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

“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. MOKOKO ABANA CONCESSION. Achievements.

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

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  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 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 Concessionis 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 1982-1990. • 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. 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. 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 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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

  32. MOKOKO ABANA CONCESSION TRACKINGSPREADSHEET

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