2001 ASME/API Gas-Lift Workshop

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

2. Testing and ModelingGas-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 2001 ASME/API Gas-Lift Workshop

3. Gas-Lift ValvesAre 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) 2001 ASME/API Gas-Lift Workshop

4. API RecommendedPractice 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 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 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 2001 ASME/API Gas-Lift Workshop

7. Original and Current Membersof the VPC • VPC Member Companies • Initial Members2001 Members • Chevron Chevron • Edinburgh Petroleum Services Exxon/Mobil (pending) • Exxon PDVSA (pending) • Shell International Shell International • Weatherford Weatherford 2001 ASME/API Gas-Lift Workshop

8. Gas-Lift Valves Testedand 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 2001 ASME/API Gas-Lift Workshop

9. Typical VPC Gas-Lift Valve Performance Plot • 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" 2001 ASME/API Gas-Lift Workshop

10. How Member CompaniesUse 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 2001 ASME/API Gas-Lift Workshop

11. 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 2001 ASME/API Gas-Lift Workshop

12. Other Companies areWelcome 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 2001 ASME/API Gas-Lift Workshop

13. Testing and ModelingGas-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 2001 ASME/API Gas-Lift Workshop