Volume 54

Study the Dissolution and Consumption of CO2 Cushion Gas in UGS through Numerical Simulation Yun Chen, Zongran Li, Yuan Zhu, Dejun Liu

Abstract

As investment in the construction of UGS increases around the world, the operational efficiency and safety of UGS have attracted attention, which includes some problems that need to be faced. Currently, the dissolution of cushion gas in reservoir fluids has been little discussed. However, with the promotion of the use of CO2 cushion gas, the impact of dissolution is one of the problems that has to be faced. We aim to show with this study that the dissolved consumption of cushion gas is critical as this affects the total gas volume. We considered two different scenario models, with and without chemical capture reactions. Through simulation, it was found that the increase in pressure increased the solubility of CO2, but the total dissolved amount decreased. The increase in reservoir temperature reduces the solubility of CO2 and also leads to a decrease in the total dissolved amount. In addition, chemical capture will affect the solubility of CO2 to a certain extent, and its extent is related to pressure. A reduction in dissolved gas means an increase in free gas, potentially making the reservoir more sensitive to gas injection pressure. Therefore, chemical capture and hydration dissolution factors become key considerations in cushion gas design and UGS operation. This research helps promote efficient operation of UGS.

Keywords underground gas storage, carbon dioxide, dissolve, pressure, temperature, reservoir