Steady-State Creep of Rock Salt: Improved Approaches for Lab Determination and Modelling

Günther, R.-M.; Salzer, K.; Popp, T.; Lüdeling, Christoph

doi:10.1007/s00603-015-0839-2

Cited by 62 publications

(19 citation statements)

References 3 publications

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“…These differences lead to a different dependence on stress and temperature meaning that the rate‐controlling microscale process can change if stress or temperature changes [ Urai et al , ]. Failure to recognize this can lead to an empirical fit to flow data that works well at the conditions of the corresponding laboratory tests but which fails when extrapolating to different stresses or temperatures [see Carter et al , ; Muhammad et al , ; Günther et al , ]. For salt, the typically observed values of Q and n for pressure solution and dislocation creep in equation imply that pressure solution should dominate at low stresses and temperatures versus dislocation creep at higher stresses and temperatures [ Urai et al , ].…”

Section: The Creep Behavior Of Rock Saltmentioning

confidence: 99%

Impact of rock salt creep law choice on subsidence calculations for hydrocarbon reservoirs overlain by evaporite caprocks

2016

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Accurate forward modeling of surface subsidence above producing hydrocarbons reservoirs requires an understanding of the mechanisms determining how ground deformation and subsidence evolve. Here we focus entirely on rock salt, which overlies a large number of reservoirs worldwide, and specifically on the role of creep of rock salt caprocks in response to production‐induced differential stresses. We start by discussing available rock salt creep flow laws. We then present the subsidence evolution above an axisymmetric finite element representation of a generic reservoir that extends over a few kilometers and explore the effects of rock salt flow law choice on the subsidence response. We find that if rock salt creep is linear, as appropriate for steady state flow by pressure solution, the subsidence response to any pressure reduction history contains two distinct components, one that leads to the subsidence bowl becoming narrower and deeper and one that leads to subsidence rebound and becomes dominant at later stages. This subsidence rebound becomes inhibited if rock salt deforms purely through steady state power law creep at low stresses. We also show that an approximate representation of transient creep leads to relatively small differences in subsidence predictions. Most importantly, the results confirm that rock salt flow must be modeled accurately if good subsidence predictions are required. However, in practice, large uncertainties exist in the creep behavior of rock salt, especially at low stresses. These are a consequence of the spatial variability of rock salt physical properties, which is practically impossible to constrain. A conclusion therefore is that modelers can only resort to calculating bounds for the subsidence evolution above producing rock salt‐capped reservoirs.

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Section: The Creep Behavior Of Rock Saltmentioning

confidence: 99%

Impact of rock salt creep law choice on subsidence calculations for hydrocarbon reservoirs overlain by evaporite caprocks

2016

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“…As classically introduced in micromechanics-based approaches, the mechanical load applied to the REV may be defined by prescribing homogeneous stress type boundary conditions 45…”

Section: Modeling Frameworkmentioning

confidence: 99%

“…It has been, however, recognized that the delayed behavior represents a fundamental component of rock deformation in many practical rock engineering projects in which the behavior of the rock mass is controlled by the creep and long-term strength properties. [36][37][38][39][40][41][42][43][44][45][46] As far as the viscoelastic behavior of jointed rocks is concerned, several studies have been devoted to experimentally identify and assess the creep properties of the intact and jointed rocks, [47][48][49][50][51][52][53][54][55][56][57][58] as well as those of the individual rock joints. [59][60][61][62][63][64][65][66] Based on the experimental data reported in the literature, models have been therefore formulated with the aim to describe the viscoelastic behavior of jointed rock masses.…”

Section: Introductionmentioning

confidence: 99%

Micromechanical approach to effective viscoelastic behavior of jointed rocks

Maghous

Aguiar

Rossi

2021

International Journal of Rock Mechanics and Mining Sciences

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Assessing the overall instantaneous behavior and strength properties of jointed materials have been the subject of important investigations in the last decades, including phenomenological or micromechanics-based contributions. However, less attention has been dedicated to delayed component of deformation in such media. This issue is addressed in this paper, which is devoted to the formulation of a micromechanical approach to effective viscoelastic properties of jointed rocks with consideration of constituents aging. At the scale of representative elementary volume (REV), the joints are modeled as planar interfaces whose behavior is described by means of generalized viscoelastic state equations under normal and shear loading conditions. Closed-form expressions for the homogenized creep tensor are derived from solving an appropriate viscoelastic concentration problem stated on the REV. The local strain and displacement jump fields are analyzed by extending the concept of strain concentration to relate the components of joint displacement jump to macroscopic strain. Main features of the theoretical overall creep behavior, such as the anisotropy associated with the privileged joint orientations, are highlighted through explicit formulations in some particular configurations of the jointed medium. Finally, the ability of the approach to accurately reproduce the creep behavior of jointed media is assessed by comparison with experimental data as well as with finite element solutions derived in the context of multilayered stratified composite modeling.

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“…(2012) explored the creep behavior and creep damage mechanism of salt rock employing digital image correlation technique. Günther et al. (2015) proposed a new experimental approach for creep tests on salt rock, which significantly improves the reliability of the determination of the stationary rate.…”

Section: Introductionmentioning

confidence: 99%

Creep properties and damage constitutive model of salt rock under uniaxial compression

Wang

Zhang

Song

et al. 2019

International Journal of Damage Mechanics

101

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To study the creep property of salt rock, uniaxial compression creep tests on salt rock specimens were carried out. The test results indicate that there is no steady creep of the salt rock used in this test in a strict sense. Even in the steady creep stage, the creep rate of salt rock changes continuously over time, but with a relatively smaller change range. When the axial stress does not exceed 9.5 MPa, the isochronous stress–strain curve of salt rock is approximately straight. While the axial stress exceeds 9.5 MPa, the isochronous stress–strain curve deflects to the strain axis, and the larger the axial stress, the more obvious the deflection. Thus, the long-term strength of the salt rock used in this test can be determined as 9.5 MPa. A mathematical expression for predicting the creep failure time of rock is proposed on the basis of assuming the change rule of rock strength over time conforms to the Usher function. Then starting from the variation in deformation modulus with respect to time in the creep process of salt rock, the elastic modulus of the damaged rock material is characterized by the deformation modulus, and the creep damage evolution equation of rock is established. Combined with the continuous damage mechanics theory, a new creep damage constitutive model for rock is proposed. The rationality of the model is verified using the uniaxial compression creep test results of salt rock. The results show that the new model can not only describe the attenuation and the steady creep of salt rock under low stress level, but also reflect the whole creep failure process under high stress level. The predicted curves under different axial stresses are all in good agreement with the test data.

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Steady-State Creep of Rock Salt: Improved Approaches for Lab Determination and Modelling

Cited by 62 publications

References 3 publications

Impact of rock salt creep law choice on subsidence calculations for hydrocarbon reservoirs overlain by evaporite caprocks

Impact of rock salt creep law choice on subsidence calculations for hydrocarbon reservoirs overlain by evaporite caprocks

Micromechanical approach to effective viscoelastic behavior of jointed rocks

Creep properties and damage constitutive model of salt rock under uniaxial compression

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