Gas-Lift Parameter Optimization Based on Multiphase Production Performance Analysis

Abstract

Abstract. In the middle and late stages of oilfield development, reservoir fluids typically exhibit pronounced multiphase flow behavior, under which conventional single-phase inflow models fail to accurately characterize reservoir deliverability, thereby limiting the accuracy of artificial lift optimization. To address this issue, a dynamic reservoir–wellbore coupled parameter optimization method accounting for multiphase inflow is proposed. Reservoir parameters are inversely estimated using rate transient analysis (RTA), enabling the establishment of a multiphase, dynamic inflow performance model. This model is dynamically coupled with wellbore multiphase flow simulation through the bottomhole flowing pressure node, thereby ensuring consistent interaction between the reservoir and the wellbore. On this basis, a two-stage reservoir–wellbore coupled optimization framework is proposed, in which oil production is first maximized under operational constraints, followed by the minimization of gas injection rate at the optimal bottomhole pressure. Field application demonstrates that, under constraints of production pressure drawdown and wellhead pressure, the optimal bottomhole flowing pressure is identified as 31.0 MPa, corresponding to a stable daily oil production of 60 m3/day. Under this operating condition, the optimal gas-lift injection pressure and injection rate are determined to be 14.0 MPa and 13,000 m3/day, respectively. By integrating multiphase dynamic inversion with reservoir–wellbore coupling, the proposed method effectively resolves the mismatch between reservoir deliverability and wellbore lifting capacity under multiphase flow conditions. The results provide a theoretical basis for the rational design and optimization of artificial lift systems in high-water-cut oil wells.