.2.1 Calculation of Overburden Gradient: Overburden pressure may be calculated from eq. below: Povb   b 

Z …………………………………………………..……..6.2.6 10

Where: P ovb : Overburden Pressure [kg.f/cm²] b

: Bulk density [g/cm³]

Z

: Depth [m]

PS!

1 Kg force = 14.2233 Psi = 0.980665 Bar =0.0980665 MPa

“If data for calculation of overburden gradient are not available, an average overburden gradient may be used. The value normally taken is 2.31 (), which corresponds to an average established for the Gulf Coast. This value produces only a small error in the case of onshore wells. PS: it should NOT be used offshore if all possible, particularly where the water is deep and the well is shallow.”

[ 22 ]

When the normal pressure gradient is not known an average value of 1.05 may be substituted for it. Pn =1.05 Briefly formula for constant gradients (  Eq ,B =1.05, G ovb,A = G ovb,B =2.31)

 Eq ,A  G ovb,A   Eq ,A =2.31-

ZB (G ovb,B   Eq ,B ) ZA

ZB Z (2.31-1.05)  Eq ,A  2.31  1.26  ( B ) ………….6.2.7 ZA ZA

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PRESSURE MEASUREMENT IN SHALE -----------------------------------------------------------------------------------------------------------------

6.3 The Ratio Method Applications: 

d-exponent



Shale density



Sonic log



Resistivity



Density log

Principle: The ratios method is based on this idea that the difference between the observed and normal values of parameters is proportional to the increase in pressure. Thus the ratio of the observed (for example, dco) to the normal (dcn) value is proportional to the formation pressure (Fig 6.3).

To apply the ratios method to dco/dcn, use the formula below: GPF  GPhyd. 

d c,n d c ,o

…………………………………6.3.1

GPF : Formation pressure gradient (mud density equivalent) GPhyd. : Normal (hydrostatic) pressure gradient (mud density equivalent)

The ratio method is unsuitable for most of shale formations. The main limitation here is that draw isodensity lines for most regions, a given set of isodensity lines is only valid for the specific abnormal pressure condition of the well on which they were computed.

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PRESSURE MEASUREMENT IN SHALE ---------------------------------------------------------------------------------------------------------------- 6.3.1 Isodensity Concept:

The equilibrium density is obtained using the following formula:

 eql   eql,n 

dc n dc o

………………….… 6.3.2

eql,n : Normal equilibrium density  eql,o : Observed equilibrium density

dc n : Normal d-exponent dc o : Observed d-exponent A set of isodensity lines can be drawn using the following formula (Fig.6.4) so that the equilibrium densities can be read off directly.

dc o  dc n 

 eql,n  eql

………………………6.6.3

 6.3.2 Establishing isodensity line (Fig. 6.5) 

take a point A located on the normal compaction trend XY



Calculate the value of dc which would be observed at point A for a given equilibrium density.



Using this value (B) draw a straight line X’Y’ parallel to XY. This represents the gradient

of

the

selected

equilibrium

density. for the given density of (  eql.A ), calculate the parameter values, dc,o that would be observed at depth A, using the following formula:  d co  d cn  EMW . …………………… 6.6.4  eql.A



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PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------Example:

dc n  180

 eql,n  1.05

,

dc o  1.80 

1.50  eql

To draw the isodensity line  eql  1.20 dc o  1.80 

1.50  1.58 1.20

The ratio method is easy and very widely used. However, because it is empirical, the results obtained are not always satisfactory. Adjustment of the calculations of the calculations on the basis of measurements (RFT.test) can appreciably improve the results of the method with the introduction of a correction coefficient(c): So that:

 eql  c   eql,n 

dc n ……………..…..6.6.5 dc o

Example: Calculated  eql  1.25 RFT eql  1.35

c

1.35  1.08 1.25

The correction coefficient remains valid as long as the cause of the abnormal pressure condition remains the same. GPF  c  GPhyd. 

d c,n d c ,o

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………………………..……..6.6.6

[ 22 ]

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PRESSURE MEASUREMENT IN SHALE -----------------------------------------------------------------------------------------------------------------

6.4 Vertical and Horizontal Models Method One of the new methods for pressure measurement in shale is estimation pore pressure by Vertical or Horizontal methods.  Applications: Interval velocities-exponent, Shale density, Resistivity/Conductivity and acoustic travel time.  Principle: For vertical assumption: D  Ppore  Povb  (Pe  Pp ,n ) e  ……………...…6.4.1  D  Where: P e : overburden pressure where the vertical line crosses the compaction line. De: depth where the vertical line crosses the compaction line. For Horizontal assumption: x

Ppore  Povb  (Povb

N  Pp ,n )  ……………....6.4.2 M

Where: N ( ) : Ratio of measured value (i.e. velocity, resistivity or acoustic travel time) to M the expected value at normal trend line at the same depth. x : an empirical exponent. The horizontal derived pressure In some case as Fig.6.7 assuming value of x is 3. (x=3)

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PRESSURE MEASUREMENT IN SHALE -----------------------------------------------------------------------------------------------------------------

N directly to pore pressure without an overburden M term(e.g. Hottmann and Johnson) require local calibration to account for changes in water depth and should be used with direction. [ 24]

Horizontal method that correlate

More realistic well data fitting on this method has been done in appendix C.

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PRESSURE MEASUREMENT IN SHALE -----------------------------------------------------------------------------------------------------------------

6.5 Pore Pressure in Overconsolidated Shale In some geological basin man can not establish normal compaction trend line, special in overconsolidated Shale basin. But predication of pore pressure in overconsolidated shale has been developed by using sonic loges and the method gave a certain results for establishing pore pressure in the over consolidated Alberta basin in Canada.  Applications:  Terzaghi stress relationship :  T    PPore 

Eaton general Eq.

: Ppore  Povb  (Povb

Where:

 A  Pp ,n ) obs  A norm

  

x

A obs : Observed attribute A norm : Normal attribute X : Empirical fitting constant 

Bowers normal compaction curve define as:

V  5000  A   Bnorm ……………………………...6.5.1

Where: V : Sonic velocity [ft/sec]  norm : Effective stress A & B: Curve fitting constant for normal compacted shale  Principle:

“  Max ”can be calculated from rearranging of Eq.6.5.1 as below: 1

   5000  B  Max   max  …………………………..….6.5.2 A   Where:  Max : Max effective stress corresponds to  Max

 Max

: Sonic velocity which is the onset point of the unloading [ft/sec]

Ppore  Povb  [(V  5000) A ]B ……………….….…6.5.3 And A´ and B´ are calculated from:

A  A  

B Max



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U ) B Max ……………………………6.5.4 (

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PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------B 

B ..................................................................6.5.5 U

Where:  Max : Max. Effective stress [SG] U : Unloading curve parameter (U= 3.13, For Golf Cost, Bower 1995) The result of predication of pore pressure by overconsolidated method illustrated on Fig.6.8. Further calculation has been done in Appendix D.

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PRESSURE MEASUREMENT IN SHALE -----------------------------------------------------------------------------------------------------------------

6.6 Compaction Concept Method  Application:   

Interval velocities-exponent, Shale density, Resistivity/Conductivity and acoustic travel time Terzaghi stress relationship Wyllie’s time Eq. for porosity

Normally

formation

pressure

in

shale

can

be

calculated

from

Eq.1.2

“    i  exp(K   v ) ” which is relationship between porosity and vertical stress as follow:

 n   i exp(  K v ) ………………….……….6.6.1 Where:

n

: Shale porosity in normal formation pressure

i K

: Porosity of shale at the surface : Porosity decline constant

: Vertical stress By using of Terzaghi stress relationship (  ovb   v  Ppore ) in Eq.6.6.1 we can calculate porosity in abnormally formation pressure as follow: v

 a   i exp[ K  ( v  Ppore )] ……………………..…6.6.2

Where:  ovb Ppore

: overburden stress : Pore pressure

Then by using Wyllie’s time Eq. for porosity and rearrange it for calculation travel time in normal and abnormal formation pressure as follow:

 t  t m     t fl  t m to:

  …………………Wyllie’s Eq. for porosity and simplified and reduced 

t  m    b ……………………..………………..6.6.3 NTNU | Atumn2009

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PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------Where m  t fl  t m and b  t m Thus travel time in normal compaction will be: t n  m   n  b ……………………………………...6.6.4 And under abnormal pressure conditions:

t a  m   a  b ……………………………………6.6.5 Substituting Eq. 6.6.1 to Eq.6.6.4 and Eq.6.6.5 leads to: t n  m   i exp(K v ) ………………………..…….6.6.6 t a  m   i exp[ K  ( ovb  Ppore )] ………..………..6.6.7

By subtracting Eq.6.6.6 & Eq. 6.6.7 and assuming that b is constant the results will be as follow: t a  t n  m   i [exp( K  ( ovb  Ppore )  exp( K   v )] ……………6.6.8

Taking logarithm in both sides and rearrangement for pore pressure gives:

Ppore   ovb 

         

1  lnm   i (t a  t n )  exp(K   v ) ……….………...6.6.9 K

Procedure: Plot Depth-transit time ( t ) Determine  i ,use multi-regression analysis Calculate  sh Plot ( t -  sh ) Determine slop m from Plot ( t -  sh ) Determine the normal trend line From normal trend line, obtain t n and t a Calculate ( t a - t n ) Calculate shale pressure.

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PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------Fig. 6.1 shows the result of pore pressure estimation by using the Compaction Concept method. [ 26]

6.7 Power Law Relationship Method  Application: Interval velocities-exponent, Shale density, Resistivity/Conductivity and acoustic travel time Terzaghi stress relationship Wyllie’s time Eq. for porosity

  

Shae pressure can be determined from power low by: Ppre  D 

  t  t n   log a  b D  ………….…6.7.1 log b a  

Where: P pore D

: Shale pressure [psi] : Depth of insert [ft]

t a

: Abnormal transit time [

t n a b

=

v D

 sec ] ft  sec : Normal transit time [ ] ft : The intercept : Slop psi : Vertical stress gradient [ ] ft

 Procedure:     

Plot Depth-transit time ( t ) Determine the normal trend line From normal trend line, obtain t n and t a Calculate ( t a - t n ) Calculate shale pressure.

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PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------Over All Conclusions: 

  



Porosity based pore predication techniques work best where a “normal compaction curve “ can be reliably developed, where the lithology is moderately constant , and where the overpressure is due to disequilibrium compaction. Lithological variability and shallow overpressure create difficulty in defining the appropriate normal compaction trend for pore pressure estimation. Wireline log analysis is still one of the major methods employed to estimate pore pressure. It is used to create models of pressure in offset wells during the planning of drilling programs. Many methods of pore pressure estimation, such as that from resistivity, sonic and density logs, require many assumptions about the rock properties, and d so, unless copious amount of calibration data has been produced, that accurate estimation of porosity from wireline logs is difficult. In this project it has been tried to show some of the benefits methods to estimate and calculating of Pore pressure in shale based on the available well data! Most of above challenges lead to an underestimate of the pore pressure, which it can lead to drilling surprise.

Recommendation and further work  



Taking direct pressure measurement in all permeable formation –nothing adequately replaces the benefit of knowing the true pore pressure. Employments of multiple techniques in pore pressure predication to help understand the uncertainty in each of the method used. For example, employing basin modeling, seismic and wireline–based predication techniques provide complementary results and valuable insights into the realistic range of uncertainty in predication. It seems that its time to work more on Direct Pressure measurement in shale and for that part of study the following points may recommend: 1. Study on techniques to measure pore pressure in shale directly. 2. Investigate near wellbore environment 3. Quick methods to directly measurement of pore pressure in shale in open hole or closed hole. 4. Completion design and cost. 5. Short term test design and cost. 6. Recommended well and test design

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PRESSURE MEASUREMENT IN SHALE -----------------------------------------------------------------------------------------------------------------

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PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------References: 1. Richard.E.Swarbrick-Chalenges of Porosity-Based Pore Pressure Predication. 2. B.E Law, G.F.Ulmishek, V.I.Slavin, Abnormal Pressures in Hydrocarbon Environments 3. Paul brown, Richard E. Swarbrick, Andrew C. Aplin and Niall Hoey, Porosity: an Essential tool for the estimation of pore fluid pressure in Shales. 4. P. Magarini, C. Lanzetta, A. Galletta, Eni. Over pressure evaluation Manual. Page 250-255. 5. Rabia. Hussain ,Well Engineering & Construction 6. Schlumberger, RFT ,ESSENTIAL OF PRESSURE TEST INTERPRETATION ,Page 11-26 7. Stephen O'Connor1, Richard E. Swarbrick, Phillip Clegg, and David T. Scott, Pore Pressure Profiles in Deep Water Environments: Case Studies from Around the World 8. W.H FERTL Abnormal Formation Pressure 9. www.netl.doe.gov/.../ANSWell/MDTool.html 10. Statoil-Hydro, Direct Pressure measurement in shale (MESPOSH) 11. http://www.halliburton.com/ps/Default.aspx?navid=159&pageid=396 12. Vaughan P.R.(1969), A note on sealing piozometers in boreholes Geotechnique

13. Morten H. Detholff, Halliburton, and Steen Agerline Petersen, NorskHydro, Seismic-While-Drilling Operation and Applications. 14. R.J. Meehan, Schlumberger Cambridge Research; L. Nutt,’ Schlumberger Wireline and Testing; N. Dutta, BP; and J. Menzies, Lasmo IDAC/SPE, Drill Bit Seismic: A Drilling Optimization Tool 15. A Review of Seismic-While Drilling (SWD) Techniques: A Journey from 1986 to 2005 A. Anchliya, SPE Indian School and Mines. 16. B.Cornish , SPE , and R .Deady , SPE, Halliburton Energy Services, Next Generation Multisensour Seismic-While-Drilling Technology 17. Ray Pratt, Peter K. Keller & SolveigLysen, HPHT Sonic Exploration WellPore WellPore Pressure Prediction and Monitoring: UtilisingVSP Look-Ahead, MWD Resistivity and MWD Sonic HPHT Sonic, A case study from the Central Grabenof the North Sea

18. Dr.Tanguy and W.A. Zoeller, SPE, Application of measurement while drilling NTNU | Atumn2009

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PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------19. Zarool Hassan bin Tajul, Petronas Carigali sdn.Bhd. SPE: The Benefits of Logging while Drilling (LWD) for formation Evaluation in the Dulang west Filed. 20. Rev.A, Baker Haugh, Advance Wireline & MWD Procedure. Page:1-1 to 3-10 21. Ed.Tollefsen, SPE, Amandaweber, SPE, and Aron Corporation, and Lisa Grant, SPE, Shell, Logging While Drilling Messurements: From Correlation to Evaluation. 22. J.P MOUCHET AND A. MITCHELL ,Abnormal pressure while drilling Page 140-167 23. Paul Radzinski, Weatherford International Ltd. LWD/MWD combo for extreme environments. 24. Martin Traugott, Amoco E&P Technology, Houston, Texas,Pore Pressure and Fracture Pressure Determinations in Deepwater 25. R.Nygaard, M.Karimi, G.Hareland and M.Tahmeen and H.Munro Pore-Pressure Predication in Overconsolidated Shales 26. A.Draou,Sonatrach,PED,Algeria and S.O.Osisanya,SPE,The university of Oklahoma, New Methods for Formation Pressure and Fracture Gradients from Well Logs. 27. G.V. Chilingar, V.A.serebryako, J.O.Robertson, Jr. Origin and Prediction of Abnormal Formation Pressures

