Effects of pore structure and wettability on methane adsorption capacity of mud rock: Insights from mixture of organic matter and clay minerals

Luo, Peng; Zhong, Ningning; Khan, Imran; Wang, Xiaomei; Wang, Huajin; Luo, Qingyong; Guo, Zhaohui

doi:10.1016/j.fuel.2019.04.072

Cited by 47 publications

(41 citation statements)

References 69 publications

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“…In actual shale reservoirs, moisture content usually exists in organic matter, which was reported to have great influence on gas adsorption performance in previous work [59][60][61][62]. To qualify the effect of moisture content on the adsorption behavior in kerogen, a certain amount of H 2 O molecules, representing 0−2.4 wt.% moisture content, were preloaded in the developed kerogen models.…”

Section: Effect Of Moisture Content On Adsorption Behaviormentioning

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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Section: Effect Of Moisture Content On Adsorption Behaviormentioning

confidence: 99%

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

et al. 2019

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“…Moreover, the hydrophilicity of clay minerals may cause this phenomenon. The wettability analysis of clay minerals and OM indicated that the clays are always hydrophilic, and OM is hydrophobic [34]. Moreover, the nonpolar functional groups in OM, such as methyl and methylene, are similar to the molecular structure of methane, whereas the molecular structure of the Si-O and Al-O bonds in clays greatly differs from that of methane molecules.…”

Section: Effect Of Mineral Composition On Adsorption Capacitymentioning

confidence: 99%

“…However, some studies have indicated that clays have a limited effect on the gas adsorption capacity of shales [31][32][33][34]. Sun [32] reported that clay content shows no obvious relationship with the adsorption volume of shale samples with TOC ranging from 1.97% to 3.49%.…”

Section: Introductionmentioning

confidence: 99%

“…Sun [32] reported that clay content shows no obvious relationship with the adsorption volume of shale samples with TOC ranging from 1.97% to 3.49%. Luo [34] studied the effects of pore structure and water wettability on the adsorption amount of shales and concluded that the adsorption capacity of OM for methane is much stronger than that of clay. They speculated that hydrophobic OM pores and hydrophilic clay pores lead to a more preferential adsorption of methane on OM than clays.…”

Section: Introductionmentioning

confidence: 99%

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Clarifying the Effect of Clay Minerals on Methane Adsorption Capacity of Marine Shales in Sichuan Basin, China

Wang

Zhou

Zhang³

et al. 2021

Energies

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The effect of clay minerals on the methane adsorption capacity of shales is a basic issue that needs to be clarified and is of great significance for understanding the adsorption characteristics and mechanisms of shale gas. In this study, a variety of experimental methods, including XRD, LTNA, HPMA experiments, were conducted on 82 marine shale samples from the Wufeng–Longmaxi Formation of 10 evaluation wells in the southern Sichuan Basin of China. The controlling factors of adsorption capacities were determined through a correlation analysis with pore characteristics and mineral composition. In terms of mineral composition, organic matter (OM) is the most key methane adsorbent in marine shale, and clay minerals have little effect on methane adsorption. The ultra-low adsorption capacity of illite and chlorite and the hydrophilicity and water absorption ability of clay minerals are the main reasons for their limited effect on gas adsorption in marine shales. From the perspective of the pore structure, the micropore and mesopore specific surface areas (SSAs) control the methane adsorption capacity of marine shales, which are mainly provided by OM. Clay minerals have no relationship with SSAs, regardless of mesopores or micropores. In the competitive adsorption process of OM and clay minerals, OM has an absolute advantage. Clay minerals become carriers for water absorption, due to their interlayer polarity and water wettability. Based on the analysis of a large number of experimental datasets, this study clarified the key problem of whether clay minerals in marine shales control methane adsorption.

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“… 13 − 15 Moreover, the adsorption capacity of organic pores and inorganic mineral pores in the shale matrix also shows a big difference. 16 − 19 Therefore, it is of great significance to carry out the quantitative characterization of the nanopore structure and origin of the shale to reveal the occurrence mechanism of methane.…”

Section: Introductionmentioning

confidence: 99%

Nanopore Structure and Origin of Lower Permian Transitional Shale, Eastern Ordos Basin, China

et al. 2022

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Nanopores in the shale play a vital role in methane adsorption, and their structural characteristics and origins are of great significance for revealing the mechanism of methane adsorption, desorption, and diffusion. In this paper, through low-temperature ashing and low-pressure gas adsorption experiments, the nanopore structure of original shales and ashed shales was quantitatively characterized, and the nanopore origins in the transitional shale of lower Permian in eastern Ordos Basin were analyzed. The results show that the pore volume (PV) and specific surface area (SSA) of nanopores in transitional shale reservoirs are 0.0217–0.0449 cm 3 /g and 13.91–51.20 m 2 /g, respectively. The average contribution rates of micropores (<2 nm), mesopores (2–50 nm), and macropores (50–100 nm) to PV are 18.78, 72.26, and 8.96%, respectively, and the average contribution rates to SSA are 66.19, 33.10, and 0.71%, respectively. In addition, it is found that the average contribution rates of inorganic minerals and organic matter to the SSA of micropores are 55.9 and 44.1%, respectively, and the average contribution rates to the SSA of mesopores are 92.3 and 7.7%, respectively. Combining the adsorption properties of the main clay minerals and kerogen in shale, it is concluded that organic pores control the adsorption of methane with an absolute advantage in transitional shales. It is of great significance to understand the mechanism of methane occurrence, desorption, and diffusion in shales by clarifying the origins of multiscale pores.

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Effects of pore structure and wettability on methane adsorption capacity of mud rock: Insights from mixture of organic matter and clay minerals

Cited by 47 publications

References 69 publications

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

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

Clarifying the Effect of Clay Minerals on Methane Adsorption Capacity of Marine Shales in Sichuan Basin, China

Nanopore Structure and Origin of Lower Permian Transitional Shale, Eastern Ordos Basin, China

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