考虑层理效应的页岩压裂模拟全耦合黏结单元法  

Modeling Shale with Consideration of Bedding Plane by Hydraulic-mechanical Coupled Cohesive Finite Element Method

作　　者：李永寿 李淳芳 赵兵 罗攀登 张振南[2] LI Yong-shou;LI Chun-fang;ZHAO Bing;LUO Pan-deng;ZHANG Zhen-nan(Research Institute of Petroleum Engineering,SINOPEC Northwest Oilfield Branch,Urumqi 830011,China;School of Naval Architecture,Ocean and Civil Engineering,Shanghai Jiao Tong University,Shanghai 200240,China)

机构地区：[1]中石化西北油田分公司石油工程技术研究院,乌鲁木齐830011 [2]上海交通大学船舶海洋与建筑工程学院,上海200240

出　　处：《科学技术与工程》2020年第35期14640-14645,共6页Science Technology and Engineering

基　　金：“十三五”国家油气重大专项(2016ZX05014-005-003)。

摘　　要：页岩水力压裂技术是目前最常用的储层改造技术。页岩中存在具有方向性的不连续结构面,使其具有较为明显的层理效应,主要体现为页岩的横观各向同性。为了在水力压裂中反映层理效应,在考虑层理效应的黏结单元方法(cohesive finite element method,CFEM)基础上,考虑力学场和渗流场的相互作用,推导界面单元全流固耦合方程。最后,通过水力压裂试验结果与模拟计算结果的对比,展现在不同地应力条件下页岩层理性对水力裂纹扩展的影响作用。在应用该方法时可以根据给定层理方向,模型自动将与层理平行(或近于平行)的黏结面转化为层面界面,而且在整个模拟过程中,不需要引入额外断裂准则,也不需要网格修正,为页岩水压致裂问题的数值模拟提供了新途径。Shale hydraulic fracturing is the main technology in unconventional resource rupture.Shale contains distributed directional bedding planes,which make the shale transverse isotropic.This bedding effect has considerable influence on the hydraulic fracture propagation.To simulate the hydraulic fracture in shale with consideration of bedding effect,the fully hydro-mechanical coupled equation of interface element was derived for the bedding plane-embedded cohesive finite element method(CFEM).With this CFEM method,the hydraulic fracturing process of shale was simulated.It was shown that the simulated results well agreed with the experimental ones.The results show that the bedding planes have significant influence on the fracture trajectory.When using the method,the cohesive elements that paralleling or almost paralleling to the bedding plane are automatically transformed into bedding elements.Moreover,no external fracture criterion is needed and no mesh modification is involved.So,the method provides an alternative approach to hydraulic fracture simulation in shale.

关 键 词：页岩 界面单元 横观各向同性 流固耦合 水力裂纹模拟 

分 类 号：TU452[建筑科学—岩土工程]