Investigation of the isosteric heat of adsorption for supercritical methane on shale under high pressure

Zhou, Shangwen; Wang, Hongyan; Zhang, Pengyu; Guo, Wei

doi:10.1177/0263617419866986

Cited by 21 publications

(15 citation statements)

References 40 publications

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“…Ji et al reported that pre-gas window shales had Q st values in the range 7.3-15.3 kJ mol −1 and a gas window shale was 18.4 kJ mol −1 [8]. These Q st values are similar to previously published values for carbon (9-24 kJ mol −1 ) [53][54][55], coal (10-22 kJ mol −1 ) [56] and shale (7-24 kJ mol −1 ) [8,[76][77][78].…”

Section: The Role Of Shale Structure and Kerogen Maturitysupporting

confidence: 80%

Supercritical methane adsorption and storage in pores in shales and isolated kerogens

et al. 2020

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Shale gas is an important hydrocarbon resource in a global context. It has had a significant impact on energy resources in the US, but the worldwide development of this methane resource requires further research to increase the understanding of the relationship of shale structural characteristics to methane storage capacity. In this study a range of gas adsorption, microscopic, mercury injection capillary pressure porosimetry and pycnometry techniques were used to characterize the full range of porosity in a series of shales of different thermal maturity. Supercritical methane adsorption methods for shale under conditions which simulate geological conditions (up to 473 K and 15 MPa) were developed. These methods were used to measure the methane adsorption isotherms of Posidonia shales where the kerogen maturity ranged from immature, through oil window, to gas window. Subcritical methane and carbon dioxide adsorption studies were used for determining pore structure characteristics of the shales. Mercury injection capillary pressure porosimetry was used to characterize the meso and macro porosity of shales. The sum of the CO 2 sorption pore volume at 195 K and mercury injection capillary pressure pore volumes (1093-5.6 nm) were equal to the corresponding total pore volume (< 1093 nm) thereby giving an equation accounting for virtually all the available shale porosity. These measurements allowed quantification of all the available porosity in shales and were used for estimating the contributions of methane stored as 'free' compressed gas and as adsorbed gas to overall methane storage capacity of shales. Both the mineral and kerogen components of shale were studied by comparing shale and the corresponding isolated kerogens so that the relative contributions of these components could be assessed. The results show that the methane adsorption characteristics were much higher for the kerogens and represented 35-60% of the total adsorption capacity for the shales used in this study, which had total organic contents in range 5.8-10.9 wt%. Microscopy studies revealed that the pore systems in clay-rich, organic-rich and microfossil-rich parts of shale are very different, and also the importance of the inter-granular organic-mineral interface.

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Section: The Role Of Shale Structure and Kerogen Maturitysupporting

confidence: 80%

Supercritical methane adsorption and storage in pores in shales and isolated kerogens

et al. 2020

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“…As illustrated in Figure , these different types of micro-nanopores make up the complex storage spaces and flow channels in shale. Furthermore, the strong heterogeneity and anisotropy of the complex pore system with the intense fluid–solid interaction − on the nanoscale cause ambiguity regarding shale gas transport characteristics and mechanisms. Therefore, the pore-size distribution, heterogeneity, and anisotropy of these microstructures are characterized and analyzed in this study.…”

Section: Resultsmentioning

confidence: 99%

Experimental and Fractal Characterization of the Microstructure of Shales from Sichuan Basin, China

