API RP 11V2
Gas-lift Valve Performance Testing
|Publication Date:||1 March 2001|
Test site recommendations (Section 3): This section outlines the equipment needed for testing valves to determine the following:
a. Valve flow coefficients (Cv).
b. Pressure drop ratio factor (Xt).
c. Gas-lift valve performance curves.
Gas-lift valve probe tests (Section 4): This test method is outlined for determining the stem travel as pressure is applied over the bellows area. The test results are combined with analysis (Appendix C) to allow the user to approximate the valve load rate over the range of expected practical application conditions. The test also defines the maximum effective valve stem travel.
Flow coefficient test procedure (Section 5): The test procedure recommends test methods required to determine the flow coefficient (Cv) as a function of stem travel. The test results, combined with analysis, allow the user to approximate the valve flow coefficient (Cv) and pressure drop ratio factor (Xt) over the range of expected practical application conditions.
Gas-lift valve performance test methods (Section 6): This test procedure lists the test methods recommended to measure valve performance (flow) for upstream and downstream pressures and other controlled conditions.
Use of test data (Section 7): This section recommends the number of tests which should be performed in order to acquire sufficient data to develop a model or correlation describing valve performance at conditions other than those tested. Reference is made to methods described in Appendices A and B.
Simplified flow performance model (Appendix A): This appendix describes a method of analysis of test data that will predict flow at conditions other than those tested. The model makes several simplifying assumptions concerning valve dynamics.
TUALP flow performance model (Appendix B): This appendix describes a method of analysis of test data that will predict flow at conditions other than those tested. The model was developed and is supported by the Tulsa University Artificial Lift Projects research program at the University of Tulsa.
Method to analyze probe test data (Appendix C): This appendix describes a mathematical method of analysis to determine loadrate and maximum effective travel when data is collected per Section 4.
Determination of test system time constant (Appendix D): This appendix gives the supporting explanation for the use of "ramp" functions in the test methods and describes how to determine a test systems time constant.