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Well data methods:

and

fitting

to

pressure

calculation

APPENDIX A: 1. Eaton Method: Well Name: 6608 10-E-3 H Felt: Norne TABLE 1: Well data DEPTH

TVD

DT

GR

NPHI

RHOB

2440.625

2363.7244

117.4046

80.2465

0.3319

2.302

2440.75

2363.8445

117.5041

79.1689

0.3327

2.3167

2440.875

2363.9646

117.6487

81.9878

0.3313

2.3353

2441

2364.0845

117.7898

83.8123

0.3223

2.33

2441.125

2364.2046

117.8284

83.1971

0.3323

2.33

2441.25

2364.3247

117.7269

90.1494

0.339

2.33

2441.375

2364.4448

117.5482

95.7786

0.3503

2.33

2441.5

2364.5649

117.3473

99.1985

0.3519

2.33

2441.625

2364.6851

117.1681

98.577

0.3394

2.3284

2441.75

2364.8052

117.0302

85.5132

0.3421

2.3202

2441.875

2364.925

116.8764

80.7847

0.3444

2.32

2442

2365.0452

116.6941

79.9678

0.3494

2.32

2442.125

2365.1653

116.5111

81.0235

0.3241

2.3244

2442.25

2365.2854

116.3445

80.7457

0.289

2.3287

2442.375

2365.4055

116.2053

76.62

0.2913

2.3246

2442.5

2365.5256

116.1282

74.5032

0.3108

2.3205

2442.625

2365.6455

116.14

84.6392

0.2964

2.3157

2442.75

2365.7656

116.2257

89.4405

0.2832

2.3118

2442.875

2365.8857

116.3676

89.8491

0.2833

2.3078

2443

2366.0059

116.5407

86.9438

0.2979

2.3068

2443.125

2366.126

116.714

76.215

0.317

2.319

2443.25

2366.2461

116.8771

83.6836

0.3184

2.3009

2443.375

2366.3662

117.1356

84.6597

0.3131

2.3157

2443.5

2366.4861

117.5365

83.1574

0.3084

2.3237

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PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------2443.625

2366.6062

118.0558

82.2568

0.3056

2.3179

2443.75

2366.7263

118.6244

83.4279

0.3052

2.31

2443.875

2366.8464

119.147

84.0728

0.322

2.31

2444

2366.9666

119.5855

81.2831

0.3183

2.3219

2444.125

2367.0867

120.0449

81.1417

0.3238

2.3475

2444.25

2367.2065

120.5087

81.5558

0.3274

2.352

2444.375

2367.3267

120.8572

80.8789

0.323

2.3285

2444.5

2367.4468

120.8677

79.6757

0.3184

2.3109

2444.625

2367.5669

120.185

80.4347

0.3132

2.3085

2444.75

2367.687

119.131

80.049

0.3194

2.322

2444.875

2367.8071

118.0887

77.4081

0.3232

2.3232

2445

2367.9272

117.2851

77.4045

0.3219

2.3176

2445.125

2368.0471

116.8237

83.1754

0.3179

2.3191

2445.25

2368.1672

116.653

84.059

0.3136

2.3199

2445.375

2368.2874

116.5115

76.9195

0.3056

2.32

2445.5

2368.4075

116.3469

78.3222

0.304

2.3265

2445.625

2368.5276

116.2236

85.6607

0.3029

2.3351

2445.75

2368.6477

116.1818

90.1324

0.3006

2.3403

2445.875

2368.7676

116.219

81.9887

0.3017

2.338

2446

2368.8877

116.2871

87.889

0.3236

2.3389

2446.125

2369.0078

116.3207

83.9365

0.3374

2.3411

2446.25

2369.1279

116.3203

80.1609

0.3278

2.341

2446.375

2369.248

116.3057

79.4951

0.3132

2.3357

2446.5

2369.3682

116.3113

81.2473

0.3103

2.3238

2446.625

2369.488

116.3901

81.4746

0.3054

2.3066

2446.75

2369.6082

116.5629

81.4743

0.3001

2.2823

2446.875

2369.7283

116.7513

82.2029

0.3001

2.3212

2447

2369.8484

116.898

82.7503

0.2991

2.3366

2447.125

2369.9685

116.9703

82.0445

0.2999

2.316

2447.25

2370.0886

116.9717

79.8115

0.3114

2.3083

2447.375

2370.2087

117.0152

82.2263

0.3245

2.323

2447.5

2370.3286

117.2242

82.5584

0.3042

2.3236

2447.625

2370.4487

117.5478

77.2398

0.2869

2.3267

2447.75

2370.5688

117.881

77.0379

0.2879

2.3384

2447.875

2370.689

118.1049

84.7637

0.2994

2.3504

2448

2370.8091

118.114

82.245

0.2807

2.333

2448.125

2370.9292

117.8998

82.2296

0.2884

2.32

2448.25

2371.0491

117.6524

81.6784

0.3063

2.3126

2448.375

2371.1692

117.4475

80.9829

0.3212

2.3213

2448.5

2371.2893

117.3019

80.7431

0.3262

2.3391

NTNU | Atumn2009

95

PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------2448.625

2371.4094

117.1866

80.9523

0.3197

2.348

2448.75

2371.5295

117.0413

77.6801

0.3042

2.3308

2448.875

2371.6497

116.8531

81.0555

0.3076

2.3224

2449

2371.7698

116.6733

78.7203

0.3008

2.32

2449.125

2371.8896

116.5405

78.509

0.2922

2.3163

2449.25

2372.0098

116.4731

83.0292

0.2941

2.3137

2449.375

2372.1299

116.4606

82.6097

0.3128

2.3289

2449.5

2372.25

116.4402

84.6979

0.309

2.3232

2449.625

2372.3701

116.387

78.7641

0.3179

2.3181

2449.75

2372.4902

116.3515

79.4627

0.3252

2.3255

2449.875

2372.6101

116.3938

83.9224

0.3274

2.3354

2450

2372.7302

116.568

83.4074

0.3239

2.3335

2450.125

2372.8503

116.9096

79.7553

0.303

2.3303

2450.25

2372.9705

117.3016

80.6818

0.3195

2.3421

2450.375

2373.0906

117.6277

84.6196

0.3197

2.3373

2450.5

2373.2107

117.8483

84.8524

0.3129

2.3258

2450.625

2373.3308

117.9491

81.3144

0.3065

2.3184

2450.75

2373.4507

117.9364

81.5475

0.2996

2.3197

2450.875

2373.5708

117.811

79.2869

0.3199

2.3123

2451

2373.6909

117.6017

83.5463

0.3157

2.3144

2451.125

2373.811

117.3436

83.4971

0.3209

2.322

2451.25

2373.9312

117.0784

81.0548

0.3257

2.322

2451.375

2374.0513

116.8508

81.074

0.3143

2.3091

2451.5

2374.1711

116.7066

83.0088

0.298

2.31

2451.625

2374.2913

116.6531

83.9225

0.3133

2.3139

2451.75

2374.4114

116.6328

83.4275

0.2894

2.318

2451.875

2374.5315

116.6209

83.1111

0.2799

2.3154

2452

2374.6516

116.5965

83.3055

0.2956

2.3119

2452.125

2374.7717

116.5467

82.7236

0.3029

2.3219

2452.25

2374.8918

116.4999

76.5878

0.3073

2.3342

2452.375

2375.0117

116.514

84.1983

0.3037

2.3178

2452.5

2375.1318

116.59

87.4743

0.3035

2.3131

2452.625

2375.252

116.7125

85.6945

0.3042

2.3174

2452.75

2375.3721

116.8548

82.3477

0.3066

2.3211

2452.875

2375.4922

116.9818

79.3766

0.3255

2.3269

2453

2375.6123

117.0626

77.4238

0.3343

2.3294

2453.125

2375.7322

117.113

85.4496

0.3351

2.33

NTNU | Atumn2009

96

PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------TABLE 2: Calculated Eaton method: GPn= 1.05 x=3

P pore  P ovb  ( P ovb  P p , n TVD DT N Dt 2363.7244 117.4046 2363.8445 117.5041 2363.9646 117.6487 2364.0845 117.7898 2364.2046 117.8284 2364.3247 117.7269 2364.4448 117.5482 2364.5649 117.3473 2364.6851 117.1681 2364.8052 117.0302 2364.925 116.8764 2365.0452 116.6941 2365.1653 116.5111 2365.2854 116.3445 2365.4055 116.2053 2365.5256 116.1282 2365.6455 116.14 2365.7656 116.2257 2365.8857 116.3676 2366.0059 116.5407 2366.126 116.714 2366.2461 116.8771 2366.3662 117.1356 2366.4861 117.5365 2366.6062 118.0558 2366.7263 118.6244 2366.8464 119.147 2366.9666 119.5855 2367.0867 120.0449 2367.2065 120.5087 2367.3267 120.8572 2367.4468 120.8677 2367.5669 120.185 2367.687 119.131 2367.8071 118.0887 2367.9272 117.2851 2368.0471 116.8237 2368.1672 116.653 2368.2874 116.5115 2368.4075 116.3469 2368.5276 116.2236 2368.6477 116.1818 2368.7676 116.219

NTNU | Atumn2009

118 118 118 118 118 118 118 118 118 118 118 118 118 118 118 118 118 118 118 118 118 118 118 118 118 118 118 118 118 118 118 118 118 118 118 118 118 118 118 118 118 118 118

 tn   )   t a  

RHOB Gob 2.302 2.3167 2.3353 2.33 2.33 2.33 2.33 2.33 2.3284 2.3202 2.32 2.32 2.3244 2.3287 2.3246 2.3205 2.3157 2.3118 2.3078 2.3068 2.319 2.3009 2.3157 2.3237 2.3179 2.31 2.31 2.3219 2.3475 2.352 2.3285 2.3109 2.3085 2.322 2.3232 2.3176 2.3191 2.3199 2.32 2.3265 2.3351 2.3403 2.338

2.30 2.31 2.32 2.33 2.33 2.33 2.33 2.33 2.33 2.32 2.32 2.32 2.32 2.33 2.33 2.32 2.32 2.32 2.31 2.31 2.31 2.31 2.31 2.32 2.32 2.31 2.31 2.32 2.33 2.34 2.34 2.32 2.32 2.32 2.32 2.32 2.32 2.32 2.32 2.32 2.33 2.33 2.34

3

Gob-(Gob-GPn) 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05

N Dt/Dt GPpore Ppore[kg/Cm2] 1.01 1.079 2550 1.01 1.076 2543 1.01 1.071 2533 1.01 1.067 2523 1.01 1.066 2520 1.01 1.069 2526 1.01 1.073 2538 1.01 1.078 2550 1.01 1.083 2561 1.01 1.087 2570 1.01 1.091 2580 1.01 1.096 2591 1.02 1.100 2603 1.02 1.105 2614 1.02 1.109 2622 1.02 1.111 2627 1.02 1.110 2626 1.02 1.107 2619 1.02 1.103 2609 1.01 1.098 2597 1.01 1.093 2585 1.01 1.088 2574 1.01 1.080 2556 1.01 1.069 2530 1.00 1.055 2496 1.00 1.039 2460 0.99 1.026 2427 0.99 1.014 2400 0.98 1.002 2372 0.98 0.990 2344 0.98 0.982 2324 0.98 0.981 2323 0.98 0.998 2362 0.99 1.024 2425 1.00 1.051 2489 1.01 1.073 2540 1.01 1.085 2570 1.01 1.090 2581 1.01 1.093 2590 1.01 1.098 2600 1.02 1.101 2608 1.02 1.102 2610 1.02 1.101 2607

97

PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------2368.8877 2369.0078 2369.1279 2369.248 2369.3682 2369.488 2369.6082 2369.7283 2369.8484 2369.9685 2370.0886 2370.2087 2370.3286 2370.4487 2370.5688 2370.689 2370.8091 2370.9292 2371.0491 2371.1692 2371.2893 2371.4094 2371.5295 2371.6497

116.2871 116.3207 116.3203 116.3057 116.3113 116.3901 116.5629 116.7513 116.898 116.9703 116.9717 117.0152 117.2242 117.5478 117.881 118.1049 118.114 117.8998 117.6524 117.4475 117.3019 117.1866 117.0413 116.8531

NTNU | Atumn2009

118 118 118 118 118 118 118 118 118 118 118 118 118 118 118 118 118 118 118 118 118 118 118 118

2.3389 2.3411 2.341 2.3357 2.3238 2.3066 2.2823 2.3212 2.3366 2.316 2.3083 2.323 2.3236 2.3267 2.3384 2.3504 2.333 2.32 2.3126 2.3213 2.3391 2.348 2.3308 2.3224

2.34 2.34 2.34 2.34 2.33 2.32 2.30 2.31 2.32 2.32 2.31 2.32 2.32 2.32 2.33 2.34 2.34 2.33 2.32 2.32 2.33 2.34 2.33 2.33

1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05

1.02 1.01 1.01 1.01 1.01 1.01 1.01 1.01 1.01 1.01 1.01 1.01 1.01 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.01 1.01 1.01

1.098 1.097 1.097 1.097 1.097 1.094 1.089 1.084 1.079 1.077 1.077 1.075 1.069 1.060 1.051 1.045 1.044 1.050 1.056 1.061 1.065 1.068 1.072 1.076

98

2602 2599 2599 2599 2598 2593 2581 2568 2557 2552 2552 2548 2534 2513 2491 2476 2475 2488 2504 2516 2525 2532 2541 2553

PRESSURE MEASUREMENT IN SHALE -----------------------------------------------------------------------------------------------------------------

Results & Charts: Well: N6608 10-E-3 H Felt: NORNE Chart 1: Sonic travel Time vs. Depth

Fig.A1 : Variation of Sonic travel Time vs. Depth

NTNU | Atumn2009

99

PRESSURE MEASUREMENT IN SHALE -----------------------------------------------------------------------------------------------------------------

Chart 2: Pressure-Depth based on Sonic log (Eaton-Method)

Pressure-Depth (sonic log-Eaton Method) 1500 2000

2500 Pressure 3500

4500

5500

2100 2200

Depth [m]

2300 2400 2500 2600

Pressure-Depth (sonic log-Eaton Method)

2700 2800 2900 3000

Fig.A2 : Pore pressure predication using Eaton sonic log method.

