浅层地热开采中砂岩单裂隙渗流传热试验研究  

Experimental Study on Seepage and Heat Transfer of A Single Fracture in Sandstone during Shallow Geothermal Extraction

作　　者：吴洪涛 王惠民 郑惠峰 盛金昌[1] 黄泰仁 田佳丽 盛丹娜 WU Hongtao;WANG Huimin;ZHENG Huifeng;SHENG Jinchang;HUANG Tairen;TIAN Jiali;SHENG Danna(College of Water Conservancy and Hydropower Engineering,Hohai University,Nanjing 210098,China;Huadong Engineering Corporation Limited,Hangzhou 311122,China)

机构地区：[1]河海大学水利水电学院,南京210098 [2]中国电建集团华东勘测设计研究院有限公司,杭州311122

出　　处：《高校地质学报》2024年第5期593-602,共10页Geological Journal of China Universities

基　　金：江苏省研究生科研与实践创新计划项目(SJCX24_0208);国家自然科学基金(42202286,42372296);中国博士后科学基金(2023M730916);河海大学大型仪器设备共享基金(GX202201B)联合资助。

摘　　要：浅层地热能的开发利用关系着“双碳”目标的顺利达成,其中目标储层岩石裂隙渗流传热特性的研究对地下水源热泵系统的成效至关重要。但以往的裂隙渗流传热研究多是考虑粗糙面、流速、围压、温度等单一因素对其传热效率的评价,并未系统探究多级流速下浅层地热储层(围压和岩石温度)变化对渗流传热演化规律的认识及其贡献程度的对比。因此,文章基于课题组自主研发的裂隙岩石渗流传热试验系统,开展了多级流速下的砂岩单裂隙渗流传热试验,分析了单裂隙渗流传热在多级流速下的全过程演化特性,探讨了浅层地热中的敏感性参数(围压和岩石温度)对渗流传热的影响规律及其贡献程度。试验结果发现:(1)出口水温和对流换热系数随水流流速的增大,其变化趋势有明显的阶段性转折;(2)围压的增大导致裂隙开度减小,流动边界层变薄,而温度梯度的增大将引起热流密度的上升,都将导致出口水温和对流换热系数呈现上升趋势;(3)岩石温度的贡献程度明显高于围压,特别是从60℃增大至70℃时,对流换热系数有了大幅度增长。The development and utilization of shallow geothermal energy is related to the successful achievement of the“doublecarbon”target.The study on seepage and heat transfer characteristics of the rock fracture in the target reservoir is critical to the effectiveness of the groundwater source heat pump system.However,most of the previous studies on seepage and heat transfer in fractures considers a single factor such as rough surface,flow velocity,confining pressure,temperature for the evaluation of its heat transfer efficiency.The understanding of the evolution mechanism of seepage and heat transfer and its contribution degree by the change of shallow geothermal reservoir(confining pressure and rock temperature)at multiple flow rates have not been systematically investigated.Therefore,based on a self-developed seepage and heat transfer system of fractured rocks,this paper carried out the seepage and heat transfer test under multiple flow rates for sandstone with a single fracture.Subsequently,the evolution characteristics of single fracture seepage and heat transfer under multiple flow rates were analyzed.Finally,the influenced mechanism and contribution degree of sensitive parameters(confining pressure and rock temperature)in shallow geothermal on seepage and heat transfer were discussed.The test results show that:(1)The trends of outlet water temperature and convective heat transfer coefficient with the increase of water flow rate have obvious transition stages.(2)The increase of confining pressure leads to the fracture closing and the thinning of flow boundary layer,while the increase of temperature gradient causes a higher outlet water temperature and convective heat transfer coefficient due to the increase of heat flux density.(3)The contribution of rock temperature is significantly higher than that of confining pressure.Especially when the temperature increases from 60℃to 70℃,the convective heat transfer coefficient increases dramatically.

关 键 词：浅层地热 砂岩 单裂隙 多级流速 对流换热系数 

分 类 号：TU463[建筑科学—结构工程]