Analyzing wellbore stability in chemically-active anisotropic formations under thermal, hydraulic, mechanical and chemical loadings

Kanfar, Majed F.; Chen, Zhixi; Rahman, Sheik S.

doi:10.1016/j.jngse.2017.02.006

Cited by 37 publications

(17 citation statements)

References 29 publications

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“…These phenomenological equations and the accompanying Navier-type equations are beyond this study's scope. A complete porochemothermoelastic solution to borehole instability can also be found in other studies (Ekbote and Abousleiman 2005;Kanfar et al 2017).…”

Section: Methodsmentioning

confidence: 60%

“…This was borne out of the fact that pure poroelastic analysis could not possibly explain borehole instability associated with chemically reactive formations and regions with unusually high subsurface temperatures (Cheng 2016). Numerous experimental pieces of evidence describing how chemical inhomogeneity and thermal imbalances downhole equally cause induced pore pressures have been presented (Kanfar et al 2017). These various dimensions of addressing borehole instability led to poromechanics analyses under different names like porochemoelasticity (Ekbote and Abousleiman 2006), porothermoelasticity (Jaeger et al 2010), porochemothermoelasticity (Ekbote and Abousleiman 2005), etc.…”

Section: Resourcementioning

confidence: 99%

“…However, most research on the analysis of borehole instability based on poroelasticity theory or one of its extended forms like Ekbote and Abousleiman (2005), Kanfar et al (2017) and Li and Weijermars (2019), only consider effective hoop, radial, and tangential stresses at a given zone without considering the influence of depth. In addition, other poromechanicsbased treatments of drilled or excavated hole instability in the industry usually do not isolate induced stresses and strains from residual stresses and strains.…”

Section: Resourcementioning

confidence: 99%

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Influence of depth on induced geo-mechanical, chemical, and thermal poromechanical effects

Ezendiokwere

Aimikhe

Dosunmu

et al. 2021

J Petrol Explor Prod Technol

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Delivering efficient and cost-effective drilled and excavated holes require effective prediction of instability along the hole profile. Most drilled and excavated hole stability analyses in the literature are performed for a given zone without considering the influence of depth. This study focused on determining the influence of depth on induced geo-mechanical, chemical, and thermal stresses and strains in drilled or excavated holes. To this end, a new porochemothermoelastic model was developed based on extended poroelastic theory, and the developed model was employed in determining induced strains and stresses for an oil and gas well case study, using data from the literature. The study delineated the different significance levels of geo-thermal-, chemical-, and thermal-induced strains and stresses as depth increased. From the results obtained, it was clear that at shallow depths, chemically induced strains and stress were the most significant formation perturbations responsible for instability of drilled and excavated holes. On the other hand, at deeper depths, geo-mechanical-induced strains and stress were the most predominant. Comparatively, thermally induced strains and stresses were found to be the least significant formation perturbations responsible for instability of drilled and excavated holes. For this case study, the results indicated that chemical strains and stresses were more prominent at depths below 170 m, accounting for more than 50% of the total stresses and strains. At 170 m, both chemical and geo-mechanical stress and strain had equal contributions to the overall stress and strain. However, as depth increased, the percentage contribution of the geo-mechanical component increased and accounted for about 80% of the total strains and stresses at 1000 m, which increased to 98.48% at depths of 6000 m and beyond. The findings of this study will provide guide for future studies on the application of extended poroelasticity theory in solving instability problems of drilled and excavated holes.

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Section: Methodsmentioning

confidence: 60%

Section: Resourcementioning

confidence: 99%

Section: Resourcementioning

confidence: 99%

See 1 more Smart Citation

Influence of depth on induced geo-mechanical, chemical, and thermal poromechanical effects

Ezendiokwere

Aimikhe

Dosunmu

et al. 2021

J Petrol Explor Prod Technol

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“…• The minimum amount of mud weight to prevent breakout failure At mud weight less than safe mud weight, the rock breaks, and the lower the mud weight, the more severe the breakout fracture; the swabbing process can have a similar effect (Kanfar et al 2017).…”

Section: Estimation Of Safe Mud Windowmentioning

confidence: 99%

Stress field analysis and its effect on selection of optimal well trajectory in directional drilling (case study: southwest of Iran)

Abdideh

Dastyaft

2021

J Petrol Explor Prod Technol

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Given the complexities of reservoir exploration and development, it is vital to understand the geomechanical properties of the reservoir and well in the drilling operation. In constructing a mechanical model of the earth, a combination of environmental geomechanical parameters, as well as the magnitude and direction of stresses, is used. In this study, stress analysis and its effect on azimuth well in deviated drilling in an oil field located in southwestern Iran are investigated. Necessary geomechanical parameters are estimated using density and slowness logs of sonic waves (shear and compression). The Mohr–Coulomb failure criterion is followed to determine a safe mud weight window. A mechanical model of the earth is designed using laboratory data and well logging, and it is validated by the results obtained from laboratory rock mechanics using the calibrated core samples. The results show that drilling in the azimuth at about 135° with an angle of about 15° is the most stable path for the well in the carbonate reservoir formation in the studied oil field.

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“…Chemo-poromechanical properties of shales are also not commonly available (Ghassemi and Diek 2003). Moreover, those available analytical solutions for transversely isotropic material assume that the plane of isotropy always perpendicular to the borehole axis, and numerical model is required to remove the assumption (Kanfar et al 2015b(Kanfar et al , 2016(Kanfar et al , 2017.…”

Section: Introductionmentioning

confidence: 99%

Anisotropic Wellbore Stability Analysis: Impact on Failure Prediction

Asaka

Holt

2020

Rock Mech Rock Eng

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Shale formations are the main source of borehole stability problems during drilling operations. Suboptimal predictions of borehole failure may partly be caused by neglecting the anisotropic nature of shales: Conventional wellbore stability analysis is based on borehole stresses computed from isotropic linear elasticity (Kirsch solution) with the assumption of no induced pore pressure. This is very convenient for a practical implementation but does not always work for shales. Here, anisotropic wellbore stability analysis was performed targeting an offshore gas field to investigate in particular the impact of elastic anisotropy on borehole failure predictions. Stress concentration around a circular borehole in anisotropic shale was calculated by the Amadei solutions, and induced pore pressure was obtained from the Skempton parameters based on anisotropic poroelasticity. Borehole failure regions and modes were then predicted using the effective stresses and those are apparently consistent with observations. A comparison with the conventional approach suggests the importance of accounting for elastic anisotropy: Predicted failure regions, modes, and also the associated mud weight limits can be completely different. This observation may have significant implications for other fields since shale often show strong elastic anisotropy.

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Analyzing wellbore stability in chemically-active anisotropic formations under thermal, hydraulic, mechanical and chemical loadings

Cited by 37 publications

References 29 publications

Influence of depth on induced geo-mechanical, chemical, and thermal poromechanical effects

Influence of depth on induced geo-mechanical, chemical, and thermal poromechanical effects

Stress field analysis and its effect on selection of optimal well trajectory in directional drilling (case study: southwest of Iran)

Anisotropic Wellbore Stability Analysis: Impact on Failure Prediction

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