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© 2014 BAKER HUGHES INCORPORATED. ALL RIGHTS RESERVED. TERMS AND CONDITIONS OF USE: BY ACCEPTING THIS DOCUMENT, THE RECIPIENT AGREES THAT THE DOCUMENT TOGETHER WITH ALL INFORMATION INCLUDED THEREIN IS THE

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Pressure Communication and FWL

detection in Tight Formations

Virochan Ganjoo, Baker Hughes Ltd (Reservoir Engineer)

Eva Gerick, GDF SUEZ E&P UK Ltd (Senior Petrophysicist)

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Agenda

￭Field and Well Context

￭Formation Evaluation

–Challenges

–Solution

￭Results

￭Data QC

￭Data Analysis and Interpretation

￭Formation Evaluation Summary

￭Conclusion

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Background

Discovered in 1988

First gas production in 2015/2016

Contribute 5% to UK gas production

Partners

GDF SUEZ E&P UK Ltd (38.75%)

Centrica Energy (48.75%)

Bayerngas (12.5%).

Largest Gas Field Discovered

Cygnus Field

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Well Location

￭ The prospect is a three way, fault-bounded block located north of the

Cygnus field, and is an extension to the field.

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Well Objectives

￭To test Cygnus fault “Block 8”

prospect.

￭To prove the extension of the

Cygnus field to the North E.

44/12a-6

￭Examine the pressure communication

between the main field and fault “Block-8”

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Leman Core Section

￭Lower Leman Sandstone

￭Porosity between 9 and 13%

￭Permeability between 0.01

and 50 mD

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Log Data

XX

XX

XX

XX

XX

XX

GR RES D/N Aco S φ Lith Gas Core

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Reservoir Section – Petrophysics

￭Shale-Sand sequence.

￭Low porosity (10 -15%).

￭Low permeability from core data.

S φ Lith Gas Core

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Reservoir Challenges

Pressure Testing and Sampling

Low Mobility Formation

Probe Based Dual Packer Based

Wellbore Conditions

Rig Time

- Solution Planning

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- Solution

High K

Low K

High K

Low K

Time, sec

Pre

ssur

e, p

si

Good PermeabilityLow PermeabilityTight

Heterogeneous / Layered Formation

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Extra Elongated Packer (XEP) - Specifications

Extra Elongated Packer

(large inflow-area)

￭Flow area – 8 sq.in

￭Available for 6”, 8 ½”, 12 ¼” hole sizes

￭Ideal for laminated / low mobility

reservoirs

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Results for Well 44/12a-6

Extra Elongated Packer

(large inflow-area)

￭8 pressure tests performed successfully

￭Mobility at 3 stations ≤ 1mD/cP

￭Lowest mobility - 0.4 mD/cP

￭Build up stability - 0.05 psi/min

￭Gas and water samples acquired

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Pressure History Plots

0.5 mD/cP 0.4 mD/cP

Time (sec)

Pre

ssu

re (

psi

a)

Pre

ssu

re (

psi

a)

Time (sec)

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Core Phi-K – Pressure Testing QC

Porosity (fraction)

Perm

eab

ility

(m

D)

Good pre-test

Core Points

Tight / supercharged pre-test

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Pressure Gradient ( Gas – Water)D

epth

TV

DSS

(ft

)

Pressure (psia)

Gas Gradient - 0.1 psi/ft

Water Gradient - 0.46 psi/ft

44/12a-6

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11100

11150

11200

11250

11300

11350

11400

11450

11500

5850 5860 5870 5880 5890 5900 5910 5920 5930 5940 5950 5960 5970 5980 5990 6000

44/12a-6

Cygnus formation pressures

xx100

xx150

xx200

xx250

xx300

xx350

xx400

xx450

Dep

th T

VD

SS (

ft)

x85

0

x86

0

x87

0

x88

0

x89

0

x90

0

x91

0

x92

0

X9

30

X9

40

X9

50

X9

60

X9

70

X9

80

X9

90

x00

0

Pressure Data Comparison

Pressure (psia)

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Cygnus FWL

44/12a-6 FWL

Free Water Level (FWL) Comparison

44/12a-6 found FWL 9ft TVDSS

higher than main Cygnus field

x85

0

x86

0

x87

0

x88

0

x89

0

x90

0

x91

0

x92

0

X9

30

xx100

xx150

xx200

xx250

xx300

xx350

Dep

th T

VD

SS (

ft)

Pressure (psia)

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Fluid Sampling

￭Water sample collected near FWL.

￭Gas samples were acquired in Leman Sandstone.

￭The PVT results for the Gas sample came back with 2 to

7% OBM contamination.

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Formation Evaluation Summary

￭A full suite of standard logs were run.

￭23 pressure points and 3 fluid samples were taken for the

formation evaluation.

￭Pressure test data confirmed by core data analysis.

￭The FWL in “Block 8” was found 9ft TVDSS higher than

main Cygnus field.

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Conclusion - Reservoir Management

￭The pressure data is an essential part of an ongoing

investigation regarding connectivity.

￭Update reservoir model.

￭Update volume in place and economics.

￭Impact on future well placement.

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￭Eva Gerick – GDF SUEZ E&P Ltd

￭Tushar Patil – Baker Hughes Ltd

Acknowledgement