NTNU | Atumn2009

100

PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------TABLE 3:

Well Name: 34 10-8 Felt: Gulfaks Depth DT 1800.0839 1800.2363 1800.3885 1800.5409 1800.6931 1800.8455 1800.9977 1801.15 1801.3024 1801.4546 1801.6069 1801.7592 1801.9116 1802.0638 1802.2162 1802.3684 1802.5208 1802.673 1802.8254 1802.9777 1803.1299 1803.2822 1803.4344 1803.5869 1803.7391 1803.8915 1804.0437 1804.196 1804.3483 1804.5007 1804.653 1804.8052 1804.9575 1805.1097 1805.2622 1805.4144 1805.5668 1805.719 1805.8713 1806.0237 1806.176

N DT 110.52 107.68 107.23 109.88 113.79 116.84 118.83 119.60 119.45 118.32 114.97 109.33 105.79 107.20 111.37 116.65 120.50 121.71 122.07 122.30 122.42 122.43 122.34 122.19 122.04 121.78 120.87 118.62 113.85 106.83 102.25 101.65 105.01 112.12 117.21 119.15 117.77 112.33 104.83 96.26 91.44

NTNU | Atumn2009

RHOB: 128.79 128.78 128.77 128.76 128.75 128.75 128.74 128.73 128.72 128.71 128.71 128.70 128.69 128.68 128.67 128.67 128.66 128.65 128.64 128.63 128.63 128.62 128.61 128.60 128.59 128.59 128.58 128.57 128.56 128.55 128.55 128.54 128.53 128.52 128.51 128.51 128.50 128.49 128.48 128.47 128.47

2.5106 2.5309 2.4833 2.4139 2.3879 2.3895 2.3814 2.3836 2.3865 2.4333 2.5356 2.6265 2.5825 2.4751 2.3916 2.3723 2.377 2.3686 2.3544 2.3432 2.3456 2.3554 2.3607 2.3677 2.3776 2.3821 2.3862 2.3935 2.4602 2.6193 2.7918 2.7689 2.5854 2.4286 2.3745 2.3748 2.3987 2.454 2.5869 2.7639 2.7885

Depth RT: 1800.0839 1800.2363 1800.3885 1800.5409 1800.6931 1800.8455 1800.9977 1801.15 1801.3024 1801.4546 1801.6069 1801.7592 1801.9116 1802.0638 1802.2162 1802.3684 1802.5208 1802.673 1802.8254 1802.9777 1803.1299 1803.2822 1803.4344 1803.5869 1803.7391 1803.8915 1804.0437 1804.196 1804.3483 1804.5007 1804.653 1804.8052 1804.9575 1805.1097 1805.2622 1805.4144 1805.5668 1805.719 1805.8713 1806.0237 1806.176

N RT 1.8132 2.092 2.1565 2.2573 2.1659 1.8692 1.4892 1.3124 1.5854 1.5401 1.4591 1.4346 1.6134 1.5853 1.5338 1.573 1.5952 1.6042 1.5701 1.6449 1.9372 2.2573 2.2764 2.107 1.7641 1.5617 1.5339 1.5641 1.6615 2.1972 3.0196 3.2613 3.0526 2.4979 1.8115 1.6181 1.6257 1.6628 1.68 1.6976 1.6929

26.37 26.36 26.35 26.33 26.32 26.31 26.29 26.28 26.27 26.25 26.24 26.23 26.21 26.20 26.19 26.17 26.16 26.15 26.13 26.12 26.11 26.09 26.08 26.07 26.06 26.04 26.03 26.02 26.00 25.99 25.98 25.96 25.95 25.94 25.92 25.91 25.90 25.88 25.87 25.86 25.84

101

PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------1806.3282 1806.4806 1806.6329 1806.7852 1806.9375 1807.0897 1807.2422 1807.3944 1807.5468 1807.699 1807.8514 1808.0037 1808.156 1808.3082 1808.4607 1808.6129 1808.7651 1808.9175 1809.0698 1809.2222 1809.3744 1809.5267 1809.6791 1809.8314 1809.9836 1810.136 1810.2883 1810.4406 1810.5929 1810.7451 1810.8975 1811.0497 1811.202 1811.3542 1811.5066 1811.6588 1811.8113 1811.9635 1812.1158 1812.2681 1812.4203 1812.5726 1812.7249 1812.8772 1813.0294 1813.1818 1813.334 1813.4865

91.31 94.52 100.90 107.15 112.59 115.87 117.08 117.81 118.06 118.05 117.84 117.61 117.37 117.09 116.92 116.99 116.95 116.07 113.28 107.96 102.82 101.60 103.90 108.44 113.55 117.28 119.88 121.65 122.78 123.49 124.02 124.59 125.15 125.59 125.67 125.30 124.90 124.69 124.56 124.44 124.29 123.87 122.54 119.83 115.96 111.45 109.06 109.79

NTNU | Atumn2009

128.46 128.45 128.44 128.43 128.43 128.42 128.41 128.40 128.39 128.39 128.38 128.37 128.36 128.35 128.35 128.34 128.33 128.32 128.31 128.31 128.30 128.29 128.28 128.27 128.27 128.26 128.25 128.24 128.23 128.23 128.22 128.21 128.20 128.19 128.19 128.18 128.17 128.16 128.15 128.15 128.14 128.13 128.12 128.11 128.11 128.10 128.09 128.08

2.64 2.4796 2.4026 2.3897 2.4068 2.4046 2.3811 2.3646 2.369 2.3872 2.4086 2.4302 2.4389 2.4293 2.4039 2.393 2.4101 2.4432 2.5408 2.6827 2.753 2.6391 2.4942 2.3982 2.3584 2.3353 2.3302 2.3217 2.3272 2.3468 2.3637 2.3707 2.3511 2.3385 2.3404 2.3431 2.3457 2.3451 2.3539 2.375 2.3788 2.3848 2.3853 2.397 2.413 2.4336 2.4291 2.4126

1806.3282 1806.4806 1806.6329 1806.7852 1806.9375 1807.0897 1807.2422 1807.3944 1807.5468 1807.699 1807.8514 1808.0037 1808.156 1808.3082 1808.4607 1808.6129 1808.7651 1808.9175 1809.0698 1809.2222 1809.3744 1809.5267 1809.6791 1809.8314 1809.9836 1810.136 1810.2883 1810.4406 1810.5929 1810.7451 1810.8975 1811.0497 1811.202 1811.3542 1811.5066 1811.6588 1811.8113 1811.9635 1812.1158 1812.2681 1812.4203 1812.5726 1812.7249 1812.8772 1813.0294 1813.1818 1813.334 1813.4865

1.6663 1.6978 1.8387 1.9774 1.9002 1.9037 1.7412 1.4506 1.5931 1.8348 2.2904 2.4362 2.3071 2.0065 1.6708 1.6102 1.6707 1.7011 1.7224 1.6438 1.5777 1.5785 1.6674 1.7438 1.6038 1.5887 1.6292 1.6515 1.6074 1.5901 1.5852 1.5626 1.5357 1.6244 1.9203 2.1285 2.1652 2.1913 1.9988 1.7854 1.6089 1.629 1.8914 1.6733 1.6437 1.6511 1.6507 1.6618

25.83 25.82 25.80 25.79 25.78 25.76 25.75 25.74 25.72 25.71 25.70 25.68 25.67 25.66 25.64 25.63 25.62 25.61 25.59 25.58 25.57 25.55 25.54 25.53 25.51 25.50 25.49 25.47 25.46 25.45 25.43 25.42 25.41 25.39 25.38 25.37 25.35 25.34 25.33 25.31 25.30 25.29 25.27 25.26 25.25 25.23 25.22 25.21

102

PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------1813.6387 1813.791 1813.9432 1814.0956 1814.2478 1814.4 1814.5524 1814.7046 1814.8569 1815.0092 1815.1616 1815.3138 1815.4662 1815.6184 1815.7709 1815.9231 1816.0756 1816.2278 1816.3801 1816.5325 1816.6848 1816.8372 1816.9895 1817.1418 1817.2942 1817.4465 1817.5989 1817.7512 1817.9036 1818.0558 1818.2083 1818.3605 1818.5129 1818.6652 1818.8176 1818.9698 1819.1222 1819.2745 1819.4269 1819.5792 1819.7316 1819.8839 1820.0361 1820.1886 1820.3408 1820.4933 1820.6456 1820.7981

112.17 115.80 118.78 120.69 121.96 122.52 122.68 122.40 122.04 121.56 120.99 120.36 119.87 119.56 119.24 118.17 114.54 108.08 100.51 93.51 91.35 93.99 98.41 104.56 111.24 117.03 119.50 119.58 119.94 120.44 120.76 120.82 120.38 118.41 114.04 109.08 106.35 106.85 110.97 116.09 119.26 120.87 121.45 121.28 120.75 120.30 120.31 120.63

NTNU | Atumn2009

128.07 128.07 128.06 128.05 128.04 128.03 128.03 128.02 128.01 128.00 127.99 127.99 127.98 127.97 127.96 127.95 127.95 127.94 127.93 127.92 127.91 127.91 127.90 127.89 127.88 127.87 127.87 127.86 127.85 127.84 127.83 127.83 127.82 127.81 127.80 127.79 127.79 127.78 127.77 127.76 127.75 127.75 127.74 127.73 127.72 127.71 127.71 127.70

2.3828 2.3873 2.3874 2.3791 2.3653 2.3613 2.3619 2.3595 2.3554 2.3721 2.4057 2.4394 2.4371 2.4131 2.3893 2.4018 2.4651 2.6063 2.8122 2.8713 2.7271 2.5629 2.4444 2.4111 2.3946 2.3938 2.3941 2.3809 2.3784 2.3736 2.3693 2.3593 2.3646 2.3848 2.459 2.5906 2.6937 2.6228 2.469 2.3667 2.3631 2.3819 2.3871 2.3653 2.3626 2.3703 2.3746 2.3613

1813.6387 1813.791 1813.9432 1814.0956 1814.2478 1814.4 1814.5524 1814.7046 1814.8569 1815.0092 1815.1616 1815.3138 1815.4662 1815.6184 1815.7709 1815.9231 1816.0756 1816.2278 1816.3801 1816.5325 1816.6848 1816.8372 1816.9895 1817.1418 1817.2942 1817.4465 1817.5989 1817.7512 1817.9036 1818.0558 1818.2083 1818.3605 1818.5129 1818.6652 1818.8176 1818.9698 1819.1222 1819.2745 1819.4269 1819.5792 1819.7316 1819.8839 1820.0361 1820.1886 1820.3408 1820.4933 1820.6456 1820.7981

1.7027 1.7375 1.745 1.767 1.7653 1.7065 1.6876 2.0032 2.736 3.3589 3.5754 3.0328 2.0608 1.6636 1.5722 1.6133 1.6492 1.7503 1.8519 1.651 1.7072 1.7162 1.6935 1.6779 1.6695 1.7649 1.9958 2.1286 2.0913 1.9319 1.7035 1.6632 1.706 1.7163 1.7358 1.7893 1.804 1.7866 1.7489 1.6733 1.5879 1.5246 1.502 1.59 1.8136 1.733 0.9377 0.6384

25.19 25.18 25.17 25.16 25.14 25.13 25.12 25.10 25.09 25.08 25.06 25.05 25.04 25.02 25.01 25.00 24.98 24.97 24.96 24.94 24.93 24.92 24.90 24.89 24.88 24.86 24.85 24.84 24.82 24.81 24.80 24.78 24.77 24.76 24.74 24.73 24.72 24.71 24.69 24.68 24.67 24.65 24.64 24.63 24.61 24.60 24.59 24.57

103

PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------1820.9504 1821.1029 1821.2552 1821.4078 1821.5602 1821.7126 1821.865 1822.0173 1822.1698 1822.3221 1822.4746 1822.627 1822.7794 1822.9318 1823.0844 1823.2367 1823.3892 1823.5415 1823.6938 1823.8463 1823.9987 1824.1511 1824.3035 1824.4559 1824.6083 1824.7609 1824.9132 1825.0657 1825.218 1825.3705 1825.5228 1825.6752 1825.8276 1825.9801 1826.1326 1826.2849 1826.4374 1826.5898 1826.7423 1826.8947 1827.0471 1829.3335 1829.486 1829.6383 1829.7908 1829.9431 1830.0956 1830.248

121.09 121.33 121.02 119.93 117.97 115.86 113.96 112.28 110.54 107.55 103.17 99.75 98.59 100.55 105.95 111.68 116.79 119.98 120.99 121.89 122.85 123.72 124.47 125.22 125.92 126.44 126.66 126.52 126.27 126.94 128.55 130.26 131.55 131.23 129.14 126.24 123.31 122.25 122.70 123.05 123.43 133.30 132.35 132.05 132.42 133.48 135.14 137.22

NTNU | Atumn2009

127.69 127.68 127.67 127.67 127.66 127.65 127.64 127.63 127.63 127.62 127.61 127.60 127.59 127.59 127.58 127.57 127.56 127.55 127.55 127.54 127.53 127.52 127.51 127.51 127.50 127.49 127.48 127.47 127.47 127.46 127.45 127.44 127.43 127.43 127.42 127.41 127.40 127.39 127.39 127.38 127.37 127.25 127.24 127.23 127.23 127.22 127.21 127.20

2.3582 2.3572 2.3641 2.3592 2.3818 2.4307 2.5254 2.671 2.8406 2.9456 3.0336 3.1421 3.2225 3.0164 2.6442 2.4163 2.3096 2.2954 2.299 2.2802 2.2606 2.2481 2.2441 2.2435 2.239 2.2274 2.2048 2.169 2.1371 2.0901 2.0118 1.9586 1.9647 2.0395 2.1001 2.1064 2.0893 2.0853 2.0854 2.0832 2.0898 2.0676 2.0742 2.0742 2.0692 2.0561 2.0508 2.0539

1820.9504 1821.1029 1821.2552 1821.4078 1821.5602 1821.7126 1821.865 1822.0173 1822.1698 1822.3221 1822.4746 1822.627 1822.7794 1822.9318 1823.0844 1823.2367 1823.3892 1823.5415 1823.6938 1823.8463 1823.9987 1824.1511 1824.3035 1824.4559 1824.6083 1824.7609 1824.9132 1825.0657 1825.218 1825.3705 1825.5228 1825.6752 1825.8276 1825.9801 1826.1326 1826.2849 1826.4374 1826.5898 1826.7423 1826.8947 1827.0471 1829.3335 1829.486 1829.6383 1829.7908 1829.9431 1830.0956 1830.248

0.5739 0.6162 0.6982 0.697 0.8197 1.1705 2.5702 5.3745 6.6584 5.6723 5.1344 5.2637 5.4982 5.6014 5.2402 4.7579 4.6996 5.0012 6.0537 8.4135 11.8444 13.9127 11.8839 8.8304 8.4084 10.2622 17.1649 35.5194 61.2075 72.7154 73.3632 77.1372 82.8329 88.5154 94.7232 103.7881 108.3376 111.3397 123.4076 138.8506 159.2353 157.8509 139.5852 135.213 131.8756 132.0082 131.6803 126.9913

24.56 24.55 24.53 24.52 24.51 24.49 24.48 24.47 24.45 24.44 24.43 24.41 24.40 24.39 24.37 24.36 24.35 24.33 24.32 24.31 24.29 24.28 24.27 24.25 24.24 24.23 24.22 24.20 24.19 24.18 24.16 24.15 24.14 24.12 24.11 24.10 24.08 24.07 24.06 24.04 24.03 23.83 23.82 23.80 23.79 23.78 23.76 23.75

104

PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------1830.4005 1830.5529 1830.7053 1830.8577 1831.0101 1831.1626 1831.3149 1834.3633 1834.5156 1834.6681 1834.8204 1834.973 1835.1254 1835.2777 1835.4302 1835.5825 1835.735 1835.8873 1836.0398 1836.1921 1836.3446 1836.4969 1836.6494 1836.8018 1836.9541 1837.1066 1837.2589 1837.4114 1837.5637 1837.7162 1837.8685 1838.021

139.14 140.46 141.19 141.31 141.10 140.70 140.17 134.69 134.68 134.25 133.48 132.97 132.56 131.61 130.00 128.01 126.13 125.72 127.49 131.83 137.73 141.95 143.05 139.69 133.47 128.42 124.84 122.83 122.18 122.15 122.26 121.90

NTNU | Atumn2009

127.19 127.19 127.18 127.17 127.16 127.15 127.15 126.99 126.98 126.97 126.96 126.95 126.95 126.94 126.93 126.92 126.91 126.91 126.90 126.89 126.88 126.87 126.87 126.86 126.85 126.84 126.83 126.83 126.82 126.81 126.80 126.79

