A prediction method for gas injection and production capacity of underground gas storages rebuilt from water-invasion sandstone gas reservoirs

Gas injection and production capacity prediction is an important link for dynamic evaluation of the multi-cycle operation performance on underground gas storages (UGS) rebuilt from water-invasion sandstone gas reservoirs. It can provide the scientific basis for UGS injection-production optimization and program adjustment. In this paper, the change rate of total cushion gas and working gas was defined. Then, based on the gas-water multiphase flow characteristics of UGS rebuilt from water-invasion sandstone gas reservoirs, a mathematical model for predicting its multi-cycle gas injection and production capacity was established by means of the inventory verification parameter calculation method. This prediction model takes into account not only the effect of UGS capacity expansion on gas injection and production capacity, but also the injected gas loss in the process of water-gas mutual flooding, so the prediction result is much more reliable and regular. It is shown from field application that this prediction model can satisfy UGS field application with high accuracy and good applicability.