首页|高温高压下不同结构形式裂缝充填花岗岩热力学特性

高温高压下不同结构形式裂缝充填花岗岩热力学特性

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深部干热岩地热能储层一般为非完整岩体，含有大量因地质构造运动形成的裂缝。构造裂缝随后被热液充填，这种储层被称为裂缝充填储层。为指导深部干热岩地热开发，利用太原理工大学自主研制 600℃高温高压岩体三轴试验机研究了中国山西芦芽山花岗岩母岩(Ⅰ类花岗岩)、热液充填体(Ⅱ类花岗岩)、充填体与母岩胶结界面横向贯通试样花岗岩(Ⅲ类花岗岩)、充填体与母岩胶结界面纵向贯通试样花岗岩(Ⅳ型花岗岩)等 4类花岗岩高温(500℃)高压(20 MPa围压)条件下的热力学特性。研究得出 4类花岗岩热膨胀系数随温度升高可分为低温缓慢波动段、中低温快速增加段以及中高温快速减小段3个阶段。4类花岗岩弹性模量随温度升高先缓慢增加后快速降低，溶蚀孔隙结构以及低键合强度矿物的存在导致热液充填体弹性模量最低。此外，得出裂缝充填花岗岩体内原生裂缝闭合的临界温度大约为 200℃;胶结界面附近充填体恢复弱面结构特性的临界温度为 250℃左右。最后，得出了 4类花岗岩高温高压条件下的破坏形式。裂缝充填花岗岩体内的母岩粗晶粒边界处、热液充填体溶蚀孔隙处和胶结界面处极有可能会在水力压裂建造储层过程中形成大范围高效导水通道，为干热岩地热开采储层建造理论和技术提供新的思路。
Thermal and mechanical properties of fracture-filled granite with different structural forms under high temperature and high pressure
The reservoir of deep hot dry rock(HDR)geothermal energy is not intact rock mass,which includes a large number of fractures induced by geological tectonic movement.The tectonic fractures are subsequently filled by hydro-thermal fluid.This kind of reservoir is so-called fracture-filled reservoir.To guide deep hot dry rock geothermal mining,this paper used a 600℃high-temperature and high-pressure rock mass triaxial testing machine independently developed by the Taiyuan University of Technology to study the thermal and mechanical characteristics under high temperature(500℃)and high pressure(20 MPa confining pressure)of four types of granite from the Luya Mountain,Shanxi,China,including parent rock(type I granite),hydrothermal fluid backfill(type II granite),cementation interface between the backfill and the parent rock laterally positioned through the specimen(type III granite),and cementation interface between the backfill and the parent rock longitudinally positioned through the specimen(type IV granite).The research shows that the thermal ex-pansion coefficient of four types of granite can be divided into three stages with the increase of temperature:the slow fluc-tuation stage at low temperature,the rapid increase stage at low and medium temperature,and the rapid decrease stage at medium and high temperature.The elastic modulus of four types of granite increases slowly and then decreases rapidly with the increase of temperature.The dissolution pore structure and the presence of minerals with low bonding strength lead to the lowest elastic modulus of hydrothermal fluid backfill.In addition,the critical temperature of the closure of pre-existing fractures in the fracture-filled granite is about 200℃.The critical temperature for the backfill near the cementa-tion interface to restore the weak-plane structure characteristics is about 250℃.Finally,the failure modes of four types of granite under high temperature and high pressure are obtained.The coarse grain boundary of the parent rock,the dissolu-tion pores of the hydrothermal fluid backfill and the cementation interface in the fracture-filled granite are very likely to form a large-scale efficient water channel during the reservoir construction by hydraulic fracturing,which provides a new idea for the theory and technology of reservoir construction for HDR geothermal exploitation.

fracture-filled granitehigh temperature and high pressuremicrostructuremineral characteristicsthermal and mechanical characteristicshot dry rock geothermal development

阴伟涛、冯子军

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太原理工大学原位改性采矿教育部重点实验室,山西太原 030024

裂缝充填花岗岩 高温高压 微观结构 矿物特征 热力学特性 干热岩地热开发

国家自然科学基金山西省基础研究计划(自由探索类)资助项目山西省科技重大专项"揭榜挂帅"资助项目

52122405202103021223071202101060301024

2024

10.13225/j.cnki.jccs.2023.0696

煤炭学报
中国煤炭学会

煤炭学报

CSTPCD北大核心
影响因子：3.013
ISSN：0253-9993
年,卷(期)：2024.49(6)
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