Mapping stress trajectories and width of the stress-perturbation zone near a cylindrical wellbore

Weijermars, Ruud

doi:10.1016/j.ijrmms.2013.08.019

Cited by 9 publications

(5 citation statements)

References 13 publications

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“…In order to closely investigate the differences yielded by the criteria, however, it is necessary to include in the analysis the principal stresses at the failure location as influenced by the presence of the wellbore. The local stress deviations are limited to a region within 10 times wellbore radius away from the wellbore [30]. However, such localized stress redistributions and stress concentrations near the wellbore are very important in the wellbore stability analysis, because prediction of the instability is determined by the deviated stress conditions at the potential failure locations.…”

Section: Effect Of Principal Stresses At Failure Locationmentioning

confidence: 99%

“…(2) When the radial deviatoric stress in an elliptical region near the wellbore is tensile (negative) and thus minimum, and the tangential stress is the maximum compressive stress, this is called a fracture cage. The term was first introduced in Weijermars [30] as follows: "-Confined space around borehole where the principal deviatoric tension stress follows concentric rings so that any radial fracture emanating from the wellbore into the fracture cage space will remain trapped inside and rotate into the direction of the concentric tension rings. A negative Frac number is a prerequisite for the occurrence of a fracture cage.…”

Section: Importance Of Stress Trajectories Stress Cages and Fracturmentioning

confidence: 99%

“…The source of fluid fill of a pre-existing radial fracture cannot be the wellbore fluid (and was indeed a separate injector [30] in the models of Figure 14a,b), because (1) compressional tangential stress of the fracture cage would tend to close and possibly seal the radial fracture, and (2) the pore pressure is higher than the wellbore pressure. This might suggest that the risk of failing a fracture cage is very low.…”

Section: Tensile Failure and Fracture Propagationmentioning

confidence: 99%

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New Interface for Assessing Wellbore Stability at Critical Mud Pressures and Various Failure Criteria: Including Stress Trajectories and Deviatoric Stress Distributions

Wang

Weijermars

2019

Energies

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This study presents a new interface for wellbore stability analysis, which visualizes and quantifies the stress condition around a wellbore at shear and tensile failure. In the first part of this study, the Mohr–Coulomb, Mogi–Coulomb, modified Lade and Drucker–Prager shear failure criteria, and a tensile failure criterion, are applied to compare the differences in the critical wellbore pressure for three basin types with Andersonian stress states. Using traditional wellbore stability window plots, the Mohr–Coulomb criterion consistently gives the narrowest safe mud weight window, while the Drucker–Prager criterion yields the widest window. In the second part of this study, a new type of plot is introduced where the safe drilling window specifies the local magnitude and trajectories of the principal deviatoric stresses for the shear and tensile wellbore failure bounds, as determined by dimensionless variables, the Frac number (F) and the Bi-axial Stress scalar (χ), in combination with failure criteria. The influence of both stress and fracture cages increases with the magnitude of the F values, but reduces with depth. The extensional basin case is more prone to potential wellbore instability induced by circumferential fracture propagation, because fracture cages persists at greater depths than for the compressional and strike-slip basin cases.

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Section: Effect Of Principal Stresses At Failure Locationmentioning

confidence: 99%

Section: Importance Of Stress Trajectories Stress Cages and Fracturmentioning

confidence: 99%

Section: Tensile Failure and Fracture Propagationmentioning

confidence: 99%

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New Interface for Assessing Wellbore Stability at Critical Mud Pressures and Various Failure Criteria: Including Stress Trajectories and Deviatoric Stress Distributions

Wang

Weijermars

2019

Energies

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“…Previous studies have shown that the stress distribution in the reservoir volume, particularly near the borehole, can be significantly perturbed due to geomechanical effects. These effects can impact both the magnitude and orientation of stresses up to a distance of approximately 10-15 borehole radii (Weijermars, 2013). We argue that the low level of seismic activity in the near-borehole region in our study is caused by such stress perturbations around the borehole.…”

Section: Prevailing Stress Regimementioning

confidence: 61%

Insights from Subsurface Monitoring for Engineering of the Stimulation Pattern in Fractured Reservoirs

