Pore structure and gas adsorption characteristics in stress-loaded shale on molecular simulation

Cui, Ruikang; Sun, Jianmeng; Liu, Haitao; Dong, Huaimin; Yan, WeiChao

doi:10.1016/j.energy.2023.129658

Cited by 7 publications

(2 citation statements)

References 42 publications

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“…5 A comparison of the primary controlling factors of the occurrence state of deep CBM and shale gas Shale gas and deep CBM both belong to self-generated and self-stored unconventional natural gas, sharing many similarities in terms of geological conditions and occurrence environments. Factors such as pore structure, temperature, and moisture are also primary controlling factors influencing the occurrence state of shale gas (Gasparik et al, 2014;Merkel et al, 2015;Shabani et al, 2018;Hu et al, 2021;Zhang et al, 2023;Cui et al, 2024). However, there are also some differences between them.…”

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confidence: 99%

The primary controlling factors of the occurrence state of deep high-rank coalbed methane in eastern Ordos Basin

Shi,

He,

Wan

et al. 2024

Front. Earth Sci.

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Introduction: This study investigates the key controlling factors of the occurrence state of deep coalbed methane (CBM). CBM is an abundant energy resource in China, particularly in deep coal seams. However, the exploration and development of deep CBM face numerous challenges, and the understanding of the controlling factors of its occurrence state is still limited.Methods: The study reveals that deep CBM primarily exists in the form of adsorbed gas and free gas within the pore-fracture system of coal. Factors such as formation temperature, formation pressure, pore structure, and water saturation collectively influence the occurrence state of deep CBM. By employing the Simplified Local Density (SLD) model and molecular simulation methods.Results and discussion: This study examines the impact of two external geological control factors (formation temperature, formation pressure) and three internal geological control factors (pore size, water saturation, Specific surface area) on deep CBM and establishes a theoretical model for gas content. Finally, the relationship between the adsorbed gas, free gas, total gas content, and burial depth is calculated using the model, uncovering the primary factors controlling the occurrence state of deep CBM. This research is of significant importance in providing key parameters for gas content in deep coal and optimizing deep CBM exploration.

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Section: Figure 10mentioning

confidence: 99%

The primary controlling factors of the occurrence state of deep high-rank coalbed methane in eastern Ordos Basin

Shi,

He,

Wan

et al. 2024

Front. Earth Sci.

Self Cite

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“…The mineral particles and organic matter in shale reservoirs contain large scale range of pores (nano/micro/millimeter scale) and micro-fractures, providing important storage space for shale gas enrichment, and also offered flow channels for shale gas seepage (Zhang et al, 2019;Zhao et al, 2022). By clarify the reasons for the complexity and heterogeneity of pore systems in shale gas reservoir, we can achieve more efficient development of deep shale gas resources (Yang et al, 2016;Zhang et al, 2020;Qiu et al, 2021;Xie et al, 2022;Cui et al, 2024). The characterization of pore structure in shale gas reservoirs involves many aspects, including pore types, pore shape, pore size, pore volume, pore specific surface area, spatial distribution of pore systems, connectivity between pores.…”

Section: Introductionmentioning

confidence: 99%

Characterization and fractal characteristics of nano-scale pore structure in shale gas reservoirs: a case study of the deep Longmaxi Formation, Zigong region, Southern Sichuan Basin, China

Zhao,

Bao,

et al. 2024

Front. Earth Sci.

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Taking the Longmaxi deep-marine shale gas reservoir in Zigong region as the research target, this paper aimed to characterize the nano-scale pore structure and investigate the reservoirs’ heterogeneity based on fractal theory. By conducting a series of experimental studies, mainly including TOC, XRD, gas adsorption (N2 and CH4), we were able to clarify the main controlling factors for the heterogeneity of deep shale pore structure. Our results indicated that the deep marine shale possessed a significant amount of organic matter, as the average TOC value is 3.68%. The XRD analysis results show that quartz and clay were the main mineral types, and the total content of these two minerals averaged 77.5%. Positive correlations were observed between TOC and quartz, while TOC decreases as the clay mineral increases, this discovery indicating that quartz is biogenic. Based on FHH (Frenkele-Halseye-Hill) method, by using the LTNA adsorption isotherms, we took relative pressure P/P0=0.5 as the boundary, then two separate fractal dimension were deduced, D1 and D2 represent the fractal characteristics of small and large pores, respectively. Our study revealed that both D1 and D2 demonstrated positive correlations with N2 adsorption pore volume and adsorption specific surface area, while negatively correlated with the adsorption average pore diameter. Moreover, the two fractal dimensions showed positive associations with TOC and quartz and negative associations with clay. Additionally, D1 and D2 also demonstrated a positive correlation with Langmuir volume. The presence of micropores was found to significantly influence the formation of an irregular pore structure in shale. As the pore size decreased, the adsorption specific surface area increased, resulting in a more intricate pore structure, and the fractal dimension of the pores elevated, ultimately. This intricate structure is beneficial for the accumulation of shale gas. These research findings offer valuable insights for the comprehensive assessment of deep shale gas, and enrich our knowledge of enrichment mechanisms in deep shale gas reservoirs.

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Occurrence of methane in organic pores with surrounding free water: A molecular simulation study

Li,

Chen,

Cai

et al. 2024

Chemical Engineering Journal

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Pore structure and gas adsorption characteristics in stress-loaded shale on molecular simulation

Cited by 7 publications

References 42 publications

The primary controlling factors of the occurrence state of deep high-rank coalbed methane in eastern Ordos Basin

The primary controlling factors of the occurrence state of deep high-rank coalbed methane in eastern Ordos Basin

Characterization and fractal characteristics of nano-scale pore structure in shale gas reservoirs: a case study of the deep Longmaxi Formation, Zigong region, Southern Sichuan Basin, China

Occurrence of methane in organic pores with surrounding free water: A molecular simulation study

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