不同冷却方式下高温花岗岩细观损伤量化和机理分析  

Quantification and mechanism analysis of meso-damage of high-temperature granite under different cooling modes

作　　者：张森 舒彪[1] 梁铭[1] 路伟 胡永鹏 薛卉 ZHANG Sen;SHU Biao;LIANG Ming;LU Wei;HU Yongpeng;XUE Hui(School of Geosciences and Info-Physics,Central South University,Changsha 410083,China)

机构地区：[1]中南大学地球科学与信息物理学院,湖南长沙410083

出　　处：《煤田地质与勘探》2022年第2期106-114,共9页Coal Geology & Exploration

基　　金：国家自然科学基金面上项目(42072304);湖南省科技创新计划项目(2021RC3009);湖南省自然科学基金青年基金项目(2021JJ40726)。

摘　　要：冷冲击是一种导致高温岩石破裂从而有效提高地热储层渗透性的方法。为了对不同加热温度下冷冲击后造成的花岗岩损伤程度进行定量分析,探究冷冲击作用下的损伤机理,利用岩石薄片观察和SEM扫描技术对自然冷却和遇水冷却下的高温花岗岩样损伤进行分析。结果表明,当加热温度从200℃提高到800℃时,岩样中心处的薄片A在自然冷却和遇水冷却下的裂隙密度分别增加了17.6%~144.7%和27.6%~163.7%,距圆心12.5 mm的薄片B在自然冷却和遇水冷却下的裂隙密度分别增加了40.1%~202.8%和61.3%~222.7%。随着加热温度的升高,花岗岩损伤程度变大;遇水冷却比自然冷却对花岗岩的损伤程度更大;而由于热梯度的存在,离试样表面越近所受的损伤程度越大。花岗岩试样热损伤是矿物颗粒膨胀和收缩、冷冲击以及热物理化学变化等机制混合作用的结果。研究结果不仅为理解冷冲击对高温花岗岩损伤的影响提供实验参考,且对指导热刺激法在储层改造中的应用至关重要。Cooling shock is an effective method to increase the permeability of geothermal reservoir by causing fractures on high temperature rock.For the purpose of quantitatively analyze the damage degree of granite caused by cooling shock at different heating temperatures and explore the damage mechanism under the action of cooling shock,the damage of high temperature granite samples under was analyzed under natural cooling and water cooling conditions by means of thin section observation and SEM scanning technology.The results show that when the heating temperature is increased from 200°C to 800°C,the crack density of the section A at the center of the rock sample increases by 17.6%-144.7%and 27.6%-163.7%respectively under natural cooling and water cooling.For the slice B 12.5 mm away from the center of the circle,the fracture density increases by 40.1%-202.8%and 61.3%-222.7%under natural cooling and water cooling conditions,respectively.The results also show that the damage degree of granite increases with the increase of heating temperature,and the damage degree of granite is greater when it is cooled by water than in air.In addition,the damage degree of granite is greater when it is closer to the sample surface due to the existence of thermal gradient.These conclusions not only provide experimental reference for understanding the effect of cooling shock on the damage of high-temperature granite,but also play a very important role in guiding the application of thermal stimulation method in reservoir reconstruction.

关 键 词：冷冲击 自然冷却 遇水冷却 裂隙密度 损伤程度 热梯度 

分 类 号：TU45[建筑科学—岩土工程]