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Arabian Journal of Geosciences

, 11:532 | Cite as

Analysis of influencing factors of wellbore stability in shale formations

  • Wei Zeng
  • Xiangjun Liu
  • Lixi Liang
  • Jian Xiong
Original Paper
  • 65 Downloads

Abstract

In the process of drilling, wellbore instability in shale formations is frequent and makes it hard to drill. In order to find causes of wellbore instability in shale formations, this paper proposed a wellbore instability analysis model to reveal the combined effects of anisotropic strength of shale, occurrence of stratification, strength reduction, and seepage stresses caused by drilling fluid on wellbore instability. The results show that when the occurrence of bedding planes is certain, it can maintain wellbore stability in the condition of lower mud weight to choose a reasonable azimuthal angle. With changes of shale strength and porous flow, the wellbore would increase the level of instability with drilling time, which means mud weight needs to be increased to keep the wellbore from collapsing.

Keywords

Wellbore stability Shale Mud density Bedding planes Anisotropic strength 

Notes

Funding information

This research was supported by the Key National Science and Technology Projects (2016ZX05044-004-001 and 2016ZX05051-004-008).

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Copyright information

© Saudi Society for Geosciences 2018

Authors and Affiliations

  • Wei Zeng
    • 1
  • Xiangjun Liu
    • 1
  • Lixi Liang
    • 1
  • Jian Xiong
    • 1
  1. 1.State Key Laboratory of Oil and Gas Reservoir Geology and ExploitationSouthwest Petroleum UniversityChengduChina

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