Water Coning

‫بسم ال‬ ‫الرحمن الرحيم‬

INTRODUCTION  For

water to be produced in the reservoir, 3 factors must be present:

 Source

of water.  Pressure drawdown.  High water relative permeability. Mohamed

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NOW LET’S DISCOVER OUT:

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WHAT IS WATER CONING?

Water coning is defined as the upward movement of water into the perforations of a producing well under certain conditions. Mohamed

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WHAT IS WATER CONING? GOC

OWC

WHAT IS WATER CONING? Low production rate

OWC

WHAT IS WATER CONING? High production rate

OWC

MECHANISM OF WATER CONING Three forces that affect the mechanism of water coning: Capillary

force.

Gravity

force.

Viscous

force.

MECHANISM OF WATER CONING (CONT’D) (1) Capillary Force:  Capillary

pressure is the difference in pressure across the interface between two immiscible fluids.

dPc Capillary force   S dSw

Pc

, psi / ft

 It

has a negligible effect on water coning and can be neglected.

Sw

MECHANISM OF WATER CONING (CONT’D) (2) Gravity Force:  Arises

from the density difference between fluids.

 Gravity force  , psi / ft 144

MECHANISM OF WATER CONING (CONT’D) (3) Viscous Force:  Results

due to pressure drawdown.

Viscous

 force   0.00633k

, psi / ft

MECHANISM OF WATER CONING (CONT’D) WOC deforms (rise up) when the viscous force has the major effect that overcome the gravitational force in the reservoir.

FACTORS THAT AFFECT THE NATURE AND SHAPE OF THE CONE Production Mobility

rate,

ratio,

Horizontal

and vertical

permeability, and Well

penetration.

IMPACT OF WATER CONING  Loss

of the total field overall recovery,  Early abandon of the afflicted well,  Reduction in the efficiency of the drive mechanism,  Corrosion of casing, tubing, and surface facilities,  High cost due to water disposal,  Strong environmental impact due to the huge volumes of water produced at the surface.

CRITICAL RATE IN VERTICAL WELLS Two Criteria : Critical

Oil Production It is defined as theRate: maximum allowable oil flow rate that can be Time To from Breakthrough. charged the well to avoid water coning.

CRITICAL RATE IN VERTICAL WELLS (CONT’D) To determine the critical flow rate, there are many approaches:  Meyer and Garder method.  Chaperon's approach: hk h 4 * q oc  4.886 * 10 ( h) q oc

o o

Where:

q

* oc

h  (0.7311  1.943 r

Kh ) Kv

CRITICAL RATE IN VERTICAL WELLS (CONT’D) Joshi

approach.  Abass and Bass Method. The Chierici-Ciucci Approach: 

Assumptions: Homogenous reservoir isotropic or anisotropic).  Limited aquifer that contribute to the energy reservoir. 

(either doesn’t of the

CRITICAL RATE IN VERTICAL WELLS (CONT’D) The Chierici-Ciucci Approach:  They

used these studies to:

 Determining

the value of the critical coning rate at given reservoirs and fluid properties.

 Optimizing

the position and length of the perforated interval at critical coning rate.

TIME TO BREAKTHROUGH IN VERTICAL WELLS Two Criteria : IfaCritical well produces above its critical Oil Production Rate: rate, the cone will breakthrough after a given time period, this Time To Breakthrough: time is called time to breakthrough Tbt.

TIME TO BREAKTHROUGH IN VERTICAL WELLS (CONT’D) 1) The Correlation:



Sobocinski-Cornelius

He correlated this equation using two dimensionless parameters:  Cone

height (z)  dimensionless breakthrough time ( T DBt ).

TIME TO BREAKTHROUGH IN VERTICAL WELLS (CONT’D) 2) The Bournazel-Jeanson Method: 

His correlation is based on experimental data:

TIME TO BREAKTHROUGH IN VERTICAL WELLS (CONT’D) 3) Kuo and Desbrisay (1983) : Prediction

of the rise in WOC

using MBE. His results depend up on: Dimensionless breakthrough time TDBt .  Dimensionless limiting water-cut limit. 

