On the relationship between stress and elastic strain for porous and fractured rock

Liu, Hui‐Hai; Rutqvist, Jonny; Berryman, James G.

doi:10.1016/j.ijrmms.2008.04.005

Cited by 208 publications

(174 citation statements)

References 36 publications

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“…The existence of the residual fracture aperture for fractured rock has been well documented in the rock-mechanics literature (e.g., Rutqvist et al 2002;Liu et al 2009). However, the existence of such an aperture is not totally clear yet for coal cleats.…”

Section: Fracture Permeabilitymentioning

confidence: 95%

“…Because of the similarity between coal-seam permeability-stress relationships and those for fractured rock, research results from the field of rock mechanics (focused on understanding fracture-matrix interactions and their effects on fracture permeability) can be utilized for this study. Recently, Liu et al (2009) developed a new theoretical relationship between stress and elastic strain for porous and fractured rock, based on the reasoning that as a result of the heterogeneous nature of rock materials, different varieties of Hooke's law should be applied for different regions of the rock having significantly different stress-strain behaviors. They applied this idea by dividing a rock body (or a fracture) conceptually into two distinct parts, and further argued that the natural strain (volume change divided by rock volume at the current stress state), rather than the engineering strain (volume change divided by the unstressed rock volume), should be used in Hooke's law for accurate modeling of the elastic deformation of the part subject to a relatively large degree of relative deformation.…”

Section: Fracture Permeabilitymentioning

confidence: 99%

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A New Coal-Permeability Model: Internal Swelling Stress and Fracture–Matrix Interaction

2009

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We have developed a new coal-permeability model for uniaxial strain and constant confining-stress conditions. The model is unique in that it explicitly considers fracture-matrix interaction during coal-deformation processes and is based on a newly proposed internal swelling stress concept. This concept is used to account for the impact of matrix swelling (or shrinkage) on fracture-aperture changes resulting from partial separation of matrix blocks by fractures that do not completely cut through the whole matrix. The proposed permeability model is evaluated using data from three Valencia Canyon coalbed wells in the San Juan Basin, where increased permeability has been observed during CH 4 gas production, as well as using published data from laboratory tests. Model results are generally in good agreement with observed permeability changes. The importance of fracture-matrix interaction in determining coal permeability, demonstrated in this study using relatively simple stress conditions, underscores the need for a dual-continuum (fracture and matrix) mechanical approach to rigorously capture coal-deformation processes under complex stress conditions, as well as the coupled flow and transport processes in coal seams.

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Section: Fracture Permeabilitymentioning

confidence: 95%

Section: Fracture Permeabilitymentioning

confidence: 99%

A New Coal-Permeability Model: Internal Swelling Stress and Fracture–Matrix Interaction

2009

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“…For this analysis, the layering of the OPA is explicitly implemented by alternating layers of different material properties, allowing the soft layer to deform more than the stiffer layer, similar to the two-part Hooke's model described in Liu et al (2009) . This allows preferential gas migration into "softer" interlayers having somewhat higher porosity and correspondingly enhancing permeability before migrating to the next interlayer.…”

Section: Modeling Approachmentioning

confidence: 99%

Modeling of Gas Migration Through Low-Permeability Clay Rock Using Information on Pressure and Deformation from Fast Air Injection Tests

2018

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The characterization of gas migration through low-permeability clay formations has been a focus of R&D programs for radioactive waste disposal, which is also of great importance for shale gas exploration, cap-rock behavior of hydrocarbon reservoirs, and CO 2 sequestration. Laboratory tests have been performed on Opalinus Clay, a Mesozoic claystone that is being investigated in Switzerland as a potential host rock for the storage of nuclear waste. The laboratory program included specific water and air injections tests, as well as oedometer and isotropic compression tests. Undisturbed core samples have been retrieved from a shallow borehole in the Mont Terri Underground Research Laboratory (URL) and from a deep borehole in northern Switzerland. For the shallow cores from Mont Terri URL, largely linear-elastic deformations associated with the gas injection test could be inferred and the change in void ratio was accounted for by the pore compressibility. The corresponding change in permeability was obtained from the results of the water tests, indicating a log-linear relation between permeability and porosity. The derived porosity change and the corresponding change in permeability were implemented in the standard TOUGH2 code, which reproduced the measured gas test results using fitted water retention data derived from laboratory measurements. Similar air injection tests performed on Opalinus Clay cores from the borehole at greater depth showed overall similar behavior, but at lower porosities, lower permeability values, and lower compressibility. These cases indicated nonlinear behavior which was implemented using an effective stress-dependent porosity change and the associ-B R. Senger

