Thermodynamic analysis of high pressure methane adsorption in Longmaxi shale

Tang, Xu; Ripepi, Nino; Stadie, Nicholas P.; Yu, Long

doi:10.1016/j.fuel.2016.12.047

Cited by 68 publications

(82 citation statements)

References 40 publications

(79 reference statements)

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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: 79%

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: 79%

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

et al. 2020

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“…Effect of temperature on methane on shale under four different conditions at different temperatures calculated by equations (17) to (20), respectively. (a) 303.15k, (b) 313.15K, (c) 323.15K and (d) 333.15K (Tang et al, 2017)…”

mentioning

confidence: 99%

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

Zhou

Wang

Zhang

et al. 2019

Adsorption Science & Technology

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The isosteric heat of adsorption (IHA) is one of the key thermodynamic variables for evaluating the interaction between shale and methane, which is rarely studied especially under high pressure. In this work, we conducted methane adsorption experiments at pressures up to 30 MPa and different temperatures on shale samples collected from Longmaxi formation in Sichuan Basin, China. Based on the definition of IHA and Langmuir adsorption model, we proposed a new method to analyze the IHA of methane on shale under four conditions. The calculated results show that the commonly used Clausius-Clapeyron equation overestimates the true isosteric heat of shale, especially under high pressure. IHA under four conditions yield a fixed order as q st,i-va > q st,r-va > q st,iþva > q st,rþva , indicating both the real gas behavior and the adsorbed-phase volume have a negative influence on it, and the effect of adsorbed-phase volume is dominant. Moreover, IHA at zero coverage (q 0 st) in Henry region determined by linear fitting can be regarded as a maximum value in the above four cases, which is independent of pressure and temperature. Therefore, q 0 st can be used as a unique descriptor to evaluate the adsorption affinity

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“…show the corresponding CH 4 density map. It is known that methane tends to accumulate on graphite nanopore walls, forming an adsorbed layer on the surface (Tang et al, 2017). The density distribution of CH 4 is nearly the same for both the EMD and NEMD simulations in the center (bulk) and near-surface regions of the pore.…”

Section: (A)-3(c)mentioning

confidence: 79%

Molecular dynamics simulation of methane transport in confined organic nanopores with high relative roughness

Kulasinski

Zheng

et al. 2019

Journal of Natural Gas Science and Engineering

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Understanding and characterizing the transport of shale gas (methane) through the nanopores of kerogens are critical for the accurate prediction of shale gas recovery. However, the key factors that regulate shale gas transport through highly roughened nanopores of shale kerogens are not fully understood. In this work, methane transport in organic nanopores with a high relative roughness is characterized using equilibrium and nonequilibrium molecular dynamics methods. According to our results, the CH 4 mass flux has a linear relationship with the pressure gradient, consistent with previous studies, while the calculated slip lengths and gas fluxes varied with different roughness geometries in the order of sigmoidal ≥ triangular > rectangular. Surface slip flow can be a major contributor to the overall gas flux, but surprisingly, the relative contribution of surface slip flow is independent of the pressure gradient. In contrast, the contributions of both slip flow and the average gas fluxes vary strongly with pore diameters. Typical contributions of the adsorbed layer to the overall gas flux are in the range 20-40% but vary from as high as 74% in a 4-nm pore to as low as 6% in a 16-nm pore. Compared to smooth nanopores, we find that, in nanopores with realistically high degrees of relative roughness, methane confinement in cavities decouples slip flow from the flow in the pore interior, significantly reducing the overall flux.

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Thermodynamic analysis of high pressure methane adsorption in Longmaxi shale

Cited by 68 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

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

Molecular dynamics simulation of methane transport in confined organic nanopores with high relative roughness

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