Numerical Simulation Analysis and Structural Optimization of a Gas Jet Pump

To address the liquid-loading problem at the bottom of deep gas-reservoir wells, a gas-driven jet pump for downhole deliquification was designed, and its key geometric parameters were optimized. Using high-pressure natural gas as the motive fluid, the device achieves stable liquid lifting and continuous drainage through efficient gas–liquid mixing. In this study, the internal flow characteristics of the gas jet pump were numerically investigated using CFD simulations within a steady VOF-RSM multiphase turbulence framework. Published experimental data for a prototype from the open literature were used to validate the numerical model, and the maximum relative deviation between simulation and measurement was 17.5%, satisfying the accuracy requirements for engineering CFD analysis. The effects of three key structural parameters—area ratio, nozzle-to-throat distance, and throat length-to-diameter ratio—on the liquid production rate and pumping efficiency were systematically examined through single-factor sensitivity analysis combined with an orthogonal experimental design. Range analysis showed the following order of influence: area ratio > throat length-to-diameter ratio > nozzle-to-throat distance. The optimal parameter combination was determined as an area ratio of 0.0494, a throat length-to-diameter ratio of 5, and a nozzle-to-throat distance of 7.2 mm. Under this optimized configuration, the maximum liquid production rate reaches 80 m3/d. To achieve a target liquid production rate of 20 m3/d, the required gas injection rate is reduced by 33%, and a peak pumping efficiency of 7.2% is achieved at gas injection rates between 2000 and 3000 m3/d.