Triaxial Deformation of the Goldwyer Gas Shale at In Situ Stress Conditions—Part I: Anisotropy of Elastic and Mechanical Properties

Mandal, Partha Pratim; Sarout, Joël; Rezaee, Reza

doi:10.1007/s00603-022-02936-2

Cited by 14 publications

(8 citation statements)

References 55 publications

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“…Viscoelastic stress relaxation model is solely dependent upon laboratory-measured creep response of investigated gas shale formation. 1-D power-law function characterizes viscoelastic deformation of rocks under insitu conditions (Mandal et al, 2022b;Sone and Zoback, 2014a;Yang and Zoback, 2016). Based on the assumption of linear viscoelastic theory, Mandal et al, 2021 have examined the geomechanical impacts of time-dependent deformation of studied rocks over engineering time scales (days to years).…”

Section: Viscous Stress Relaxationmentioning

confidence: 99%

“…TOC, and Porosity). Given the availability of continuous minerology, TOC and porosity log, n can be estimated from its weak phase component indirectly (Mandal et al, 2022b). Following computation of all relevant inputs, we can derive differential stress across lithological formations by constraining relative variation of in-situ principal stress magnitudes φ with depth.…”

Section: Viscous Stress Relaxationmentioning

confidence: 99%

“…In this study, we are going to report the application of the viscoelastic experimental conditions of heterogenous shale rock samples. This process helped in creating a statistically reliable creep database and their adaptability beyond the experimented formations (Mandal et al, 2022b). The profile of least principal stress is built from the viscous rock properties of the studied formations from the established laboratory database.…”

Section: Introductionmentioning

confidence: 99%

“…List of parameters to in-situ stress state and SHmax magnitude at 1450 m depth within Goldwyer formation can be obtained from Young's modulus using stress partitioning theory whileMandal et al (2022b) utilized power-law correlation between B and n observed from the reported laboratory creep database. It is also found that strong dependency of power-law exponent n with rock's weak phase component (ClayTocPHI -Mixture of Clay,…”

mentioning

confidence: 99%

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Viscoelastic Stress Relaxation for Estimating Shmin Magnitude in Deep Sedimentary Formations

Mandal

Sarout

Rezaee

et al. 2022

56th U.S. Rock Mechanics/Geomechanics Symposium

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General adaptability of viscoelastic stress relaxation from laboratory time-dependent deformation (creep) measurement to derive the least principal stress Shmin magnitudes at depths in sedimentary rocks is proposed. It is based upon a simple viscous rheological model and steady-state tectonic strain loading. Creep data reveals different viscoelastic behavior of rocks mostly controlled by the varying mineral composition and the direction of creep measurement (perpendicular/parallel to the bedding plane). First, this approach is applied in a vertical drilled well then verify in another vertical well located in the Canning Basin where the target resources are ultralow permeable unconventional gas shale reservoirs. A continuous Shmin magnitude profile at depth is obtained from wireline logs through the following: (i) combination of laboratory power-law fitting coefficients, (ii) geological horizontal stress accumulation by constant tectonic loading, and (iii) relatively uniform stress variation of principal stress components (∅= (S_2- S_3)/(S_1- S_3 )) along with depth. Eaton’s extended model could not capture the stress layering effect precisely and may introduce more uncertainty because of its dependency on several unpredictable parameters while the proposed rheology model relies upon laboratory constituent parameters (B, n) where B is the inverse of static Young’s modulus E and n describes time dependency of rock deformation under a given stress.

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Section: Viscous Stress Relaxationmentioning

confidence: 99%

Section: Viscous Stress Relaxationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Viscoelastic Stress Relaxation for Estimating Shmin Magnitude in Deep Sedimentary Formations

Mandal

Sarout

Rezaee

et al. 2022

56th U.S. Rock Mechanics/Geomechanics Symposium

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“…Yang et al 10 tested the typical anisotropic mechanical properties and brittleness of Longmaxi shales under conventional triaxial compression and proposed a new brittleness index to evaluate the shales with different failure modes. Mandal et al 11 performed the constant rate multistage triaxial tests on Goldwyer gas shale formation, and the anisotropy of elastic and mechanical properties of shales was analysed. However, the influence mechanisms of the continuous initiation and propagation of microcracks on fracture‐induced shale anisotropy remain unclear.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the anisotropic mechanical response of layered shales

Gao,

Gong,

Liang

et al. 2023

Energy Science & Engineering

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Layered shales exist widely and are often encountered during shale gas development. However, the mechanical response of layered shales is significantly affected by the existence of beddings, resulting in the obvious anisotropy characteristics regarding deformation, strength and failure mode. To clarify the underlying mechanisms of shale anisotropy that control the safety of engineering projects, the numerical simulation and theoretical analysis were conducted. The results show that with the growth of confining pressure, the compressive resistance of shales gradually increases, the shear fractures govern the instability and the anisotropy index decreases. Furthermore, several strength criteria for layered rock masses were summarized, and the modified Jaeger strength criterion was proposed by introducing the anisotropic parameter . It can effectively reflect the failure modes and strength features of layered shales under triaxial conditions with a higher accuracy. Besides, the variation of cohesion and internal friction angle of layered shale samples was comprehensively analysed under the triaxial conditions. Clearly, as the inclination angle of bedding planes increases, the cohesion of layered shales first decreases, but then increases under triaxial compression, showing the ‘U’‐shaped changing trend. Additionally, the internal friction angle of layered shales gradually increases with the increase in the inclination of bedding planes.

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Triaxial Deformation of the Goldwyer Gas Shale at In Situ Stress Conditions—Part II: Viscoelastic Creep/Relaxation and Frictional Failure

2023

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To understand the geomechanical implications of long-term creep (time-dependent deformation) response of gas shale, short-duration creep was recorded from laboratory triaxial tests on ten Goldwyer gas shale samples in the onshore Canning Basin at in situ stress conditions under constant differential axial stress. A simple power-law function captures primary creep behaviour involving elastic compliance constant B and time-dependent factor n. Experimental creep data revealed larger axial creep strain in clay and organic-rich rocks, than those dominated by carbonates. Anisotropic nature of creep was observed depending upon the direction of constant axial stress application (perpendicular or parallel to the bedding plane). Upon the application of linear viscoelastic theory on laboratory creep fitting coefficients, differential horizontal stress accumulation over a geological time scale was estimated from the viscoelastic stress relaxation concept. Further, this model was used to derive lithology-dependent least principal stress (Shmin) magnitude at depth for two vertical wells intersecting the Goldwyer gas shale formations. This newly proposed Shmin model was found to have a profound influence on designing hydraulic fracture simulation. Further, pore size distribution and specific surface area value SN2 were derived from low-pressure gas adsorption experiments. These physical properties along with weak mineral components were linked with creep constitutive parameters to understand the physical mechanisms of creep. A strong correlation was noted between SN2 and creep parameters n and B. Finally, an attempt was made to investigate how gas shale composition and failure frictional properties can influence shear fracturing.

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Triaxial Deformation of the Goldwyer Gas Shale at In Situ Stress Conditions—Part I: Anisotropy of Elastic and Mechanical Properties

Cited by 14 publications

References 55 publications

Viscoelastic Stress Relaxation for Estimating Shmin Magnitude in Deep Sedimentary Formations

Viscoelastic Stress Relaxation for Estimating Shmin Magnitude in Deep Sedimentary Formations

Investigation of the anisotropic mechanical response of layered shales

Triaxial Deformation of the Goldwyer Gas Shale at In Situ Stress Conditions—Part II: Viscoelastic Creep/Relaxation and Frictional Failure

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