November 12, 2001 2001 Fall ASME/API Gas-Lift Workshop 1

2001 ASME/API Gas-Lift Workshop2001 ASME/API Gas-Lift Workshop

Testing and Modeling Gas-Lift ValvesTesting and Modeling Gas-Lift Valves

byby

Cleon Dunham, Oilfield Automation Consulting Cleon Dunham, Oilfield Automation Consulting

Ken Decker, Decker TechnologyKen Decker, Decker Technology

November 12, 2001 2001 Fall ASME/API Gas-Lift Workshop 2

Testing and ModelingTesting and ModelingGas-Lift Valves Gas-Lift Valves

OutlineOutline• Gas-lift valves are importantGas-lift valves are important• API Recommended Practice 11V2API Recommended Practice 11V2• Gas-lift Valve Performance Clearinghouse (VPC)Gas-lift Valve Performance Clearinghouse (VPC)• VPC membersVPC members• Valves tested by VPCValves tested by VPC• Typical VPC resultsTypical VPC results• How member companies use VPC resultsHow member companies use VPC results• Future plansFuture plans

November 12, 2001 2001 Fall ASME/API Gas-Lift Workshop 3

Gas-Lift ValvesGas-Lift ValvesAre Important Are Important

Gas-lift valves are needed to:Gas-lift valves are needed to:• Allow gas-lift wells to unload (work down) to the Allow gas-lift wells to unload (work down) to the

desired operating depthdesired operating depth• Remain open and transmit enough gas to allow Remain open and transmit enough gas to allow

transfer to the next valvetransfer to the next valve• Remain in good condition during unloadingRemain in good condition during unloading

– Not be eroded by completion fluidNot be eroded by completion fluid

• Close and remain closed when lifting from deeperClose and remain closed when lifting from deeper– Not leakNot leak– Not allow well fluids to back flow into the annulusNot allow well fluids to back flow into the annulus

• Re-open when needed for re-start (kick off)Re-open when needed for re-start (kick off)

November 12, 2001 2001 Fall ASME/API Gas-Lift Workshop 4

API RecommendedAPI RecommendedPractice 11V2 Practice 11V2

Prior to API RP 11V2:Prior to API RP 11V2:• Gas-lift valve open/close calculations based on Gas-lift valve open/close calculations based on

steady state force/balance equationsteady state force/balance equation• Gas passage based on Thornhill-CraverGas passage based on Thornhill-Craver

– These didn't represent real performance in dynamic These didn't represent real performance in dynamic operationoperation

– Gas-lift designers were forced to use rules of thumbGas-lift designers were forced to use rules of thumb

• API RP 11V2 published in January, 1995API RP 11V2 published in January, 1995– Provided standards for gas-lift valve testing & modelingProvided standards for gas-lift valve testing & modeling– But offered no specific process to implement these But offered no specific process to implement these

standards on a routine basisstandards on a routine basis

November 12, 2001 2001 Fall ASME/API Gas-Lift Workshop 5

Gas-Lift Valve Performance Gas-Lift Valve Performance Clearinghouse (VPC) Clearinghouse (VPC)

VPC formed in 1996 as JIP (joint industry VPC formed in 1996 as JIP (joint industry project) to test & model valvesproject) to test & model valves

• VPC tests a gas-lift valve to determine:VPC tests a gas-lift valve to determine:– When it will open/re-open under dynamic conditionsWhen it will open/re-open under dynamic conditions– How far it will open under various upstream & How far it will open under various upstream &

downstream pressure conditionsdownstream pressure conditions– How much gas it will transmit at each openingHow much gas it will transmit at each opening– When it will close under dynamic conditionsWhen it will close under dynamic conditions

• If a valve does not open, move, or close correctly, If a valve does not open, move, or close correctly, this is detectedthis is detected

• Typically, one example valve of each type or Typically, one example valve of each type or model is testedmodel is tested