2.0536 2.0422 2.0482 2.05 2.0516 2.0379 2.0332 2.0635 2.0838 2.0938 2.0898 2.086 1.9445 1.6301 1.563 1.6529 1.9275 2.1906 2.278 2.276 2.2679 2.2424 2.2254 2.2073 2.1738 2.1203 2.0828 2.0711 2.0592 2.0522 2.0644 2.1428

1830.4005 1830.5529 1830.7053 1830.8577 1831.0101 1831.1626 1831.3149 1834.3633 1834.5156 1834.6681 1834.8204 1834.973 1835.1254 1835.2777 1835.4302 1835.5825 1835.735 1835.8873 1836.0398 1836.1921 1836.3446 1836.4969 1836.6494 1836.8018 1836.9541 1837.1066 1837.2589 1837.4114 1837.5637 1837.7162 1837.8685 1838.021

116.3481 109.7276 96.4492 91.4525 98.9225 121.3915 159.567 111.4122 61.0703 24.2287 11.2326 7.2641 5.196 4.0781 3.4241 3.1296 3.0205 2.926 2.9522 3.0789 3.2645 3.4146 3.9611 5.3632 9.037 25.7394 58.8549 65.1747 33.7731 11.7541 5.1558 3.0448

23.74 23.72 23.71 23.70 23.69 23.67 23.66 23.39 23.38 23.37 23.35 23.34 23.33 23.31 23.30 23.29 23.27 23.26 23.25 23.23 23.22 23.21 23.20 23.18 23.17 23.16 23.14 23.13 23.12 23.10 23.09 23.08

105

PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------TABLE 4: Calculation and results based on Eaton Method:

GPob 2.5106 2.52 2.50 2.46 2.42 2.41 2.39 2.39 2.39 2.41 2.47 2.55 2.57 2.52 2.46 2.41 2.40 2.38 2.37 2.36 2.35 2.35 2.36 2.36 2.37 2.38 2.38 2.39 2.42 2.52 2.66 2.71 2.65 2.54 2.46 2.42 2.41 2.43 2.51 2.64 2.71 2.68 2.58 2.49 2.44

Rt a/N GPob-(GPob-GPn) N Dt/Dt Rt GP(Dt) GP(Rt) 1.03 1.165 0.069 1.200 0.071 1.03 1.196 0.079 1.232 0.082 1.03 1.201 0.082 1.237 0.084 1.03 1.172 0.086 1.207 0.088 1.03 1.132 0.082 1.165 0.085 1.03 1.102 0.071 1.135 0.073 1.03 1.083 0.057 1.116 0.058 1.03 1.076 0.050 1.109 0.051 1.03 1.078 0.060 1.110 0.062 1.03 1.088 0.059 1.120 0.060 1.03 1.120 0.056 1.153 0.057 1.03 1.177 0.055 1.212 0.056 1.03 1.216 0.062 1.253 0.063 1.03 1.200 0.061 1.236 0.062 1.03 1.155 0.059 1.190 0.060 1.03 1.103 0.060 1.136 0.062 1.03 1.068 0.061 1.100 0.063 1.03 1.057 0.061 1.089 0.063 1.03 1.054 0.060 1.085 0.062 1.03 1.052 0.063 1.083 0.065 1.03 1.051 0.074 1.082 0.076 1.03 1.051 0.087 1.082 0.089 1.03 1.051 0.087 1.083 0.090 1.03 1.052 0.081 1.084 0.083 1.03 1.054 0.068 1.085 0.070 1.03 1.056 0.060 1.088 0.062 1.03 1.064 0.059 1.096 0.061 1.03 1.084 0.060 1.116 0.062 1.03 1.129 0.064 1.163 0.066 1.03 1.203 0.085 1.240 0.087 1.03 1.257 0.116 1.295 0.120 1.03 1.265 0.126 1.302 0.129 1.03 1.224 0.118 1.261 0.121 1.03 1.146 0.096 1.181 0.099 1.03 1.096 0.070 1.129 0.072 1.03 1.078 0.062 1.111 0.064 1.03 1.091 0.063 1.124 0.065 1.03 1.144 0.064 1.178 0.066 1.03 1.226 0.065 1.262 0.067 1.03 1.335 0.066 1.375 0.068 1.03 1.405 0.066 1.447 0.067 1.03 1.407 0.065 1.449 0.066 1.03 1.359 0.066 1.400 0.068 1.03 1.273 0.071 1.311 0.073 1.03 1.199 0.077 1.235 0.079

NTNU | Atumn2009

Depth Ppore(Dt) Depth Ppore(Rt) 1800.0839 3112 1800.0839 75.07 1800.2363 3365 1800.2363 89.18 1800.3885 3407 1800.3885 92.56 1800.5409 3166 1800.5409 97.84 1800.6931 2851 1800.6931 93.17 1800.8455 2633 1800.8455 78.13 1800.9977 2503 1800.9977 59.52 1801.15 2454 1801.15 51.18 1801.3024 2463 1801.3024 64.25 1801.4546 2534 1801.4546 62.10 1801.6069 2762 1801.6069 58.24 1801.7592 3211 1801.7592 57.11 1801.9116 3544 1801.9116 65.79 1802.0638 3406 1802.0638 64.47 1802.2162 3037 1802.2162 62.00 1802.3684 2643 1802.3684 63.96 1802.5208 2397 1802.5208 65.08 1802.673 2326 1802.673 65.57 1802.8254 2306 1802.8254 63.95 1802.9777 2292 1802.9777 67.67 1803.1299 2285 1803.1299 82.40 1803.2822 2285 1803.2822 99.06 1803.4344 2289 1803.4344 100.14 1803.5869 2298 1803.5869 91.33 1803.7391 2306 1803.7391 73.85 1803.8915 2320 1803.8915 63.84 1804.0437 2373 1804.0437 62.53 1804.196 2510 1804.196 64.05 1804.3483 2839 1804.3483 68.92 1804.5007 3436 1804.5007 96.44 1804.653 3918 1804.653 141.34 1804.8052 3988 1804.8052 155.13 1804.9575 3617 1804.9575 143.39 1805.1097 2971 1805.1097 112.80 1805.2622 2600 1805.2622 76.77 1805.4144 2475 1805.4144 67.09 1805.5668 2563 1805.5668 67.51 1805.719 2953 1805.719 69.41 1805.8713 3633 1805.8713 70.33 1806.0237 4692 1806.0237 71.26 1806.176 5472 1806.176 71.07 1806.3282 5496 1806.3282 69.78 1806.4806 4954 1806.4806 71.42 1806.6329 4073 1806.6329 78.65 1806.7852 3400 1806.7852 85.88

106

PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------2.42 2.41 2.40 2.38 2.38 2.38 2.39 2.41 2.43 2.43 2.42 2.40 2.41 2.43 2.48 2.58 2.67 2.65 2.57 2.49 2.42 2.38 2.35 2.34 2.33 2.34 2.35 2.36 2.36 2.35 2.34 2.34 2.34 2.34 2.35 2.36 2.37 2.38 2.38 2.39 2.40 2.42 2.42 2.42 2.40 2.39 2.39 2.38 2.38 2.37 2.37

1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03

NTNU | Atumn2009

1.141 1.108 1.097 1.090 1.088 1.088 1.089 1.091 1.094 1.096 1.098 1.097 1.097 1.106 1.133 1.188 1.248 1.263 1.235 1.183 1.130 1.094 1.070 1.054 1.044 1.038 1.034 1.029 1.024 1.021 1.020 1.023 1.026 1.028 1.029 1.030 1.031 1.034 1.046 1.069 1.105 1.149 1.174 1.167 1.142 1.106 1.078 1.061 1.050 1.045 1.044

0.074 0.074 0.068 0.056 0.062 0.071 0.089 0.095 0.090 0.078 0.065 0.063 0.065 0.066 0.067 0.064 0.062 0.062 0.065 0.068 0.063 0.062 0.064 0.065 0.063 0.062 0.062 0.061 0.060 0.064 0.076 0.084 0.085 0.086 0.079 0.071 0.064 0.064 0.075 0.066 0.065 0.065 0.065 0.066 0.068 0.069 0.069 0.070 0.070 0.068 0.067

1.175 1.142 1.130 1.123 1.120 1.120 1.122 1.124 1.127 1.129 1.131 1.130 1.130 1.139 1.167 1.224 1.285 1.301 1.272 1.218 1.164 1.126 1.102 1.086 1.076 1.070 1.065 1.060 1.055 1.051 1.051 1.054 1.057 1.059 1.060 1.061 1.062 1.065 1.077 1.101 1.138 1.184 1.210 1.202 1.176 1.139 1.110 1.093 1.081 1.076 1.075

0.076 0.076 0.070 0.058 0.064 0.074 0.092 0.098 0.093 0.081 0.067 0.065 0.067 0.068 0.069 0.066 0.064 0.064 0.067 0.070 0.065 0.064 0.066 0.067 0.065 0.064 0.064 0.063 0.062 0.066 0.078 0.086 0.088 0.089 0.081 0.073 0.065 0.066 0.077 0.068 0.067 0.067 0.067 0.068 0.070 0.071 0.071 0.072 0.072 0.070 0.069

1806.9375 1807.0897 1807.2422 1807.3944 1807.5468 1807.699 1807.8514 1808.0037 1808.156 1808.3082 1808.4607 1808.6129 1808.7651 1808.9175 1809.0698 1809.2222 1809.3744 1809.5267 1809.6791 1809.8314 1809.9836 1810.136 1810.2883 1810.4406 1810.5929 1810.7451 1810.8975 1811.0497 1811.202 1811.3542 1811.5066 1811.6588 1811.8113 1811.9635 1812.1158 1812.2681 1812.4203 1812.5726 1812.7249 1812.8772 1813.0294 1813.1818 1813.334 1813.4865 1813.6387 1813.791 1813.9432 1814.0956 1814.2478 1814.4 1814.5524

2930 2689 2606 2557 2540 2541 2554 2569 2585 2603 2614 2609 2611 2671 2873 3319 3842 3980 3722 3273 2851 2587 2422 2318 2254 2215 2186 2156 2128 2105 2101 2119 2139 2150 2156 2162 2170 2192 2264 2421 2671 3008 3210 3146 2950 2681 2484 2368 2294 2263 2254

1806.9375 1807.0897 1807.2422 1807.3944 1807.5468 1807.699 1807.8514 1808.0037 1808.156 1808.3082 1808.4607 1808.6129 1808.7651 1808.9175 1809.0698 1809.2222 1809.3744 1809.5267 1809.6791 1809.8314 1809.9836 1810.136 1810.2883 1810.4406 1810.5929 1810.7451 1810.8975 1811.0497 1811.202 1811.3542 1811.5066 1811.6588 1811.8113 1811.9635 1812.1158 1812.2681 1812.4203 1812.5726 1812.7249 1812.8772 1813.0294 1813.1818 1813.334 1813.4865 1813.6387 1813.791 1813.9432 1814.0956 1814.2478 1814.4 1814.5524

107

81.93 82.17 73.87 59.38 66.49 78.83 102.94 110.93 103.99 88.01 70.70 67.68 70.80 72.39 73.54 69.58 66.28 66.37 70.93 74.90 67.79 67.07 69.18 70.36 68.16 67.33 67.13 66.03 64.71 69.27 84.74 95.95 98.01 99.50 89.17 77.93 68.82 69.91 83.69 72.30 70.82 71.25 71.28 71.91 74.09 75.96 76.41 77.62 77.59 74.55 73.62

PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------2.36 2.36 2.37 2.39 2.41 2.42 2.42 2.40 2.40 2.43 2.52 2.67 2.77 2.75 2.66 2.55 2.48 2.44 2.42 2.40 2.39 2.39 2.38 2.37 2.37 2.37 2.38 2.42 2.50 2.60 2.61 2.54 2.45 2.41 2.40 2.39 2.38 2.37 2.37 2.37 2.37 2.36 2.36 2.36 2.36 2.37 2.40 2.46 2.57 2.70 2.82

1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03 1.03

NTNU | Atumn2009

1.046 1.049 1.053 1.058 1.063 1.068 1.070 1.073 1.083 1.117 1.184 1.273 1.368 1.400 1.361 1.300 1.223 1.150 1.093 1.070 1.069 1.066 1.061 1.059 1.058 1.062 1.079 1.121 1.172 1.202 1.196 1.151 1.101 1.071 1.057 1.052 1.053 1.058 1.062 1.061 1.059 1.055 1.052 1.055 1.065 1.082 1.102 1.120 1.137 1.155 1.187

0.080 0.109 0.134 0.143 0.121 0.082 0.066 0.063 0.065 0.066 0.070 0.074 0.066 0.068 0.069 0.068 0.067 0.067 0.071 0.080 0.086 0.084 0.078 0.069 0.067 0.069 0.069 0.070 0.072 0.073 0.072 0.071 0.068 0.064 0.062 0.061 0.065 0.074 0.070 0.038 0.026 0.023 0.025 0.028 0.028 0.033 0.048 0.105 0.220 0.272 0.232

1.077 1.080 1.085 1.090 1.095 1.100 1.102 1.105 1.115 1.151 1.219 1.311 1.409 1.442 1.402 1.339 1.260 1.184 1.125 1.102 1.101 1.098 1.093 1.090 1.090 1.094 1.112 1.154 1.207 1.238 1.232 1.186 1.134 1.103 1.089 1.083 1.085 1.089 1.093 1.093 1.090 1.086 1.084 1.087 1.096 1.115 1.135 1.154 1.171 1.189 1.222

0.082 0.112 0.138 0.147 0.125 0.085 0.068 0.065 0.066 0.068 0.072 0.076 0.068 0.071 0.071 0.070 0.069 0.069 0.073 0.083 0.088 0.087 0.080 0.071 0.069 0.071 0.071 0.072 0.075 0.075 0.074 0.073 0.070 0.066 0.064 0.063 0.067 0.076 0.073 0.039 0.027 0.024 0.026 0.029 0.029 0.034 0.049 0.108 0.226 0.280 0.239

1814.7046 1814.8569 1815.0092 1815.1616 1815.3138 1815.4662 1815.6184 1815.7709 1815.9231 1816.0756 1816.2278 1816.3801 1816.5325 1816.6848 1816.8372 1816.9895 1817.1418 1817.2942 1817.4465 1817.5989 1817.7512 1817.9036 1818.0558 1818.2083 1818.3605 1818.5129 1818.6652 1818.8176 1818.9698 1819.1222 1819.2745 1819.4269 1819.5792 1819.7316 1819.8839 1820.0361 1820.1886 1820.3408 1820.4933 1820.6456 1820.7981 1820.9504 1821.1029 1821.2552 1821.4078 1821.5602 1821.7126 1821.865 1822.0173 1822.1698 1822.3221

2269 2289 2315 2348 2385 2414 2433 2452 2519 2766 3292 4093 5082 5450 5003 4359 3633 3017 2590 2433 2428 2406 2376 2357 2353 2379 2499 2798 3196 3449 3399 3034 2650 2445 2348 2314 2323 2354 2380 2379 2360 2333 2319 2337 2401 2522 2662 2797 2924 3065 3327

1814.7046 1814.8569 1815.0092 1815.1616 1815.3138 1815.4662 1815.6184 1815.7709 1815.9231 1816.0756 1816.2278 1816.3801 1816.5325 1816.6848 1816.8372 1816.9895 1817.1418 1817.2942 1817.4465 1817.5989 1817.7512 1817.9036 1818.0558 1818.2083 1818.3605 1818.5129 1818.6652 1818.8176 1818.9698 1819.1222 1819.2745 1819.4269 1819.5792 1819.7316 1819.8839 1820.0361 1820.1886 1820.3408 1820.4933 1820.6456 1820.7981 1820.9504 1821.1029 1821.2552 1821.4078 1821.5602 1821.7126 1821.865 1822.0173 1822.1698 1822.3221

108

90.50 131.65 168.51 181.75 149.28 93.96 72.73 68.01 70.20 72.13 77.52 83.01 72.38 75.40 75.93 74.78 74.01 73.62 78.75 91.34 98.75 96.74 88.03 75.75 73.66 75.99 76.60 77.70 80.64 81.49 80.61 78.63 74.62 70.13 66.84 65.70 70.39 82.49 78.17 37.44 23.62 20.80 22.67 26.35 26.32 32.00 49.10 126.27 306.25 396.30 327.20

PRESSURE MEASUREMENT IN SHALE -----------------------------------------------------------------------------------------------------------------

Chart & Results: y = -0.0287x + 178.65 R² = 0.0222

DT 160.00

150.00

140.00

Sonic Log [mic-s/ft]

130.00

120.00

110.00 DT Linear (DT)

100.00

90.00

80.00

70.00

60.00 1700

1750

1800

1850

1900

1950

2000

2050

Depth [m]

Fig. A3: Variation of traveltime sonic log vs.depth

NTNU | Atumn2009

109

PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------Ppore(Dt) 12000 y = 0.2542x + 1708.6 R² = 0.0003 10000

8000

6000

Ppore(Dt) Linear (Ppore(Dt))

4000

2000

0 1750

1800

1850

1900

1950

2000

2050

Fig. A4: Pore pressure predication using Eaton sonic travel time method.

