2001 ASME/API Gas-Lift Workshop Testing and Modeling Gas-Lift Valves by Cleon Dunham, Oilfield Automation Consulting Ken Decker, Decker Technology November 12, 2001 2001 Fall ASME/API Gas-Lift Workshop

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 November 12, 2001 2001 Fall ASME/API Gas-Lift Workshop

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) November 12, 2001 2001 Fall ASME/API Gas-Lift Workshop

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 November 12, 2001 2001 Fall ASME/API Gas-Lift Workshop

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 November 12, 2001 2001 Fall ASME/API Gas-Lift Workshop

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 November 12, 2001 2001 Fall ASME/API Gas-Lift Workshop

Original and Current Members of the VPC VPC Member Companies Initial Members 2001 Members Chevron Chevron Edinburgh Petroleum Services Exxon/Mobil Exxon Shell International Shell International Weatherford Weatherford November 12, 2001 2001 Fall ASME/API Gas-Lift Workshop

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, Camco BKF-12, McMurry Macco RF-1, Weatherford RF-1BL, Weatherford RFX-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 Altec AT1-0, Camco NOVA, Camco DCR-DK November 12, 2001 2001 Fall ASME/API Gas-Lift Workshop

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" November 12, 2001 2001 Fall ASME/API Gas-Lift Workshop

How Member Companies Use VPC Results For example, in at least one member company: 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 November 12, 2001 2001 Fall ASME/API Gas-Lift Workshop

2001 Fall 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 November 12, 2001 2001 Fall ASME/API Gas-Lift Workshop

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 February or 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 November 12, 2001 2001 Fall ASME/API Gas-Lift Workshop

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 November 12, 2001 2001 Fall ASME/API Gas-Lift Workshop