Time-dependent closure of a borehole in a viscoplastic rock

Xie, Xiyang; Fjær, Erling; Detournay, Emmanuel

doi:10.1016/j.gete.2019.02.001

Cited by 11 publications

(5 citation statements)

References 14 publications

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“…Literature indicates the importance of shale creep (Chen and Small 2008;Sone and Zoback 2013;Lund and Kleiven 2016;Farhat et al 2016Farhat et al , 2017Nopola and Roberts 2016). Future work should focus on extending the elastoplastic rock model to a viscoelastic-plastic model (Liu et al 2016;Shahsavari et al 2016) or an elasto-viscoplastic one (Xie et al 2019).…”

Section: Discussionmentioning

confidence: 99%

Can Heating Induce Borehole Closure?

et al. 2020

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The current study shows that heating a cased borehole in low-permeability shale rock can induce plastic deformation, leading to the closure of the casing annulus and decreasing annulus connectivity. The thermally induced borehole closure is interesting for the field operation of plug and abandonment (P&A), as it potentially saves operation cost and time by avoiding cutting casing and cementing. Lab experiments and numerical simulations are implemented to investigate the thermally induced borehole closure. Pierre shale and a field shale are tested. The lab experiments are performed by heating the borehole wall in a 10-cm-OD hollow cylinder specimen. Here, a novel experimental setup is applied, allowing for measuring temperature and pore pressure at different radii inside the specimen. Both the experimental data and the post-test CT images of the rock samples indicate the rock failure by borehole heating, and under certain conditions, heating results in an annulus closure. The decrease of hydraulic conductivity through the casing annulus is observed, but this decrease is not enough to form the hydraulic-sealed annulus barrier, based on the results obtained so far. Lab-scale finite-element simulations aim to match the lab results to obtain poro-elastoplastic parameters. Then the field-scale simulations assess the formation of shale barriers by heating in field scenarios. Overall, (i) the lab experiments show that heating a borehole can increase the pore pressure in shale and hence induce rock failure; (ii) the numerical simulations match the experimental results reasonably well and indicate that the heating-induced borehole closure can sufficiently seal the casing annulus in the field-scale simulation.

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Section: Discussionmentioning

confidence: 99%

Can Heating Induce Borehole Closure?

et al. 2020

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“…This section briefly demonstrates the performance of the proposed model for general initial‐boundary value problems. For this purpose, we simulate the time‐dependent closure of a borehole in shale, which is relevant to wellbore stability 3 and leakage prevention 4,5 . We consider a borehole with a radius of 0.1 m, represented in 2D as a circle inside a square domain in plane strain conditions.…”

Section: Borehole Studymentioning

confidence: 99%

“…Shale often accumulates a significant amount of irrecoverable deformation over time. This viscoplastic deformation plays an important role in a variety of subsurface practices, such as in‐situ stress estimation, 1,2 borehole drilling, 3 leakage prevention, 4,5 and hydraulic fracturing 6–8 . This importance has motivated a number of experimental investigations into creep of shale at multiple scales (eg, Refs.…”

Section: Introductionmentioning

confidence: 99%

An anisotropic viscoplasticity model for shale based on layered microstructure homogenization

Choo

Semnani

White

2020

Num Anal Meth Geomechanics

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Viscoplastic deformation of shale is frequently observed in many subsurface applications. Many studies have suggested that this viscoplastic behavior is anisotropic—specifically, transversely isotropic—and closely linked to the layered composite structure at the microscale. In this work, we develop a two‐scale constitutive model for shale in which anisotropic viscoplastic behavior naturally emerges from semianalytical homogenization of a bilayer microstructure. The microstructure is modeled as a composite of soft layers, representing a ductile matrix formed by clay and organics, and hard layers, corresponding to a brittle matrix composed of stiff minerals. This layered microstructure renders the macroscopic behavior anisotropic, even when the individual layers are modeled with isotropic constitutive laws. Using a common correlation between clay and organic content and magnitude of creep, we apply a viscoplastic modified Cam‐Clay plasticity model to the soft layers, while treating the hard layers as a linear elastic material to minimize the number of calibration parameters. We then describe the implementation of the proposed model in a standard material update subroutine. The model is validated with laboratory creep data on samples from three gas shale formations. We also demonstrate the computational behavior of the proposed model through simulation of time‐dependent borehole closure in a shale formation with different bedding plane directions.

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“…This section briefly demonstrates the performance of the proposed model for general initial-boundary value problems. For this purpose, we simulate the the time-dependent closure of a borehole in shale, which is relevant to wellbore stability [3] and leakage prevention [4,5]. We consider a borehole with a radius of 0.1 m, represented in 2D as a circle inside a square domain in plane strain conditions.…”

Section: Borehole Studymentioning

confidence: 99%

“…Shale often accumulates a significant amount of irrecoverable deformation over time. This viscoplastic deformation plays an important role in a variety of subsurface practices, such as in-situ stress estimation [1,2], borehole drilling [3], leakage prevention [4,5], and hydraulic fracturing [6][7][8]. This importance has motivated a number of experimental investigations into creep of shale at multiple scales (e.g.…”

Section: Introductionmentioning

confidence: 99%

An anisotropic viscoplasticity model for shale based on layered microstructure homogenization

Choo,

Semnani,

White

2020

Preprint

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Viscoplastic deformation of shale is frequently observed in many subsurface applications. Many studies have suggested that this viscoplastic behavior is anisotropic and closely linked to the layered composite structure at the microscale. In this work, we develop a two-scale constitutive model for shale in which anisotropic viscoplastic behavior naturally emerges from semi-analytical homogenization of a bi-layer microstructure. The microstructure is modeled as a composite of soft layers, representing a ductile matrix formed by clay and organics, and hard layers, corresponding to a brittle matrix composed of stiff minerals. This layered microstructure renders the macroscopic behavior anisotropic, even when the individual layers are modeled with isotropic constitutive laws. Using a common correlation between clay and organic content and magnitude of creep, we apply a viscoplastic Modified Cam-Clay plasticity model to the soft layers, while treating the hard layers as a linear elastic material to minimize the number of calibration parameters. We then describe the implementation of the proposed model in a standard material update subroutine. The model is validated with laboratory creep data on samples from three gas shale formations. We also demonstrate the computational behavior of the proposed model through simulation of time-dependent borehole closure in a shale formation with different bedding plane directions.

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Time-dependent closure of a borehole in a viscoplastic rock

Cited by 11 publications

References 14 publications

Can Heating Induce Borehole Closure?

Can Heating Induce Borehole Closure?

An anisotropic viscoplasticity model for shale based on layered microstructure homogenization

An anisotropic viscoplasticity model for shale based on layered microstructure homogenization

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