Three stages of methane adsorption capacity affected by moisture content

Fan, Kunkun; Li, Yajun; Elsworth, Derek; Dong, Mingzhe; Yin, Chuancun; Li, Yanchao; Chen, Zhili

doi:10.1016/j.fuel.2018.05.120

Cited by 50 publications

(42 citation statements)

References 53 publications

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“…It is generally believed that water reduces the shale gas adsorption evidently (Ross and Bustin, 2007;Gasparik et al, 2012;Tan et al, 2014;Yuan et al, 2014;Merkel et al, 2015). Researchers found that water affects methane adsorption in three stages, which are related to the intrinsic properties of the shale (Yang et al, 2016;Fan et al, 2018). Similarly to the moist coal adsorption, the critical water content was also found in the moist shale adsorption, which means that water has little effect on adsorption when the water content is greater than the critical value (Merkel et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation of methane adsorption and desorption in water-bearing shale

Han

Fang

et al. 2020

Capillarity

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Methane adsorption and desorption in shale can significantly be affected by water due to the water-bearing depositional environment of shale and the application of hydraulic fracturing technology in shale gas production. The characteristics of shale gas adsorption and desorption are comprehensively affected by the temperature, pressure, and especially, the water content in the reservoir. To further explore the impact of water on shale gas adsorption and desorption, the adsorption-desorption experiments of methane in waterbearing shale at different temperatures and different pressures are performed. Afterward, the adsorption behavior and desorption hysteresis are characterized by employing the Langmuir model and Langmuir+λ model. Finally, the ways of the pressure, temperature, and water combinedly affect shale gas adsorption behavior and desorption hysteresis are analyzed. The results show that adsorption and desorption of methane in the water-bearing shale are irreversible, which are consistent with the Langmuir model and the Langmuir+λ model, respectively. An increase in temperature will reduce adsorption and promote desorption, as an increase in temperature essentially enhances the thermal movement of methane molecules. Water lowers the adsorption and desorption of methane in shale, as the water molecules occupy the adsorption sites in organic pores and clay mineral pores in different ways. However, the effect of temperature and water content on adsorption is closely related to the pressure. The lower the pressure, the more significant the effect of temperature and water content. The combined effect analysis demonstrates that the impact of water on methane adsorption in shale is much more significant than that of the temperature. Still, desorption is simultaneously affected by both temperature and water content. As the pressure decreases in the desorption process, the desorption rate is dominantly affected by water when the pressure is lower than 8 MPa, and the desorption rate is aggressively affected by temperature when the pressure is at above 8 MPa.

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Section: Introductionmentioning

confidence: 99%

Experimental investigation of methane adsorption and desorption in water-bearing shale

Han

Fang

et al. 2020

Capillarity

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“…Wang and Yu (2016) through sorption experiments on dry and wet samples under high pressure conditions demonstrated that the adsorption capacity of wet samples is weak, and the effective adsorption sites of methane are mainly distributed in small pores (< 4 nm), and the pores in the range of 2-7 nm are competing adsorption sites for methane and water. Fan et al (2018) carried out methane adsorption experiments under different temperature and moisture content conditions and concluded that methane adsorption shows a decreasing trend with increasing moisture content, and the changes can be divided into a linear decreasing stage, a flat stage, and a convex decreasing stage (Fig. 4).…”

Section: Effects Of Pressure Temperature and Moisture Content On Sorp...mentioning

confidence: 99%

Sorption characteristics in coal and shale: A review for enhanced methane recovery

2021

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The exploration and exploitation of hydrocarbon resources within coal and shale reservoirs is an engineering challenge. Well-developed internal micro-pore structures, complex sorption mechanism as well as numerous influencing factors affecting the gas flow are generally not well-accounted in the commercial life-cycle of shale gas and coalbed methane wells. Although large number of studies have been conducted to propose improved sorption models and study the influencing factors on adsorption and desorption characteristics of methane and CO 2 in coal and shale reservoirs, a systematic review of such studies for efficient understanding of the accumulated literature is missing, especially with a focus towards coal and shale reservoirs. In that context, this study presents a review of sorption characteristics of methane in coal and shale. Firstly, theoretical mechanisms for methane sorption are introduced, followed by description of sorption models. Further, three factors influencing the sorption of gas in coal and shale are described: total organic carbon and clays, pore structures, and reservoir conditions. Finally, the preferential sorption characteristics of hydrocarbons and carbon dioxide are described, and the methods to promote methane desorption for enhanced recovery are discussed, which include technologies such as gas injection, microwave heating, and hydraulic fracturing.

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“…According to the pore structure characteristics, gas existence, and migration in the coal seam, the following assumptions are drawn [23,32,33]: (1) as shown in Figure 3, the coal seam is regarded as the anisotropic dual-porosity, dual-permeability elastic continuity medium, and the coal seam consists of fractures and coal matrix, while pores exist in the coal matrix; (2) the relationship between adsorbed gas content and gas pressure follows the Langmuir equation; (3) gas is assumed to be satisfied with ideal gas; (4) the coal seam Gas extraction reduces the pressure near borehole which will break the gas adsorption equilibrium in the coal matrix. e absorbed gas desorbs into the space of pores and transports to the fractures driven by the pressure and concentration gradients via diffusion and seepage accordingly [34,35].…”

Section: Dual-porosity Characteristics Of Coal Seams and Basicmentioning

confidence: 99%

Hydraulic‐Mechanical Coupling Model with Dual‐Porosity Dual‐Permeability for Anisotropy Coal Seams and Its Application in Mine Gas Extraction

Huo

Jing

et al. 2019

Advances in Civil Engineering

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The parameters of pore-fracture structure and permeability have a controlling effect on the behaviors of gas adsorption/desorption and transportation in coal reservoir. A mathematic model for coal seams is of great significance to evaluate the mass migration within the coal fracture-matrix system. In this paper, the hydraulic-mechanical coupling model considering both dual-porosity dual-permeability and anisotropy characteristics is first established by using the methods of theoretical analysis, nuclear magnetic resonance (NMR) test, and numerical simulation. Then, this model is applied to simulate the gas migration characteristics of No. 3 coal seam in Changping Mine, China. Results show that the pore structure of No. 3 coal seam is characterized by small radius of pores and pore throats, which is determined by the NMR test, verifying the dual-permeability dual-porosity of coal seams. Both matrix permeability and fracture permeability increase approximately linearly with the process of mine gas extraction. The increased magnitude of the matrix permeability is greater than that of the fracture permeability. The permeability is inversely proportional to the anisotropy coefficient. The pressure gradient within the coal matrix and fracture increases first and then decreases with the extraction time. This pressure gradient is proportional to the anisotropy coefficient at the early stage of extraction and is inversely proportional to the anisotropy coefficient at the later stage. The seepage and diffusion flux are proportional to the anisotropy coefficient. The proportion of matrix-to-fracture seepage flux to the total flux increases first and then decreases to a certain value. The proposed model provides a guide for accurate designation of gas extraction from coal seams.

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Three stages of methane adsorption capacity affected by moisture content

Cited by 50 publications

References 53 publications

Experimental investigation of methane adsorption and desorption in water-bearing shale

Experimental investigation of methane adsorption and desorption in water-bearing shale

Sorption characteristics in coal and shale: A review for enhanced methane recovery

Hydraulic‐Mechanical Coupling Model with Dual‐Porosity Dual‐Permeability for Anisotropy Coal Seams and Its Application in Mine Gas Extraction

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