Dynamic analysis of heat extraction rate by supercritical carbon dioxide in fractured rock mass based on a thermal-hydraulic-mechanics coupled model  

作　　者：Chunguang Wang Xingkai Shi Wei Zhang Derek Elsworth Guanglei Cui Shuqing Liu Hongxu Wang Weiqiang Song Songtao Hu Peng Zheng 

机构地区：[1]College of Energy and Mining Engineering,Shandong University of Science and Technology,Qingdao 266590,China [2]New-energy Development Center of Sinopec Shengli Oilfield,Dongying 257001,China [3]Energy and Mineral Engineering and G3 Center,Penn State University,University Park,PA 16802,USA [4]Key Laboratory of Ministry of Education on Safe Mining of Deep Metal Mines,Northeastern University,Shenyang 110004,China [5]Shandong Provincial Geo-Mineral Engineering Co.,Ltd,Jinan 250013,China [6]Qingdao Wofu New Energy Science and Technology Co.,Ltd,Qingdao 266010,China

出　　处：《International Journal of Mining Science and Technology》2022年第2期225-236,共12页矿业科学技术学报（英文版）

基　　金：The financial support from the National Natural Science Foundation of China(Nos.41772154 and 42102338);Natural Science Foundation of Shandong Province(Nos.ZR2019MA009 and ZR2020QE115);SDUST Research Fund of China(No.2018TDJH102)。

摘　　要：Heat production from geothermal reservoirs is a typical heat transfer process involving a cold working fluid contacting a hot rock formation.Compared to the thermal-physical characteristics of water,supercritical CO_(2)(scCO_(2))has a higher heat storage capacity over a wide temperature-pressure range and may be favored as a heat transfer fluid.Singularly characteristic of scCO_(2)-based heat extraction is that the hydraulic-thermal properties of the scCO_(2) vary dramatically and dynamically with the spatial pressure gradient during unsteady-state flow along fracture.This highly nonlinear behavior presents a challenge in the accurate estimation of heat extraction efficiency in scCO_(2)-based EGS.In this paper,a thermal-h ydraulic-mechanical(THM)coupled model is developed by considering deformation of the fractured reservoir,non-Darcy flow and the varying thermal-physical properties of scCO_(2).The proposed model is validated by matching the modeling temperature distribution with published data.The results show that during continuous injection of scCO_(2),the fracture first widens and then narrows,ultimately reopening over the long term.The sequential fracture deformation behaviors are in response to the combined impacts of mechanical compression and thermally-induced deformation.By controlling the injection parameters of the scCO_(2),it is found that the heat extraction rate is positively correlated to its pore pressure or mass flow rate.The heat extraction rate can be significantly enhanced,when the inlet temperature of scCO_(2) is below its critical temperature.As a result,the heat increment recovered per unit mass of scCO_(2) decreases as the hot rock is gradually cooled.Meanwhile,the heat increment recovered per unit mass of scCO_(2) decreases by increasing the inlet temperature of scCO_(2) or its mass flow rate,but increases as the outlet pressure rises.Furthermore,multi-linear regression indicates that controlling the inlet temperature of the scCO_(2) can significantly improve the thermodynamic efficiency

关 键 词：Supercritical CO_(2) Heat extraction Hot rock Geothermal energy Fracture-matrix interaction 

分 类 号：TK123[动力工程及工程热物理—工程热物理]