NTNU | Atumn2009

110

PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------RT: 251

y = -0.0868x + 177.04 R² = 0.0634

201

151

RT: Linear (RT:) 101

51

1 1700

1750

1800

1850

1900

1950

2000

2050

Fig.A5 : Variation of Resistivity Vs. depth

NTNU | Atumn2009

111

PRESSURE MEASUREMENT IN SHALE -----------------------------------------------------------------------------------------------------------------

Ppore(Rt) 20100.00

18100.00

y = -6.4919x + 13725 R² = 0.0232

16100.00

14100.00

12100.00

10100.00

Ppore(Rt) Linear (Ppore(Rt))

8100.00

6100.00

4100.00

2100.00

100.00 1750

1800

1850

1900

1950

2000

2050

Fig. A6: Pore pressure predication using Eaton Resistivity method.

NTNU | Atumn2009

112

PRESSURE MEASUREMENT IN SHALE -----------------------------------------------------------------------------------------------------------------

Appendix B Equivalent-Depth Method:

Well Name: 6608 10-E-3 H Felt: Norne ZB  GPn 10 Z  b  10

Ppore ,B 

: [Kg/cm 2 ]

Povb

: [Kg/cm 2 ]

Ppore,A  Ppore,B  Povb,A  Povb,B  : [Kg/cm 2 ]

TABLE 5: WELL DATA AND PRESSURE CALCULATION PHI 0.34 0.34 0.34 0.31 0.31 0.31 0.31 0.32 0.32 0.32 0.26 0.26 0.26 0.34 0.34 0.34 0.34 0.34 0.34 0.34 0.34 0.32 0.32 0.32 0.31 0.31 0.34 0.34 0.31

TVD PHI RHOB 2364.685 0.3394 2.3284 2364.805 0.3421 2.3202 2364.925 0.3444 2.32 2366.366 0.3131 2.3157 2366.486 0.3084 2.3237 2366.606 0.3056 2.3179 2366.726 0.3052 2.31 2366.846 0.322 2.31 2366.967 0.3183 2.3219 2367.087 0.3238 2.3475 2556.64 0.2631 2.3606 2556.761 0.2645 2.3665 2556.881 0.2636 2.3655 2562.775 0.3445 2.3843 2562.895 0.3383 2.3936 2563.016 0.3397 2.395 2563.136 0.3403 2.3877 2563.256 0.3435 2.3803 2563.377 0.3446 2.3721 2563.497 0.3431 2.373 2563.617 0.3449 2.3771 2564.219 0.323 2.3809 2564.339 0.3164 2.3779 2564.459 0.3163 2.375 2564.579 0.3111 2.38 2564.7 0.3074 2.3743 2567.827 0.3359 2.3858 2567.948 0.338 2.3784 2574.564 0.3103 2.4093

NTNU | Atumn2009

Pob 550.5933 548.6821 548.6626 547.9794 549.9004 548.5557 546.7138 546.7415 549.586 555.6736 603.5205 605.0574 604.8302 611.0425 613.4546 613.8422 612 610.1318 608.0585 608.3178 609.3974 610.5148 609.7741 609.0591 610.3699 608.9366 612.6322 610.7606 620.2896

PPore(B) 248.2919 248.3045 248.3171 248.4685 248.481 248.4937 248.5063 248.5189 248.5315 248.5441 268.4472 268.4599 268.4725 269.0914 269.104 269.1166 269.1293 269.1419 269.1545 269.1672 269.1798 269.2429 269.2556 269.2682 269.2808 269.2935 269.6218 269.6345 270.3292

Ppore(A) 248.2919 248.3045 248.3171 248.4685 248.481 248.4937 248.5063 248.5189 248.5315 248.5441 268.4472 268.4599 268.4725 308.7411 311.1533 311.5409 309.6986 307.8305 305.7572 306.0164 307.0961 312.2921 311.5515 310.8364 310.8589 309.4257 310.3308 308.4593 320.7786

TVD 2364.685 2364.805 2364.925 2366.366 2366.486 2366.606 2366.726 2366.846 2366.967 2367.087 2556.64 2556.761 2556.881 2562.775 2562.895 2563.016 2563.136 2563.256 2563.377 2563.497 2563.617 2564.219 2564.339 2564.459 2564.579 2564.7 2567.827 2567.948 2574.564

113

PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------0.31 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.32 0.32 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26

2574.684 2624.337 2624.457 2624.577 2624.698 2625.9 2626.02 2640.445 2640.565 2688.798 2688.918 2690.595 2690.715 2714.275 2714.395 2719.532 2719.651 2748.604 2748.723 2753.841 2753.96 2754.079 2771.293 2771.411 2776.989 2777.107 2782.091 2782.21 2782.329 2803.067 2803.186 2809.347 2809.465 2810.532 2810.65 2810.769 2810.887 2812.072 2812.19 2814.44 2814.559 2817.99 2818.108 2819.765 2819.884 2820.002 2820.83 2820.949

NTNU | Atumn2009

0.309 0.2643 0.2576 0.2552 0.2554 0.261 0.2554 0.2642 0.2613 0.2586 0.2599 0.2634 0.2609 0.263 0.2614 0.2566 0.2648 0.2634 0.2636 0.2621 0.2639 0.2611 0.2628 0.2607 0.2648 0.2566 0.2612 0.2637 0.2633 0.3182 0.3212 0.2555 0.2605 0.2588 0.2578 0.263 0.2602 0.2629 0.2559 0.2559 0.2575 0.259 0.2614 0.258 0.2642 0.2614 0.261 0.2636

2.4011 2.1571 2.1638 2.1728 2.1597 2.1061 2.0997 2.2725 2.2738 2.3029 2.3111 2.263 2.26 2.1695 2.1708 2.2062 2.2204 2.354 2.5382 2.1626 2.1511 2.1463 2.2497 2.2305 2.2511 2.215 2.2911 2.2788 2.2837 2.6474 2.6031 2.2639 2.3164 2.2758 2.2496 2.2193 2.1995 2.1772 2.195 2.3836 2.4075 2.4789 2.4862 2.4543 2.4559 2.4529 2.2222 2.2178

618.2073 566.0957 567.8801 570.2682 566.8559 553.0407 551.3854 600.0411 600.4117 619.2033 621.4358 608.8817 608.1015 588.862 589.2408 599.9831 603.8713 647.0214 697.6808 595.5456 592.4043 591.1079 623.4577 618.1633 625.1279 615.1293 637.4049 634.01 635.4004 742.084 729.6973 636.008 650.7845 639.6208 632.2838 623.7939 618.2546 612.2443 617.2757 670.85 677.605 698.5516 700.6381 692.0549 692.5352 691.7182 626.8449 625.63

270.3418 275.5554 275.568 275.5806 275.5932 275.7195 275.7321 277.2467 277.2593 282.3238 282.3364 282.5125 282.5251 284.9989 285.0114 285.5508 285.5634 288.6034 288.6159 289.1533 289.1658 289.1783 290.9857 290.9982 291.5838 291.5963 292.1196 292.1321 292.1445 294.322 294.3345 294.9814 294.9939 295.1058 295.1182 295.1307 295.1431 295.2675 295.28 295.5162 295.5287 295.889 295.9014 296.0753 296.0878 296.1002 296.1872 296.1996

318.6963 231.0224 232.8068 235.1949 231.7826 217.9674 216.3121 264.9678 265.3384 284.13 286.3625 273.8084 273.0283 253.7887 254.1675 264.9098 268.798 311.9481 362.6076 260.4723 257.331 256.0346 288.3844 283.09 290.0547 280.056 302.3316 298.9367 300.3271 443.8613 431.4746 300.9347 315.7113 304.5475 297.2105 288.7206 283.1813 277.171 282.2025 335.7767 342.5317 363.4783 365.5648 356.9817 357.4619 356.6449 291.7716 290.5567

2574.684 2624.337 2624.457 2624.577 2624.698 2625.9 2626.02 2640.445 2640.565 2688.798 2688.918 2690.595 2690.715 2714.275 2714.395 2719.532 2719.651 2748.604 2748.723 2753.841 2753.96 2754.079 2771.293 2771.411 2776.989 2777.107 2782.091 2782.21 2782.329 2803.067 2803.186 2809.347 2809.465 2810.532 2810.65 2810.769 2810.887 2812.072 2812.19 2814.44 2814.559 2817.99 2818.108 2819.765 2819.884 2820.002 2820.83 2820.949

114

PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.31 0.31 0.31 0.31 0.31 0.31 0.31 0.31 0.31 0.31 0.31 0.31 0.31 0.31 0.31 0.31 0.31 0.31 0.31 0.34

2825.09 2825.208 2826.036 2826.155 2826.273 2826.51 2826.746 2826.865 2826.983 2827.101 2831.361 2831.48 2857.853 2857.971 2858.681 2858.799 2858.917 2859.035 2863.524 2863.642 2863.76 2865.532 2865.65 2865.768 2865.886 2866.004 2867.893 2868.011 2879.582 2879.7 2879.818 2879.936 2880.054 2880.172 2880.29 2880.408 2880.88 2880.998 2881.234 2881.352 2881.47 2882.531 2882.649 2882.767 2884.065 2884.183 2884.301 2884.89

NTNU | Atumn2009

0.2557 0.2643 0.2592 0.2566 0.2569 0.2556 0.2649 0.2553 0.2593 0.2614 0.264 0.2565 0.2575 0.2573 0.2596 0.2565 0.2589 0.2575 0.2624 0.2592 0.255 0.2555 0.2558 0.2592 0.2628 0.2613 0.2616 0.2596 0.3098 0.3107 0.3082 0.308 0.3093 0.3104 0.3096 0.306 0.3082 0.305 0.3141 0.3105 0.3057 0.309 0.3106 0.3113 0.3107 0.3097 0.3089 0.3392

2.4566 2.4673 2.4817 2.4818 2.4815 2.4828 2.4833 2.4898 2.4921 2.488 2.4964 2.4862 2.4345 2.4312 2.479 2.4458 2.4273 2.4098 2.3924 2.4024 2.403 2.4166 2.4387 2.4508 2.4299 2.4258 2.2872 2.3051 2.4437 2.4322 2.4239 2.4126 2.4039 2.3907 2.3664 2.3795 2.3626 2.352 2.353 2.3895 2.4433 2.3924 2.4 2.3921 2.3193 2.2906 2.2619 2.2843

694.0116 697.0636 701.3375 701.3951 701.3397 701.7659 701.9659 703.8328 704.5125 703.3828 706.821 703.9624 695.7444 694.83 708.6669 699.205 693.9449 688.9704 685.0695 687.9614 688.1616 692.4843 698.846 702.3423 696.3816 695.2352 655.9445 661.1052 703.6835 700.4007 698.0391 694.8134 692.3362 688.5627 681.5918 685.3931 680.6366 677.6106 677.9543 688.499 704.0294 689.6168 691.8358 689.5867 668.9011 660.6509 652.3999 658.9955

296.6344 296.6469 296.7338 296.7463 296.7587 296.7835 296.8084 296.8208 296.8332 296.8456 297.2929 297.3053 300.0746 300.087 300.1615 300.1739 300.1863 300.1987 300.67 300.6824 300.6948 300.8808 300.8932 300.9056 300.918 300.9304 301.1288 301.1412 302.3561 302.3685 302.3809 302.3933 302.4057 302.418 302.4304 302.4428 302.4924 302.5047 302.5295 302.5419 302.5543 302.6658 302.6782 302.6905 302.8268 302.8392 302.8516 302.9135

358.9383 361.9904 366.2642 366.3218 366.2664 366.6926 366.8926 368.7595 369.4392 368.3095 371.7477 368.8891 360.6711 359.7567 373.5937 364.1317 358.8716 353.8971 349.9962 352.8881 353.0883 357.4111 363.7727 367.269 361.3083 360.1619 320.8712 326.0319 404.1725 400.8897 398.5281 395.3024 392.8252 389.0517 382.0808 385.8821 381.1256 378.0997 378.4433 388.988 404.5185 390.1058 392.3248 390.0757 369.3902 361.1399 352.889 356.6942

2825.09 2825.208 2826.036 2826.155 2826.273 2826.51 2826.746 2826.865 2826.983 2827.101 2831.361 2831.48 2857.853 2857.971 2858.681 2858.799 2858.917 2859.035 2863.524 2863.642 2863.76 2865.532 2865.65 2865.768 2865.886 2866.004 2867.893 2868.011 2879.582 2879.7 2879.818 2879.936 2880.054 2880.172 2880.29 2880.408 2880.88 2880.998 2881.234 2881.352 2881.47 2882.531 2882.649 2882.767 2884.065 2884.183 2884.301 2884.89

115

PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------0.34 0.34 0.31 0.31 0.31 0.31 0.31 0.31 0.34 0.34 0.34 0.34 0.34 0.34 0.34 0.32 0.32 0.32 0.32 0.32 0.32 0.31 0.31 0.31 0.31 0.31 0.32 0.32 0.32 0.31 0.31 0.32 0.32 0.32 0.32 0.32 0.32 0.32 0.32 0.32 0.31 0.31 0.26 0.26

2885.008 2885.126 2886.306 2886.424 2886.542 2887.25 2887.367 2887.486 2887.721 2887.839 2887.957 2888.075 2888.193 2888.311 2888.429 2888.665 2888.783 2888.901 2889.019 2889.137 2889.255 2889.373 2889.491 2889.609 2890.788 2890.906 2891.024 2891.142 2891.26 2891.378 2891.496 2891.614 2891.732 2891.85 2891.968 2892.204 2892.322 2892.44 2892.676 2892.794 2892.912 2893.03 2893.619 2893.738

