A Nearly Complete Characterization of Permeability to Hydrocarbon Gas and Liquid for Unconventional Reservoirs: A Challenge to Conventional Thinking

Cui, Albert; Wüst, Raphael A.J.; Nassichuk, Brent R.; Glover, Ken; Brezovski, Ron; Twemlow, Cory E.

doi:10.1190/urtec2013-176

Cited by 25 publications

(15 citation statements)

References 14 publications

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“…Stress disturbances in low permeable rocks induce the nucleation and propagation of cracks which largely control their hydraulic properties by forming preferential pathways for groundwater flows (Brace 1980;Guéguen et al 1996). Assessing the crack permeability behavior of low permeable geological media subjected to stress alterations is thus essential in strategic geoengineering applications such as geologic storage of hazardous substances (Armand et al 2014;Tsang et al 2015), geological sequestration of greenhouse gases (Tsang et al, 2007;Lemieux, 2011), and energy resources extraction (Dahm et al 2015, Cui et al 2013, Han et al 2015.…”

Section: Introductionmentioning

confidence: 99%

Discrete Element Modeling of Permeability Evolution During Progressive Failure of a Low-Permeable Rock Under Triaxial Compression

2021

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Understanding permeability evolution caused by the nucleation, propagation and coalescence of cracks enables to better assess fluid migration in the vicinity of underground excavations, boreholes or reservoirs. In this study, we propose a three-dimensional approach combining a bonded particle model and a dual-permeability pore network model to investigate the crack permeability behavior of low-permeable rocks. First, we verify the performances of the numerical scheme by comparing its predictions to analytical permeability solutions for microcracked and fractured porous samples respectively. Then, we simulate a triaxial compression test on an argillaceous rock sample with periodic permeability measurements. The model is able to reproduce the stressstrain-permeability evolution observed experimentally, from the early stage of microcracking up to the residual post-failure state: i) permeability does not change significantly before reaching the crack damage threshold, ii) permeability increases by several orders of magnitude after failure due to the appearance of a discrete shear band across the sample. The good agreement between the numerical results and the experimental observations confirms the relevance of the proposed approach to simulate the crack permeability behavior of low permeable rocks during their progressive failure. Based on this result, we simulate triaxial compression tests under different confining pressures to propose relationships between post-failure permeability and residual mean stress.

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Section: Introductionmentioning

confidence: 99%

Discrete Element Modeling of Permeability Evolution During Progressive Failure of a Low-Permeable Rock Under Triaxial Compression

2021

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“…Very few studies are published that include slippage measurements on stressed shale samples (Soeder 1988;Aljamaan et al 2013;Cui et al 2013;Sinha et al 2013;Heller et al 2014), and no studies provide a targeted investigation and discussion of the utility of slippage measurements as a means of shale pore structure analysis. The current study provides a dataset of slippage measurements on Eagle Ford Shale plugs oriented both perpendicular and parallel to bedding at a variety of stress states.…”

Section: Introductionmentioning

confidence: 99%

Klinkenberg gas slippage measurements as a means for shale pore structure characterization

Letham

Bustin

2015

Geofluids

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Established techniques that have been successfully used to characterize pore systems in conventional reservoir rocks lack the resolution and scalability required to adequately characterize the nano-to micrometer scale pore systems found in shale and cannot be applied on stressed samples. We have therefore investigated the utility of Klinkenberg gas slippage measurements for shale pore structure characterization. In contrast to other approaches, slippage measurements characterize the effective porosity of core samples and can be applied at stress conditions experienced in the reservoir during production. Slippage measurements on horizontally and vertically oriented samples from the Eagle Ford Shale Formation, Texas, USA, at a range of stress states revealed two orders of magnitude in slippage variation over five orders of magnitude permeability range. Slippage measurements are negatively correlated with permeability and follow similar trends to those found in other studies on higher permeability rocks. The samples had varying degrees of slippage anisotropy, which allowed interpretation of the relative contribution of tortuosity and pore size to permeability anisotropy. Slippage and therefore average effective pore size was found to vary up to one order of magnitude at a given permeability, warranting investigation of the significance this might have on flow properties and ultimately hydrocarbon production from shale.

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“…We verify this reduced model based on the experimental data of Cui. 4 In the experiments, permeability of shale rocks was measured with helium. The same pressure was used for the axial and radial confining in the core cell.…”

Section: Energy and Fuelsmentioning

confidence: 99%

“…In summary, both mechanical deformation and flow regime have significant impacts on the apparent permeability and the reduced model has been well validated by Cui's data. 4 This reduced model is applicable for gas reservoirs without the adsorption phenomenon.…”

Section: Energy and Fuelsmentioning

confidence: 99%

General Gas Permeability Model for Porous Media: Bridging the Gaps Between Conventional and Unconventional Natural Gas Reservoirs

2016

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Many field observations have indicated that permeabilities of both conventional and unconventional gas reservoirs are not constant when gas pressure drops. For conventional reservoirs, permeability will decrease while for unconventional gas rocks, the apparent permeability may increase as gas pressure decreases to a lower magnitude. Evolution trends of permeability for different natural gas reservoirs are distinct. These differences are observed by laboratory experiments of sandstones, coals, or shales. In this study, we present a general permeability model to bridge the gaps between conventional and unconventional gas reservoirs. This model coupled three critical factors namely effective stress, adsorption, and flow regimes to reflect dynamic performances of permeability. On the basis of specific reservoirs properties, the model degenerates into four reduced types. The first reduced model is applicable for reservoirs with lower adsorption capacity. The second reduced model is adopted by unconventional reservoirs like coal seams when the intrinsic permeability is big and adsorption capacity is high. For the third reduced model, effective stress is the dominating factor for permeability evolution, which means that it is applicable for conventional reservoirs like sandstones. Unconventional gas reservoirs with low adsorption capacity like gas shales can apply the fourth reduced model because the flow regimes dominate the evolution. These reduced models are verified against the experimental data. Results show that effective stress is the main reason for the change of permeability for conventional gas reservoirs. Both effective stress and flow regimes together determine the apparent permeability of unconventional gas reservoirs. The impact of adsorption on permeability is relatively small. Permeability evolution trends can be classified into different zones for conventional and unconventional gas reservoirs. When the gas is depleted from reservoirs, the gas permeability has two bounds. For the upper bound, permeability is only affected by flow regimes and the apparent permeability will increase when gas pressure drops. For the lower bound, permeability is only affected by effective stress and the apparent permeability will decrease when the gas is depleted from the reservoirs.

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A Nearly Complete Characterization of Permeability to Hydrocarbon Gas and Liquid for Unconventional Reservoirs: A Challenge to Conventional Thinking

Cited by 25 publications

References 14 publications

Discrete Element Modeling of Permeability Evolution During Progressive Failure of a Low-Permeable Rock Under Triaxial Compression

Discrete Element Modeling of Permeability Evolution During Progressive Failure of a Low-Permeable Rock Under Triaxial Compression

Klinkenberg gas slippage measurements as a means for shale pore structure characterization

General Gas Permeability Model for Porous Media: Bridging the Gaps Between Conventional and Unconventional Natural Gas Reservoirs

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