单丹丹 闫铁 李玮

摘      要：为探究影响增强型地热系统（Enhanced Geothermal System，EGS）高效运行的各项因素，以单裂隙热储为研究对象，基于裂隙岩体热流耦合数学模型，对单裂隙下EGS热流耦合进行数值模拟，利用有限元软件COMSOL实现对裂隙岩体温度场与渗流场的耦合求解，分析热储层内渗流、温度的分布规律，以及基岩渗透率、热传导系数等岩体热物性参数变化;裂隙宽度、裂隙流流速、开采时间等基本计算参数变化对裂隙岩体渗流与传热的影响，得出在一定范围内基岩渗透率与热传导系数增大会使系统运行寿命提高，裂隙宽度及裂隙流流速对热开采效率的影响呈现正相关性。

关  键  词：增强型地热系统;裂隙岩体;热流耦合;COMSOL;数值模拟

中图分类号：TK 529        文献标识码： A       文章编号： 1671-0460（2020）04-0716-05

Abstract： In order to explore the factors affecting the efficient operation of enhanced geothermal system （Enhanced Geothermal System，EGS）， taking a single-fracture thermal reservoir as the research object， based on the mathematical model of thermal-hydraulic coupling of fracture rock mass， the numerical simulation of EGS thermal-hydraulic coupling under a single-fracture was carried out. The coupling solution of temperature field and seepage field of fracture rock mass was realized by using finite element software COMSOL， and the distribution of seepage and temperature in thermal reservoir was analyzed， as well as the variation of thermal physical parameters of rock mass， such as permeability and heat conduction coefficient of bedrock. The influence of basic calculation parameters such as fracture width， fracture flow velocity and mining time on seepage and heat transfer of fracture rock mass was investigated. The results showed that the increase of bedrock permeability and heat conduction coefficient in a certain range will increase the operating life of the system， and the influence of fracture width and fracture flow velocity on thermal mining efficiency was positively correlated.

Key words： Enhanced Geothermal System; Fractured rock mass; Thermal-hydraulic coupling; COMSOL; Numerical simulation

增強型地热系统（Enhanced Geothermal System，EGS）[1-6]是干热岩资源开采的最有效技术手段，通常采用的储层压裂改造技术有水力剪切和水力压裂两种[7，8]。高温热储的渗流传热模型总体包括三大类：等效连续介质模型、离散裂隙网络模型以及这2种模型的综合[9，10]。如果裂隙在岩体中紧密分布，而且各表征单元较小，就可以当作等效连续介质来处

理[11]。而当裂隙在岩体中稀疏分布，就应看成是裂隙与基质岩块组成的裂隙网络系统，单裂隙属于裂隙系统最基本的单元，对其进行渗流传热耦合研究，可以为复杂的裂隙在该方面的研究提供理论参考。目前EGS还没有进行大规模商业开采，因此，数值模拟仍是研究的主要手段。从最早的干热岩热量提取到如今，学术界已建立了很多数值模型[12]。……