Doonechaly,

Bröker,

Hertrich

et al. 2024

Preprint

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Stimulation operations enhance the performance of geothermal reservoirs by boosting fluid flow and heat transfer. Predicting stimulation outcomes is challenging due to complexity of reservoir properties and limited observations given by operational conditions. Factors like stress state, natural structures, pressure distribution, and injection patterns play crucial roles in engineering of a stimulation operation. This study provides in-depth observations from a hectometer-scale stimulation experiment conducted at the Bedretto Underground Laboratory for Geosciences and Geoenergies within a densely monitored crystalline rock volume with an overburden of more than 1 km. We found that hydraulic connectivity, pressure compartments, and the characteristics of existing geological structures play pivotal roles in the propagation patterns of seismic events. Notably, the initiation and distribution of seismicity are markedly influenced by the zonal isolation and the structured propagation of pressure front across the reservoir. The research highlights the necessity of adapting stimulation strategies to the unique geomechanical as well as geological characteristics of the reservoir, as evident from the distinct activation patterns observed between the first and second injection cycles. The spatial extent of the stimulated volume can be partially guided by the number of stimulation cycles and injection pressure level, as farther structures are increasingly likely to be activated in the subsequent cycles. The results also indicate that the Kaiser effect is more pronounced in regions closer to the injection borehole. However, this effect can be attenuated due to stress changes caused by stimulation, consistent with a proposition from a recent study. Our findings underscore the critical importance of understanding the interplay between hydraulic pressures and stress states to optimize the stimulation of geothermal reservoirs effectively.

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“…Both isotropic and anisotropic of shale rock were considered. Based on the basic theories established a long time before, researches now focus on borehole stability under dynamic loading conditions, and the influence of anisotropic strata, including anisotropy of sedimentary tectonics, strength parameters, and elastic parameters . Using these contributions, more accurate predictions were achieved.…”

Section: Introductionmentioning

confidence: 99%

Large‐scale experiments of the borehole instability on shale formation influenced by drill pipe rotation

Sun

Meng

Dai

et al. 2019

Energy Science & Engineering

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Wellbore instability happens mostly in the shale formation. Early researches have studied thoroughly on the physicochemical and mechanical mechanism that causes instability. However, only a few works have considered the influence of field drilling operations, such as drill pipe rotation. In this paper, a true triaxial cell is used to simulate the downhole field situations, and a drill pipe rotation device is innovatively designed and implemented into the true triaxial cell. Using this facility, the influence of drill pipe rotation on shale instability has been performed. Different rotation speed, weight on bit, drilling fluid pressure, and microcracks on borehole have been considered. The enlargement of the wellbore is quantitatively plotted and compared.Results show that the drill pipe rotation contributes to a more enlargement of the wellbore, and a higher rotation speed causes a more severe collapse. The drill string weight on bit also contributes to the enlargement of the wellbore, with a larger weight on bit induces a larger diameter of the collapsed wellbore. Compared with the rotation speed and weight on bit, the influence of drilling fluid density is relatively less significant. However, the influence of microcracks caused by hitting of drilling tools is profound. For a cracked shale formation, the wellbore diameter can be enlarged for more than 40%. Then, the variation of borehole collapse with time and depth under drill pipe rotation influence is analyzed. In all of these four factors, the significant sequence is microcracks > weight on bit > rotation speed > drilling fluid pressure.In all the collapse phenomena, the collapse is more severe in the minimum horizontal stress direction. This is explained by the analysis of the stress distribution in the whole circumferential angle (360°) of the wellbore. Overall, this work fills the gap of the influence of drilling operations on wellbore instability. K E Y W O R D Sborehole enlargement, drill pipe rotation, true triaxial cell, wellbore instability 2896 | SUN et al.

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Mapping stress trajectories and width of the stress-perturbation zone near a cylindrical wellbore

Cited by 9 publications

References 13 publications

New Interface for Assessing Wellbore Stability at Critical Mud Pressures and Various Failure Criteria: Including Stress Trajectories and Deviatoric Stress Distributions

New Interface for Assessing Wellbore Stability at Critical Mud Pressures and Various Failure Criteria: Including Stress Trajectories and Deviatoric Stress Distributions

Insights from Subsurface Monitoring for Engineering of the Stimulation Pattern in Fractured Reservoirs

Large‐scale experiments of the borehole instability on shale formation influenced by drill pipe rotation

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