The impact of constitutive modeling of porous rocks on 2-D wellbore stability analysis

Coelho, Lúcia Carvalho; Soares, Angelo; Ebecken, Nelson F. F.; Alves, José L. D.; Landau, Luiz

doi:10.1016/j.petrol.2004.08.004

Cited by 19 publications

(8 citation statements)

References 22 publications

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“…The laboratory data show that the critical stress C * for the onset of shear‐enhanced compaction decreases with increasing porosity and grain size, and in terms of the effective mean stress and differential stress the initial yield envelope maps out an elliptic cap in the stress space. Such an elliptic cap has been adopted to model the stress profile, tectonic evolution and fluid flow in sedimentary formations [ Fisher et al , 1999; Casey and Butler , 2004; Karner et al , 2005; Bjorlykke et al , 2005], borehole instability [ Coelho et al , 2005], and initiation of compaction localization due to geometric heterogeneity [ Tembe et al , 2006]. In this study we move beyond the initial yield stage to consider the subsequent evolution of the yield stresses after the onset of shear‐enhanced compaction.…”

Section: Summary and Discussionmentioning

confidence: 99%

Shear‐enhanced compaction and strain localization: Inelastic deformation and constitutive modeling of four porous sandstones

2006

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[1] We studied the mechanics of compactant failure in four sandstones associated with a broad range of failure modes in the brittle-ductile transition. While Berea and Bentheim sandstones can fail by compaction localization, homogeneous cataclastic flow dominates failure modes in Adamswiller and Darley Dale sandstones at high effective pressures. We acquired new experimental data to complement previous studies, focusing on the strain hardening behavior in samples under drained conditions. The initial yield stresses were identified as the critical stresses at the onset of shear-enhanced compaction, subsequent yield stresses were considered to depend on hardening given by plastic volumetric strain. The yield stresses were described by elliptical yield caps in the stress space, and we compared the cap evolution with two constitutive models: the critical state model and the cap model. Bentheim sandstone showed the best agreement with both models to relatively large strains. Darley Dale sandstone showed the best agreement with the associated flow rule as prescribed by the normality condition, which is implicitly assumed in both constitutive models. Shear-enhanced compaction in Bentheim and Berea sandstones was appreciably more than that predicted for an associative flow rule, with the implication that a nonassociative model is necessary for capturing the inelastic and failure behavior of these sandstones over a broad range of effective pressures. With reference to the nonassociative model formulated by Rudnicki and Rice, bifurcation analysis would predict the transition of failure mode from shear band to compaction band and ultimately to cataclastic flow, in qualitative agreement with the experimental observations.Citation: Baud, P., V. Vajdova, and T. Wong (2006), Shear-enhanced compaction and strain localization: Inelastic deformation and constitutive modeling of four porous sandstones,

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Section: Summary and Discussionmentioning

confidence: 99%

Shear‐enhanced compaction and strain localization: Inelastic deformation and constitutive modeling of four porous sandstones

2006

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“…In order to calibrate the meso-scale tensile strength, σ t and the tensile characteristic length, t , a direct tension test was simulated. In absence of specific information relevant to Bleurswiller sandstone, the area beneath the stress-displacement curve and the peak stress (Figure 3b) were compared with typical fracture energy and macroscopic tensile strength for sandstones found in the literature, 15 fracture energy of G f =33 J/m 2 and a macroscopic tensile strength of 3 MPa. It should be noted that macroscopic values of fracture energy is greater than the meso-scale value due to the presence of shear stresses in addition to the normal stresses on the facets which leads to the combination of tensile and frictional behaviors (mixed fracture mode) even under macroscopic mode 1 fracture conditions.…”

Section: Fracture Testmentioning

confidence: 99%

“…The transition from one type of response to another is typically gradual [1] and poses considerable challenges due to the competition of the microscopic processes that characterize each of the two aforementioned macroscopic phenomena. This intermediate behavior has been found to be crucial for a variety of applications, including the tectonics of faulting [7][8][9], the coupling between strain localization and fluid flow [10,11], reservoir compaction [12,13] and borehole instability [14,15].…”

Section: Introductionmentioning

confidence: 99%

A lattice discrete particle model for pressure-dependent inelasticity in granular rocks

