Semi-analytical method for modeling wellbore breakout development
File(s)
Author(s)
Setiawan, Ngurah Beni
Zimmerman, Robert W
Type
Journal Article
Abstract
Borehole breakout initiation, progression, and stabilization are modeled using a semi-analytical method based on Melentiev’s graphical conformal mapping procedure, and Kolosov–Muskhelishvili complex stress potentials. The only input data required are the elastic moduli of the rock, the Coulomb strength parameters (cohesion and angle of internal friction), and the far-field stresses. The stresses around the borehole wall are computed, the region in which the rock has failed is then “removed”, creating a new borehole shape. This process is iterated until a shape is obtained for which the breakout will progress no further, and a stable state has been reached. This modeling shows that stresses around the flank of the breakout evolve so as to reduce the propensity for shear failure, which helps to explain why the breakout width remains relatively constant throughout the process, even as the breakout region deepens radially. The failed area around the borehole becomes smaller and more localized, as the breakout tip sharpens and deepens. Using the Mogi–Coulomb failure criterion, a good match is obtained between the modeled breakout geometry and the geometry observed by Herrick and Haimson in laboratory experiments on an Alabama limestone. The new method leads to a correlation between breakout geometry, rock strength properties, and in situ stress. The paper ends with a critical discussion of the possibility of inferring the in situ stress state from observed breakout geometries.
Date Issued
2022-05-07
Date Acceptance
2022-03-08
Citation
Rock Mechanics and Rock Engineering, 2022, 55, pp.2987-3000
ISSN
0723-2632
Publisher
Springer Science and Business Media LLC
Start Page
2987
End Page
3000
Journal / Book Title
Rock Mechanics and Rock Engineering
Volume
55
Copyright Statement
© The Author(s) 2022. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
License URL
Identifier
https://link.springer.com/article/10.1007/s00603-022-02850-7
Subjects
Science & Technology
Technology
Physical Sciences
Engineering, Geological
Geosciences, Multidisciplinary
Engineering
Geology
Breakouts
In situ stress
Breakout geometry
Breakout width
Mogi-Coulomb
BOREHOLE BREAKOUTS
STRESS
FAILURE
INSTABILITY
ORIENTATION
TELEVIEWER
EVOLUTION
DAMAGE
Geological & Geomatics Engineering
0905 Civil Engineering
0914 Resources Engineering and Extractive Metallurgy
Publication Status
Published
Date Publish Online
2022-05-07