Stability analysis of vertical boreholes using the Mogi-Coulomb failure criterion

A. M. Al-Ajmi, R. W. Zimmerman

Research output: Contribution to journalArticle

195 Citations (Scopus)

Abstract

A main aspect of wellbore stability analysis is the selection of an appropriate rock failure criterion. The most commonly used criterion for brittle failure of rocks is the Mohr-Coulomb criterion. This criterion involves only the maximum and minimum principal stresses, σ1 and σ3, and therefore assumes that the intermediate stress σ2 has no influence on rock strength. As the Mohr-Coulomb criterion ignores the strengthening effect of the intermediate stress, it is expected to be too conservative in estimating the critical mud weight required to maintain wellbore stability. Recently, Al-Ajmi and Zimmerman [Relationship between the parameters of the Mogi and Coulomb failure criterion. Int J Rock Mech Min Sci 2005;42(3):431-39.] developed the Mogi-Coulomb failure criterion, and showed that it is reasonably accurate in modelling polyaxial failure data from a variety of rocks. We then develop a model for the stability of vertical boreholes, using linear elasticity theory to calculate the stresses, and the fully-polyaxial Mogi-Coulomb criterion to predict failure. Our model leads to easily computed expressions for the critical mud weight required to maintain wellbore stability.

Original languageEnglish
Pages (from-to)1200-1211
Number of pages12
JournalInternational Journal of Rock Mechanics and Mining Sciences
Volume43
Issue number8
DOIs
Publication statusPublished - Dec 2006

Keywords

  • Drucker-Prager failure criterion
  • Failure criteria
  • Mogi failure criterion
  • Polyaxial test data
  • Wellbore stability

ASJC Scopus subject areas

  • Geotechnical Engineering and Engineering Geology

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