Long Term Testing of Liquid Flow Through Gas Lift Valves

This paper presents the results obtained in an extensive Gas Lift Valves (GLVs)flow trials, which were performed in an experimental liquid flow test loop. The objective was to evaluate GLVs performance with respect to their back flow retention condition, after being exposed to large volumes of flowing liquids. In case of a check valve failure, remediation strategies were also presented and evaluated. Four different GLVs were subjected to brine flow. The tests consisted of a minimum of 15 flow cycles comprising a volume of 150 m3 (942 bbl) each, at a flowrate of 0.32 m3/min (2 bbl/min). In between cycles, the GLV was tested for back flow. The check valve test was performed with the GLV installed in its original position at the flow test loop (i.e., no need to disassemble the GLV and move it to another facility). In case of back flow failure detection, remediation strategies, such as flushing with industrial water and cycles of pressurization and depressurization, were tested. None of the four GLVs tested completed the minimum of 15 cycles without any failure. After flushing the system with industrial water, three GLVs regained its back flow retention capabilities and the other still presented the back flow failure. In some cases, the check valve presented failure when tested inside the flow loop, but did not present the same failure when moved to the Nitrogen/calibration test bench. This event has indicated the importance of testing the back flow retention inside the flow test loop. It was also observed that pressurization and de-pressurization speed can affect the results. Testing of liquid flow through GLVs usually involves a small volume of liquid, which may not be enough to cause problems with the check valve. In this paper we present new tests results with larger liquid volumes of liquid passing through the GLVs. The results are important to understand the condition of GLVs to handle higher flow liquid volumes.