Numerical Simulation for the Dynamic Breakout of a Borehole Using Boundary Element Method

Wan, Cheng; Jiang, Guosheng; Zhou, Zhidong; Wei, Zijun; Li, Xiaodong

doi:10.1007/s10706-019-00802-7

Cited by 10 publications

(6 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…(2024) 10:114 Hence, knowing the stress concentrations around the borehole, the tensile and shear stabilities can be assessed, using the well-known continuum-based approaches. Although a few studies on the stability of elliptical wellbores have been done by past authors, unfortunately, these models are primarily applicable to vertical and low-angle wells, as the out-of-plane shear stresses are disregarded Angell-Olsen 1995, Aadnoy andEdland ( 2001), Chen et al (2019), Cheng et al (2019). For high-angle wells, the anti-plane shear stresses significantly impact the stability of the well, and thus cannot be neglected for rigorous stability analyses.…”

Section: Equivalent Ellipsementioning

confidence: 99%

“…Yet, they provide a powerful tool for sensitivity analyses and calibration of numerical models, in some cases. Most studies conducted on the post-failure stability analysis of the wellbore have been based on finite element analysis (Tsopela et al 2020;Lin et al 2020;Cheng et al 2019;Zhang et al 2019;Li et al 2017;, except the notable semi-analytical model for stress distribution around a notched circular opening presented by Exadaktylos et al (2002) and analytical models, for the same problem, conducted by Muskheishvilli (1963)) and Mitchell (1966).…”

Section: Mechanical Stabilitymentioning

confidence: 99%

See 1 more Smart Citation

Stability of highly inclined non-circular wellbores in isotropic formations

Oyedokun,

Schubert

2024

Geomech. Geophys. Geo-energ. Geo-resour.

View full text Add to dashboard Cite

The shear and tensile stabilities of highly inclined non-circular wellbores are investigated in this study. Using the equivalent-ellipse hypothesis, the non-circular geometry was approximated as an ellipse, and the corresponding stress concentration equations are presented. With the new set of stress concentration equations, a comprehensive study of the tensile and shear stabilities of an elliptical borehole was conducted, including the impact of well inclination and azimuthal angles, horizontal stress difference, degree of ellipticity, and orientation of the maximum horizontal stress to the major axis of the ellipse. Using five commonly used shear failure criteria, we observed that both Mohr–Coulomb and Drucker Prager (inscribed) failure criteria predicted higher collapse pressures, relative to the others including Drucker Prager (inscribed), Mogi-Coulomb, and Modified Lade. While Drucker Prager's (circumscribed) failure criterion underestimates the collapse pressure. Both the linear elastic and poroelastic models were used in investigating the fracture initiation orientation and pressure of highly inclined elliptical boreholes. The prediction from the poroelastic model is always less than the linear elastic model. In some instances, they predict different fracture initiation orientations. From this study, we observed that generally, a near-circular wellbore is more stable than elliptical borehole in both shear and tension. Nevertheless, there are some well inclination and azimuthal angles than can make an elliptical borehole have more shear and tensile stabilities than a near-circular wellbore.

show abstract

Section: Equivalent Ellipsementioning

confidence: 99%

Section: Mechanical Stabilitymentioning

confidence: 99%

Stability of highly inclined non-circular wellbores in isotropic formations

Oyedokun,

Schubert

2024

Geomech. Geophys. Geo-energ. Geo-resour.

View full text Add to dashboard Cite

show abstract

“…In addition to physical models and laboratory studies on borehole breakouts, various theoretical and numerical models have also been conducted to investigate breakouts. Although the frst theoretical models presented for the breakout had simple assumptions, the episodic progression of the breakout was not investigated in them [7,22], but in the following, more complete numerical models based on the fnite element method and the discrete element method were presented, which are able to predict the breakout in a proper way [23][24][25][26][27][28][29][30][31][32].…”

Section: Introductionmentioning

confidence: 99%

Effect of Eccentricity on Breakout Propagation around Noncircular Boreholes

Bahrehdar

Lakirouhani

2023

Advances in Civil Engineering

View full text Add to dashboard Cite

Investigating the shear failure caused by the concentration of compressive stress around noncircular boreholes is important both in the field and in the laboratory. This article deals with the numerical analysis of elliptical boreholes under a nonisotropic in situ stress field using the Mogi–Coulomb nonlinear failure criterion. The purpose of the presented numerical model is to simulate the progressive shear failure (breakout) around the borehole and investigate the impact of the eccentricity of the borehole on the stability and depth and width of the failure area. According to the obtained results, the breakout is V-shaped and is formed along the minimum principal stress. As the eccentricity of the borehole increases, the final dimension of the breakout becomes smaller; in other words, the increase in ellipticity strengthens the borehole against shear failure. However, as the eccentricity increases, the stress concentration at the breakout tip increases. Another finding of the study conducted in this article is the significant relationship between the width and the depth of the breakout failure, which makes the idea of estimating both horizontal in situ stresses using breakout dimensions seriously doubtful. Also, the interesting result obtained is that the stress concentration factor at the breakout tip for boreholes with different eccentricities is the same at the end of the breakout.

show abstract

“…In the classical theory solution, by substituting the stresses around the borehole calculated from the Kirsch's relations in the failure criterion, the failure area around the borehole is obtained, but with this method, only the first layer of failure is calculated [26], while breakout goes step by step to achieve stability. Progressive breakout failure has also been investigated using numerical techniques [25,[27][28][29][30]. In numerical solution, it is assumed that the initial failure width in the borehole wall remains constant and the failure depth increases, something similar to what happens in laboratory experiments [27].…”

Section: Introductionmentioning

confidence: 99%

Sensitivity Analysis of Effective Parameters in Borehole Failure, Using Neural Network

Jolfaei

Lakirouhani

2022

Advances in Civil Engineering

View full text Add to dashboard Cite

After drilling a borehole in the ground and in a rocky environment, the materials around the borehole are crushed and separated in layers from the borehole wall; this causes the borehole cross section to lose its original circular shape, which redistributes stresses and further failure. This type of episodic failure, which occurs symmetrically and V-shaped on both sides of the borehole and along the minor principal stress, is called breakout. The dimensions of breakout, i.e., its depth and width, are two important indicators that have recently been used in estimating in situ stresses; however, the dimensions of the breakout area depend on the in situ stresses and mechanical properties of the rock, which have not been well addressed so far. This paper presents a comprehensive investigation of breakout dimensions using finite element numerical analysis. The proposed numerical model is based on the equations governing the two-dimensional breakout phenomenon under nonisotropic in situ stresses and plane strain condition. According to the results, increasing the failure function of the area around the breakout tip causes the breakout to expand, until the failure function is less than 1 for all points around the breakout tip, at which point the breakout expansion is stopped and breakout reaches stability. In the other part of the article, using 121 datasets obtained from numerical analysis, an artificial neural network is trained to predict breakout dimensions based on the input parameters of the problem. The main finding of this section is a model that shows that among the parameters affecting the borehole breakout, the internal friction angle of the rock has the greatest impact on the dimensions of the breakout.

show abstract

Numerical Simulation for the Dynamic Breakout of a Borehole Using Boundary Element Method

Cited by 10 publications

References 12 publications

Stability of highly inclined non-circular wellbores in isotropic formations

Stability of highly inclined non-circular wellbores in isotropic formations

Effect of Eccentricity on Breakout Propagation around Noncircular Boreholes

Sensitivity Analysis of Effective Parameters in Borehole Failure, Using Neural Network

Contact Info

Product

Resources

About