地热储层岩体粗糙裂隙的热流耦合效应研究  

Thermal-hydraulic coupling effect in rough fractures of geothermal reservoir

作　　者：刘先珊[1] 李宇 李满 杨欣[1] LIU Xianshan;LI Yu;LI Man;YANG Xin(School of Civil Engineering,Chongqing University,Chongqing 400045,China)

机构地区：[1]重庆大学土木工程学院,重庆400045

出　　处：《哈尔滨工程大学学报》2024年第5期852-862,共11页Journal of Harbin Engineering University

基　　金：国家自然科学基金项目(52279094);山西省交通新技术发展有限公司(SXJTJS-02040-2022-第9号)。

摘　　要：为了解决地热开采涉及复杂的多物理场耦合问题,提高开采效率,本文针对开采过程中的渗流-传热问题以离散元软件3DEC构建岩体粗糙裂隙热-流耦合数值模型。考虑不同三维形貌特征的岩体裂隙,模拟水力开度为19.17μm在不同流速时的水-岩温度变化规律。结果表明:由于裂隙形貌的阻滞作用,粗糙面出水口温度下降较慢,出水口温度有所上升,模型达到稳态所需的时间随流速和对流换热系数的增大而减小。裂隙形貌对流体和岩体温度分布均有影响,粗糙裂隙面的冷锋形态和裂隙面的形貌密切相关。光滑裂隙热突破快于粗糙裂隙,增加裂隙面的粗糙度有助于延长热突破时间。粗糙裂隙面相对于光滑裂隙面的总热量提取率略有提升,流速和对流换热系数的增加显著提高总热量提取率。通过本文研究可以为地热能系统的设计提供重要参数和指导,能够提高地热能开发利用效率。Concerning complex multiphysics coupling issues involved in geothermal extraction and improving mining efficiency,a numerical model of thermal-fluid coupling in rough rock fractures was constructed using the discrete element software 3DEC to address the seepage-heat transfer problem during extraction.Rock mass cracks with dif-ferent three-dimensional morphological characteristics were considered,and the water-rock temperature change law was simulated with a hydraulic opening of 19.17μm at different flow rates.Results showed that,due to the bloc-king effect of the crack morphology,the temperature of the outlet on the rough surface gradually decreased,and the temperature of the outlet increased.The time required for the model to reach a steady state decreased with the in-crease in flow rate and convective heat transfer coefficient.The morphology of the fracture affects the temperature distribution of fluids and rocks.The cold front morphology of the rough fracture surface was closely related to the morphology of the fracture surface.The thermal breakthrough of smooth fissures was faster than that of rough fis-sures.Increasing the roughness of the fissure surface helped prolong the thermal breakthrough time.The total heat extraction rate from rough fracture surfaces was slightly higher than that from smooth fracture surfaces,and increas-ing flow rate and convective heat transfer coefficient significantly increased the total heat extraction rate.This study provides important parameters and guidance for the design of geothermal energy systems and can improve the effi-ciency of geothermal energy development and utilization.

关 键 词：干热岩 渗流-传热 三维形貌 水力开度 流速 对流换热系数 粗糙裂隙面 热采率 热突破 

分 类 号：P314[天文地球—固体地球物理学]