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Walrick van Zandvoord PDO2003 Fall Gaslift workshop Kuala Lumpur - 21 & 22 October 2003
Petroleum Development Oman
Gaslift Management in PDO
Gaslift Management in PDONorthern Directorate
By Walrick van Zandvoord
Walrick van Zandvoord PDO2003 Fall Gaslift workshop Kuala Lumpur - 21 & 22 October 2003
Petroleum Development Oman
Gaslift Management in PDO
• Introduction• Designs, Improvements, Opportunities and challenges• Gaslift management and processes• Automatic Validation Tester (AVT) and Wireless gaslift
trial• Overview per area and examples• Conclusion
Gaslift Management in PDO Agenda
Walrick van Zandvoord PDO2003 Fall Gaslift workshop Kuala Lumpur - 21 & 22 October 2003
Petroleum Development Oman
Gaslift Management in PDO
Location
• Country size similar to Kansas
• Population 2.5 million
• Accelerated development
• 75 % income depends on hydrocarbon
Walrick van Zandvoord PDO2003 Fall Gaslift workshop Kuala Lumpur - 21 & 22 October 2003
Petroleum Development Oman
Gaslift Management in PDO
People
Walrick van Zandvoord PDO2003 Fall Gaslift workshop Kuala Lumpur - 21 & 22 October 2003
Petroleum Development Oman
Gaslift Management in PDO
People
Walrick van Zandvoord PDO2003 Fall Gaslift workshop Kuala Lumpur - 21 & 22 October 2003
Petroleum Development Oman
Gaslift Management in PDO
Beaches & Wadis
Walrick van Zandvoord PDO2003 Fall Gaslift workshop Kuala Lumpur - 21 & 22 October 2003
Petroleum Development Oman
Gaslift Management in PDO
MUSCAT
Sur
Sohar
Salalah
ARABIAN SEA
GULF OF OMAN
100 km
• PDO (since ‘66) is a JV between60 % Government of Oman34 % Shell4 % TotalFina2 % Partex
• Shell is technical advisor
Production 700 kb/d (90% of Oman’s
Oil production)
66 producing stations
117 oil producing fields
Over 3000 active wells
620 gaslift strings. 28% of production,
200,000 bbl/d
85% of gaslift production from North
Majority of fields under water flood
Walrick van Zandvoord PDO2003 Fall Gaslift workshop Kuala Lumpur - 21 & 22 October 2003
Petroleum Development Oman
Gaslift Management in PDO
Gaslift wells in the Northern Directorate
• The North of PDO has primarily carbonate reservoirs with depths varying from as shallow as 800m to 2700m deep.
• Now there are approximately 500 Gaslift wells constituting 50% of the oil producers.
• In the North, Gaslift wells produce 45% of the oil and 42% of the gross.
Walrick van Zandvoord PDO2003 Fall Gaslift workshop Kuala Lumpur - 21 & 22 October 2003
Petroleum Development Oman
Gaslift Management in PDO
Design
• Design in most wells has 2 to 5 mandrels, depending on well depth and expected deepest operating point
• IPO valves are run in >95% of the wells• Mostly unloading valve sizes are the same as operating valve
size to allow the operating point to be the orifice or unloading valve.
• Redesigns are done where well behaviour becomes too unstable
Walrick van Zandvoord PDO2003 Fall Gaslift workshop Kuala Lumpur - 21 & 22 October 2003
Petroleum Development Oman
Gaslift Management in PDO
Initial Performance
Operating @ mandrel 2 (through
unloading valve)
Later Performance
Operating @ mandrel 4
Future Performance
after on-stream of Water Injector
Operating @ mandrel 3 (through
unloading valve)
Walrick van Zandvoord PDO2003 Fall Gaslift workshop Kuala Lumpur - 21 & 22 October 2003
Petroleum Development Oman
Gaslift Management in PDO
Optimisation and Challenges
• Well by Well– Unstable wells– Leaking valves or tubing– Well integrity (e.g. liftgas injected in shallow aquifers)– Possibility to lift deeper– Scale clean outs
• Group optimisation– Surface controlled gaslift rates through SCADA / DCS– Set-points based on optimal distribution of liftgas using WinGLUE– Tables are created for different compressor availabilities for optimal
distribution.