November 12, 2001 2001 Fall ASME/API Gas-Lift Workshop 6

Gas-Lift Valve Performance Gas-Lift Valve Performance Clearinghouse (VPC) Clearinghouse (VPC)

Based on these tests, the VPC develops Based on these tests, the VPC develops accurate gas-lift valve performance modelsaccurate gas-lift valve performance models

• To develop these models, the VPC determines:To develop these models, the VPC determines:– Accurate opening pressure, at operating temperatureAccurate opening pressure, at operating temperature– Accurate closing pressure, at operating conditionsAccurate closing pressure, at operating conditions– Flow characteristic (Cv) of valveFlow characteristic (Cv) of valve– Load rate of bellows and/or springLoad rate of bellows and/or spring– Maximum effective stem travelMaximum effective stem travel

• These models can be used for:These models can be used for:– Gas-lift designGas-lift design– Gas-lift performance analysisGas-lift performance analysis– Comparing actual vs. theoretical performanceComparing actual vs. theoretical performance

November 12, 2001 2001 Fall ASME/API Gas-Lift Workshop 7

Original and Current MembersOriginal and Current Membersof the VPC of the VPC

VPC Member CompaniesVPC Member Companies

Initial MembersInitial Members 2001 Members2001 Members

ChevronChevron ChevronChevron

Edinburgh Petroleum ServicesEdinburgh Petroleum Services Exxon/MobilExxon/Mobil

Exxon Exxon Shell InternationalShell International

Shell InternationalShell International WeatherfordWeatherford

Weatherford Weatherford

November 12, 2001 2001 Fall ASME/API Gas-Lift Workshop 8

Gas-Lift Valves TestedGas-Lift Valves Testedand Modeled by the VPC and Modeled by the VPC

Gas-Lift Valves and Orifices Tested/Modelled by the VPC Through 2000Gas-Lift Valves and Orifices Tested/Modelled by the VPC Through 2000  

1" IPO Gas-Lift Valves1" IPO Gas-Lift ValvesAltec AT1-CF, Camco BK, Weatherford R-1, Weatherford R-1BL, Camco/Merla NM-16R, 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-1McMurry Macco R-1D, McMurry Macco JR-STDN, McMurry Macco C-1  

1" PPO Gas-Lift Valves1" PPO Gas-Lift ValvesCamco BKF-6, Camco BKR-5, Camco SRF-10, Camco BKF-12, McMurry Macco RF-1, Camco BKF-6, Camco BKR-5, Camco SRF-10, Camco BKF-12, McMurry Macco RF-1, Weatherford RF-1BL, Weatherford RFX-1BLWeatherford RF-1BL, Weatherford RFX-1BL  

1" Alternative Operation Gas-Lift Valves1" Alternative Operation Gas-Lift ValvesAltec AT1-VL, Weatherford RPDV-2, Camco/Merla LNM-31R, Camco/Merla WFM-14RAltec AT1-VL, Weatherford RPDV-2, Camco/Merla LNM-31R, Camco/Merla WFM-14R  

1.5" IPO Gas-Lift Valves1.5" IPO Gas-Lift ValvesCamco R-20, Weatherford R-2, Camco/Merla N-17R, McMurry Macco C2Camco R-20, Weatherford R-2, Camco/Merla N-17R, McMurry Macco C2  

11" Gas-Lift Orifices" Gas-Lift OrificesAltec AT1-0, Camco NOVA, Camco DCR-DKAltec AT1-0, Camco NOVA, Camco DCR-DK

November 12, 2001 2001 Fall ASME/API Gas-Lift Workshop 9

Typical VPC Gas-Lift Valve Typical VPC Gas-Lift Valve Performance PlotPerformance Plot

Typical VPC Gas-Lift Valve Performance PlotTypical VPC Gas-Lift Valve Performance Plot

Camco BK with12/64ths VPCPvoT= 964 Pcf=920 Temp=150

Camco BK with16/64ths VPCPvoT= 964 Pcf=920 Temp=150

Camco BK with20/64ths VPCPvoT= 964 Pcf=920 Temp=150

Flo

wra

te -

(M

scf/

d)

