Numerical simulation for heat extraction of CO2-EGS with thermal-hydraulic-mechanical coupling method based on discrete fracture models

被引：0

作者：

Sun Z. ^{[1
]}

Jiang C. ^{[1
]}

Zhang K. ^{[1
]}

Zhuang L. ^{[2
]}

Ren X. ^{[3
]}

Wang Q. ^{[4
]}

机构：

[1] School of Petroleum Engineering in China University of Petroleum(East China), Qingdao

[2] Extreme Engineering Research Center in Korea Institute of Civil Engineering and Building Technology, Gaoyang

[3] Green Energy Geothermal (Shaanxi) in Development Company Limited, Xianyang

[4] National Geothermal Energy Development and Utilization Research and Application Technology Promotion Center, Beijing

来源：

Zhongguo Shiyou Daxue Xuebao (Ziran Kexue Ban)/Journal of China University of Petroleum (Edition of Natural Science) | 2020年 / 44卷 / 06期

关键词：

CO[!sub]2[!/sub]-EGS; Coupled model; Fracture topology; Heat extraction efficiency; Numerical simulation;

D O I：

10.3969/j.issn.1673-5005.2020.06.010

中图分类号：

学科分类号：

摘要：

Enhanced geothermal system (EGS) is an important technology for the development and utilization of geothermal energy in hot dry rocks. Novel EGS using CO2 (CO2-EGS) has the advantages of energy saving, high efficiency and greenhouse gas emission reduction. In this study, based on the fractal geometry theory, discrete fracture models with different fracture length, intensity and connectivity were established. Considering the local thermal non-equilibrium principle, a numerical approach for CO2-EGS to simulate the thermal-hydraulic-mechanical (THM) coupling processes was presented and solved by the finite element method. The results show that the characteristic parameters of thermal reservoir fractures, spatial topological structure and injection-production pressure gradient play critical roles in the heat extraction efficiency and service life of the CO2-EGS process. Furthermore, CO2-EGS with a high connectivity between injector and producer can be highly efficient in heat extraction under high pressure gradient, but a poor connectivity can have a rapid decline in heat extraction with the pressure gradient increasing. Reasonable matching between the static characteristic parameters of fractures and the injection-production pressure difference is the key factor for maximizing the heat production efficiency of the CO2-EGS process. © 2020, Editorial Office of Journal of China University of Petroleum(Edition of Natural Science). All right reserved.

引用

页码：79 / 87

页数：8

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