Optimized lower pressure limit for condensate underground gas storage using a dynamic pseudo-component model

Abstract

In the context of gas injection in reservoirs, the dilution process of components' thermodynamic properties has not been adequately represented in traditional numerical simulation methods. This study focuses on the Dalaoba condensate underground gas storage (CUGS) in China and establishes a dynamic pseudo-component model to identify the equilibrium point for gas storage facility efficiency and the condensate oil recovery rate. Using a multi-objective particle swarm optimization approach, thermodynamic parameters are estimated as functions of the injected gas volume. This dynamic pseudo-component model is then utilized to find the optimized lower pressure limit for CUGS by assessing condensate oil production, gas flow capability, and water encroachment. Results show that the dynamic pseudo-component model can represent the process of thermodynamic property changes towards lighter components during natural gas injection. The case study demonstrates that conventional models overestimate condensate oil production, while the dynamic model achieves an accuracy rate of 92.8 % with historical data. The dynamic pseudo-component model offers valuable insights for large-scale gas injection simulation, promoting stable and efficient natural gas storage and supply in CUGS.