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“…However, as described by Settari and Mourits (1998), in practice it is more important to consider the nonlinear stress-dependent effects on porosity and permeability over the range of stress expected in a problem. Such properties may be derived directly from laboratory data and fitted to theoretical or empirical functions (e.g., Liu et al, 2009) or by calibration to field experiments (e.g., Rutqvist et al, 2008).…”

Section: Comparison Of Rocmas and Tough-flac To Other Thm Codesmentioning

confidence: 99%

Disposal systems evaluations and tool development : Engineered Barrier System (EBS) evaluation.

Rutqvist¹,

Liu²,

Steefel³

et al. 2011

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Eric Sonnenthal (LBNL) Engineered Barrier System (EBS) Evaluation This page is intentionally left blank Engineered Barrier System (EBS) Evaluation 5 Executive SummaryKey components of the nuclear fuel cycle are short-term storage and long-term disposal of nuclear waste. The latter encompasses the immobilization of used nuclear fuel (UNF) and radioactive waste streams generated by various phases of the nuclear fuel cycle, and the safe and permanent disposition of these waste forms in geological repository environments. The engineered barrier system (EBS) plays a very important role in the long-term isolation of nuclear waste in geological repository environments. EBS concepts and their interactions with the natural barrier are inherently important to the long-term performance assessment of the safety case where nuclear waste disposition needs to be evaluated for time periods of up to one million years. Making the safety case needed in the decision-making process for the recommendation and the eventual embracement of a disposal system concept requires a multi-faceted integration of knowledge and evidence-gathering to demonstrate the required confidence level in a deep geological disposal site and to evaluate longterm repository performance.The focus of this report is the following:• Evaluation of EBS in long-term disposal systems in deep geologic environments with emphasis on the multi-barrier concept;• Evaluation of key parameters in the characterization of EBS performance;• Identification of key knowledge gaps and uncertainties;• Evaluation of tools and modeling approaches for EBS processes and performance.The above topics will be evaluated through the analysis of the following:• Overview of EBS concepts for various NW disposal systems;• Natural and man-made analogs, room chemistry, hydrochemistry of deep subsurface environments, and EBS material stability in near-field environments;• Reactive Transport and Coupled Thermal-Hydrological-Mechanical-Chemical (THMC) processes in EBS;• Thermal analysis toolkit, metallic barrier degradation mode survey, and development of a Disposal Systems Evaluation Framework (DSEF).This report will focus on the multi-barrier concept of EBS and variants of this type which in essence is the most adopted concept by various repository programs. Empasis is given mainly to the evaluation of EBS materials and processes through the analysis of published studies in the scientific literature of past and existing repository research programs. Tool evaluations are also emphasized, particularly on THCM processes and chemical equilibria. Although being an increasingly important aspect of NW disposition, short-term or interim storage of NW will be briefly discussed but not to the extent of the EBS issues relevant to disposal systems in deep geologic environments. Interim storage will be discussed in the report Evaluation of Storage Concepts FY10 Final Report (Weiner et al. 2010). Engineered Barrier System (EBS) Evaluation 6This page is intentionally left blank Engineered Barrier System (EBS) Eva...

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On the relationship between stress and elastic strain for porous and fractured rock

Cited by 208 publications

References 36 publications

A New Coal-Permeability Model: Internal Swelling Stress and Fracture–Matrix Interaction

A New Coal-Permeability Model: Internal Swelling Stress and Fracture–Matrix Interaction

Modeling of Gas Migration Through Low-Permeability Clay Rock Using Information on Pressure and Deformation from Fast Air Injection Tests

Disposal systems evaluations and tool development : Engineered Barrier System (EBS) evaluation.

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