Downstream Pressure - (psig)

0

500

1000

1500

0 200 400 600 800 1000

Camco BK. 1" IPOVPC Performance ModelVarious Port SizesNo Choke

12/64"

20/64"

16/64"

November 12, 2001 2001 Fall ASME/API Gas-Lift Workshop 10

How Member CompaniesHow Member CompaniesUse VPC Results Use VPC Results

For example, in at least one member company:For example, in at least one member company:• Only gas-lift valves that have been tested and Only gas-lift valves that have been tested and

modeled by the VPC are recommended for usemodeled by the VPC are recommended for use– Any valve found to be inadequate is not recommended Any valve found to be inadequate is not recommended

for usefor use

• VPC gas-lift valve models have been VPC gas-lift valve models have been implemented in WinGLUEimplemented in WinGLUE

– They are used in gas-lift design & performance analysisThey are used in gas-lift design & performance analysis

• In some cases, valves that have been found to be In some cases, valves that have been found to be inadequate have been redesigned or replace by inadequate have been redesigned or replace by the manufacturerthe manufacturer

– This is clearly a win/win for all concernedThis is clearly a win/win for all concerned

November 12, 2001 2001 Fall ASME/API Gas-Lift Workshop 11

Future Plans of the VPC Future Plans of the VPC

In 2001 and beyond, the VPC members have In 2001 and beyond, the VPC members have agreed to:agreed to:

• Continue gas-lift valve testing and modelingContinue gas-lift valve testing and modeling– Valves/orifices nominated by usersValves/orifices nominated by users– Selected new valvesSelected new valves– Several valves of a type/model to check for consistencySeveral valves of a type/model to check for consistency

• Conduct appropriate evaluationsConduct appropriate evaluations– Potential for erosion during unloadingPotential for erosion during unloading– Effect of chokes on erosion potentialEffect of chokes on erosion potential– Potential life cycle of bellowsPotential life cycle of bellows– Impact of various metallurgiesImpact of various metallurgies

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

Other Companies areOther Companies areWelcome to Join the VPC Welcome to Join the VPC

The VPC is a "joint industry project." The VPC is a "joint industry project." • It is funded and controlled by its membersIt is funded and controlled by its members

– It is not a profit making organizationIt is not a profit making organization– Its purpose is to advance gas-lift performance through Its purpose is to advance gas-lift performance through

improved gas-lift valve understandingimproved gas-lift valve understanding– Any gas-lift operator or service company is welcomeAny gas-lift operator or service company is welcome– The VPC meets annually, usually in February or October, The VPC meets annually, usually in February or October,

to agree on the budget and plan for the next yearto agree on the budget and plan for the next year

• Member companies have found great value in:Member companies have found great value in:– Having accurate, reliable information on their valvesHaving accurate, reliable information on their valves– Having accurate performance models of their valvesHaving accurate performance models of their valves– Being able to screen out valves that are not satisfactoryBeing able to screen out valves that are not satisfactory

November 12, 2001 2001 Fall ASME/API Gas-Lift Workshop 13

Testing and ModelingTesting and ModelingGas-Lift Valves Gas-Lift Valves

Conclusions Conclusions • Most gas-lift wells require gas-lift valves to lift Most gas-lift wells require gas-lift valves to lift

effectivelyeffectively• Valves do not perform as previously assumedValves do not perform as previously assumed

– The steady state force balance equation is not sufficientThe steady state force balance equation is not sufficient– Thornhill-Craver can not accurately predict gas passageThornhill-Craver can not accurately predict gas passage

• To effectively design and analyze gas-lift wells, To effectively design and analyze gas-lift wells, we must understand gas-lift valve performancewe must understand gas-lift valve performance

– API RP 11V2 provides the needed standardsAPI RP 11V2 provides the needed standards– The VPC provides the mechanism to implement these The VPC provides the mechanism to implement these

standards for the industrystandards for the industry