Walrick van Zandvoord PDO2003 Fall Gaslift workshop Kuala Lumpur - 21 & 22 October 2003
Petroleum Development Oman
Gaslift Management in PDO
• Group optimisation - Continued– Optimally distribute– Minimise deferment when compressors are down
• Challenges– Gas measurements are of insufficient quality. Flowing surveys are
therefore essential – Well integrity problems are experienced in some areas, e.g. tubing
leaks, mandrel leaks, casing leaks
Optimisation and Challenges
Walrick van Zandvoord PDO2003 Fall Gaslift workshop Kuala Lumpur - 21 & 22 October 2003
Petroleum Development Oman
Gaslift Management in PDO
• Challenges - Continued– Long integrity repair jobs– Well integrity problems has Impact on well models– Continuous changes in the reservoir pressure, PI, water cut etc. – The dynamics of reservoir not captured in well models. – Young & bright, but in-experienced production engineers.
• Solutions– Dedicated production engineers on well integrity– Surveillance engineers responsible for only 50 - 70 wells in total– Intensive training and bringing in coaches
Optimisation and Challenges
Walrick van Zandvoord PDO2003 Fall Gaslift workshop Kuala Lumpur - 21 & 22 October 2003
Petroleum Development Oman
Gaslift Management in PDO
Process
• Dedicated gaslift process– Monitor and trouble shoot using SCADA and test data– Understand the problem and correct– Further investigation– Analyse results of investigation– Determine improvement potential, costs and justify activity. – Design new gaslift string and schedule activity– Set valves, check valves with AVT tester, test old valves and feedback– Kick off the well and evaluate the results– Review and file report
Walrick van Zandvoord PDO2003 Fall Gaslift workshop Kuala Lumpur - 21 & 22 October 2003
Petroleum Development Oman
Gaslift Management in PDO
Gaslift Control
Gaslift Metering
ReservoirData
Well Data
ProductionData
Tubingpressure
Casingpressure
SCADA
WinGLUEGaslift optimisation
Software
SGAS-CAODirect monitoring
& Control of Individual Wells
DCSControls Gaslift rates to the wells
PDO Gaslift Management Set-up
Walrick van Zandvoord PDO2003 Fall Gaslift workshop Kuala Lumpur - 21 & 22 October 2003
Petroleum Development Oman
Gaslift Management in PDO
• WinGLUE gaslift QC database set up• Automated links• Central storage of gaslift analyses• Most wells available in the SCADA system (RTAP /
SOFS or the latest PC based FIELDWARE). • AVT tester is used for QC valves before running and
recently also pulled valves
Process Improvements
Walrick van Zandvoord PDO2003 Fall Gaslift workshop Kuala Lumpur - 21 & 22 October 2003
Petroleum Development Oman
Gaslift Management in PDO
• Implemented in the well services workshop• TROP, stem travel, R ratio etc. • Rejected at agreed tolerances, e.g. TROP
difference < 15 PSI• >25% of the valves were rejected on TROP. • Visible improvements
Decker’s Automatic Validation Tester (AVT )
Walrick van Zandvoord PDO2003 Fall Gaslift workshop Kuala Lumpur - 21 & 22 October 2003
Petroleum Development Oman
Gaslift Management in PDO
• Testing of pulled valves just started. >60% fail on leaking bellows.
• Keep track of a “problem log” to increase understanding
• Network connection is essential• Staff in the well services more conscious
Decker’s Automatic Validation Tester (AVT )
Walrick van Zandvoord PDO2003 Fall Gaslift workshop Kuala Lumpur - 21 & 22 October 2003
Petroleum Development Oman
Gaslift Management in PDO
Specific Overview per AreaArea L
• Constrained due to flaring restriction (no compressor ullage)• Workshop was organised • Deliverables of the workshop:
– Coaching / training – Saving of 3.6 million scf/d of liftgas– Well integrity problems found and repaired– Detailed gaslift surveillance was carried out and many wells were stabilised– Many gaslift measurements wrong and corrected– For 2003 the estimated impact on production is approximately around 1200
bbl/d.
Walrick van Zandvoord PDO2003 Fall Gaslift workshop Kuala Lumpur - 21 & 22 October 2003
Petroleum Development Oman
Gaslift Management in PDO
Specific Overview per AreaArea Q
• In Area Q, test data quality is an issue • Some wells were found quit based on flowing
surveys• Some wells found with scale obstruction.
Cleaned out and restored. • Total increase in the Area Q was 600 bbl/d or 10%
of the total gaslift production. 3% 2002 year average impact.
