Time-dependent borehole stability in hard-brittle shale

作     者：Chuan-Liang Yan Lei-Feng Dong Kai Zhao Yuan-Fang Cheng Xiao-Rong Li Jin-Gen Deng Zhen-Qi Li Yong Chen Chuan-Liang Yan;Lei-Feng Dong;Kai Zhao;Yuan-Fang Cheng;Xiao-Rong Li;Jin-Gen Deng;Zhen-Qi Li;Yong Chen

作者机构：Key Laboratory of Unconventional Oil&Gas Development(China University of Petroleum(East China))Ministry of EducationQingdao266580ShandongChina School of Petroleum EngineeringChina University of Petroleum(East China)Qingdao266580ShandongChina College of Petroleum EngineeringXi©an Shiyou UniversityXi©an710065ShaanxiChina State Key Laboratory of Petroleum Resources and ProspectingChina University of Petroleum(Beijing)Beijing102249China 

出 版 物：《Petroleum Science》 (石油科学（英文版）)

年 卷 期：2022年第19卷第2期

页      面：663-677页

核心收录：

学科分类：0820[工学-石油与天然气工程] 082001[工学-油气井工程] 08[工学] 

基　　金：financially supported by the National Natural Scienceof China(52074224,U1762216) the Key Research and Development Program of Shandong Province(2019GGX103025) 

主　　题：Shale Rock damage Drilling fluid density Borehole stability 

摘      要：Rock damage appears in brittle shale even prior to peak stress(i.e.,before failure)due to the occurrence of microcracks in these *** this work,a coupled hydromechanical model was built by incorporating the mechanical and fluid seepage induced stresses around a wellbore during *** borehole instability mechanism of hard-brittle shale was *** results show that even if a well is simply drilled into a hard-brittle shale formation,the formation around the borehole can be subjected to rock *** maximum failure ratio of the formation around the borehole increases with drilling time.A lower drilling fluid density corresponds to a faster increase in the failure ratio of the borehole with time and a shorter period of borehole *** the initial drilling fluid density is too low,serious rock damage occurs in the formation around the *** though a high-density drilling fluid is used after drilling,long-term borehole stability is difficult to *** drilling in hard-brittle shale,drilling fluid with a proper density should be used rather than increasing the density of the drilling fluid only after borehole collapse occurs,which is more favorable for maintaining long-term borehole stability.