Numerical Simulation of Gas Production from Gas Shale Reservoirs—Influence of Gas Sorption Hysteresis

Ekundayo, Jamiu M.; Rezaee, Reza

doi:10.3390/en12183405

Cited by 18 publications

(10 citation statements)

References 31 publications

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“…The nanoscale pores in the shale constitute a complex pore network [6][7][8][9]. In particular, the micropores (pore diameter <2 nm) and mesopores (2-50 nm) have the characteristics of a large specific surface area and high degree of heterogeneity, thereby increasing the complexity of the accumulation and migration mechanism of shale gas [10][11][12][13][14]. The difficulty in the characterization of shale reservoirs is the quantitative description of micropore and mesopore structures.…”

Section: Introductionmentioning

confidence: 99%

Fractal Characteristics of Micro- and Mesopores in the Longmaxi Shale

2020

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To better understand the variability and heterogeneity of pore size distributions (PSDs) in the Longmaxi Shale, twelve shale samples were collected from the Xiaoxi and Fendong section, Sichuan Province, South China. Multifractal analysis was employed to study PSDs of mesopores (2–50 nm) and micropores (<2 nm) based on low-pressure N2/CO2 adsorption (LP-N2/CO2GA). The results show that the PSDs of mesopores and micropores exhibit a multifractal behavior. The multifractal parameters can be divided into the parameters of heterogeneity (D−10–D10, D0–D10 and D−10–D0) and the parameters of singularity (D1 and H). For both the mesopores and micropores, decreasing the singularity of the pore size distribution contributes to larger heterogeneous parameters. However, micropores and mesopores also vary widely in terms of the pore heterogeneity and its controlling factors. Shale with a higher total organic carbon (TOC) content may have a larger volume of micropores and more heterogeneous mesopores. Rough surface and less concentrated pore size distribution hinder the transport of adsorbent in mesopores. The transport properties of micropores are not affected by the pore fractal dimension.

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Section: Introductionmentioning

confidence: 99%

Fractal Characteristics of Micro- and Mesopores in the Longmaxi Shale

2020

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“…This percentage could be as high as 60-85% for organic-rich shale [6]. Previous studies suggested that the total GIP in shale reservoirs is affected by the total organic carbon (TOC) content, organic matter type, thermal maturity, and pore structure [7,8]. Wu et al carried out adsorption experiments of light hydrocarbons and carbon dioxide on shale samples and isolated kerogen, respectively [9].…”

Section: Introductionmentioning

confidence: 99%

Molecular Investigation of CO2/CH4 Competitive Adsorption and Confinement in Realistic Shale Kerogen

et al. 2019

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The adsorption behavior and the mechanism of a CO2/CH4 mixture in shale organic matter play significant roles to predict the carbon dioxide sequestration with enhanced gas recovery (CS-EGR) in shale reservoirs. In the present work, the adsorption performance and the mechanism of a CO2/CH4 binary mixture in realistic shale kerogen were explored by employing grand canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulations. Specifically, the effects of shale organic type and maturity, temperature, pressure, and moisture content on pure CH4 and the competitive adsorption performance of a CO2/CH4 mixture were investigated. It was found that pressure and temperature have a significant influence on both the adsorption capacity and the selectivity of CO2/CH4. The simulated results also show that the adsorption capacities of CO2/CH4 increase with the maturity level of kerogen. Type II-D kerogen exhibits an obvious superiority in the adsorption capacity of CH4 and CO2 compared with other type II kerogen. In addition, the adsorption capacities of CO2 and CH4 are significantly suppressed in moist kerogen due to the strong adsorption strength of H2O molecules on the kerogen surface. Furthermore, to characterize realistic kerogen pore structure, a slit-like kerogen nanopore was constructed. It was observed that the kerogen nanopore plays an important role in determining the potential of CO2 subsurface sequestration in shale reservoirs. With the increase in nanopore size, a transition of the dominated gas adsorption mechanism from micropore filling to monolayer adsorption on the surface due to confinement effects was found. The results obtained in this study could be helpful to estimate original gas-in-place and evaluate carbon dioxide sequestration capacity in a shale matrix.

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“…It has been proven in Section that a linear decline in the Gibbs adsorption isotherm is due to the Gibbs discarded amount ρ v a, which was subtracted from mass balance calculation. Hence, it is reasonable to use the intercept method − , to calculate the saturated density of adsorbed phase according to the physical meaning of the linear decline (see Figure ). However, the intercept method can only obtain the saturated density for the linear descending part.…”

Section: Discussionmentioning

confidence: 99%

“…However, some research studies , have reported that the physical adsorbents such as coal and shale also have a negative adsorption phenomenon, − that is, the adsorption isotherm exhibits a distinct decline at relatively higher pressure instead of a widely accepted type I isotherm. Even more unfortunately, the negative adsorption phenomenon − gives rise to two challenging difficulties in adsorption isotherm measurement; one is mass balance miscalculation , and the other is negative adsorption isotherm calibration. ,− …”

Section: Introductionmentioning

confidence: 99%

“…Other studies , assumed that the methane-adsorbed phase density ρ a and the liquid-phase density ρ b of 421 kg/m 3 follow the empirical formula: ρ a = ρ b exp – [0.0025( T – T b )]. In addition, a majority of studies ,, calculated the adsorbed phase density from multiparameters fitting according to the Langmuir model or the Dubinin Astakhov model; a minority of studies − ,, determined the adsorbed phase density from fitting the data sets in the linear descending part of adsorption isotherm.…”

Section: Introductionmentioning

confidence: 99%

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Establishing a New Piecewise Method for Understanding and Rectifying Mass Balance Miscalculation of Gas Adsorption on Coal and Shale

et al. 2021

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Sorption isotherms provide fundamental information for investigating the mechanism and phenomenon of gas adsorption on carboniferous rocks. However, adsorption isotherms of physical adsorbents, such as coal and shale, give rise to an unexpected and often negative adsorption phenomenon, which is decreased gas uptake under high pressure. Here, we demonstrate that a Gibbs discarded amount should be responsible for the negative adsorption phenomenon. The Gibbs discarded amount, a product of the free gas density and the adsorbed phase volume, increases continuously with the increased pressure during sorption isotherm measurement, but the Gibbs discarded amount has been subtracted from the absolute adsorption amount in the mass balance calculation. This leads to not only a linear decline in the sorption isotherm after adsorption saturation, but also underestimation of the absolute adsorption capacity on the whole adsorption isotherm. Hence, a piecewise method is developed to correct the error caused by the Gibbs discarded amount and is examined by experimental data of CH4-coal sorption, CH4-shale sorption, and CO2-coal sorption. Results indicate that the piecewise method is valid in rectifying the underestimation of Gibbs sorption isotherm and that the Gibbs discarded amount cannot be neglected any longer in the porous rock adsorption; various densities of the adsorbed phase estimated by the piecewise method are more practicable than a constant density as normal. This method may reduce both the experimental and computational effort required for the determination of absolute sorption isotherms.

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Numerical Simulation of Gas Production from Gas Shale Reservoirs—Influence of Gas Sorption Hysteresis

Cited by 18 publications

References 31 publications

Fractal Characteristics of Micro- and Mesopores in the Longmaxi Shale

Fractal Characteristics of Micro- and Mesopores in the Longmaxi Shale

Molecular Investigation of CO2/CH4 Competitive Adsorption and Confinement in Realistic Shale Kerogen

Establishing a New Piecewise Method for Understanding and Rectifying Mass Balance Miscalculation of Gas Adsorption on Coal and Shale

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