CASE STUDY ON A VERTICAL WELL A vertical well was given these data:  ρw=62.4

lb/cuft  ρo=59 lb/cuft  βo=1.0841 res cuft/ scf  Kh=1000 md  Kv=0.6Kh md

 h=175

ft  h =15 ft p µ

o



=60 cp

re=1900 ft

Q

=4000 STB/day o

CASE STUDY ON A VERTICAL WELL (CONT’D) (1) Critical Oil Rate:  Using Chaperon’s Approach, calculate Qoc :  At this base case we find: Qoc =100 STB/day 

Make a sensitivity on µo, kh , and hp to find their effect on Qoc.

EFFECT OF OIL VISCOSITY ON THE CRITICAL RATE µo

Qoc

60

100

55

110

50

120

45

135

40

150

35

170

30

200

25

240

20

300

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EFFECT OF PERMEABILITY ON THE CRITICAL RATE Kh

Kv

Qoc

1000

600

100

950

570

95

900

540

90

850

510

85

800

480

80

750

450

75

700

420

70

650

390

65

600

360

60

500

300

50

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EFFECT OF PERFORATION LOCATION ON THE CRITICAL RATE hp

Qoc

15

100

20

95

25

88.5

30

82.5

40

71.5

50

61.5

60

52

70

43

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AT THIS CASE STUDY: hp....kh....µo

Q

350 300 250 200 oc 150 100 50 0 0

0.2

0.4

0.6

0.8

1

1.2

Normalized parameter

 We

can find that µo & kh and hp have the same effect on Qoc in the interval from µo =36 to 60 cp.  µo affects Qoc sharply from µo =20 to 36 cp. Mohamed

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CASE STUDY ON A VERTICAL WELL (CONT’D) (2) Time to Breakthrough:  Using

Bournazel-Jeanson method, calculate Tbt :  At this base case we find: Tbt =30 days.  Make a sensitivity on µo, kh & Qo to get their effect on Tbt.

EFFECT OF VISCOSITY ON TBT

µo Tbt 60

30

50

33

40

38

30

45

20

58

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EFFECT OF ROCK PERMEABILITY ON TBT Kh

Kv Tbt

1000 600 30 900

540 27

800

480 24

700

420 21

600

360 18

500

300 15

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EFFECT OF OIL PRODUCTION RATE ON TBT Qo

Tbt

4000

30

3000

40

2000

60

1000

123

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AT THIS CASE STUDY:

 µo and kh may have the same effect on Tbt.  Qo has the great effect on Tbt.  µo affects Tbt sharply from 20 to 39 cp.

WATER CONING IN HORIZONTAL WELLS

WATER CONING IN HORIZONTAL WELLS (CONT’D) 

Water-oil interface deforms into a crest.



As production rate is increased, the height of the water crest also increases until the rate reaches a critical rate, at which the crest becomes unstable and water flows into the well. (2-phase interface coning)

FACTORS AFFECT CONING IN HORIZONTAL WELLS  Effect  Effect  Effect  Effect  Effect  Effect

of of of of of of

Length. production rate. well spacing. anisotropy ratio. well position. reservoir geometry.

EFFECT OF LENGTH 1.

Simulation Kleppe:

Study

by

Kossack

and



A 1500ft horizontal well would produce the same amount of oil as two vertical wells in a typical sector pattern.



A 2000ft horizontal well would perform even better than three vertical wells.

EFFECT OF LENGTH (CONT’D)

to shut in is the time the well produces before shut-in is necessary due to high water-cut. STB/D 8000 TIME TO SHUT-IN

 Time

STB/D 4000

LENGTH OF HORIZONTAL SECTION

EFFECT OF LENGTH (CONT’D) 2.

Work of Butler: S: spacing between Hz. wells. L: length of Hz. well.



A length equal to one quarter of the spacing between parallel horizontal wells has the same critical rate as a vertical well.



Critical rates in horizontal wells are proportional to the length of the horizontal wells.

EFFECT OF RATE 1.

Study by Karcher:



For favorable mobility ratio critical rate did not exhibit any major sensitivity.



For unfavorable mobility ratio recovery dropped from 11.6% to 6.5% as rate increased from 22 to 42 times the critical rate.

EFFECT OF RATE (CONT’D) 2.

