Investigation of heat extraction with flowing CO2 from hot dry rock by numerical study

Abstract

Abstract To develop the geothermal energy in hot dry rock (HDR), a seepage thermal storage is proposed to be built by the fracturing technology, and CO2 is used as working medium of heat extraction from the HDR. In this study, based on the geological and geothermal conditions in Yangbajing of China, a physical model of the thermal storage is built by numerical method, and the radiative heat from the rock is considered. Effects of the injection parameters, the thermal storage properties and the perforation position on the seepage and heat characteristics of CO2 are studied. Some quantitative results, such as the temperature variation, the heat extraction and the thermal storage life, are obtained. It shows that the power of heat extraction increases with the injection pressure and the flow rate. There is an optimal injection flow for the cumulative heat extraction. Furthermore, the permeability distribution in the thermal storage, as well as the perforation position, has significant influence on the thermal storage life. Consistent variation of the permeability along the depth of the thermal storage is more beneficial to the development of the HDR. It is expected that this study could provide reference for the construction of the related geothermal system.