NTNU | Atumn2009

0.3417 0.3402 0.3096 0.3085 0.3145 0.3081 0.309 0.3137 0.3418 0.3427 0.3419 0.3439 0.341 0.335 0.3373 0.3248 0.318 0.3213 0.3178 0.3196 0.3177 0.3127 0.3129 0.3095 0.3062 0.3122 0.32 0.3203 0.3165 0.3134 0.3128 0.3177 0.3226 0.3216 0.3214 0.3211 0.3181 0.3233 0.3202 0.3181 0.3058 0.3062 0.2635 0.2776

2.3204 2.3507 2.2768 2.275 2.2885 2.2263 2.1897 2.1902 2.3017 2.3429 2.369 2.385 2.398 2.3775 2.3236 1.8889 1.854 2.0785 2.1875 2.2246 2.2314 2.2437 2.2812 2.2968 2.5448 2.4948 2.4629 2.441 2.4215 2.4035 2.397 2.4003 2.4055 2.4192 2.4317 2.4208 2.4215 2.4152 2.3618 2.3216 2.2814 2.2512 2.2163 2.2354

669.4373 678.2066 657.1541 656.6614 660.5851 642.7884 632.2468 632.4171 664.6668 676.5919 684.1571 688.8059 692.5888 686.696 671.1554 545.6399 535.5804 600.4581 631.9729 642.7174 644.7083 648.2886 659.1506 663.6854 735.6478 721.2233 712.0304 705.7278 700.1187 694.9428 693.0916 694.0741 695.6062 699.5964 703.2399 700.1447 700.3758 698.5821 683.1922 671.591 659.9889 651.2789 641.3129 646.8661

302.9259 302.9383 303.0621 303.0745 303.0869 303.1612 303.1736 303.186 303.2107 303.2231 303.2355 303.2479 303.2603 303.2727 303.2851 303.3098 303.3222 303.3346 303.347 303.3594 303.3718 303.3841 303.3965 303.4089 303.5328 303.5452 303.5576 303.5699 303.5823 303.5947 303.6071 303.6195 303.6319 303.6443 303.6566 303.6814 303.6938 303.7062 303.731 303.7433 303.7557 303.7681 303.83 303.8424

367.136 375.9053 357.6432 357.1504 361.0741 343.2774 332.7359 332.9061 362.3655 374.2905 381.8557 386.5046 390.2874 384.3947 368.8541 247.4173 237.3577 302.2354 333.7503 344.4948 346.4857 348.7776 359.6396 364.1744 436.1368 421.7123 413.8078 407.5052 401.896 395.4318 393.5806 395.8515 397.3835 401.3737 405.0172 401.9221 402.1531 400.3594 384.9695 373.3683 360.4779 351.7679 306.2396 311.7928

2885.008 2885.126 2886.306 2886.424 2886.542 2887.25 2887.367 2887.486 2887.721 2887.839 2887.957 2888.075 2888.193 2888.311 2888.429 2888.665 2888.783 2888.901 2889.019 2889.137 2889.255 2889.373 2889.491 2889.609 2890.788 2890.906 2891.024 2891.142 2891.26 2891.378 2891.496 2891.614 2891.732 2891.85 2891.968 2892.204 2892.322 2892.44 2892.676 2892.794 2892.912 2893.03 2893.619 2893.738

116

PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------Results & Charts: Well: N6608 10-E-3 H Felt:

Norne

Depth-Porosity 0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

2200 2300 2400 2500 2600 2700 2800 2900 3000

Fig.B1 : variation of porosity vs. depth in Norne felt well nr: N6608 10-E-3 H

PorePressure(Eq.Depth-Method) 0

50

100

150

200

250

300

350

400

450

500

2200 2300 2400 2500 2600 2700 2800 2900 3000

Fig. B2: Predication of pore pressure using equivalent depth method. NTNU | Atumn2009

117

PRESSURE MEASUREMENT IN SHALE -----------------------------------------------------------------------------------------------------------------

Appendix C Vertical-Horizontal Method: Well Name: 34 10-C-11 Felt: Gulfaks

Fig. C1: Principle of predication pore pressure in Horizontal & Vertical Methods.

NTNU | Atumn2009

118

PRESSURE MEASUREMENT IN SHALE -----------------------------------------------------------------------------------------------------------------

TABLE 6: Well data & calculation: GPn=1.05 D  Ppore  Povb  (Pe  Pp ,n ) e   D

Vertical Method:

N Horizontal Method: Ppore  Povb  (Povb  Pp ,n )  M

x

x=3, & x=2,…..

[kg/cm2] Vp

TVD

RHOB

Pob

Pp,n

[kg/cm2]