Ashari

Buscarnera

Cusatis

2017

International Journal of Rock Mechanics and Mining Sciences

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This paper deals with the formulation, calibration, and validation of a Lattice Discrete Particle Model (LDPM) for the simulation of the pressure-dependent inelastic response of granular rocks. LDPM is formulated in the framework of discrete mechanics and it simulates the heterogeneous deformation of cemented granular systems by means of discrete compatibility/equilibrium equations defined at the grain scale. A numerical strategy is proposed to generate a realistic microstructure based on the actual grain size distribution of a sandstone and the capabilities of the method are illustrated with reference to the particular case of Bleurswiller sandstone, i.e. a granular rock that has been extensively studied at the laboratory scale. LDPM micromechanical parameters are calibrated based on evidences from triaxial experiments, such as hydrostatic compression, brittle failure at low confinement and plastic behavior at high confinement. Results show that LDPM allows exploring the effect of fine-scale heterogeneity on the inelastic response of rock cores, achieving excellent quantitative performance across a wide range of stress conditions. In addition, LDPM simulations demonstrate its capability of capturing different modes of strain localization within a unified mechanical framework, which makes this approach applicable for a wide variety of geomechanical settings. Such promising performance suggests that LDPM may constitute a viable alternative to existing discrete numerical methods for granular rocks, as well as a versatile tool for the interpretation of their complex deformation/failure patterns and for the development of continuum models capturing the effect of micro-scale heterogeneity.

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“…Вопрос о смене характера разрушения от хрупкого к вязкому в пористых горных по-родах является актуальным для различных областей геологии и геофизики [25][26][27][28][29]. Клю-чевым направлением исследований в этой области является развитие механических моде-лей пластичности для описания особенностей интегрального механического отклика (включая разрушение) пористых хрупких геологических материалов и сред.…”

Section: ключевые словаunclassified

The Possibilities and Limitations of the Homogenized Description of Inelastic Behavior of Brittle Porous Materials Under Constrained Conditions

2017

PNRPU MB

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Астафуров С.В., Шилько Е.В., Псахье С.Г. О возможностях и ограничениях усредненного описания неупругого поведения хрупких пористых материалов в стесненных условиях // Вестник Пермского национального исследователь-ского политехнического университета. Механика. -2017Механика. - . -№ 1. -С. 208-232. DOI: 10.15593/perm.mech/2017 Astafurov S.V., Shilko E.V., Psakhie S.G. The possibilities and limitations of the homogenized description of inelastic behavior of brittle porous materials under constrained conditions. PNRPU Mechanics Bulletin. 2017 В работе с использованием компьютерного моделирования методом подвижных клеточных автоматов проведено исследование особенностей неупругого деформиро-вания и разрушения микроскопических областей пористых хрупких материалов в усло-виях неравноосного сжатия. Акцент в исследовании сделан на анализе применимости классических макроскопических критериев пластичности и прочности для интегрально-го описания механического отклика представительных объемов микроскопического масштаба. Проанализирована связь параметров интегрального механического отклика микроскопических областей с объемным содержанием пор, характером их пространст-венного распределения в объеме материала и прочностными свойствами материала стенок каркаса. На примере осевого сжатия образцов в условиях постоянного бокового давления исследована стадийность процессов накопления и роста повреждений в стенках пористого каркаса и их связь с интегральным неупругим откликом. Показано, что с ростом величины бокового давления происходит смена характера разрушения пористого материала от упруго-хрупкого к неупругому, локализованному в форме поло-сы сдвига, и далее к объемному катакластическому. Значения характерных боковых давлений, при которых происходит смена механизма разрушения, существенным обра-зом зависят от чувствительности прочности стенок каркаса к локальному давлению. Анализ результатов моделирования показал, что традиционные условия (критерии) пластичности, учитывающие вклад локального среднего напряжения в линейном при-ближении, адекватно описывают отклик микроскопических представительных объемов хрупких пористых материалов в стесненных условиях только от начала неупругого деформирования до стадии формирования системы относительно коротких невзаимо-действующих трещин. Важно отметить, что разупрочнение представительных микро- Ключевые слова:хрупкий пористый материал, неупругая деформация, полоса локализованного сдвига, катакла-стическое течение, разрушение, функция текучести, прочность, компьютерное моделирование, метод подвижных клеточных автоматов.

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The impact of constitutive modeling of porous rocks on 2-D wellbore stability analysis

Cited by 19 publications

References 22 publications

Shear‐enhanced compaction and strain localization: Inelastic deformation and constitutive modeling of four porous sandstones

Shear‐enhanced compaction and strain localization: Inelastic deformation and constitutive modeling of four porous sandstones

A lattice discrete particle model for pressure-dependent inelasticity in granular rocks

The Possibilities and Limitations of the Homogenized Description of Inelastic Behavior of Brittle Porous Materials Under Constrained Conditions

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