A study of relative permeability for transient two-phase flow in a low permeability fractal porous medium

Li, Zhenglan; Duan, Yunlong; Fang, Quantang; Wei, Mingqiang

doi:10.26804/ager.2018.04.02

Cited by 22 publications

(7 citation statements)

References 32 publications

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“…However, in unconventional reservoirs (such as tight sandstone reservoir, shale reservoir, tight limestone, and volcanic reservoir), the correlation between porosity and permeability is not as close as that in conventional reservoirs [5][6][7]. More and more researchers have realized that the throat in the reservoir is the key factor to affect the seepage capacity of the reservoir, and it also determines the oil and gas production capacity of the reservoir [8][9][10][11][12]. Nelson [13] has introduced the distribution of throat sizes in different types of rocks.…”

Section: Introductionmentioning

confidence: 99%

Characteristics of Pore-Throat in Tight Sandstones of the Jurassic Ahe Formation in the Northern Tarim Basin

et al. 2022

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In order to clarify the characteristics of pore-throat in tight sandstone reservoirs in the Dibei area of the Kuqa Depression in the Tarim Basin (Northwest China) and to make clear its impact on reservoir quality and productivity, microscopic observation and quantitative analysis of 310 tight sandstones in the Kuqa Depression are carried out by using various methods. Microscopic observation shows that the shapes of the pores are flat, oval, and long-narrow. A great number of throats connect the nanoscale pores in the form of a network. Quantitative analyses including RCMP (rate-controlled mercury penetration), HPMI (high-pressure mercury injection), NA (nitrogen adsorption), and routine and stress-dependent core analysis show that the peak of pores radius ranges from 125 μm to 150 μm, and the throat radius is in the range of 1 μm-4 μm. The throat space accounts for about 2/3 of the total space of the tight sandstones, which is the major storage space for natural gas. The space shape has a great influence on the reservoir seepage capacity, particularly under the condition of overburden pressure. The pores with throat radius greater than 300 nm have free fluid, and they contribute more than 98% of the reservoir permeability. The pore spaces with throat radius among 300 nm-52 nm can release fluids by reservoir stimulation. The pore-throats with radius < 52 nm cannot release the irreducible hydrocarbon fluids. In addition, formation pressure is easy to destroy tight sandstone reservoir. The research results will provide insights into the efficient recovery of natural gas in tight sandstones.

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Section: Introductionmentioning

confidence: 99%

Characteristics of Pore-Throat in Tight Sandstones of the Jurassic Ahe Formation in the Northern Tarim Basin

et al. 2022

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“…It has been increasingly believed that the wave-induced fluid flow at different scales is primarily responsible for the seismic wave attenuation in fluid-saturated sedimentary rocks (Biot, 1956;White, 1975;O'Connell and Budiansky, 1977;Cleary, 1978;Mavko and Nur, 1979;Pride et al, 2004;Li et al, 2018;Müller et al, 2010). The wave-induced fluid flow occurs in the presence of pore pressure gradients, which is predominantly caused by the heterogeneities either in the rock matrix or in the saturating pore fluids.…”

Section: Introductionmentioning

confidence: 99%

Combined effects of permeability and ﬂuid saturation on seismic wave dispersion and attenuation in partially-saturated sandstone

Wei

Wang

Han

et al. 2021

Adv. Geo-Energy Res.

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Knowledge of dispersion and attenuation is essential for better reservoir characterization and hydrocarbon identification. However, limited by reliable laboratory data at seismic frequency bands, the roles of rock and fluid properties in inducing dispersion and attenuation are still poorly understood. Here we perform a series of laboratory measurements on two sandstones under both dry and partially water-saturated conditions at frequencies ranging from 2 to 600 Hz. Two samples, Bentheimer and Bandera sandstones, have similar porosity of ∼20% but different permeability of 1830 mD and 33 mD. At vacuum-dry conditions, the bulk dispersion and attenuation in Bandera sandstone with more clay contents are distinctly larger than those in Bentheimer sandstone, suggesting clay contents might contribute to the inelasticity of the rock frame. The partially water-saturated results show the combined effects of rock permeability and fluid saturation on bulk dispersion and attenuation. Because of the high compressibility of gas, even a few percent of gas (∼5%) can substantially dominate the pore-fluid relaxation by providing a quick and short communication path for pore pressure gradients. The consequent bulk dispersion and attenuation are negligible. However, when the sample is approaching a fully water-saturated condition (gas saturation <5%), the gas effect gradually decreases. Instead, the rock permeability begins to play an essential role in the pore-fluid relaxation. For Bandera sandstone with lower permeability, a partially relaxed status of pore fluids is achieved when the gas saturation is lower than 5%, accompanied by significant attenuation and dispersion.

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“…Coal bed methane (CBM) is an essential part of the world's clean energy mix (Øren and Bakke, 2002). Fracture and pore structure are extremely complex, which is the key factor affecting the migration behavior of coalbed methane Li et al, 2018;Zeng et al, 2020). In the process of CBM extraction, various factors affect the fracture and pore structure of a coal seam, such as gas adsorption-desorption, the thermal conductivity of the coal seam, the long-term effects of ground stress, and extruded deformation, which has an obvious impact on permeability (Arand and Hesser, 2017;Li et al, 2020;.…”

Section: Introductionmentioning

confidence: 99%

A multi-field coupling model of gas flow in fractured coal seam

Liu

Gao

et al. 2021

Adv. Geo-Energy Res.

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The structure of fractures and pores has a dominant impact on the heat transfer-seepagedeformation process of a coal seam. Previous models have primarily used the cubic permeability model to characterize coal seam permeability properties. In this study, we developed a new multi-field coupling model, which includes fracture and pore structure, coal seam temperature, effective stress and gas seepage. Two major extraction scenarios were simulated: the unconstrained plane strain state and the uniaxial plane strain state. In addition, two microstructural parameters were applied to characterize coal permeability: the maximum fracture length and the fractal dimension for the fracture. The results show that the fractal seepage model provides a more realistic and reliable characterization of resource migration and extraction processes in unconventional reservoirs than the cubic-law permeability model. Compared with the cubic-law permeability model, the permeability calculated by the model proposed in this paper changes about 17.09%-91.56%. Furthermore, coal seam permeability is proportional to the maximum fracture length and the fractal dimension for the fracture. The permeability changes about 17.09% and 17.18% with the different fractal dimension, and about 87.17% and 91.56% with the different maximum fracture length. However, the fractal dimension and coal seam permeability are inversely proportional to seam temperature.

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A study of relative permeability for transient two-phase flow in a low permeability fractal porous medium

Cited by 22 publications

References 32 publications

Characteristics of Pore-Throat in Tight Sandstones of the Jurassic Ahe Formation in the Northern Tarim Basin

Characteristics of Pore-Throat in Tight Sandstones of the Jurassic Ahe Formation in the Northern Tarim Basin

Combined effects of permeability and ﬂuid saturation on seismic wave dispersion and attenuation in partially-saturated sandstone

A multi-field coupling model of gas flow in fractured coal seam

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