Abstract—As high temperature in hot dry rocks(HDR), the process of injecting cold fracturing fluid to form fractures and circulating working fluid to extract heat energy from enhanced geothermal system(EGS) all inevitably involve the low-temperature induction imposing on hot dry rocks. Considering the temperature-dependent parameter changes of matrix and fluid, we establish thermal-hydraulic-mechanical full coupling model to investigate the effect of low-temperature induction on heat mining performance of EGS. This paper begins with experimentally study to obtain the possible distribution of sub-fractures in EGS caused by the thermal stress cracking induced by thermal drawdown; Then we discuss the heat mining performance in terms of whether the sub-fractures are considered and whether the thermal stress aroused by low-temperature fluid circulation is taken account during mining process. We find that thermal stress induced by low-temperature circulation brings contraction of matrix and influences seepage capacity of fractures by changing effective stress in EGS mining.
Index Terms—Low-temperature induction, heat mining performance, thermal-hydraulic-mechanical(THM) coupling, hot dry rocks(HDR)
Wei Zhang is with the China University of Petroleum, Upc, CO 266580 China (e-mail: 18562029717@163.com).
Zhan-qing Qu and Tian-kui Guo is with the China University of Petroleum, Upc, CO 266580 China (e-mail: quzhq@upc.edu.cn, guotiankui@126.com)
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Cite: Wei Zhang, Zhan-qing Qu, and Tian-kui Guo, "Effect of Low-temperature Induction on Heat Mining Performance of EGS in Hot Dry," International Journal of Engineering and Technology vol. 10, no. 5, pp. 408-413, 2018.
