1. PECTEN CAMEROON COMPANY Subsidiary of SHELL E&P Int’l
“A PRACTICAL APPROACH TO OPTIMIZING A MATURING FIELD”
PRESENTED BY:
ANDREW MABIAN
PECTEN CAMEROON COMPANY
Subsidiary of SHELL E&P Int’l
PREPARED BY:
SAM WILDMAN
ALTEC GAS LIFT, INC
ASME Gas Lift workshop

2. MOKOKO ABANA CONCESSION Results to date are as follows:
Achievements
Optimization training and calibration facility setup June/July 2000
Well work proceeded October 2000 ( 45 wells program )
Well work approximately 75% completed
Results to date are as follows:
1573 BOPD gained
-1374 MCFGPD less injection required
Quicker recovery time after upsets
Average daily production above 26,000 BOPD

3. The Mokoko Abana Concession is located approximately
40 miles off Cameroon’s
southwest coast.

4. MOKOKO ABANA CONCESSION
FIELD LAYOUT

5. MOKOKO ABANA CONCESSION
FIELD BACKGROUND
Drilling of the field initiated 1982.
9 platforms set and drilled
12 platforms by 1997.
11 producing platforms.

6. MOKOKO ABANA CONCESSION
FIELD BACKGROUND
80 producing wells.
4 natural flowing wells.
74 gas lifted wells.
2 ESP wells.

7. MOKOKO ABANA CONCESSION
FIELD BACKGROUND
Production peak at 50,000 BOPD 1986.
6 sands.
7 fields/blocks
Laminated Sandstone reservoirs.
Water flood initiated 1984.

8. Infrastructure upgraded 1997
MOKOKO ABANA CONCESSION
FIELD BACKGROUND
Infrastructure upgraded 1997
Pumps and compressors installed down field on Echo platform to lower production pipeline pressure.
2 ESP pumps installed 2000.

9. INDIVIDUAL WELL TEST INDICATED FIELD CAPABLE OF PRODUCING
MOKOKO ABANA CONCESSION
PRE-OPTIMIZATION 1/1/2000
INDIVIDUAL WELL TEST INDICATED FIELD CAPABLE OF PRODUCING
26,000 BOPD.
63,000 BWPD
45,510 MCFPD FORMATION
34,000 MCFPD GAS LIFT INJECTION

10. MOKOKO ABANA CONCESSION DAILY AVERAGE PRODUCTION
PRE-OPTIMIZATION 1/1/2000
DAILY AVERAGE PRODUCTION
24,000+ BOPD.
58,152 BWPD
42,009 MCFPD FORMATION
31,385 MCFPD GAS LIFT INJECTION

11. PRE-OPTIMIZATION GAS LIFT SYSTEM PROBLEMS IDENTIFIED.
MOKOKO ABANA CONCESSION
PRE-OPTIMIZATION GAS LIFT SYSTEM PROBLEMS IDENTIFIED.
Gas lift valve calibration arrangement - Cycle time inefficient.
Down hole problems identification - More surveys data needed.
Injection gas pressure low - Best wells in North field.
Manual onsite well by well allocation of gas lift gas.
Surveillance process - Needed improvement.

12. PRE - OPTIMIZATION GAS LIFT SYSTEM PROBLEMS IDENTIFIED.
MOKOKO ABANA CONCESSION
PRE - OPTIMIZATION GAS LIFT SYSTEM PROBLEMS IDENTIFIED.
Extended kick off time after compressors shut downs.
Freezing at injection gas control valves.
Low rate wells using excess gas lift gas.
Multi zone production.
Wells data files - Incomplete.

13. MOKOKO ABANA CONCESSION
PROBLEM DISCUSSION
Gas lift valve calibration - Cycle time inefficient
Gas Lift valves and stock located onshore.
Setup and calibration performed onshore by vendor.
2 weeks cycle time from problem identification to remedial action.

14. MOKOKO ABANA CONCESSION
ACTION/RESULTS
Purchased and installed valve calibration unit offshore.
Moved valve inventory to offshore location.
Altec technician trained Pecten personnel in valve calibration
Time lapse from identification to implementation cut to few hours.
Valves tested for stem travel.
Check valve integrity tested.
Check valve function ability checked (sticking in low pressure seal)
Designed for port sizes identified and adhered to.
Valves flexed and aged previous to final calibration.

15. Down hole problem identification - More survey data needed
MOKOKO ABANA CONCESSION
PROBLEM DISCUSSION
Down hole problem identification - More survey data needed
Appropriate tool to run pressure gauges not existing - common practice was to choke / shut-in well until gauges were at lowest point, then re-open well.
Well test taken during survey not representative due to the above.
Annular fluid levels - not available.

16. MOKOKO ABANA CONCESSION
ACTION/RESULTS
Purchased Anti-blowup tools.
Purchased Echometer for annular fluid level identification.
Offshore personnel trained on the use of above mentioned tools.
More Flowing surveys are being performed.
Test data more accurate.
Annular fluid levels taken on every gas lifted well: 17 wells found not to be lifting at lowest possible point.
Pecten purchasing Shell Line for real time surface readout pressure data gathering and surveillance enhancement.

