摘要：The elastic models combined with the Mohr-Coulomb criterion are frequently used to assess the wellbore stability problem. However, the elastic models are generally too conservative to predict the minimum wellbore pressure. In addition, the Mohr-Coulomb criterion underestimates the strength of the rock in neglecting the strengthening effect of the intermediate stress. In this study, the Mogi-Coulomb criterion which is a triaxial failure criterion is used to investigate the wellbore stability analysis. The rock is modeled with a strain hardening plastic material. The wellbore stability problem is formulated under undrained conditions. Large strain deformations are assumed to occur in the plastic region whereas small strain deformations are prevalent in the elastic region. The stresses in the elastic region are derived using the classical Kirsch equations. By adopting an associated flow rule assumption, plastic strains increments are expressed in the plastic region. Using the proposed approach, semi-analytical solutions of stresses in the plastic region are obtained by solving a set of three differential equations. The minimum wellbore pressure is determined by applying an appropriate controlled-deformation borehole criterion. The numerical results from the case example has enabled to plot the distribution of the stresses and the wellbore pressure around the wellbore. The curves have the possibility to show the stresses variation from the plastic region to the elastic region. The current model has the advantage to predict less wellbore pressure in comparison with elastics models. Moreover, it also accurately accounts the strengthening effect of the intermediate stress on the strength of the rock.
Copyright 2019 ARMA, American Rock Mechanics Association.

发表日期：2019-01-01

期刊分区（SCI为中科院分区）：无

收录情况：EI（工程索引）

发表期刊名称：53rd U.S. Rock Mechanics/Geomechanics Symposium

通讯作者：兰威,李海涛,爱玲,Matamba

第一作者：邓金根,刘伟

论文类型：会议论文

论文概要：兰威,邓金根,刘伟,李海涛,爱玲,Matamba，Wellbore stability analysis using an elasto-plastic Mogi-Coulomb model，53rd U.S. Rock Mechanics/Geomechanics Symposium，2019，

论文题目：Wellbore stability analysis using an elasto-plastic Mogi-Coulomb model