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 - 2001

MOKOKO ABANA CONCESSION FIELD LAYOUT

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.

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

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.

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

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

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.

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.

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.

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.

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

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.

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.

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.

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.

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

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.

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.

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.

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.

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.

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

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

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

I-8 ESP and Gas Lift - Completion sketch

I-8 Completion design: Cable issues 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.

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

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)

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

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

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.

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.