PRESENTED BY: ANDREW MABIAN PECTEN CAMEROON COMPANY Subsidiary of SHELL E&P Int’l PREPARED BY:

1. “A PRACTICAL APPROACH TO OPTIMIZING A MATURING FIELD” PRESENTED BY: ANDREW MABIAN PECTEN CAMEROON COMPANY Subsidiary of SHELL E&P Int’l PREPARED BY: ANDREW MABIAN PECTEN CAMEROON COMPANY SAM WILDMAN ALTEC GAS LIFT, INC ASME Gas Lift workshop - 2001

2. MOKOKO ABANA CONCESSION FIELD LAYOUT

3. MOKOKO ABANA CONCESSION FIELD BACKGROUND • Drilling of the field initiated 1982. • 9 platforms set and drilled 1982-1990. • 12 platforms by 1997. • 11 producing platforms.

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

5. 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.

6. 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

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

8. 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.

9. 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. • Designed for port sizes identified and adhered to. • Valves flexed and aged previous to final calibration.

10. 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.

11. 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.

12. 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

13. 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.

14. 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.

15. MOKOKO ABANA CONCESSION ACTION/RESULTS • Developing system to provide computer control of gas volume. • Installing gas lift automation on platforms and wells. • Gas lift Automation System commissioned. • FieldWare GasLift application for remote monitoring and control of gas lifted wells/lift gas allocation in place.

16. 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.

17. 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

18. 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.

19. 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.

20. 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.

21. 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.

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

23. 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

24. MOKOKO ABANA CONCESSION Summary / Results 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

25. MOKOKO ABANA CONCESSION PROBLEM DISCUSSION Possible to use Simultaneous G/L and ESP? • Evaluate and address Risks • Establish Benchmarks • Test operation and measure results

26. I-8 ESP and Gas Lift - Completion sketch

27. MOKOKO ABANA CONCESSION I-8 Completion design: Cable issues Risks Ingress of gas to cable - explosive decompression causing damage ==> Lead sheathed cable (REDALEAD size 4, galv armor) Ingress of gas through field splice/pothead ==> No field splice - cable splice done in factory before shipping QCI penetrator ==> Checked gas tolerant within expected conditions Critical issue is pressure bleed down of casing ==> Sought advice from REDA, applied additional factor to avoid bleeding pressure down too quickly.

28. MOKOKO ABANA CONCESSION I-8 ESP and Gas Lift ESP ESP + gas lift Gas lift ESP + gas lift

29. MOKOKO ABANA CONCESSION Flowing Pressure during Trial ESP only ESP + G/L G/L only ESP + G/L BHP lowered only slightly with ESP+gas lift (Higher BHP with gas lift only)

30. MOKOKO ABANA CONCESSION Water Cut - 2001 Steady increase in water cut vs. time

31. MOKOKO ABANA CONCESSION Recommendations Continue trial on I-8 to validate water cut trends Test on “gas lift only” again (once water cut stable) to validate water cut trends with different drawdowns Possible to apply ESP+G/L technique on other platforms if well productivities exceed pump capacities

32. 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.

33. 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.