ORCID Profile
0000-0002-7942-584X
Current Organisations
China University of Geosciences, Wuhan
,
China University of Mining and Technology
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Publisher: Elsevier BV
Date: 10-2022
Publisher: Elsevier BV
Date: 04-2020
Publisher: American Association of Petroleum Geologists
Date: 2019
Publisher: Springer Science and Business Media LLC
Date: 28-04-2021
Publisher: Elsevier BV
Date: 16-01-2020
DOI: 10.1007/S12182-019-00422-Z
Abstract: Although coal swelling/shrinking during coal seam gas extraction has been studied for decades, its impacts on the evolution of permeability are still not well understood. This has long been recognized, but no satisfactory solutions have been found. In previous studies, it is normally assumed that the matrix swelling/shrinking strain can be split between the fracture and the bulk coal and that the splitting coefficient remains unchanged during gas sorption. In this study, we defined the fracture strain as a function of permeability change ratio and back-calculated the fracture strains at different states. In the equilibrium state, the gas pressure is steady within the coal in the non-equilibrium state, the gas pressure changes with time. For equilibrium states, the back-calculated fracture strains are extremely large and may be physically impossible in some case. For non-equilibrium states, two experiments were conducted: one for a natural coal s le and the other for a reconstructed one. For the fractured coal, the evolution of permeability is primarily controlled by the transition of coal fracture strain or permeability from local matrix swelling effect to global effect. For the reconstituted coal, the evolution of pore strain or permeability is primarily controlled by the global effect.
Publisher: Elsevier BV
Date: 10-2018
Publisher: Elsevier BV
Date: 12-2021
Publisher: Society of Petroleum Engineers (SPE)
Date: 28-02-2023
DOI: 10.2118/214322-PA
Abstract: Measurements of coal permeability are normally analyzed without considering the interaction among microfracture and pore size distributions within the s le (control volume). Without this inclusion, nearly all permeability predictions are monomodal as reported in the literature. However, experimental observations are multimodal for most cases. In this study, we hypothesize that these discrepancies or mismatches between measurements and analytical predictions are due to the exclusion of the interaction among microfracture and pore size distributions within the s le (control volume). We report a first experimental study of triple-porosity interactions on a prismatic s le containing millimeter-scale fractures (Ⅰ) and micron- (Ⅱ) through nanometer-scale (Ⅲ) pores. Migration speeds of sorbing (e.g., CH4) gases are conditioned by the strain field, which is in turn conditioned by effective stresses and swelling strains. These distinct pore populations exhibit characteristic times for a time-staged equilibration of the strain field as multiple plateaus. This time-staged evolution of strain in turn delimits the evolving fracture permeability into a series of stages. The relatively high permeability of fractures and micropores defines a brief intermediate equilibrium permeability, after which the nanopore system controls the final permeability evolution. Our results indicate that the multimodal evolution of coal fracture permeability can be explained by the time-staged evolution of strain due to multiporosity interactions and could be defined by a time-staged equilibration of the strain fields as multiple plateaus.
Publisher: Elsevier BV
Date: 02-2018
Publisher: Springer Science and Business Media LLC
Date: 24-10-2019
No related grants have been discovered for Rui Shi.