et al. 2021

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Comprehensive characterization and analysis of the microstructure characteristics of shale are significant for understanding its transport mechanisms and determining highly efficient production programs. In this study, composition analysis, scanning electron microscopy imaging, and gas adsorption−desorption measurements are first conducted on 29 marine shale samples from the Longmaxi Formation, Sichuan Basin, China, to obtain their petrophysical properties and microstructure characteristics. Then, surface fractal dimension, pore fractal dimension, lacunarity, and succolarity are introduced to analyze the microstructure of these shale samples. Finally, the correlations between total organic carbon (TOC) content and microstructures and the relationships among the microstructures are analyzed systematically. The results show that the complex pore network in these shales is constituted by microfractures, intergranular pores, intragranular pores, dissolved pores, and organic pores. The typical type IV adsorption isotherm and type H3 hysteresis loop are identified from nitrogen adsorption−desorption data. TOC content has positive influences on the adsorption capacity and nanopore distribution. The surface fractal dimensions under low and high relative pressure are similar in these marine shale samples, which is different from the two-section characteristic of continental and marinecontinental shale. The statistical self-similarity characteristic of the pore-size distribution in these shales is further confirmed based on the analytical fractal dimension equation. The normalized lacunarity can quantitatively characterize the heterogeneity of the poresize distribution of these shales in two-dimensional space. The succolarity analysis in two-dimensional space explains the low fluid transport capacity of these shales. Universal and logically explained correlations are found between TOC content and microstructures. Moreover, logically explained correlations also exist among the microstructures of the shale samples evaluated.

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“…With respect to research into the relationship between isosteric enthalpy and adsorption capacity, some studies have held that there existed a positive correlation between isosteric enthalpy and adsorption capacity, − while others believed the opposite, ,,,, considering that there was a negative correlation between the two. This was mainly caused by two reasons.…”

Section: Resultsmentioning

confidence: 99%

“…An analysis of the thermodynamic characteristics of methane adsorption in shale would contribute to an understanding of important information relating to the interaction between methane and shale. , Many researchers have focused on changes in thermodynamic potentials in the adsorption process, such as isosteric enthalpy and isosteric entropy, ,− ,,− and conclusive results have been obtained. Nonetheless, two different opinions concerning the relationship between isosteric enthalpy and adsorption capacity exist, and a definitive explanation has not yet been formed.…”

Section: Introductionmentioning

confidence: 99%

Study on the Adsorption and Thermodynamic Characteristics of Methane under High Temperature and Pressure

Gao

et al. 2020

Energy Fuels

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The understanding of the adsorption and thermodynamic characteristics of methane adsorbed by shale under high pressure and high temperature (HPHT) is of great significance for evaluating deep shale gas reserves and for optimizing shale gas development. In this study, a strict framework for analyzing the adsorption−thermodynamic characteristics of methane adsorption in shale under HPHT conditions was proposed. Further, data processing and explanation of the framework were carried out through reference to published experimental data. When real gas behavior and phase density changes were considered, the temperaturedependent parameters were corrected on the dual-site Langmiur model (DSL) model to reflect the absolute adsorption isotherm at each temperature. These were successfully calculated by combining those with the global fitting method. Compared with other adsorption models that reflected surface heterogeneity, the modified DSL model was found to well characterize the adsorption behavior of shale under HPHT conditions. The thermodynamic potentials of the methane adsorption process were further calculated from the results obtained from the modified DSL model. It was found that in the two groups of shale samples with different total organic carbon (TOC) contents, the change law of isosteric enthalpy with adsorption capacity was different. The abnormal entropy change behavior of methane adsorption in shale with higher TOC content was explained, and a new position concerning the long-standing controversy relating to entropy change was put forward. In addition, both the total entropy and internal energy during the methane adsorbed phase under HPHT increased with an increase in adsorption capacity, and the total entropy in the adsorbed phase revealed a positive relationship with temperature. By introducing a thermodynamic graphic method to draw a clearer and more intuitive U a −n a −S a three-dimensional surface, more thermodynamic potential information could be obtained. The framework proposed in this study could also be used to help future research on the influence of basic physical parameters on adsorption and thermodynamic properties and to provide a foundation for improving the evaluation of deep shale gas reserves.

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Investigation of the isosteric heat of adsorption for supercritical methane on shale under high pressure

Cited by 21 publications

References 40 publications

Supercritical methane adsorption and storage in pores in shales and isolated kerogens

Supercritical methane adsorption and storage in pores in shales and isolated kerogens

Experimental and Fractal Characterization of the Microstructure of Shales from Sichuan Basin, China

Study on the Adsorption and Thermodynamic Characteristics of Methane under High Temperature and Pressure

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