Work of Zagalai and Murphy:



Reservoir simulation study of horizontal wells in the Helder-Field (Dutch Continental Shelf). Results: A horizontal well is affected more adversely by high gross rates. Rate has a strong influence on water cut performance (Q increase W.C. increase).



 

EFFECT OF WELL SPACING 1.

Work of Wattenbarger:

Yang

and

They found that increasing drainage width in horizontal wells resulted in delayed breakthrough.

EFFECT OF WELL SPACING (CONT’D) 2. 

Work of Lacy et al.:

They found that higher well spacing is desirable in horizontal wells for two reasons: 1) Incremental reserves should be proportional to incremental costs. 2) Early production data demonstrates that the horizontal wells can drain a large area in a small time even in tight reservoirs.

EFFECT OF ANISOTROPY RATIO (CONT’D)  As

Kv increases, Qcv decreases. But for horizontal wells, an increase in Kv results in an increase in Qch.

High values of the vertical permeability Kv resulted in later breakthrough of water.

EFFECT OF WELL POSITION  Critical

rate was analyzed by determining the critical rate for well positions corresponding to ZD values of 1.0, 0.75, 0.50, 0.25.  ZD: the dimensionless number, L Ht

Hoil WOC

EFFECT OF WELL POSITION (CONT’D) Horizontal Reservoir Length (ft.)

Qc (STBPD)

ZD= 1.0

500 1000 2000 3000

120 220 380 540

(a=1.0) Qc

Qc

Qc

(STBPD)

(STBPD)

(STBPD)

100 200 340 480

80 140 240 340

40 80 140 200

ZD= 0.75

ZD= 0.50

ZD= 0.25

EFFECT OF WELL POSITION (CONT’D)

EFFECT OF WELL POSITION (CONT’D)

EFFECT OF RESERVOIR GEOMETRY We have three reservoir 1.Case (A): 4500*4500 2.Case (B): 2250*4500 (Rectangular) 3.Case (C): 1250*4500  It

geometries: sq.ft. (Square) sq.ft. sq.ft.

(Base Case)

was observed that increasing the area of the reservoir results in an increase in the critical rate.

EFFECT OF RESERVOIR GEOMETRY (CONT’D) HORIZONTAL RESERVOIR ZD = 1.0 ZD = 0.5 4500’x4500’ 2250’x4500’ 4500’x4500’ 2250’x4500’

Well Length (ft)

Qc

Qc

Qc

Qc

(STBPD) (STBPD) (STBPD) (STBPD)

1000

260

240

160

160

2000

460

420

300

260

3000

680

640

440

400

CHAPERON’S APPROACH  Assumptions: The

well was assumed to be near the

top. The

flow would be radial around the well bore.

It

might approach linear properties as the distance from the well bore increase.

WE WILL WORK ON OUR CASE USING: Chaperon method: Qoc

~  0.00049

kh h 2

o

5L   w  o  ye

L=well length(ft) Ye=the drainage area half length(ft) Water density& oil density (gm/cc)

CASE STUDY ON A HORIZONTAL WELL A horizontal well was given these data:  ρ w=

62.4 lb/ cuft  ρo= 59 lb/ cuft  βo=1.05 res cuft/ scf  Kh=5500 md  Kv=0.6*Kh md

Mohamed

 h=59

ft  Φ=0.3  µo=60 cp  L=500 m  Qo=6000 bbl/day

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CASE STUDY ON A HORIZONTAL WELL (CONT’D) (1) Critical Oil Rate:  Calculate Qoc .  At this base case we find that: Qoc =47 STB/day  Make

a sensitivity on µo, kh , and L to find their effect on Qoc.

EFFECT OF PERMEABILITY ON THE CRITICAL RATE Kh

µo

h

L(m)

Ye(ft)

ρw

ρo

Qoc

5500

60

59

500

1500

62.4

59

47

5000

43

4500

38

4000

34

3500

30

3000

27

2500

21

2000

17

1500

13

1000

8.5

EFFECT OF WELL LENGTH ON THE CRITICAL RATE µo

Kh

60 5500

L(m)

Ye(ft)

500

1500

ρw

ρo

h

62.4 59 59

Qc 47

400

38

300

28

EFFECT OF OIL VISCOSITY ON THE CRITICAL RATE µo

Kh

L(m) Ye(ft) h(ft)

60 5500 500

1500

59

ρw

ρo

Qc

62.4 59

47

50

56

40

70.5

30

94

20

141

AT THIS CASE STUDY:

 We

can find that kh & L have the same effect on Qoc.

