位移约束和温度耦合下致密砂岩热诱导微裂纹发育规律研究  

Research on the development law of thermal-induced microcracks in tight sandstone under displacement constraint and temperature coupling

作　　者：李明昊 李皋[1,2] 张毅 杨旭 李红涛[1,2] 冯佳歆 宿腾跃 LI Minghao;LI Gao;ZHANG Yi;YANG Xu;LI Hongtao;FENG Jiaxin;SU Tengyue(College of Petroleum and Natural Gas Engineering,Southwest Petroleum University,Chengdu,Sichuan 610500,China;Underbalanced/Gas Drilling Laboratory,National Engineering Research Center of Oil and Gas Drilling and Completion Technology,Chengdu,Sichuan 610500,China;PetroChina Southwest Oil and Gas Field Engineering and Technology Research Institute,Chengdu,Sichuan 610017,China)

机构地区：[1]西南石油大学石油与天然气工程学院,四川成都610500 [2]油气钻完井技术国家工程研究中心欠平衡/气体钻井实验室,四川成都610500 [3]中国石油西南油气田工程技术研究院,四川成都610017

出　　处：《岩石力学与工程学报》2025年第1期174-184,共11页Chinese Journal of Rock Mechanics and Engineering

基　　金：四川省自然科学青年基金项目(2023NSFSC0929)。

摘　　要：柱塞岩样加热后内部细观局部可膨胀位移存在差异,导致微裂纹非均质性显著,因此在研究岩石受热后力学行为时,局部可膨胀位移约束也是必要考虑因素之一。以砂岩为例,首先通过加热后岩石薄片多点观测提取裂纹特征,进一步基于多晶离散元法重构数字岩芯,并开展热损伤仿真,探究位移约束及温度耦合影响下砂岩微裂纹发育机制和力学参数变化特征。研究表明:(1)粒内裂纹发育受加热温度和可膨胀位移的影响,损伤加剧表现为:沿解理面形成优势倾向→交叉状共轭剪切裂纹→小尺寸颗粒内裂纹密度增大。(2)Ф25 mm×50 mm岩样经200℃~1000℃加热后,最大可膨胀位移随温度升高呈线性增长趋势,但温度对可膨胀位移值的离散性影响并不显著。裂纹数量在初期随可膨胀位移线性大幅增长,后趋缓至平稳。800℃后,粒内拉伸裂纹数量反超粒间拉伸裂纹,占比最高,而粒内剪切破坏在1000℃以下几乎不发生。(3)更高的温度会抑制可膨胀位移对微裂纹发育的促进作用,具体体现为:经400℃加热后,微裂纹增长率为668.3%,升温至1000℃后微裂纹增长率却降低至12.8%。随着可膨胀位移增高,微裂纹的非均匀发育使得岩石宏观非均质性增强,结构更加劣化,力学参数降低。Differences in meso local expandable displacements within the specimen after heating of the plunger rock samples lead to significant microcracking non-homogeneity,so local expandable displacement constraints are also one of the necessary considerations when investigating the mechanical behavior of rocks after heating.Using sandstone as an example,the crack features by multi-point measurements of heated rock slices were determined first.Furthermore,digital cores are reconstructed using the polycrystalline discrete element method,and thermal damage simulations are carried out to investigate the mechanism of microcrack formation in sandstone as well as the variation characteristics of mechanical parameters under the combined influence of displacement constraints and temperature.The research findings are as follows.(1)Heating temperature and expandable displacement influence the development of intragranular cracks,resulting in preferential orientations along cleavage planes,conjugate shear cracks in a crossed pattern,and increased crack density within small particles.(2)AfterФ25 mm×50 mm rock samples were heated at 200℃-1000℃,the maximum expandable displacement increased linearly with temperature,but the effect of temperature on the dispersion of expandable displacement values was not significant.The number of cracks increased linearly with the expandable displacement at the beginning,and then slowed down to a stable level.800℃heating,the number of intra-grain tensile cracks exceeded the inter-grain tensile cracks in the highest proportion,while the intra-grain shear damage almost did not occur below 1000℃.(3)Higher temperatures inhibit the promotion of microcrack development by expandable displacements.For example,after heating at 400℃,the microcrack growth rate is 668.3%,but it drops to 12.8%after heating at 1000℃.As the expandable displacement increases,the non-uniform development of microcracks makes the rock macroscopically non-homogeneous,and the structure is more deteriorated leading to a decreas

关 键 词：岩石力学 致密砂岩 位移约束 热诱导 微裂纹 细观力学 

分 类 号：TU45[建筑科学—岩土工程]