Development of geothermal energy from depleted high temperature gas reservoir via supercritical CO2 injection

Key words:  supercritical CO₂  high temperature depleted gas reservoirs  geothermal energy exploitation  heat mining capacity  heat transmission fluid

Abstract:

The potential for heat mining from depleted high temperature gas reservoirs is very high. In this study, geothermal energy exploitation from depleted gas reservoirs via injection of supercritical CO₂ was proposed and investigated using heat transfer and numerical reservoir simulation methods. The heat mining capacity of supercritical CO₂ was calculated and its related influence factors were analyzed. The simulation results show that the heat mining capacity of supercritical CO₂ can be 50% higher than that of water due to superior mobility of CO₂ and good thermophysical properties at high pressure and temperature conditions. Geothermal exploitation via CO₂ injection can not only produce geothermal energy, but also can achieve the goal of CO₂ geological storage. Geothermal development from depleted gas reservoirs can significantly reduce its initial capital investment via using the existing wells and surface facilities, and it can prolong the gas reservoir 's economic life.