Heat Extraction Evaluation of CO 2 and Water Flow through Different Fracture Networks for Enhanced Geothermal Systems

Zhixue Sun (), Wentong Song, Hao Zhang, Xueyuan Li, Shuang Xie and Haifeng Nie
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Zhixue Sun: School of Petroleum Engineering, China University of Petroleum (East China), Qingdao 266580, China
Wentong Song: School of Petroleum Engineering, China University of Petroleum (East China), Qingdao 266580, China
Hao Zhang: School of Petroleum Engineering, China University of Petroleum (East China), Qingdao 266580, China
Xueyuan Li: School of Petroleum Engineering, China University of Petroleum (East China), Qingdao 266580, China
Shuang Xie: Northwest Oil Field Branch of Sinopec, Urumqi 830011, China
Haifeng Nie: Tarim Oilfield Company, Alar 842209, China

Energies, 2023, vol. 17, issue 1, 1-13

Abstract: Enhanced geothermal system (EGS) technologies have been developed to improve geothermal energy production from hot dry rock (HDR). In this study, discrete fracture network models for geometric topological networks that consider different parameters (the fracture density and the fracture length index) were built on the basis of fractal geometry theory. The heat extraction processes of CO 2 and water as the working fluid through different discrete fracture networks were simulated with the application of the thermal–hydraulic–mechanical (THM) coupled method. A series of sensitivity analyses were carried out to reveal the influences of fracture parameters on heat transfer processes. Based on the simulation results, heat extraction efficiencies and temperature distributions in the reservoir of CO 2 and water as the working fluid were compared, which showed that CO 2 as the working fluid can bring a faster thermal breakthrough. It was found that the fracture length index a = 2.5 and the fracture density I = 5.0 can provide the highest heat extraction rate compared with other cases. This study provides a detailed analysis of fracture parameters and working fluids, which will contribute to the optimized management of geothermal energy production.

Keywords: enhanced geothermal systems; thermal–hydraulic–mechanical coupled; CO 2; heat extraction rate; fracture topology (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2023
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