µ

affects Qoc sharply from 20 to 40 cp.

µ

may be consider have the same effect of

o o

CASE STUDY ON A HORIZONTAL WELL (CONT’D) (2) Time to Breakthrough:  Using Papatzacos’ method:

CASE STUDY ON A VERTICAL WELL (CONT’D)  Calculate

Tbt .  At this base case, we find that: Tbt =67 days.  Make

a sensitivity on µo, L, kh, Φ & Qo to get their effect on Tbt.

EFFECT OF VISCOSITY ON TBT µo

Βo

Qo

6

1.0

600

5

0

0

L(m

h

ρw

ρo

Kh

Kv

qd

Tdbt

Φ

5

62.

5

550

330

5.48

0.03

0.

9

4

9

0

0

1

1

3

) 500

5

Tbt 67

0.03

67.

7

1

4.57

0 4

3.65

0.04

67.

0

5

7

5

3

0.06 2.74

68

EFFECT OF WELL LENGTH ON TBT µo

βo

Qo

L

h

ρw

ρo

Kh

Kv

Qd

Tdbt

Φ

Tbt

6

1.0

600

60

5

62.

5

550

330

4.5

0.037

0.

80.

0

5

0

0

9

4

9

0

0

7

4

3

5

50

5.4

0.031

67

0

8

40

6.8

0.024

53

0

5

7

30

9.4

0.018

0

1

6

40

EFFECT OF ROCK PERMEABILITY ON TBT µo

βo

6 0

1.0 5

Qo

L(m )

h

ρw

ρo

600 500 0

5 9

62. 4

5 9

Kh

Kv

qd

Tdbt

Φ

Tbt

550 330 0 0

5.4 8

0.03

0. 3

67

500 300 0 0

6.0 0.028 3

66.7

450 270 0 0

6.7 0.025

66.5

400 240 0 0

7.5 0.022 4

66.4

350 210 0 0

8.6 0.019 1

66.3

300 180 0 0

10

0.016 7

66.2

250 150

12

0.013

66

EFFECT OF POROSITY ON TBT

µo

βo

Qo

L(m

h

ρw

ρo

5

62.

5

9

4

9

Kh

Kv

qd

Tdbt

6.3

0.02

1

7

Φ

Tbt

) 6

1.0

0

5

600 500 0

550 330 0

0

0.3 67 0.2

56

5

0.2 44. 5 0.1

33

5

0.1 22

EFFECT OF OIL PRODUCTION RATE ON TBT µo

βo

Qo L(m h

qd

Tdbt

Φ

Tbt

5.4

0.03

0.

67

8

1

3

500

4.5

0.03

0

7

7

400

3.6

0.04

0

5

7

300

2.7

0.06

136.

0

4

3

5

200

1.8

0.09

209.

7

5

ρw

ρo

5

62.

5

9

4

9

kh

kv

) 6

1.0

0

5

600 500 0

0 Mohamed

550 330 0

0

2 May 6, 2017

80.5 101

65

AT THIS CASE STUDY:

We can find on horizontal wells:  Qo have the greatest effect on Tbt,  Φ either has a contrast effect on Tbt  L play a major role in Tbt.

STUDY RESULTS FOR THE HORIZONTAL WELLS 1. µo has the chief effect on

Qoc. 2. Qo has the greatest effect

on Tbt.

REMEDIAL PROCEDURES Why do we need remedial procedures?

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REMEDIATION OF WATER CONING Can Be Divided into Two Categories:  After

coning occurs.

 Before

coning occurs.

REMEDIATION OF WATER CONING SqueezeAfter coning occurs cement:  Perforation

at or closed to OWC.  Squeeze cement into the formation.  Formation of impermeable barriers. Mohamed

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O.W.C Water May 6, 2017

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REMEDIATION OF WATER CONING (CONT’D) After coning occurs Plug off lower perforatio n:

Oil

O.W.C

 Seal

the lower perforation

Water

REMEDIATION OF WATER CONING (CONT’D) After coning occurs Mobility reduction:  Polymer  M<=1

injection.

