Abstract
The main objectives of this study were to test three one-inch nitrogen-charged gas-lift valves from different manufacturers and to develop or modify existing procedures to accurately predict valve flow performance. During the testing program more than 360 air flow performance curves were collected under simulated downhole conditions. Injection pressures ranged from 400 psig to 1800 psig and sampled data included orifice, throttling and transition flow regimes. Various techniques to calculate the minimum injection pressure to sustain orifice flow based on the dynamic tubing sensitivity, were also investigated.
Testing demonstrated that different valves experience different flow rates, even when the port sizes installed in the gas-lift valves are the same. Our study showed that one-inch valves have lower flow capacities than 1-1/2-inch valves. Various sensitivity tests were performed to identify which valve components obstruct the flow in the smaller valves. Testing procedures to fully describe the flow characteristics of gas-lift valves are also presented. These procedures were proposed to be adopted as API Recommended Practice 11V2 for gas-lift valve testing methods.
