using well test analysis techniques to determine reservoir … … · devex 2014 presentation 14...
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Michael Judt, Aberdeen, May 7 2014. Devex 2014 Presentation www.taqaglobal.com
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Michael Judt (TAQA)
DEVEX conference, Aberdeen
7th May 2014
Using Well Test Analysis
Techniques to determine
Reservoir Properties and drained
Volume from the first successful
appraisal well in the Northern Part
of the Pelican Field.
Cormorant Alpha
drilling and production
platform, UK, Northern
North Sea
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Michael Judt, Aberdeen, May 7 2014. Devex 2014 Presentation www.taqaglobal.com
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Location of the Cormorant Alpha Area licences
Shetland
Islands
The Pelican Main Field
Block 211/26
Main Reservoir: Brent
Production Start up
January 1996
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Michael Judt, Aberdeen, May 7 2014. Devex 2014 Presentation www.taqaglobal.com
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Pelican Main Top Brent Structure Map
• Sub Sea Field, tied back to Cormorant Alpha Platform
• Formation: Brent, Depth 12000 ft , Water Depth 150 m
• Low Permeability because of Depth
• Production Start up 1996
• OOIP around 500 MMbbl,
• Cumulative Oil to Date: 70.7 MMbbl
• Recovery Factor to Date 14.4%
• Currently 6 producing Wells and 3 Water Injectors
• Liquid Production 10000 bbl/d, Oil 7500 bbl/d
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Michael Judt, Aberdeen, May 7 2014. Devex 2014 Presentation www.taqaglobal.com
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Main, +- 500 MM OOIP
Shoulder
Head
Egg
Beak / Fish
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The Pelican
Michael Judt, Aberdeen, May 7 2014. Devex 2014 Presentation www.taqaglobal.com
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P22S1 CPI Log
• Well found initial Pressure (7485 psia at top Perf’s)
• All Brent sands were perforated.
• Production start up 30 August 2013
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Zone Gross Net NTG Permeability kh Porosity Sw
ft ft mD mDft Frac Frac
Tarbert 16.8 11.5 0.683 35.2 405 0.195 0.191
Upper Ness 112.1 58.0 0.517 251.5 14589 0.149 0.199
Lower Ness 79.9 74.5 0.932 37.7 2808 0.189 0.229
Etive 287.0 85.0 0.296 6.8 580 0.187 0.389
Rannoch 132.8 24.5 0.184 2.3 57 0.159 0.465
Broom 115.2 93.0 0.807 4.0 369 0.147 0.451
Total 743.9 346.5 0.466 54.3 18807 0.169 0.338
Michael Judt, Aberdeen, May 7 2014. Devex 2014 Presentation www.taqaglobal.com
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Pelican P22S1 September 2013
Period 1: Flow Test
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Michael Judt, Aberdeen, May 7 2014. Devex 2014 Presentation www.taqaglobal.com
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Pelican P22S1 September 2013
Period 1: Flow Test Analysis
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Well Location,
Numerical Model
Distance to Faults:
320 ft, 590 ft
Production Time 304 hrs
Cumulative Production 147 Mbbl
Permability Thickness (Kh) 2060 mDft
Effective Permeability (k) 9.15 mD
Skin -1.93
Radius of Drainage (Rd) 1492 ft
Con. OOIP(based on Rd/4) 6 MMbbl
Con. OOIP(Linear P Decline) 35 MMbbl
Productivity Index 2.3 bbl/psi/d
Time to reach PSS 2-12 Months
This Kh is 10% of the Log Kh
Michael Judt, Aberdeen, May 7 2014. Devex 2014 Presentation www.taqaglobal.com
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Pelican P22S1 September 2013
Period 1: Pressure Build up 13 September
2013
• Short (4 hours) pressure Build up
• Well near two perpendicular Faults
• Distance to faults around 100 ft
• Permeability Thickness 3120 mDft
• Effective Permeability 13.9 mD
• Skin -2.91
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Michael Judt, Aberdeen, May 7 2014. Devex 2014 Presentation www.taqaglobal.com
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P22S1 November 2013
Period 2: Linear Pressure Decline
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Production Time 847 hrs
Cumulative Production 356 Mbbl
Pressure Decline Rate -0.257 psi/hr
Radius of Drainage (Rd) 3070 ft
Con. OOIP(based on Rd/4) 26 MMbbl
Con. OOIP(Linear P Decline) 90 MMbbl
Michael Judt, Aberdeen, May 7 2014. Devex 2014 Presentation www.taqaglobal.com
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P22S1 January 2014
Period 3: Pressure Build Up Survey 19/01/2014
Pressure Build Up No. 9,10
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Michael Judt, Aberdeen, May 7 2014. Devex 2014 Presentation www.taqaglobal.com
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P22S1 January 2014
Period 3: Pressure Build up No. 09, 10 Analysis
• Asked for 24 hr Pressure Build up
• Got 2x build up 63 / 79 hr long
• Model: Slanted well in a closed Rectangle
• Longest side of rectangle uncertain
• Depletion from P* = 1900 psia
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Michael Judt, Aberdeen, May 7 2014. Devex 2014 Presentation www.taqaglobal.com
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P22S1 January 2014
Period 3: Pressure Build up No. 09, 10 AnalysisProduction Time 3378 hrs
Cumulative Production 983 Mbbl
Permability Thickness (Kh) 2060 mDft
Effective Permeability (k) 9.14 mD
Skin -1.5
Radius of Drainage (Rd) 4971 ft
Con. OOIP(based on Rd/4) 69 MMbbl
Con. OOIP(Well Test Model) 56 MMbbl
Con. OOIP(P* Mbal) 30 MMbbl
Michael Judt, Aberdeen, May 7 2014. Devex 2014 Presentation www.taqaglobal.com
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P22S1 March 2014
Period 4: Further Pressure Build Up Surveys
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Michael Judt, Aberdeen, May 7 2014. Devex 2014 Presentation www.taqaglobal.com
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P22S1 March 2014
Period 4: Pressure Analysis
Production Time 5080 hrs
Cumulative Production 1279 Mbbl
Permability Thickness (Kh) 2060 mDft
Effective Permeability (k) 9.14 mD
Skin -1.48
Radius of Drainage (Rd) 6096 ft
Connected OOIP(based on Rd/4) 103 MMbbl
Connected OOIP(Well Test Model) 50 MMbbl
Connected OOIP(P* Mbal) 31 MMbbl
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Michael Judt, Aberdeen, May 7 2014. Devex 2014 Presentation www.taqaglobal.com
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The Pelican North Shoulder is isolated from the Main field, as P22S1 found initial Reservoir pressure.
Well P22S1 has a productivity Index of around 2.0 bbl/psi/d, which is in line with the average well test permeability of 9 – 13 md and is similar to the average productivity of a Pelican Main well.
The Permeability thickness derived from Well Test Analysis is only 10-20% of the Permeability thickness derived from Core / Log Analysis. This is a recurrent Theme in Pelican and the reasons for the large difference are not well understood.
The “dynamically” connected volume to P22S1 is between 31 and 90 MMbbl, the mean volume is around 50 MMbbl.
A variety of techniques to derive the connected volume are available in Reservoir Engineering, but most depend on knowing the drainage area shape and size, which in itself implies knowledge about the connected volume.
Summary and Conclusions
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Michael Judt, Aberdeen, May 7 2014. Devex 2014 Presentation www.taqaglobal.com
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• TAQA UK Ltd
• Hub 1 Cormorant Alpha Team
Acknowledgements
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