Ppore(vertical) TVD

N trend (vp) Ppore(Horizontal) TVD

665.97 1940.094

2.048

397.33 203.7098

182.6348025 1940.094 655.413597

212.77 1940.094

666.57 1940.246

2.036

395.03 203.7258

180.5468925 1940.246

654.90355

213.60 1940.246

660.06 1940.398

2.015

390.99 203.7418

174.4039964 1940.398 654.393503

208.52 1940.398

661.82

1940.55

2.005

389.08 203.7578

173.0880003

210.35

664.78 1940.702

2

388.14 203.7737

173.1266605 1940.702 653.374749

213.10 1940.702

664.78 1940.854

2.011

390.31 203.7897

175.3088171 1940.854 652.865372

213.64 1940.854

667.17 1941.007

2.009

389.95 203.8057

175.7371658 1941.007 652.355325

215.93 1941.007

661.23 1941.159

2.001

388.43 203.8217

172.3088158 1941.159 651.845613

211.57 1941.159

655.98 1941.311

1.998

387.87 203.8377

170.0433764 1941.311 651.336236

207.72 1941.311

655.40 1941.463

2.01

390.23 203.8536

172.2283648 1941.463 650.826859

207.73 1941.463

650.81 1941.616

2.037

395.51 203.8696

175.9805038 1941.616 650.316477

204.30 1941.616

648.54 1941.768

2.058

399.62 203.8856

179.3376119 1941.768 649.806765

202.73 1941.768

653.10

1941.92

2.064

400.81 203.9016

182.0889009

207.32

651.95 1942.072

2.037

395.60 203.9176

176.5094734 1942.072 648.787676

206.69 1942.072

652.52 1942.224

2.032

394.66 203.9336

175.7786421 1942.224 648.277294

207.63 1942.224

711.22 1942.377

2.057

399.55 203.9495

198.7451632 1942.377 647.767917

251.77 1942.377

716.71 1942.529

2.104

408.71 203.9655

209.4591636 1942.529 647.258205

257.90 1942.529

732.24 1942.681

2.108

409.52 203.9815

214.5106289 1942.681 646.748828

267.89 1942.681

734.41 1942.833

2.082

404.50 203.9975

210.0828917 1942.833 646.239116

267.89 1942.833

668.97 1942.985

2.065

401.23 204.0135

187.8094747 1942.985 645.728734

223.86 1942.985

668.37 1943.138

2.072

402.62 204.0294

189.025655 1943.138 645.219357

223.96 1943.138

664.19

1943.29

2.059

400.12 204.0454

185.2031099

660.06 1943.442

2.041

396.66 204.0614

180.4087798 1943.442 644.200268

217.61 1943.442

651.38 1943.594

2.025

393.58 204.0774

174.4665683 1943.594 643.689886

210.71 1943.594

662.41 1943.746

2.045

397.50 204.0934

182.0503427 1943.746 643.180509

220.45 1943.746

673.21 1943.898

2.084

405.11 204.1093

193.1356233 1943.898 642.671132

230.24 1943.898

676.27 1944.051

2.1

408.25 204.1253

197.254326 1944.051 642.161085

233.48 1944.051

672.60 1944.203

2.067

401.87 204.1413

189.7351818 1944.203 641.651038

230.20 1944.203

661.82 1944.355

2.023

393.34 204.1573

177.7727866 1944.355 641.141661

221.34 1944.355

659.47 1944.507

2

388.90 204.1733

172.5802933 1944.507 640.631949

219.56 1944.507

NTNU | Atumn2009

1940.55 653.884126

1941.92 649.297388

1943.29 644.709645

220.79

119

1940.55

1941.92

1943.29

PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------655.98 1944.659

1.999

388.74 204.1892

171.2815868 1944.659 640.122572

217.25 1944.659

662.41 1944.812

2.01

390.91 204.2052

175.5794209 1944.812

639.61286

222.83 1944.812

670.78 1944.964

2.039

396.58 204.2212

183.9539182 1944.964 639.102478

230.21 1944.964

674.43 1945.116

2.064

401.47 204.2372

190.0156775 1945.116 638.593101

234.04 1945.116

676.27 1945.268

2.083

405.20 204.2532

194.3352437 1945.268 638.083389

236.41 1945.268

1945.42

2.09

406.59 204.2691

197.4719368

241.18

677.51 1945.573

2.093

407.21 204.2852

196.7611025 1945.573 637.063295

238.50 1945.573

668.37 1945.725

2.075

403.74 204.3011

190.4297137 1945.725 636.553918

231.45 1945.725

665.38 1945.877

2.054

399.68 204.3171

185.4325655 1945.877 636.044541

229.03 1945.877

666.57 1946.029

2.044

397.77 204.3331

183.9182104 1946.029 635.534829

230.11 1946.029

672.60 1946.181

2.052

399.36

204.349

187.4407846 1946.181 635.025452

235.24 1946.181

678.12 1946.334

2.068

402.50 204.3651

192.3287702 1946.334 634.514735

240.19 1946.334

685.00 1946.486

2.084

405.65

204.381

197.6002249 1946.486 634.005358

246.07 1946.486

699.18 1946.638

2.097

408.21

204.397

204.3970005 1946.638 633.495981

256.61 1946.638

698.52

1946.79

2.111

410.97

204.413

206.9786772

257.26

689.45 1946.943

2.12

412.75

204.429

206.0952959 1946.943 632.476222

251.92 1946.943

692.02 1947.095

2.113

411.42

204.445

205.5475245 1947.095

631.96651

253.79 1947.095

687.53 1947.247

2.107

410.28 204.4609

203.0857157 1947.247 631.457133

250.83 1947.247

679.99 1947.399

2.108

410.51 204.4769

201.0289243 1947.399 630.947086

245.92 1947.399

679.99 1947.552

2.11

410.93 204.4929

201.4669823 1947.552

630.43704

246.41 1947.552

690.09 1947.704

2.111

411.16 204.5089

204.7763557 1947.704 629.927328

253.98 1947.704

686.90 1947.856

2.12

412.95 204.5249

205.6196032 1947.856

629.41795

252.59 1947.856

683.74 1948.008

2.113

411.61 204.5409

203.3465853 1948.008 628.907904

250.47 1948.008

683.74

1948.16

2.099

408.92 204.5568

200.6676308

250.27

675.04 1948.313

2.086

406.42 204.5728

195.5012322 1948.313

627.88848

243.99 1948.313

681.23 1948.465

2.096

408.40 204.5888

199.4135262 1948.465 627.378768

249.20 1948.465

697.21 1948.617

2.117

412.52 204.6048

208.3423594 1948.617

626.86939

261.40 1948.617

703.81 1948.769

2.142

417.43 204.6207

215.1777554 1948.769 626.359678

267.43 1948.769

713.27 1948.921

2.164

421.75 204.6367

222.1950076 1948.921 625.849297

275.08 1948.921

717.40 1949.074

2.179

424.70 204.6527

226.3161964 1949.074 625.339585

278.96 1949.074

713.95 1949.226

2.195

427.86 204.6687

228.5262606 1949.226 624.830208

278.25 1949.226

713.95 1949.378

2.202

429.25 204.6847

229.9398833 1949.378 624.320496

279.09 1949.378

1949.53

2.2

428.90 204.7007

226.7275116

272.79

699.18 1949.683

2.186

426.20 204.7167

222.7072474 1949.683 623.300402

269.28 1949.683

695.25 1949.835

2.17

423.11 204.7326

218.4882179 1949.835 622.791025

266.14 1949.835

704.48 1949.987

2.152

419.64 204.7486

217.7070093 1949.987 622.281648

271.53 1949.987

711.22 1950.139

2.151

419.47 204.7646

219.474445 1950.139 621.771936

276.01 1950.139

708.51 1950.291

2.16

421.26 204.7806

220.5127801 1950.291 621.261554

275.31 1950.291

709.18 1950.444

2.172

423.64 204.7966

223.0933129 1950.444 620.751842

276.88 1950.444

698.52 1950.596

2.167

422.69 204.8125

219.1052438 1950.596 620.242465

270.16 1950.596

692.66 1950.748

2.155

420.39 204.8285

215.0914125 1950.748 619.732753

266.00 1950.748

681.86

703.81

NTNU | Atumn2009

1945.42 637.574012

1946.79 632.986269

1948.16 628.398526

1949.53 623.810114

120

1945.42

1946.79

1948.16

1949.53

PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------690.73

1950.9

2.148

419.05 204.8445

213.2007874

683.74 1951.052

2.148

419.09 204.8605

211.1453978 1951.052 618.712659

260.35 1951.052

685.00 1951.205

2.146

418.73 204.8765

211.1867244 1951.205 618.203282

261.53 1951.205

686.90 1951.357

2.147

418.96 204.8925

212.004622 1951.357

617.69357

263.29 1951.357

683.11 1951.509

2.153

420.16 204.9084

212.077077 1951.509 617.183523

261.41 1951.509

694.60 1951.661

2.167

422.93 204.9244

218.3007337 1951.661 616.673476

270.37 1951.661

700.49 1951.813

2.173

424.13 204.9404

221.2418939 1951.813 616.164099

274.95 1951.813

706.49 1951.966

2.173

424.16 204.9564

223.0118393 1951.966 615.654387

279.10 1951.966

706.49 1952.118

2.172

424.00 204.9724

222.8655162 1952.118 615.144675

279.42 1952.118

705.15

1952.27

2.168

423.25 204.9884

221.7511392

278.71

706.49 1952.422

2.175

424.65 205.0044

223.5490541 1952.422 614.124581

280.38 1952.422

711.90 1952.575

2.181

425.86 205.0203

226.298657 1952.575 613.614869

284.44 1952.575

709.86 1952.727

2.187

427.06 205.0363

226.9457996 1952.727 613.105157

284.01 1952.727

713.95 1952.879

2.192

428.07 205.0523

229.1180504 1952.879 612.594441

287.19 1952.879

714.64 1953.031

2.186

426.93 205.0683

228.186291 1953.031 612.085064

287.53 1953.031

707.83 1953.184

2.185

426.77 205.0843

226.1290553 1953.184 611.575352

283.78 1953.184

709.18 1953.336

2.18

425.83 205.1003

225.5835951 1953.336

611.06564

284.62 1953.336

705.15 1953.488

2.179

425.67 205.1163

224.2908138 1953.488 610.555258

282.50 1953.488

706.49

1953.64

2.182

426.28 205.1322

225.3080839

283.90

705.82 1953.793

2.178

425.54 205.1482

224.3844792 1953.793 609.535834

283.59 1953.793

703.14 1953.945

2.173

424.59 205.1642

222.6924624 1953.945 609.026122

282.01 1953.945

692.02 1954.097

2.173

424.63 205.1802

219.4944781 1954.097 608.516745

275.42 1954.097

690.09 1954.249

2.179

425.83 205.1962

220.1433993 1954.249 608.006028

274.93 1954.249

687.53 1954.402

2.179

425.86 205.2122

219.428867 1954.402 607.496316

273.65 1954.402

681.86 1954.554

2.159

421.99 205.2281

213.8506042 1954.554 606.986604

269.08 1954.554

682.48 1954.706

2.149

420.07 205.2441

212.1360184 1954.706 606.477227

269.32 1954.706

679.36 1954.858

2.16

422.25 205.2601

213.3809982 1954.858

605.96651

268.27 1954.858

681.23 1955.011

2.194

428.93 205.2761

220.6500745 1955.011 605.456798

271.92 1955.011

671.99 1955.163

2.226

435.22 205.2921

224.0929932 1955.163 604.947421

267.47 1955.163

663.00 1955.315

2.227

435.45 205.3081

221.4758737 1955.315 604.437709

261.07 1955.315

658.89 1955.467

2.174

425.12 205.3241

209.826672 1955.467 603.926993

255.87 1955.467

661.23

1955.62

2.116

413.81 205.3401

199.2975321

651.95 1955.772

2.089

408.56

205.356

191.0127807 1955.772 602.907904

247.85 1955.772

658.30 1955.924

2.097

410.16

205.372

194.7253706 1955.924 602.397857

253.24 1955.924

652.52 1956.076

2.109

412.54

205.388

195.2135399 1956.076 601.888145

249.97 1956.076

652.52 1956.229

2.115

413.74

205.404

196.4365643 1956.229 601.377763

250.65 1956.229

657.14 1956.381

2.137

418.08

205.42

202.3160666 1956.381 600.868386

255.51 1956.381

658.30 1956.533

2.149

420.46

205.436

205.0949647 1956.533 600.358339

257.36 1956.533

667.77 1956.685

2.156

421.86 205.4519

209.56625 1956.685 599.848627

265.00 1956.685

679.36 1956.838

2.164

423.46 205.4679

214.8051169 1956.838 599.338245

273.79 1956.838

727.23

2.242

438.76 205.4839

243.8502402

308.51

1956.99

NTNU | Atumn2009

1950.9 619.222706

1952.27 614.633958

1953.64 610.045546

1955.62 603.417281

1956.99 598.828198

264.72

255.38

121

1950.9

1952.27

1953.64

1955.62

1956.99

PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------861.21 1957.142

2.395

468.74 205.4999

304.1646727 1957.142 598.318486

380.47 1957.142

914.18 1957.294

2.518

492.85 205.5159

337.8229109 1957.294 597.808774

412.50 1957.294

908.59 1957.447

2.403

470.37 205.5319

314.4095829 1957.447 597.298058

395.13 1957.447

805.23 1957.599

2.238

438.11 205.5479

262.1397092 1957.599 596.788346

343.43 1957.599

703.81 1957.751

2.17

424.83 205.5639

223.5203661 1957.751 596.278634

291.49 1957.751

693.31 1957.904

2.167

424.28 205.5799

219.9320221 1957.904 595.768252

285.51 1957.904

705.15 1958.056

2.175

425.88 205.5959

716.02 1958.208

2.191

735.14 1958.361

595.25854

293.36 1958.056

429.04 205.6119

231.2101059 1958.208 594.747823

300.99 1958.208

2.24

438.67 205.6279

246.000517 1958.361 594.238111

315.58 1958.361

742.48 1958.513

2.277

445.95 205.6438

255.2019622 1958.513 593.728399

323.07 1958.513

730.80 1958.665

2.229

436.59 205.6598

242.8013202 1958.665 593.218687

313.07 1958.665

713.27 1958.817

2.153

421.73 205.6758

223.2003554 1958.817 592.707971

297.76 1958.817

685.00

1958.97

2.121

415.50 205.6918

208.7879007

279.93

683.74 1959.122

2.162

423.56 205.7078

216.4878922 1959.122 591.688547

282.38 1959.122

686.90 1959.274

2.209

432.80 205.7238

226.6981406 1959.274 591.178835

288.04 1959.274

699.83 1959.427

2.231

437.15 205.7398

234.8682898 1959.427 590.668118

298.02 1959.427

699.83 1959.579

2.239

438.75 205.7558

236.4858745 1959.579 590.158406

299.03 1959.579

701.82 1959.731

2.242

439.37 205.7718

237.6952551 1959.731 589.648359

300.83 1959.731

698.52 1959.883

2.23

437.05 205.7877

234.4412463 1959.883 589.138647

298.30 1959.883

703.14 1960.035

2.211

433.36 205.8037

232.0999877 1960.035 588.628935

299.86 1960.035

702.48 1960.188

2.192

429.67 205.8197

228.2349224 1960.188 588.118218

298.32 1960.188

707.83

1960.34

2.209

433.04 205.8357

233.1398419

303.06

706.49 1960.492

2.245

440.13 205.8517

239.8663072 1960.492 587.098459

305.68 1960.492

704.48 1960.645

2.275

446.05 205.8677

245.2272083 1960.645 586.588413

307.39 1960.645

712.58 1960.797

2.279

446.87 205.8837

248.3461178 1960.797 586.078031

312.79 1960.797

739.53 1960.949

2.272

445.53 205.8997

254.2559636 1960.949 585.568319

326.57 1960.949

768.59 1961.102

2.272

445.56 205.9157

261.5372346 1961.102 585.058272

339.86 1961.102

769.38 1961.254

2.243

439.91 205.9316

256.0890597 1961.254

584.54856

337.30 1961.254

752.25 1961.406

2.208

433.08 205.9477

245.0867695 1961.406 584.038178

326.78 1961.406

718.79 1961.559

2.192

429.97 205.9636

233.2447736 1961.559 583.528131

310.12 1961.559

705.82 1961.711

2.201

431.77 205.9796

231.4445554 1961.711 583.018419

304.52 1961.711

717.40 1961.863

2.211

433.77 205.9956

236.689746 1961.863 582.508372

311.83 1961.863

743.22 1962.015

2.206

432.82 206.0116

242.60572 1962.015 581.998326

323.91 1962.015

769.38 1962.168

2.209

433.44 206.0276

249.709912 1962.168 581.487609

335.27 1962.168

784.82

1962.32

2.213

434.26 206.0436

254.1564819

783.99 1962.472

2.24

439.59 206.0596

259.3129278 1962.472

580.46785

344.81 1962.472

741.00 1962.625

2.255

442.57 206.0756

251.8467381 1962.625 579.957803

329.19 1962.625

731.52 1962.777

2.278

447.12 206.0916

253.9387908 1962.777 579.447086

327.33 1962.777

722.98 1962.929

2.284

448.33 206.1076

727.23 1963.082

2.329

783.17 1963.234

2.408

NTNU | Atumn2009

224.978409 1958.056

1958.97 592.198259

1960.34 587.608171

1962.32 580.977562

252.884988 1962.929

341.68

1958.97

1960.34

1962.32

578.93704

323.96 1962.929

457.20 206.1236

262.9098006 1963.082 578.426993

330.86 1963.082

472.75 206.1396

292.3470907 1963.234 577.917281

365.62 1963.234

122

PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------770.18 1963.387

2.48

486.92 206.1556

303.4932067 1963.387 577.406229

368.61 1963.387

777.43 1963.539

2.423

475.77 206.1716

294.0639092 1963.539 576.896517

365.61 1963.539

775.81 1963.691

2.35

461.47 206.1876

279.4001505 1963.691

576.38647

356.78 1963.691

714.64 1963.843

2.306

452.86 206.2035

255.2265783 1963.843 575.876423

323.79 1963.843

713.27 1963.996

2.301

451.92 206.2195

253.9152932 1963.996 575.366711

322.95 1963.996

712.58 1964.148

2.286

449.00 206.2356

250.8299492 1964.148

321.55 1964.148

713.95

1964.3

2.303

452.38 206.2515

254.5996529

726.51 1964.453

2.331

457.91 206.2675

263.5703806 1964.453 573.836236

333.91 1964.453

730.08 1964.605

2.353

462.27 206.2835

268.8932179 1964.605 573.325854

338.30 1964.605

738.79 1964.757

2.331

457.98 206.2995

266.9012651 1964.757 572.815472

340.67 1964.757

741.74

1964.91

2.353

462.34 206.3155

272.0344526

344.74

730.80 1965.062

2.405

472.60 206.3315

279.4549196 1965.062 571.795378

345.06 1965.062

721.58 1965.214

2.423

476.17 206.3475

280.5755521 1965.214 571.285666

342.27 1965.214

720.18 1965.367

2.363

464.42 206.3635

268.4560885 1965.367 570.774615

335.95 1965.367

730.80 1965.519

2.296

451.28 206.3795

258.1865806 1965.519 570.264903

334.92 1965.519

732.96 1965.671

2.282

448.57 206.3955

256.0545339 1965.671 569.754521

334.82 1965.671

739.53 1965.824

2.296

451.35 206.4115

260.5652245 1965.824 569.244809

339.64 1965.824

745.46 1965.976

2.314

454.93 206.4274

265.6725885 1965.976 568.735097

344.57 1965.976

730.08 1966.128

2.311

454.37 206.4435

261.1471206 1966.128 568.224046

337.48 1966.128

722.28 1966.281

2.301

452.44 206.4595

257.143562 1966.281 567.714334

332.99 1966.281

707.16 1966.433

2.33

458.18 206.4755

258.721654 1966.433 567.203952

328.29 1966.433

680.61 1966.585

2.389

469.82 206.4914

262.5954833 1966.585

566.69424

317.82 1966.585

688.17 1966.737

2.38

468.08 206.5074

263.1552451 1966.737 566.184193

322.41 1966.737

1966.89

2.324

457.11 206.5234

254.0903742

321.76

699.18 1967.042

2.27

446.52 206.5394

244.8478348 1967.042 565.165104

319.77 1967.042

693.95 1967.194

2.258

444.19 206.5554

241.0201862 1967.194 564.655057

316.17 1967.194

699.18 1967.346

2.253

443.24 206.5714

241.6044733 1967.346

564.14501

318.92 1967.346

690.09 1967.499

2.248

442.29 206.5873

238.015595 1967.499 563.635298

313.87 1967.499

689.45 1967.651

2.247

442.13 206.6033

237.6795761 1967.651 563.125921

313.79 1967.651

686.26 1967.803

2.241

440.98 206.6193

235.6010479 1967.803 562.616544

311.85 1967.803

677.51 1967.955

2.257

444.17 206.6353

236.1454261 1967.955 562.106497

308.51 1967.955

683.74 1968.107

2.287

450.11 206.6513

243.9966775 1968.107

315.20 1968.107

707.83

1968.26

2.318

456.24 206.6672

731.52 1968.412

2.326

457.85 206.6832

265.2361697 1968.412 560.577361

344.82 1968.412

729.37 1968.564

2.295

451.79 206.6992

258.615582 1968.564 560.067649

340.82 1968.564

725.81 1968.716

2.267

446.31 206.7152

252.2057394 1968.716 559.557267

336.52 1968.716

699.18 1968.868

2.234

439.85 206.7312

238.3663402 1968.868

559.04789

320.68 1968.868

685.63 1969.021

2.244

441.85 206.7472

236.4054288 1969.021 558.538178

314.75 1969.021

705.82 1969.173

2.277

448.38 206.7631

248.8287603 1969.173 558.028801

328.98 1969.173

721.58 1969.325

2.306

454.13 206.7791

258.9487982 1969.325 557.518084

340.04 1969.325

720.18 1969.477

2.286

