Transcript 2000 ASME/API Gas-Lift Workshop

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
1
Testing and Modeling
Gas-Lift Valves
Outline
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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
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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
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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
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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
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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:
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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
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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
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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
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Typical VPC Gas-Lift Valve
Performance Plot
Typical VPC Gas-Lift Valve Performance Plot
Flowrate - (Mscf/d)
1500
Camco BK. 1" IPO
VPC Performance Model
Various Port Sizes
No Choke
Camco BK with
12/64ths VPC
PvoT= 964 Pcf=
920 Temp=150
1000
Camco BK with
16/64ths VPC
PvoT= 964 Pcf=
920 Temp=150
20/64"
500
16/64"
Camco BK with
20/64ths VPC
PvoT= 964 Pcf=
920 Temp=150
12/64"
0
0
200
400
600
800
1000
Downstream Pressure - (psig)
November 12, 2001
2001 Fall ASME/API Gas-Lift Workshop
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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
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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
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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
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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
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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
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