17. Injection gas pressure low - Best wells in North field
MOKOKO ABANA CONCESSION
PROBLEM DISCUSSION
Injection gas pressure low - Best wells in North field
900# 2,590 MCFPD
900# 1,137 MCFPD
970# 2,546 MCFPD
EXCESS GAS
890# 3,454 MCFPD
930# 2,255 MCFPD
980# 4,303 MCFPD
880# 4,641 MCFPD
990# 5,860 MCFPD
1000#
980# 3,945 MCFPD
840# 3,728 MCFPD
990# 725 MCFPD
OIL SALES

18. MOKOKO ABANA CONCESSION
ACTION/RESULTS
Revised gas lift designs for platforms nearest compression point to preserve pipeline pressure.
Replaced orifice valves with live valves to:
1 - Prevent casing bleed down during system upsets
2 - Get full benefit of gas lift pressure
Optimized injection gas to each well as per Winglue projection.
Recovery time after system upsets improved ( eliminated re-pressuring of annular areas )
Reduced injection gas volumes to high water cut wells.
Improved available injection gas volumes/pressures in North field.

19. Manual onsite well by well allocation of gas lift gas
MOKOKO ABANA CONCESSION
PROBLEM DISCUSSION
Manual onsite well by well allocation of gas lift gas
Recovery time is delayed by re-pressuring wells after systems upsets.
High water cut wells located nearest compression point take priority when coming back online.

20. MOKOKO ABANA CONCESSION
ACTION/RESULTS
Developing system to provide computer control of gas volume.
Installing gas lift automation on platforms and wells.
Gas lift project testing and installation phase in progress.
Implementation of Field Ware application for remote control of gas lifted wells/lift gas allocation.

21. Surveillance process - Needed improvement
MOKOKO ABANA CONCESSION
PROBLEM DISCUSSION
Surveillance process - Needed improvement
Earlier attempts at surface injection gas optimization had not been successful.
Recommended field wide gas lift allocation - not successful.

22. MOKOKO ABANA CONCESSION
ACTION/RESULTS
Altec technician trained all field personnel in basic gas lift principles, optimization, trouble shooting techniques.
Altec technician visited each platform with senior operator - Discussed each well focussing on:
1 - Injection gas pressure available on platform
2 - Wells with freezing problems across manual control valve
3 - Wells that require manipulation to kick-off
Staffed well analyst position offshore.
Buy in from:
* Production operators
* Operations foremen
* Production advisors
* Engineering

23. MOKOKO ABANA CONCESSION
PROBLEM DISCUSSION
Extended kick-off time after compressors shut downs
Freezing at injection gas control valves
Wells would not kick-off after extended shut-downs due to:
1 - Improper gas lift valves designs
2 - Large ported valves used
Incorrect thermal gradients data used in simulations/analysis.

24. MOKOKO ABANA CONCESSION
ACTION/RESULTS
Reviewed gas lift designs and implemented changes.
Designed gas lift with IPO valve as operating valve.
Eliminated methanol injection on “C” and “D” platforms.
Reduced cycle time after systems upsets and platform shut-downs.
Increased operating casing pressure allowing better recovery time.

25. Low rate wells using excess gas lift gas
MOKOKO ABANA CONCESSION
PROBLEM DISCUSSION
Low rate wells using excess gas lift gas
Wells producing less than 200 BFPD required a high GLR to keep them in stable flow.

26. MOKOKO ABANA CONCESSION
ACTION/RESULTS
Checked annular fluid levels for all wells.
Modeled wells for intermittent lift application.
Installed Altec 1” ABBA(TM) pilot valve along with standing valve in intermittent lift candidates.
Averaged 17% increase in oil production from candidates wells.
Averaged 22% decrease in injection gas to candidate wells.

27. Multi zones production
MOKOKO ABANA CONCESSION
PROBLEM DISCUSSION
Multi zones production
Most wells have more than one selective isolated between packers.
Zones produced individually - Production not optimized.

28. MOKOKO ABANA CONCESSION
ACTION/RESULTS
Set standing valve between zones when lower interval is lower pressure:
* Preventing cross flow during shut-ins / production.
*Allows multiple zones to remain open and contribute as pressures allows.
More sands produced through same conduit, depleting reserves in a more timely manner.
Zones commingled with standing valves have exceeded modeled production rates and reserves estimations

29. Wells data files - Incomplete
MOKOKO ABANA CONCESSION
PROBLEM DISCUSSION
Wells data files - Incomplete
Well work data, well model files, installation drawings or designs - not consolidated.
Data files incomplete and not updated.

30. MOKOKO ABANA CONCESSION
ACTION/RESULTS
Build electronic well summary for each well.
Performed well work is reported and available onshore electronically.
Winglue database is maintained on a shared drive in network.
Databases are checked for accuracy before use.
Common and correct/updated database accessible by all.
Migration to WellView software to capture lessons learned.

31. Summary / Results MOKOKO ABANA CONCESSION 1573 BOPD gained
Optimization training and calibration facility setup June/July 2000
Well work proceeded October 2000 ( 45 wells program )
Well work approximately 75% completed
More efficient surveillance process
Results to date are as follows:
1573 BOPD gained
-1374 MCFGPD less injection required
Quicker recovery time after upsets
Average daily production above 26,000 BOPD

32. MOKOKO ABANA CONCESSION
TRACKING SPREADSHEET