层理对页岩液氮破裂影响的数值模拟研究  

Numerical Simulation Study of Influence of Bedding Planes on Shale Liquid Nitrogen Fracture

作　　者：蔡悦翔 孙志伟 王奎胜 包春燕 刘明浩[3] CAI Yuexiang;SUN Zhiwei;WANG Kuisheng;BAO Chunyan;LIU Minghao(School of Civil Engineering,Shaoxing University,Shaoxing,Zhejiang 312000;Center of Rock Mechanics and Geohazards,Shaoxing University,Shaoxing,Zhejiang 312000;State Key Laboratory of Frozen Soil Engineering,Chinese Academy of Sciences,Lanzhou,Gansu 730000)

机构地区：[1]绍兴文理学院土木工程学院,浙江绍兴312000 [2]绍兴文理学院岩石力学与地质灾害实验中心,浙江绍兴312000 [3]中国科学院冻土工程国家重点实验室,甘肃兰州730000

出　　处：《绍兴文理学院学报》2022年第8期35-41,共7页Journal of Shaoxing University

基　　金：冻土工程国家重点实验室开放基金项目“裂隙岩石冻胀损伤弱化与破裂机制的物理试验及数值模拟研究”(SKLFSE201815).

摘　　要：层理、裂隙等结构面的存在是改善页岩气采收率的重要因素.为分析在液氮压裂条件下,层理对页岩低温破裂的影响,模拟了单、多层页岩模型在冷冲击作用下的破裂过程,分析了层理密度、层理方向、高径比等参数对页岩温度和最小主应力分布以及裂纹扩展的影响作用,探讨了层理在页岩储层体积改造过程中的重要作用.结果表明:(1)裂缝向平行层理方向扩展时,层理面的弱胶结作用使得阻止裂缝扩展的能力较弱,除小部分向着弱层理面转向,主体裂缝垂直接触面扩展,而裂缝向垂直层理方向扩展时,层理面阻止裂缝扩展的能力较强,裂缝易发生转向和分叉;(2)由于裂缝扩展方向垂直层理的阻碍作用,垂直层理页岩破坏率比平行层理页岩要低;层理密度越高,岩石高径比越大,页岩的破坏率越低.The existence of bedding and fracture is an essential factor in improving the recovery factor of shale gas.In order to analyze the effect of bedding on the low-temperature fracture of shale under the condition of liquid nitrogen fracturing,the fracture process of single-layer and multi-layer shale models under the action of cold shock was simulated,the effects of the parameters such as thickness,direction and ratio of height to diameter on the distribution of temperature,minimum principal stress and crack propagation were analyzed.The results show that(1)when the fracture is spreading in the direction of parallel bedding,the weak cementation effect of the bedding plane makes it weaker to prevent the fracture from spreading.Except for a small part turning towards the weak bedding plane,the primary fracture extends perpendicular to the contact surface.When the fracture is spreading vertically in the bedding plane,it is stronger to prevent the fracture from spreading,the fracture tending to turning and bifurcation;(2)the failure rate of the vertically bedded shale is lower than that of the horizontally bedded shale because of the blocking effect of the vertically bedded shale in the propagation direction of fractures.The higher the thickness of bedding,the greater the ratio of height to the diameter,and the lower the failure rate of shale.

关 键 词：页岩 层理 液氮 数值模拟 

分 类 号：TU45[建筑科学—岩土工程]