450.22 206.7951

254.6814409 1969.477 557.008707

337.60 1969.477

694.60

NTNU | Atumn2009

257.164601

574.85566

1964.3 574.345948

1964.91

572.30509

1966.89 565.674481

561.59645

1968.26 561.086738

324.24

331.93

123

1964.3

1964.91

1966.89

1968.26

PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------722.28 1969.629

2.254

443.95 206.8111

248.9972405 1969.629

556.49933

335.49 1969.629

696.56 1969.782

2.226

438.47 206.8271

236.3326437 1969.782 555.989618

320.67 1969.782

690.73 1969.934

2.211

435.55

206.843

231.7227232 1969.934 555.480241

316.60 1969.934

684.37 1970.086

2.214

436.18

206.859

230.4695202 1970.086 554.969524

313.89 1970.086

681.86 1970.238

2.24

441.33

206.875

234.8844876 1970.238 554.460147

315.27 1970.238

1970.39

2.256

444.52

206.891

238.0875919

317.10

686.26 1970.543

2.263

445.93

206.907

240.8433221 1970.543 553.441058

320.57 1970.543

697.21 1970.695

2.269

447.15

206.923

245.2955649 1970.695 552.931011

327.33 1970.695

706.49 1970.847

2.275

448.37 206.9389

249.1794379 1970.847 552.421299

332.95 1970.847

728.65 1970.999

2.274

448.21 206.9549

255.0911649 1970.999 551.911922

343.37 1970.999

733.69 1971.151

2.271

447.65 206.9709

255.8750349 1971.151 551.401875

345.48 1971.151

756.85 1971.304

2.272

447.88 206.9869

261.9901997 1971.304 550.891829

354.98 1971.304

750.73 1971.456

2.268

447.13 207.0029

259.7366655 1971.456 550.382117

352.51 1971.456

711.22 1971.608

2.288

451.10 207.0188

253.3195617 1971.608 549.872739

338.30 1971.608

678.74

1971.76

2.345

462.38 207.0348

255.1464715

326.99

720.18 1971.912

2.447

482.53 207.0508

287.2340871 1971.912 548.853985

360.59 1971.912

759.17 1972.065

2.49

491.04 207.0668

305.7955667 1972.065 548.343603

384.03 1972.065

780.70 1972.217

2.435

480.23 207.0828

300.1094901 1972.217 547.834226

385.85 1972.217

776.62 1972.369

2.349

463.31 207.0987

282.2524674 1972.369 547.325184

373.63 1972.369

688.17 1972.521

2.286

450.92 207.1147

246.6069672 1972.521 546.815807

328.60 1972.521

669.57 1972.673

2.287

451.15 207.1307

241.1804381 1972.673

546.30576

318.61 1972.673

688.17 1972.825

2.297

453.16 207.1466

248.8791339 1972.825 545.796383

330.43 1972.825

699.83 1972.977

2.3

453.78 207.1626

252.9265121 1972.977 545.287006

337.12 1972.977

707.83 1973.129

2.307

455.20 207.1786

256.6280875 1973.129 544.777629

342.13 1973.129

723.68 1973.282

2.306

455.04 207.1946

260.8310075 1973.282 544.267582

349.61 1973.282

715.33 1973.434

2.31

455.86 207.2105

259.4018635 1973.434 543.758205

346.64 1973.434

711.90 1973.586

2.313

456.49 207.2265

259.0992751 1973.586 543.249163

345.73 1973.586

709.86 1973.738

2.316

457.12 207.2425

259.1751047 1973.738 542.739786

345.44 1973.738

708.51

1973.89

2.312

456.36 207.2585

258.0584559

344.70

707.83 1974.042

2.297

453.44 207.2745

254.9593668 1974.042 541.720027

696.56 1974.195

2.288

451.70 207.2904

690.09 1974.347

2.288

691.37 1974.499

681.86

1970.39 553.950435

1971.76 549.363362

1973.89 542.230409

1971.76

1973.89

343.09 1974.042

541.21065

337.05 1974.195

451.73 207.3064

248.1809548 1974.347 540.701273

334.16 1974.347

2.284

450.98 207.3224

247.8200986 1974.499 540.191896

334.76 1974.499

693.95 1974.651

2.28

450.22 207.3384

247.8370864 1974.651 539.681849

335.98 1974.651

700.49 1974.803

2.271

448.48 207.3543

247.9999697 1974.803 539.172806

338.52 1974.803

703.81 1974.955

2.266

447.52 207.3703

248.0076951 1974.955 538.663429

339.86 1974.955

713.27 1975.107

2.25

444.40 207.3863

247.5427279 1975.107 538.154052

342.60 1975.107

1975.26

2.255

445.42 207.4022

249.1470434

344.36

711.90 1975.412

2.261

446.64 207.4182

249.4377247 1975.412 537.134628

343.89 1975.412

722.28 1975.564

2.266

447.66 207.4342

253.3087125 1975.564 536.625251

349.14 1975.564

724.39 1975.716

2.277

449.87 207.4502

256.0985113 1975.716 536.115874

351.60 1975.716

715.33

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250.020092 1974.195

1970.39

1975.26 537.644005

124

1975.26

PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------732.24 1975.868

2.291

452.67 207.4661

759.94

1976.02

2.334

461.20 207.4821

770.18 1976.172

2.361

466.57 207.4981

284.3663421 1976.172 534.587408

379.94 1976.172

776.62 1976.324

2.352

464.83 207.5141

284.1484566 1976.324 534.078031

381.14 1976.324

781.52 1976.476

2.314

457.36

207.53

277.8207681 1976.476 533.568654

377.85 1976.476

749.22 1976.629

2.29

452.65

207.546

265.3867577 1976.629 533.058272

364.37 1976.629

743.97 1976.781

2.29

452.68

207.562

264.1152245 1976.781

532.54923

362.78 1976.781

729.37 1976.933

2.291

452.92

207.578

260.587899 1976.933 532.039853

357.69 1976.933

721.58 1977.085

2.289

452.55 207.5939

258.1666154 1977.085 531.531145

354.64 1977.085

715.33 1977.237

2.28

450.81 207.6099

254.7390447 1977.237 531.021098

351.32 1977.237

706.49 1977.389

2.272

449.26 207.6259

250.754394 1977.389 530.511721

346.95 1977.389

704.48 1977.541

2.265

447.91 207.6418

248.8543679 1977.541 530.003014

345.60 1977.541

692.66 1977.693

2.259

446.76 207.6578

244.3220048 1977.693 529.493972

339.95 1977.693

696.56 1977.845

2.253

445.61 207.6737

244.3176798 1977.845 528.984595

341.40 1977.845

695.25 1977.997

2.255

446.04 207.6897

244.3863085 1977.997 528.474883

341.36 1977.997

690.73 1978.149

2.252

445.48 207.7057

242.522858 1978.149 527.965841

339.30 1978.149

693.31 1978.302

2.257

446.50 207.7217

244.3168733 1978.302 527.456463

341.36 1978.302

690.09 1978.454

2.252

445.55 207.7376

242.4350847 1978.454 526.947421

339.67 1978.454

690.73 1978.606

2.255

446.18 207.7536

243.2676959 1978.606 526.437709

340.62 1978.606

683.74 1978.758

2.254

446.01 207.7696

241.0460972 1978.758 525.928332

337.59 1978.758

683.74

1978.91

2.255

446.24 207.7855

241.2945693

338.04

686.26 1979.062

2.264

448.06 207.8015

243.8805023 1979.062 524.910248

340.55 1979.062

697.21 1979.214

2.332

461.55 207.8175

260.594626 1979.214 524.400871

353.59 1979.214

694.60 1979.366

2.424

479.80 207.8334

278.1022333 1979.366 523.891159

363.11 1979.366

697.21 1979.518

2.426

480.23 207.8494

279.3050667 1979.518 523.382117

365.01 1979.518

699.83

1979.67

2.336

462.45 207.8654

262.2947853

356.27

695.25 1979.822

2.256

446.65 207.8813

245.1884355 1979.822 522.364032

345.38 1979.822

699.18 1979.974

2.259

447.28 207.8973

246.9635194 1979.974 521.853985

347.74 1979.974

701.15 1980.127

2.26

447.51 207.9133

247.7771286 1980.127 521.344608

349.01 1980.127

703.14 1980.278

2.258

447.15 207.9292

247.9965413 1980.278 520.835901

349.93 1980.278

701.82

1980.43

2.263

448.17 207.9452

248.6602223

350.27

690.73 1980.583

2.266

448.80 207.9612

246.1023073 1980.583 519.816477

697.86 1980.735

2.266

448.83 207.9771

248.224856 1980.735

519.30777

349.59 1980.735

696.56 1980.887

2.259

447.48 207.9931

246.512021 1980.887 518.798727

348.53 1980.887

702.48 1981.039

2.261

447.91 208.0091

248.6536535 1981.039

518.28935

351.56 1981.039

706.49 1981.191

2.269

449.53

208.025

251.4187976 1981.191 517.780308

354.46 1981.191

713.27 1981.343

2.285

452.74

208.041

256.5223074 1981.343 517.270596

359.41 1981.343

754.54 1981.495

2.367

469.02

208.057

283.5535604 1981.495 516.761219

385.19 1981.495

791.51 1981.647

2.491

493.63 208.0729

316.8374181 1981.647 516.252177

414.39 1981.647

796.60 1981.799

2.536

502.58 208.0889

326.9370591 1981.799 515.743135

422.66 1981.799

796.60 1981.951

2.419

479.43 208.1049

303.8008534 1981.951 515.233423

406.02 1981.951

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260.9921467 1975.868 535.606497 276.52585

1976.02 535.096785

1978.91

525.41929

1979.67 522.872739

1980.43 520.326859

356.71 1975.868 372.63

1976.02

1978.91

1979.67

1980.43

346.15 1980.583

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PRESSURE MEASUREMENT IN SHALE -----------------------------------------------------------------------------------------------------------------

Chart & Results: Well Name: 34 10-C-11 Felt: Gulfaks Chart nr: 1

Velocity vs. depth:

Velosity,Vp[mic,sec/m] 400.00

500.00

600.00

700.00

800.00

900.00

1000.00

1935 1940 1945 1950 1955

Deth[m]

1960 1965 1970 1975 1980 1985 1990

Fig. C2: Velocity vs. depth.

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PRESSURE MEASUREMENT IN SHALE -----------------------------------------------------------------------------------------------------------------

Well Name: 34 10-C-11 Felt: Gulfaks

Chart nr: 2 Pore pressure based on Vertical Method:

Pressure calculation [Vertical Method] Pressure [kg/cm2] 150

200

250

300

1935 1940 1945 1950

Depth[m]

1955 1960 1965 1970 1975 1980 1985 1990

Fig.C3: Pore pressure predication using vertical method.

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PRESSURE MEASUREMENT IN SHALE -----------------------------------------------------------------------------------------------------------------

Well Name: 34 10-C-11 Felt: Gulfaks

Chart nr: 3

Pore pressure based on Horizontal Method: N Ppore  Povb  (Povb  Pp ,n )  M

x

X=3

PorePressure[Horizontal Method] Pressure [kg/cm2] 150.00

200.00

250.00

300.00

350.00

400.00

450.00

1935 1940 1945 1950

Depth[m]

1955 1960 1965 1970 1975 1980 1985 1990

Fig. C4 : Pore pressure predication using Horizontal method.

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PRESSURE MEASUREMENT IN SHALE -----------------------------------------------------------------------------------------------------------------

Well Name: 34 10-C-11 Felt: Gulfaks Chart nr: 4

Pore pressure based on Horizontal Method: Ppore  Povb  (Povb

N  Pp ,n )  M

x

X=2

PorePressure[Horizontal Method] Pressure [kg/cm2] 150.00

200.00

250.00

300.00

350.00

400.00

1935 1940 1945 1950

Depth[m]

1955 1960 1965 1970 1975 1980 1985 1990

Fig. C5: Pore pressure predication using Horizontal method.

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PRESSURE MEASUREMENT IN SHALE -----------------------------------------------------------------------------------------------------------------

Appendix D Estimation of pore pressure on over consolidated shale: Well Name: 34 10-F-4 H Felt: Gulfaks

:

A

Well Name: 34 10-F-4 H : B Felt: Nor ne: N6608 10-E-3 H V  5000  A   Bnorm 1

 Max

   5000  B   max  A  

Ppore  Povb  [(V  5000) A ]B

A  A  

B Max



U ) B Max (

B U TABLES7: Well data & calculation: B 

A

Gulfax:

34 10-F-4 H

B

Norne

N6608 10-E-3 H

Max stress

6200

A

4.45

B

0.92

U

3.15

Felt Norne Gulfax

A'

B' 2.3 0,94 2.65 0,95

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PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------B

A

ft

DT(Norne) DT(Gulfax) DEPTH[ft] 117.4046 95.041 4920.079 117.5041 94.687 4921.391 117.6487 95.261 4922.703 117.7898 117.8284

95.856 4924.015 95.57 4925.327

117.7269 117.5482

95.652 4926.639 95.482 4927.951

117.3473 117.1681

95.075 4929.263 93.625 4930.575

117.0302 116.8764 116.6941

93.372 4931.887 92.496 4933.199 92.75 4934.511

116.5111 116.3445 116.2053 116.1282

93.015 93.564 94.03 94.693

4935.823 4937.135 4938.447 4939.759

116.14 116.2257 116.3676 116.5407 116.714 116.8771

94.273 94.383 94.438 94.885 94.395 93.54

4941.071 4942.383 4943.695 4945.007 4946.319 4947.631

117.1356 117.5365 118.0558 118.6244 119.147 119.5855 120.0449 120.5087 120.8572 120.8677 120.185 119.131 118.0887 117.2851 116.8237

93.217 93.308 93.122 93.5 93.822 94.367 95.266 95.955 96.167 94.938 95.328 96.971 98.426 98.398 99.308

4948.943 4950.255 4951.567 4952.879 4954.191 4955.503 4956.815 4958.127 4959.439 4960.751 4962.063 4963.375 4964.687 4965.999 4967.311

116.653 116.5115 116.3469 116.2236

98.638 98.28 95.531 93.617

4968.623 4969.935 4971.247 4972.559

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PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------116.1818 116.219 116.2871 116.3207 116.3203 116.3057 116.3113 116.3901 116.5629 116.7513 116.898 116.9703 116.9717 117.0152 117.2242 117.5478 117.881 118.1049 118.114 117.8998 117.6524 117.4475 117.3019 117.1866 117.0413 116.8531 116.6733 116.5405 116.4731 116.4606 116.4402 116.387 116.3515 116.3938 116.568 116.9096 117.3016 117.6277 117.8483 117.9491 117.9364 117.811 117.6017

85.337 85.411 74.53 76.924 75.492 77.122 78.689 77.623 74.991 76.283 75.472 76.492 76.84 76.506 74.954 71.1 71.101 72.611 73.352 68.438 64.551 60.674 67.651 71.042 74.085 75.103 74.705 68.055 68.36 68.501 70.411 71.745 73.003 74.508 75.822 77.122 76.909 76.848 77.32 79.599 117.5365 118.0558 118.6244

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4973.871 4975.183 4976.495 4977.807 4979.119 4980.431 4981.743 4983.055 4984.367 4985.679 4986.991 4988.303 4989.615 4990.927 4992.239 4993.551 4994.863 4996.175 4997.487 4998.799 5000.111 5001.423 5002.735 5004.047 5005.359 5006.671 5007.983 5009.295 5010.607 5011.919 5013.231 5014.543 5015.855 5017.167 5018.479 5019.791 5021.103 5022.415 5023.727 5025.039 5026.351 5027.663 5028.975

132

PRESSURE MEASUREMENT IN SHALE -----------------------------------------------------------------------------------------------------------------

Chart Nr:

Fig. D1: sonic travel time vs. depth. NTNU | Atumn2009

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PRESSURE MEASUREMENT IN SHALE -----------------------------------------------------------------------------------------------------------------

Fig. D2: Velocity and Normal compaction Curve.

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PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------TABLE 8: Pore Pressure on overcosolidated Shale:

Well Nr:

A TVD[m]

B

Ppore[SG] Ppore[SG]

764.295

0.82

0.812

767.34 782.565 843.465 846.51 1368.728 1738.391 1828.218 1958.24 1978.032 2058.116 2098.005 2237.771 2377.841 2437.827 2477.717

0.82 0.83 0.83 0.83 0.834 1.25 0.8 1.26 1.15 0.81 0.81 0.81 0.824 0.824 0.824

0.82 0.82 0.82 0.83 0.83 1.2 0.8 1.06 1.05 0.83 0.83 0.83 0.832 0.834 0.834

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PRESSURE MEASUREMENT IN SHALE -----------------------------------------------------------------------------------------------------------------

Fig. D3: Pore pressure predication using Eaton Method.

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PRESSURE MEASUREMENT IN SHALE -----------------------------------------------------------------------------------------------------------------

Fig.D4: Pore pressure predication using Bower’s method.

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PRESSURE MEASUREMENT IN SHALE -----------------------------------------------------------------------------------------------------------------

Fig.D5: Pore pressure predication using overcosolidated model.

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PRESSURE MEASUREMENT IN SHALE -----------------------------------------------------------------------------------------------------------------

APPENDIX E:

Nomenclature: A & B: Curve fitting constant for normal compacted shale A obs : Observed attribute A norm : Normal attribute a : Formation factor constant a : Lithology constant a : The intercept b : Slop C c : Average Constant Compression index D : density D : Depth of insert [ft] De : depth where the vertical line crosses the compaction line. DST : Drill Stem Test e : Void ratio e i : Void ratio corresponded to v =1 psi E : young’s Modulus GPF : Formation pressure gradient (mud density equivalent) GPhyd. : Normal (hydrostatic) pressure gradient (mud density equivalent)

K : Porosity decline constant K : constant LWD : Logging While Drilling MESPOSH: Measure Pressure on Shale (direct measurement) M : (1.85=Geometrical factor by Perez-Rosales) M : Geometrical factor m : Cementation factor m : Lithology constant NCC: Normal Compaction Curve N ): Ratio of measured value (i.e. velocity, resistivity or acoustic travel time) to the M expected value at normal trend line at the same depth.

(

Pp : Pores pressure

P e : overburden pressure where the vertical line crosses the compaction line. P pore : Shale pressure [psi] R w : Resistivity of the fluid saturating the rock R w : Resistivity of bound water R o : Resistivity of the system NTNU | Atumn2009

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PRESSURE MEASUREMENT IN SHALE ----------------------------------------------------------------------------------------------------------------R Sh : Resistivity of Shale Rt : Formation resistivity SWD : Seismic While Drilling Sw : Water saturation T : Temperature ( o F) U: Unloading curve parameter (U= 3.13, For Golf Cost, Bower 1995) V: Sonic velocity [ft/sec] VSP-WD : Vertical Seismic Profiling While Drilling WBM : Water Based Mud v psi : Vertical stress gradient [ ] ft D β : Constant =297.6  : Porosity of shale @ depth D

=

 i : Initial shale porosity @ surface Φ r : Residual Porosity Φ r : (0.1 =satisfactory for sand)  Z, tot   ob : Total stress or Overburden v : Effective stress  norm : Effective stress  Max : Max effective stress corresponds to  Max  Max : Max. Effective stress [SG]  v : Vertical stress  ovb : overburden stress Δt

: Formation

transit travel time ([

s s ] or [ ]) ft m

Δt m :Matrix transit travel time Δt fl : Fluid transit travel time

 sec ] ft  sec ] t n : Normal transit time [ ft Trel : Relative Time Difference

t a

: Abnormal transit time [

Tds : Travel Time across the Drill-String Tf : Travel Time across the Formation Ʋp : formation velocity Ʋm : Matrix velocity Ʋfl : fluid velocity  Max : Sonic velocity which is the onset point of the unloading [ft/sec]

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