Investigation of methane adsorption mechanism on Longmaxi shale by combining the micropore filling and monolayer coverage theories

Zhou, Shangwen; Yang, Ning; Wang, Hongyan; Liu, Honglin; Han, Xue

doi:10.26804/ager.2018.03.05

Cited by 66 publications

(40 citation statements)

References 55 publications

(71 reference statements)

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“…As adsorbed gas is considered to be adsorbed on the surface of pores in shale [4,5], the nanopore structure and shale composition have significant effects on the methane adsorption capacity [18][19][20]. It has been proven that a higher organic matter content brings a larger surface area and a larger methane adsorption capacity [21][22][23][24][25].…”

Section: Introductionmentioning

confidence: 99%

Nanostructure Effect on Methane Adsorption Capacity of Shale with Type III Kerogen

et al. 2020

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This study focuses on the nanostructure of shale samples with type III kerogen and its effect on methane adsorption capacity. The composition, pore size distribution, and methane adsorption capacities of 12 shale samples were analyzed by using the high-pressure mercury injection experiment, low-temperature N2/CO2 adsorption experiments, and the isothermal methane adsorption experiment. The results show that the total organic carbon (TOC) content of the 12 shale samples ranges from 0.70% to ~35.84%. In shales with type III kerogen, clay minerals and organic matter tend to be deposited simultaneously. When the TOC content is higher than 10%, the clay minerals in these shale samples contribute more than 70% of the total inorganic matter. The CO2 adsorption experimental results show that micropores in shales with type III kerogen are mainly formed in organic matter. However, mesopores and macropores are significantly affected by the contents of clay minerals and quartz. The methane isothermal capacity experimental results show that the Langmuir volume, indicating the maximum methane adsorption capacity, of all the shale samples is between 0.78 cm3/g and 9.26 cm3/g. Moreover, methane is mainly adsorbed in micropores and developed in organic matter, whereas the influence of mesopores and macropores on the methane adsorption capacity of shale with type III kerogen is small. At different stages, the influencing factors of methane adsorption capacity are different. When the TOC content is <1.4% or >4.5%, the methane adsorption capacity is positively correlated with the TOC content. When the TOC content is in the range of 1.4–4.5%, clay minerals have obviously positive effects on the methane adsorption capacity.

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Section: Introductionmentioning

confidence: 99%

Nanostructure Effect on Methane Adsorption Capacity of Shale with Type III Kerogen

et al. 2020

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“…Adsorbed gas content is an essential parameter to predict the production of shale reservoirs (Chen et al 2019;Zhou et al 2018). Methane adsorption has attracted much attention to understanding the storage and adsorption mechanisms in shale (Ren et al 2017;Singh and Cai 2018).…”

Section: Edited By Yan-hua Sunmentioning

confidence: 99%

Pore structure characterization and its effect on methane adsorption in shale kerogen

et al. 2020

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Pore structure characterization and its effect on methane adsorption on shale kerogen are crucial to understanding the fundamental mechanisms of gas storage, transport, and reserves evaluation. In this study, we use 3D scanning confocal microscopy, scanning electron microscopy (SEM), X-ray nano-computed tomography (nano-CT), and low-pressure N2 adsorption analysis to analyze the pore structures of the shale. Additionally, the adsorption behavior of methane on shales with different pore structures is investigated by molecular simulations. The results show that the SEM image of the shale sample obviously displays four different pore shapes, including slit pore, square pore, triangle pore, and circle pore. The average coordination number is 4.21 and the distribution of coordination numbers demonstrates that pores in the shale have high connectivity. Compared with the adsorption capacity of methane on triangle pores, the adsorption capacity on slit pore, square pore, and circle pore are reduced by 9.86%, 8.55%, and 6.12%, respectively. With increasing pressure, these acute wedges fill in a manner different from the right or obtuse angles in the other pores. This study offers a quantitative understanding of the effect of pore structure on methane adsorption in the shale and provides better insight into the evaluation of gas storage in geologic shale reservoirs.

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“…For high-pressure and -temperature sorption, Gibbs excess adsorption is adopted to describe its unique behaviors [79]. Generally, adsorbed gas and bulk gas both exist for an adsorbate-adsorbent system, where adsorbed gas is distributed on the pore surface as a layer and bulk gas is far from the surface.…”

Section: Gibbs Excess Adsorptionmentioning

confidence: 99%

Review of Formation and Gas Characteristics in Shale Gas Reservoirs

et al. 2020

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An accurate understanding of formation and gas properties is crucial to the efficient development of shale gas resources. As one kind of unconventional energy, shale gas shows significant differences from conventional energy ones in terms of gas accumulation processes, pore structure characteristics, gas storage forms, physical parameters, and reservoir production modes. Traditional experimental techniques could not satisfy the need to capture the microscopic characteristics of pores and throats in shale plays. In this review, the uniqueness of shale gas reservoirs is elaborated from the perspective of: (1) geological and pore structural characteristics, (2) adsorption/desorption laws, and (3) differences in properties between the adsorbed gas and free gas. As to the first aspect, the mineral composition and organic geochemical characteristics of shale samples from the Longmaxi Formation, Sichuan Basin, China were measured and analyzed based on the experimental results. Principles of different methods to test pore size distribution in shale formations are introduced, after which the results of pore size distribution of samples from the Longmaxi shale are given. Based on the geological understanding of shale formations, three different types of shale gas and respective modeling methods are reviewed. Afterwards, the conventional adsorption models, Gibbs excess adsorption behaviors, and supercritical adsorption characteristics, as well as their applicability to engineering problems, are introduced. Finally, six methods of calculating virtual saturated vapor pressure, seven methods of giving adsorbed gas density, and 12 methods of calculating gas viscosity in different pressure and temperature conditions are collected and compared, with the recommended methods given after a comparison.

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Investigation of methane adsorption mechanism on Longmaxi shale by combining the micropore filling and monolayer coverage theories

Cited by 66 publications

References 55 publications

Nanostructure Effect on Methane Adsorption Capacity of Shale with Type III Kerogen

Nanostructure Effect on Methane Adsorption Capacity of Shale with Type III Kerogen

Pore structure characterization and its effect on methane adsorption in shale kerogen

Review of Formation and Gas Characteristics in Shale Gas Reservoirs

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