“Favorable mobility ratio”

REMEDIATION OF WATER CONING (CONT’D) After coning occurs Cross Linked Polymer Gels:  Injecting

a gelling fluid into the well or into a high permeability watered-out zone.



Restricting flow in that zone.

REMEDIATION OF WATER CONING (CONT’D) After coning occurs Cross Linked Polymer Gels:  Problems

of Cross-Linked Gels:

Retention

and adsorption of the cross-

linking agents on the rock surface. Long

term stability of polymers.

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REMEDIATION OF WATER CONING (CONT’D) After coning occurs Cross Linked Polymer Gels:  Problems

of Cross-Linked Gels:.

Environmental

undesirability of using cross-linking agents such as chromium.

Difficulty

in controlling gelation kinetic placement of the gel deep into the formation. Mohamed

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REMEDIATION OF WATER CONING (CONT’D) After coning occurs PH Triggered Gels:  Placed

deep into the water bearing parts of the reservoir.

 Doesn’t

involve any cross linking polymer for inducing gelation.

REMEDIATION OF WATER CONING (CONT’D) After coning occurs PH Triggered Gels: Advantages:

Depends

on the pH of the polymer

solution.  More environmentally friendly. Easily reversible and readily cleans up. Mohamed

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REMEDIATION OF WATER CONING (CONT’D) After coning occurs shut in well: Stabilize

OWC.

Oil

O.W.C Water

REMEDIATION OF WATER CONING (CONT’D) Before coning occurs

Fracturing: Fracturing

the formation. Increasing QC by 3 times.

Multilateral wells: Intelligent

completions.

PREVENTING CONING PROBLEM BY COMPLETION CONTROL  Perforation  Dual

under oil water contact.

Completion.

 Downhole

Water Sink Technology.

PREVENTING CONING PROBLEM BY COMPLETION CONTROL(CONT’D) Could be the best choice in case of: Bottom Strong

water drive

tendency to water coning

PERFORATION UNDER OIL-WATER CONTACT Technique Description: Perforation interval is extended to the water zone. The comingled production of water and oil in one string.

Oil Zone O.W.C . Water Zone

PERFORATION UNDER OIL-WATER CONTACT (CONT’D) The Main Purpose of this Technique:  Maintain

radial flow of fluid.

Disadvantages:  Unwanted

environmental problems caused by the disposal of the contaminated water.  Corrosion to the tubing.  High lifting cost.

DUAL COMPLETION (CONT’D) Two perforations in the oil zone:

Oil zone .O.W.C Water zone

DUAL COMPLETION (CONT’D) Perforation in both oil & water zones:

Oil zone .O.W.C

Water zone

DOWNHOLE WATER SINK TECHNOLOGY

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DWS SYSTEMS There are 2 applicable systems:  Drainage-injection

systems.

 Drainage-production

systems.

DWS SYSTEMS (CONT’D) Drainage Injection System

DWS SYSTEMS (CONT’D) Drainage Production System

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THE FIELD FIELD APPLICATIONS  California  East

Field.

Texas Field.

CALIFORNIA FIELD APPLICATION Conventional Completion: 6 BOPD with 99 % W.C. DWS Completion: 900 BWPD 25 BOPD 58 % W.C.

EAST TEXAS FIELD APPLICATION Conventional Completion: Watered-out

well

DWS Completion: 24 BOPD with 97 % W.C.

ADVANTAGES OF DWS  Eliminate

or reduce water from the upper perforation.

 Produce

uncontaminated water from the lower perforation.

 Improves  Reduces

productivity up to 77%.

the pressure drawdown.

TECHNIQUE RECOMMENDATIONS  Optimum

well Production rates should be

used.  Adjusting

the oil and water drainage

rates.  creates

opposing pressure drops on the water-oil contact.

 thereby

stabilizing the cone.

COMPARISON BETWEEN DWS AND CONVENTIONAL WELLS

DWS AND CONVENTIONAL WELLS (CONT’D)