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2001 ASME/API Gas-Lift Workshop

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Presentation on theme: "2001 ASME/API Gas-Lift Workshop"— Presentation transcript:

1 2001 ASME/API Gas-Lift Workshop
Testing and Modeling Gas-Lift Valves by Ken Decker, Decker Technology Cleon Dunham, Oilfield Automation Consulting Feb. 6, 2001 2001 ASME/API Gas-Lift Workshop

2 Testing and Modeling Gas-Lift Valves
Outline Gas-lift valves are important API Recommended Practice 11V2 Gas-lift Valve Performance Clearinghouse (VPC) VPC members Valves tested by VPC Typical VPC results How member companies use VPC results Future plans Feb. 6, 2001 2001 ASME/API Gas-Lift Workshop

3 Gas-Lift Valves Are Important
Gas-lift valves are needed to: Allow gas-lift wells to unload (work down) to the desired operating depth Remain open and transmit enough gas to allow transfer to the next valve Remain in good condition during unloading Not be eroded by completion fluid Close and remain closed when lifting from deeper Not leak Not allow well fluids to back flow into the annulus Re-open when needed for re-start (kick off) Feb. 6, 2001 2001 ASME/API Gas-Lift Workshop

4 API Recommended Practice 11V2
Prior to API RP 11V2: Gas-lift valve open/close calculations based on steady state force/balance equation Gas passage based on Thornhill-Craver These didn't represent real performance in dynamic operation Gas-lift designers were forced to use rules of thumb API RP 11V2 published in January, 1995 Provided standards for gas-lift valve testing & modeling But offered no specific process to implement these standards on a routine basis Feb. 6, 2001 2001 ASME/API Gas-Lift Workshop

5 Gas-Lift Valve Performance Clearinghouse (VPC)
VPC formed in 1996 as JIP (joint industry project) to test & model valves VPC tests a gas-lift valve to determine: When it will open/re-open under dynamic conditions How far it will open under various upstream & downstream pressure conditions How much gas it will transmit at each opening When it will close under dynamic conditions If a valve does not open, move, or close correctly, this is detected Typically, one example valve of each type or model is tested Feb. 6, 2001 2001 ASME/API Gas-Lift Workshop

6 Gas-Lift Valve Performance Clearinghouse (VPC)
Based on these tests, the VPC develops accurate gas-lift valve performance models To develop these models, the VPC determines: Accurate opening pressure, at operating temperature Accurate closing pressure, at operating conditions Flow characteristic (Cv) of valve Load rate of bellows and/or spring Maximum effective stem travel These models can be used for: Gas-lift design Gas-lift performance analysis Comparing actual vs. theoretical performance Feb. 6, 2001 2001 ASME/API Gas-Lift Workshop

7 Original and Current Members of the VPC
VPC Member Companies Initial Members 2001 Members Chevron Chevron Edinburgh Petroleum Services Exxon/Mobil (pending) Exxon PDVSA (pending) Shell International Shell International Weatherford Weatherford Feb. 6, 2001 2001 ASME/API Gas-Lift Workshop

8 Gas-Lift Valves Tested and Modeled by the VPC
Gas-Lift Valves and Orifices Tested/Modelled by the VPC Through 2000 1" IPO Gas-Lift Valves Altec AT1-CF, Camco BK, Weatherford R-1, Weatherford R-1BL, Camco/Merla NM-16R, McMurry Macco R-1D, McMurry Macco JR-STDN, McMurry Macco C-1 1" PPO Gas-Lift Valves Camco BKF-6, Camco BKR-5, Camco SRF-10, McMurry Macco RF-1, Weatherford RF-1BL 1" Alternative Operation Gas-Lift Valves Altec AT1-VL, Weatherford RPDV-2, Camco/Merla LNM-31R, Camco/Merla WFM-14R 1.5" IPO Gas-Lift Valves Camco R-20, Weatherford R-2, Camco/Merla N-17R, McMurry Macco C2 1" Gas-Lift Orifices Camco NOVA, Camco DCR-DK Feb. 6, 2001 2001 ASME/API Gas-Lift Workshop

9 Typical VPC Gas-Lift Valve Performance Plot
Camco BK. 1" IPO VPC Performance Model Various Port Sizes No Choke 20/64" 16/64" 12/64" Feb. 6, 2001 2001 ASME/API Gas-Lift Workshop

10 How Member Companies Use VPC Results
For example, in Shell: Only gas-lift valves that have been tested and modeled by the VPC are recommended for use Any valve found to be inadequate is not recommended for use VPC gas-lift valve models have been implemented in WinGLUE They are used in gas-lift design & performance analysis In some cases, valves that have been found to be inadequate have been redesigned or replace by the manufacturer This is clearly a win/win for all concerned Feb. 6, 2001 2001 ASME/API Gas-Lift Workshop

11 2001 ASME/API Gas-Lift Workshop
Future Plans of the VPC In 2001 and beyond, the VPC members have agreed to: Continue gas-lift valve testing and modeling Valves/orifices nominated by users Selected new valves Several valves of a type/model to check for consistency Conduct appropriate evaluations Potential for erosion during unloading Effect of chokes on erosion potential Potential life cycle of bellows Impact of various metallurgies Feb. 6, 2001 2001 ASME/API Gas-Lift Workshop

12 Other Companies are Welcome to Join the VPC
The VPC is a "joint industry project." It is funded and controlled by its members It is not a profit making organization Its purpose is to advance gas-lift performance through improved gas-lift valve understanding Any gas-lift operator or service company is welcome The VPC meets annually, usually in October, to agree on the budget and plan for the next year Member companies have found great value in: Having accurate, reliable information on their valves Having accurate performance models of their valves Being able to screen out valves that are not satisfactory Feb. 6, 2001 2001 ASME/API Gas-Lift Workshop

13 Testing and Modeling Gas-Lift Valves
Conclusions Most gas-lift wells require gas-lift valves to lift effectively Valves do not perform as previously assumed The steady state force balance equation is not sufficient Thornhill-Craver can not accurately predict gas passage To effectively design and analyze gas-lift wells, we must understand gas-lift valve performance API RP 11V2 provides the needed standards The VPC provides the mechanism to implement these standards for the industry Feb. 6, 2001 2001 ASME/API Gas-Lift Workshop

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