Practical application of failure criteria in determining safe mud weight windows in drilling operations

作     者：R.Gholam A.Moradzadeh V.Rasoul J.Hanach 

作者机构：Department of Mining Petroleum and Geophysics Shahrood University of Technology Departmentof Petroleum Engineering Curtin University Geological Division Iranian Offshore Oilfield Company 

出 版 物：《Journal of Rock Mechanics and Geotechnical Engineering》 (岩石力学与岩土工程学报（英文版）)

年 卷 期：2014年第6卷第1期

页      面：13-25页

核心收录：

学科分类：081801[工学-矿产普查与勘探] 08[工学] 0818[工学-地质资源与地质工程] 

主　　题：Mud weight windows Failure criterion Breakout Fracturing Intermediate principal stress 

摘      要：Wellbore instability is reported frequently as one of the most significant incidents during drilling *** of wellbore instability includes estimation of formation mechanical properties and the state of in situ *** this analysis,the only controllable parameter during drilling operation is the mud *** the mud weight is larger than anticipated,the mud will invade into the formation,causing tensile failure of the *** the other hand,a lower mud weight can result in shear failures of rock,which is known as borehole *** predict the potential for failures around the wellbore during drilling,one should use a failure criterion to compare the rock strength against induced tangential stresses around the wellbore at a given mud *** Mohr–Coulomb failure criterion is one of the commonly accepted criteria for estimation of rock strength at a given state of ***,the use of other criteria has been debated in the *** this paper,Mohr–Coulomb,Hoek–Brown and Mogi–Coulomb failure criteria were used to estimate the potential rock failure around a wellbore located in an onshorefield of *** log based analysis was used to estimate rock mechanical properties of formations and state of *** results indicated that amongst different failure criteria,the Mohr–Coulomb criterion underestimates the highest mud pressure required to avoid breakouts around the *** also predicts a lower fracture gradient *** addition,it was found that the results obtained from Mogi–Coulomb criterion yield a better comparison with breakouts observed from the caliper logs than that of Hoek–Brown *** was concluded that the Mogi–Coulomb criterion is a better failure criterion as it considers the effect of the intermediate principal stress component in the failure analysis.