西南石油大学学报(自然科学版)

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Research on Wellbore Stability of Shale Gas Based on
Hoek-Brown Criterion

Liang Lixi, Liu Xiangjun   

  1. State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,Chengdu,Sichuan 610500,China
  • Online:2014-10-01 Published:2014-10-01

Abstract:

The wellbore stability is one of the key technologies in order to achieve rule horizontal wellbore in shale with low cost.
Due to the occurrence and the difficulty in obtaining mechanical parameters of the underground structural planes,the evaluation
method of borehole stability by weak surface theory and Mohr-Coulomb criterion has not yet been applied in engineering,and
was only studied in theory. In this paper,wellbore stability has been evaluated by using Hoek - Brown criterion. The core
numerical model with different fractures has been created,and the tri-axial compression test with different confine pressures
has been carried out by means of the numerical simulation. Relationship between the parameters mb,S and rock mass structure
has been analyzed using the result of the numerical simulation. And the method to determine the parameters mb,S has been
established with fracture development index. The analysis of engineering example shows that collapse pressure obtained with
the theory are consistent with the actual drilling performance in shale formation and a new method for evaluating borehole
stability of shale gas wells has been provided.

Key words: shale, wellbore stability, Hoek-Brown criterion, structural planes, rock strength