Impact of Local Effects on the Evolution of Unconventional Rock Permeability

Ma, Xinxing; Li, Xianwen; Zhang, Shouwen; Zhang, Yanming; Hao, Xiangie; Liu, Jishan

doi:10.3390/en12030478

Cited by 8 publications

(5 citation statements)

References 31 publications

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“…Ma et al [5] introduced the local force to define the interactions between the matrix and the fracture and derived a set of partial differential equations to define the full coupling of rock deformation and gas flow both in the matrix and fracture systems. Permeability evolution profiles during unconventional gas extraction were obtained by solving the full set of cross-coupling formulations.…”

Section: Overview Of Work Presented In This Special Issuementioning

confidence: 99%

Recent Advances in Flow and Transport Properties of Unconventional Reservoirs

et al. 2019

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As a major supplement to conventional fossil fuels, unconventional oil and gas resources have received significant attention across the globe. However, significant challenges need to be overcome in order to economically develop these resources, and new technologies based on a fundamental understanding of flow and transport processes in unconventional reservoirs are the key. This special issue collects a series of recent studies focused on the application of novel technologies and theories in unconventional reservoirs, covering the fields of petrophysical characterization, hydraulic fracturing, fluid transport physics, enhanced oil recovery, and geothermal energy.

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Section: Overview Of Work Presented In This Special Issuementioning

confidence: 99%

Recent Advances in Flow and Transport Properties of Unconventional Reservoirs

et al. 2019

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“…One approach is to use the Klinkenberg correction term (slip coefficient) as the product factor to modify a poroelasticity-based model. For example, the models proposed by Wei et al 23 and Ma et al 24 multiplied the correction term of slip flow by the poroelasticity-based model, similar to the model proposed by Gao et al 25 The Knudsen number, which is the ratio of the average free path to the characteristic length of the flow path, is the most important parameter affecting the correction term. The equivalent hydraulic diameter of shale, depending on the empirical value or formula, may lead to errors in the Knudsen number, thereby leading to errors in the correction factor, which ultimately reduces the accuracy of the poroelasticity-based model.…”

Section: Introductionmentioning

confidence: 99%

Novel Shale Permeability Model Considering the Internal Dependencies of Effective Stress, Gas Sorption, and Flow-Regime Effects

Liu

2023

Energy Fuels

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Traditional theoretical models used to predict shale permeability generally ignore the influence of the effective stress and gas sorption-induced strain on the gas transport process. Consequently, the predicted permeability may deviate from the experimental results, wherein the coupling effect of the fluid and solid is involved. To improve the accuracy of the permeability model for shale stones, a hydraulic diameter-based generic permeability model was proposed that couples the effective stress, gas sorption, and flow-regime effects. Three special degenerate case models, based on the generic model, were validated using three corresponding experimental conditions. Sensitivity studies have demonstrated that the flow-regime effect is sensitive to the size of the equivalent hydraulic diameter, whereas the poroelastic effect is sensitive to the initial porosity and compressibility factor of the shale bulk. The two effects cannot be decoupled from shale permeability during the experimental process. The contribution of the adsorption effects to permeability, as reflected by the Langmuir pressure constant of the matrix, is greater in the high-pressure region, where pore elasticity dominates. The contribution of the adsorption effects to permeability, as reflected by the Knudsen number, is weaker in the low-pressure region, where the flow regime dominates. In addition, the contribution of the adsorption effect varies much more in the poroelasticity deformation than in the fluid dynamics.

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“…The numerical simulator explains matrixfracture interactions under constant total volume and constant confining stress conditions. On the basis of Zhang et al, 21 Ma et al 23 added the influence of flow regimes on permeability evolution for gas injection, and Liu et al 24 investigated matrixfracture nonequilibrium through temporal and spatial evolution of effective stresses. These models are able to explain experimental results caused by matrix-fracture nonequilibrium for certain testing conditions.…”

Section: Introductionmentioning

confidence: 99%

Evolution of Shale Permeability under the Influence of Gas Diffusion from the Fracture Wall into the Matrix

Zeng

Liu

et al. 2020

Energy Fuels

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Permeability is the most important property that controls the transfer of gas mass across a hierarchy of scales within a shale gas reservoir. When gas diffuses from the fracture wall into the matrix, the gas adsorbs onto shale grains. This adsorption may result in matrix swelling. In previous studies, it is commonly assumed that this swelling is uniform within the matrix. Under this assumption, the impact of the gas diffusion process would be neglectable. In this study, we hypothesize that this uniform swelling assumption is responsible for the inconsistencies between poroelastic solutions and experimental or field observations as reported in the literature. We introduce a volumetric ratio of the gas-invaded volume to the whole matrix volume to quantify the impact of matrix swelling volume expansion on the evolution of shale permeability. The gradual matrix pressure increase in the vicinity of fracture walls leads to local swelling. As the gas invaded zone expands within the matrix, the local effect weakens. When the matrix is completely invaded by the injected gas, a new homogeneous state is achieved, and the local effect ends. We find that the evolution of shale permeability from initial to final homogeneous states is a result of the propagation of the gas invaded area. We apply this approach to generate a series of shale permeability maps. These maps explain experimental observations under a spectrum of conditions from constant confining pressure, to constant average pore pressure, to constant effective stress, and to constant total volume conditions.

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Impact of Local Effects on the Evolution of Unconventional Rock Permeability

Cited by 8 publications

References 31 publications

Recent Advances in Flow and Transport Properties of Unconventional Reservoirs

Recent Advances in Flow and Transport Properties of Unconventional Reservoirs

Novel Shale Permeability Model Considering the Internal Dependencies of Effective Stress, Gas Sorption, and Flow-Regime Effects

Evolution of Shale Permeability under the Influence of Gas Diffusion from the Fracture Wall into the Matrix

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