Full cycle modeling of inter-seasonal compressed air energy storage in aquifers

Abstract

To study the operational characteristics of inter-seasonal compressed air storage in aquifers, a coupled wellbore-reservoir 3D model of the whole subsurface system is built. The hydrodynamic and thermodynamic properties of the wellbore-reservoir system during the initial fill, energy injection, shut-in, and energy production periods are analysed. The effects of well spacing and air injection temperature on the seasonal storage process are investigated. The results show that the ranges of variation in wellbore-aquifer pressure and temperature are within the acceptable level during the whole operational process. The maximum wellhead pressure, reaching 13.08 MPa, occurs during the first injection in the initial fill period. The temperature of the air released from the wellhead is 6 °C lower than the initial injection temperature due to heat loss. The horizontal transport distance of injected air in the aquifer is 2173.5 m away from the central well at the end. The overall energy storage efficiency is 94.3% and the energy lost by the wellbore during production is 0.09%. Parametric analysis shows that the system has an optimal performance at a well spacing of 150 m. The energy storage efficiency is 5% higher at an air injection temperature of 20 °C than 50 °C. The results strongly confirm the feasibility of IS-CAESA.