基于热力耦合的近场动力学方法高温岩石水力压裂数值模拟  

A numerical simulation of high-temperature rock hydraulic fracturing based on coupled thermo-mechanical peridynamics

作　　者：陈骞 王志良[1] 申林方[1] 华涛 李邵军[2] 徐则民[1] CHEN Qian;WANG Zhi-liang;SHEN Lin-fang;HUA Tao;LI Shao-jun;XU Ze-min(Faculty of Civil Engineering and Mechanics,Kunming University of Science and Technology,Kunming,Yunnan 650500,China;State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan,Hubei 430071,China)

机构地区：[1]昆明理工大学建筑工程学院,云南昆明650500 [2]中国科学院武汉岩土力学研究所岩土力学与工程国家重点实验室,湖北武汉430071

出　　处：《岩土力学》2024年第8期2502-2514,共13页Rock and Soil Mechanics

基　　金：国家自然科学基金(No.11962008,No.42167022,No.42067043,No.41931294)。

摘　　要：基于近场动力学方法分别采用键型模型计算岩石热扩散过程和常规态型模型模拟岩石位移场的演化,根据物质点间的断键数量确定材料损伤值以实时追踪裂隙面的扩展,通过在裂隙面处施加水压和水温实现水与岩石间的相互作用,建立了考虑热力耦合效应模拟高温岩石水力压裂过程的数值计算模型。根据岩石加热裂隙扩展的试验结果,验证了计算模型的有效性。最后,讨论了水压、岩石初始温度及弹性模量等因素对水力压裂岩石裂隙结构形态的影响,并基于综合敏感度属性识别评价方法,分析了各影响因素对岩石裂隙形态参数的敏感性。研究结果表明:水压较小或岩石初始温度较低时,主裂隙几乎呈对称分布,基本上无裂隙分支现象;随着水压或初始温度的增加,裂隙逐渐增多并产生分叉现象,同时裂隙总长度和张开度也均呈增长趋势。当岩石弹性模量均值较小时,水力裂隙较为发育且萌生许多微小裂隙;随着弹性模量均值的增大,水力裂隙分支及微裂隙数量明显减少,裂隙总长度和张开度也相应地减小,而岩石起裂时间则近似呈线性增加的趋势。岩石材料参数和环境参数的敏感性综合评价表明,岩石裂隙扩展对弹性模量和水压呈高度敏感,而对水温则表现为不敏感。Based on the peridynamics method,the bond model was applied to treat the thermal diffusion of rock and the conventional state model was adopt to simulate the displacement evolution.According to the number of broken bonds between material points,the material damage was determined to track real-time fracture propagation.The interaction between water and rock was realized by applying pressure and temperature of water to fracture surface.And a numerical model was proposed to simulate hydraulic fracturing in high-temperature rock considering the thermal-mechanical coupling effect.The accuracy of the proposed model was verified according to the test results of rock heating fracture propagation.Finally,the morphology of hydraulic fracturing-induced rock fractures were discussed considering the effects of water pressure,rock initial temperature and elastic modulus,the sensitivity of each factor to fracture geometry parameters was analyzed based on the comprehensive sensitivity attribute identification method.The results indicate that under conditions of low water pressure or initial rock temperature,the primary fractures exhibit a near-symmetric distribution,and there is almost no fracture branching.With the increase of water pressure or initial temperature,the number of fracture gradually increases and the bifurcation occurs,the total length and opening degree of fracture also increase.When the mean elastic modulus of rock is small,the fractures are well developed and many tiny cracks appear.With the increase of the average elastic modulus,the number of fracture branches and micro-fractures decreases obviously,and the total length and opening degree of fractures also decrease accordingly,while the rock fracture initiation time increases approximately linearly.The comprehensive sensitivity evaluation of rock material parameters and environmental parameters shows that rock fracture propagation is highly sensitive to elastic modulus and water pressure,but insensitive to water temperature.

关 键 词：高温岩石 水力压裂 热力耦合 近场动力学 裂隙演化 

分 类 号：TU454[建筑科学—岩土工程]