增强型地热系统热-水动力-力学(THM)耦合模拟——以河北马头营凸起区为例  

Thermal-Hydrodynamic-Mechanical (THM) Coupling Simulation of Enhanced Geothermal System Development in Matouying Uplift Area,Hebei Province

作　　者：冯波 曹云龙 齐晓飞 崔振鹏 张兰新 Feng Bo;Cao Yunlong;Qi Xiaofei;Cui Zhenpeng;Zhang Lanxin(College of New Energy and Environment,Jilin University,Changchun 130021,China;The Second Geological Team of Hebei Coal Field Geology Bureau,Xingtai 054001,Heibei,China;Shandong Provincial Geo-Mineral Engineering Exploration Institute,Jinan 250014,China)

机构地区：[1]吉林大学新能源与环境学院,长春130021 [2]河北省煤田地质局第二地质队,河北邢台054001 [3]山东省地矿工程勘察院,济南250014

出　　处：《吉林大学学报（地球科学版）》2023年第6期1892-1906,共15页Journal of Jilin University：Earth Science Edition

基　　金：国网青海省电力公司科研项目(B7280722E072);吉林省科技厅重点研发项目(20200403147SF)。

摘　　要：增强型地热系统(EGS)的裂隙热储层在长期开采过程中,由于不断地提取高温干热岩体的热量,致使高温花岗岩岩体温度下降,进而诱发岩体产生二次破裂,甚至出现流体短路,降低地热系统开采效率。为了保证EGS热能的稳定提取,需要建立试验场地的热-水动力-力学(THM)耦合模型,分析水动力和热效应对该储层裂隙发育规律的影响。本文基于河北马头营凸起区EGS开发场地的循环注水试验数据,建立场地热-水动力-力学耦合模型,通过模型模拟结果与现场观测结果进行比较,先验证了THM耦合模型的准确性,然后利用校正后的模型预测了不同注入方案下,EGS储层渗透率的提高和增产带的空间范围,揭示了储层裂隙增产带的范围受温度、压力、注入速率的影响情况。结果表明:经过63 d的增产处理,该模型预测的增产层体积约为10万m^(3);提高注水压力能刺激现有的裂隙发生剪切性破裂,拓宽增产带的区域;减小注水的温度有助于提升流体的穿透能力,扩大储层的增产带;在水力压裂的开始阶段,适当利用冷水注入有利于提高储层渗透率,且提高注入速率会使储层增产带的范围扩大。In the long-term mining process of the fractured thermal reservoir of the enhanced geothermal system(EGS),due to the constant extraction of heat from the high-temperature dry hot rock mass,the temperature of the high-temperature granite mass drops,which induces the secondary fracture of the rock mass,and even the occurrence of fluid short circuit reduces the mining efficiency of the geothermal system.In order to ensure the stable extraction of EGS heat energy,it is necessary to establish the coupling model of fluid-solid heat transfer,hydrodynamic and fracture deformation in the test site,and analyze the influence of hydrodynamic and thermal effects on the fracture development law of the reservoir.Based on the test data of circulating water injection at the EGS development site in Matouying Bulge area,Hebei Province,this paper established a coupling model of thermo-hydro-mechanical(THM)of microfractures in the site.The accuracy of the THM coupling model was verified by comparing the model simulation results with the field observation results.The increase of permeability of EGS reservoir and the spatial range of stimulation zone reveal that the range of stimulation zone of reservoir fracture is affected by temperature,pressure and injection flow.The results show that increasing the water injection pressure can stimulate the shear fracture of existing fractures and broaden the area of stimulation zone.Reducing the temperature of water injection can improve the permeability of fluid and expand the reservoir stimulation zone.In the initial stage of hydraulic fracturing,the proper use of cold water injection is conducive to improving the reservoir permeability,and increasing the injection flow will expand the range of reservoir stimulation zone.

关 键 词：增强型地热系统 水力压裂 马头营凸起区 热-水动力-力学(THM)耦合模型 TOUGH2Biot 

分 类 号：TK529[动力工程及工程热物理—热能工程]