Walrick van Zandvoord PDO2003 Fall Gaslift workshop Kuala Lumpur - 21 & 22 October 2003
Petroleum Development Oman
Gaslift Management in PDO
Well was tested at 2000 bbl/d net oil, low BSW
through 3 1/2”
Tubing upsize was expected to double production
Flowing survey could only be matched with 800 bbl/d less and tubing upsize was canceled
Theoretical pressures
Actual pressures
well 110
200 bbl/d gain from switching on gaslift
Walrick van Zandvoord PDO2003 Fall Gaslift workshop Kuala Lumpur - 21 & 22 October 2003
Petroleum Development Oman
Gaslift Management in PDO
Specific Overview per AreaArea F
• Area F consists of two large fields• Field N has mostly natural producers.
– Flow limited by Gas Oil Gravity Drainage (GOGD)
– N compressors are full. Cutting back liftgas looked at.
• Field F is partly water-flood and partly GOGD• Workshop held. Opportunities found:
– Reduce liftgas consumption to free up compressor space (cutting back lift-gas, running velocity strings, 3 1/2” to 2 7/8” tubing)
– Many wells without RTU’s
Walrick van Zandvoord PDO2003 Fall Gaslift workshop Kuala Lumpur - 21 & 22 October 2003
Petroleum Development Oman
Gaslift Management in PDO
Area FWireless Gaslift Valves Trial
• Wireless gaslift valves (2) were installed in a well in Field F in 2002.
• Communication through a modem with PC in CCR and Main Office
• Down-hole pressures and temperatures displayed • Full control from the desktop was achieved• Live optimisation• Modem on bottom valve broke down, but still operating. • Confirmed bad batch of modems (50%)
Walrick van Zandvoord PDO2003 Fall Gaslift workshop Kuala Lumpur - 21 & 22 October 2003
Petroleum Development Oman
Gaslift Management in PDO
Area F Wireless Gaslift Valves Trial
• Business case for large scale implementation being made, but– 15 - 20 times higher costs than conventional gaslift
– Even with one third of costs, large scale implementation means 12,000,000 bbl or 16,000 bbl/d extra production is required or 8% of production.
• Most promising to replace PPO valves
Walrick van Zandvoord PDO2003 Fall Gaslift workshop Kuala Lumpur - 21 & 22 October 2003
Petroleum Development Oman
Gaslift Management in PDO
Specific Overview per AreaArea Y
• Advanced automation; Gaslift control valves linked to the DCS & SCADA. Full control and optimisation.
• Main challenge is well integrity and continuously changing well performance.
• Additional people have been put on the job in Area Y (surveillance engineers). They complement the work of the other production engineers.
• Coaches brought in
Walrick van Zandvoord PDO2003 Fall Gaslift workshop Kuala Lumpur - 21 & 22 October 2003
Petroleum Development Oman
Gaslift Management in PDO
Specific Overview per AreaArea Y - Well Examples
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
25-Apr 25-Apr 25-Apr 25-Apr 25-Apr 25-Apr 25-Apr
Tubing Pressure Casing Pressure
Walrick van Zandvoord PDO2003 Fall Gaslift workshop Kuala Lumpur - 21 & 22 October 2003
Petroleum Development Oman
Gaslift Management in PDO
0
1000
2000
3000
4000
5000
6000
7000
22-Sep 22-Sep 22-Sep 22-Sep 22-Sep 22-Sep 22-Sep 22-Sep
Tubing Pressure Casing Pressure
Specific Overview per AreaArea Y - Well Examples
Walrick van Zandvoord PDO2003 Fall Gaslift workshop Kuala Lumpur - 21 & 22 October 2003
Petroleum Development Oman
Gaslift Management in PDO
Benefits
• Reduction in Liftgas usage (~2.5 mln m3/d)• Cost savings on Gaslift compressor requirements.• Enabled production of high GOR wells• Create compressor capacity to handle new oil producers.• Stabilising wells• In some cases lifting deeper• Sum of the measurable initial production increases after
activities in 2003 is around 4500 bbl/d (2% of total North) with. Year average value is 0.7%.
Walrick van Zandvoord PDO2003 Fall Gaslift workshop Kuala Lumpur - 21 & 22 October 2003
Petroleum Development Oman
Gaslift Management in PDO
What is happening next …..?
• Further enhance staff competence and skills• Complete implementation of the AVT tester• Trial new technology such as Bubble breaker, Bubble
gaslift and surface controlled gaslift valves• Bringing in a dedicated production engineer for gaslift• Continue with the efforts, because it pays back.