26766cbb47cff2943fc9eea85cd4a7c7.ppt
- Количество слайдов: 32
“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 1
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 2
The Mokoko Abana Concession is located approximately 40 miles off Cameroon’s southwest coast. 3
MOKOKO ABANA CONCESSION FIELD LAYOUT 4
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. 5
MOKOKO ABANA CONCESSION FIELD BACKGROUND *80 producing wells. *4 natural flowing wells. *74 gas lifted wells. *2 ESP wells. 6
MOKOKO ABANA CONCESSION FIELD BACKGROUND • Production peak at 50, 000 BOPD 1986. • 6 sands. • 7 fields/blocks • Laminated Sandstone reservoirs. • Water flood initiated 1984. 7
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. 8
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 9
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 10
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. 11
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. 12
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. 13
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. 14
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. 15
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. 16
MOKOKO ABANA CONCESSION PROBLEM DISCUSSION Injection gas pressure low - Best wells in North field 900# 2, 590 MCFPD 970# 2, 546 MCFPD EXCESS GAS 890# 3, 454 MCFPD 930# 2, 255 MCFPD 980# 4, 303 MCFPD 1000# 980# 3, 945 MCFPD 900# 1, 137 MCFPD 990# 725 MCFPD 990# 5, 860 MCFPD 880# 4, 641 MCFPD 840# 3, 728 MCFPD OIL SALES 17
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. 18
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. 19
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. 20
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. 21
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 22
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. 23
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 shutdowns. • Increased operating casing pressure allowing better recovery time. 24
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. 25
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. 26
MOKOKO ABANA CONCESSION PROBLEM DISCUSSION Multi zones production • Most wells have more than one selective isolated between packers. • Zones produced individually - Production not optimized. 27
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 28
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. 29
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 Well. View software to capture lessons learned. 30
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 31
MOKOKO ABANA CONCESSION TRACKING SPREADSHEET 32