Modeling of the Correlation Between Mineral Size and Shale Pore Structure at Meso- and Macroscales

Zhou, Wuhua; Xie, Shucheng; Bao, Zhang; Carranza, E.J.M; Wang, Y.; Tang, Min

doi:10.1007/s11004-021-09954-w

Cited by 6 publications

(4 citation statements)

References 32 publications

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“…Besides, natural and hydraulic fractures exist in the shale reservoir, forming multiscale pore systems and different gas transport mechanisms in shale. , Kerogen is the most widely distributed and abundant group of sedimentary organic matter in shale, which strongly associates with shale gas production . The composition and structure of kerogen are still not completely accurate, and thus it is represented by different molecular models which perform a few characteristics of the real kerogen to some extent. , What’s more, inorganic matter accounts for a large percentage of the shale composition, the role of which thus cannot be ignored . Therefore, this section will focus on different molecular models of shale construction and gas adsorption simulations performed on them.…”

Section: Molecular Models Of Shalementioning

confidence: 99%

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A Review of Molecular Models for Gas Adsorption in Shale Nanopores and Experimental Characterization of Shale Properties

Zhang

Xin

et al. 2023

ACS Omega

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Shale gas, as a promising alternative energy source, has received considerable attention because of its broad resource base and wide distribution. The establishment of shale models that can accurately describe the composition and structure of shale is essential to perform molecular simulations of gas adsorption in shale reservoirs. This Review provides an overview of shale models, which include organic matter models, inorganic mineral models, and composite shale models. Molecular simulations of gas adsorption performed on these models are also reviewed to provide a more comprehensive understanding of the behaviors and mechanisms of gas adsorption on shales. To accurately understand the gas adsorption behaviors in shale reservoirs, it is necessary to be aware of the pore structure characteristics of shale reservoirs. Thus, we also present experimental studies on shale microstructure analysis, including direct imaging methods and indirect measurements. The advantages, disadvantages, and applications of these methods are also well summarized. This Review is useful for understanding molecular models of gas adsorption in shales and provides guidance for selecting experimental characterization of shale structure and composition.

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Section: Molecular Models Of Shalementioning

confidence: 99%

“… 24 , 31 What’s more, inorganic matter accounts for a large percentage of the shale composition, the role of which thus cannot be ignored. 32 Therefore, this section will focus on different molecular models of shale construction and gas adsorption simulations performed on them.…”

Section: Molecular Models Of Shalementioning

confidence: 99%

A Review of Molecular Models for Gas Adsorption in Shale Nanopores and Experimental Characterization of Shale Properties

Zhang

Xin

et al. 2023

ACS Omega

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“…Liu et al, 11 Li et al, 12 Dou and Wang, 13 and Gong et al 14 investigated the effect of mineral inhomogeneity on fracture extension. Zhou et al 15 and Fazeli et al 16 investigated the effect of brittle minerals and clay minerals on the pore structure of shale microscopically. Song et al, 17 Yang et al, 18 and Liu et al 19 reconstructed generic and easy-to-implement pore-scale models by micro-CT imaging.…”

Section: Introductionmentioning

confidence: 99%

Study on the Fracture Extension Pattern of Shale Reservoir Fracturing under the Influence of Mineral Content

Sun,

Hou,

Liang

et al. 2024

ACS Omega

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This study aimed to investigate the effect of the microstructure of shale on fracture initiation and extension during hydraulic fracturing. The Longmaxi Formation shale reservoir in the Sichuan Basin was considered as the research object; its structure was modeled from a microscopic perspective, and a zero-thickness cohesive unit was embedded within the solid unit. Numerical simulations were performed to study the effect of mineral content on the microextension of the hydraulic fracture, extension behavior, and evolution law of shale. The results showed that changes in the mineral content resulted in changes in the forces between molecules within the minerals, which, in turn, affected the shale's brittleness. The percentages of brittle mineral content in the Long I, II, and III reservoir sections are 60.37, 47.60, and 53.56%, respectively. The fracture initiation pressures of the three reservoirs were 29.22, 31.42, and 30.22 MPa, respectively, and a linear correlation was found between the fracture initiation pressures and the brittle mineral contents of the reservoir sections. An increase in the reservoirs' percentage of brittle mineral content facilitated the fracture initiation, with a corresponding gradual decrease in the resistance to fracture initiation. The pore pressures of the fractures in the three reservoirs after fracture initiation were 0.90, 1.18, and 1.00 MPa, respectively. The larger the percentage of brittle minerals was, the lower was the fracture pore pressure. The greater the length, number, area, and width of the cracks were, the more likely they were to form longer and wider cracks. Hence, reservoirs with a high percentage of brittle minerals should be prioritized as the target formations for hydraulic fracturing operations. The results of this study reveal how the mineral content affects the extension of microscopic hydraulic fractures in shale reservoirs. As such, this work can provide a theoretical basis for rationally selecting a hydraulic fracturing operation layer in shale gas reservoirs.

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“…Clay type, crystal structure, and pore structure in shale gas reservoirs are altered by diagenesis, leading to a decrease in reservoir porosity and permeability. Hence, the extent of CH 4 adsorption is also controlled by diagenesis, and there are apparent differences in the occurrence of diagenetic processes and their influence on the pore structure of clay minerals. − Specifically, diagenesis results in changes of clay mineral density and porosity caused by mechanical compaction, clay mineral types and pore structure evolution caused by chemical compaction (illitization of smectite), the changes of porosity and pore connectivity caused by cementation, dissolution and recrystallization, etc. − The evolution of pore structure of clay minerals is a complex process. Although previous research has provided some crucial results, the dynamic evolution of clay adsorption capacity at different diagenetic stages, especially the reconstruction of the pore evolution process and evolution model of clay minerals, is not well investigated yet.…”

Section: Introductionmentioning

confidence: 99%

Review of the Effect of Diagenetic Evolution of Shale Reservoir on the Pore Structure and Adsorption Capacity of Clay Minerals

et al. 2022

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This Review summarizes the diagenetic evolution of clay mineral structure and pores in shale gas reservoirs. In the early diagenetic stage and in period A of the middle diagenetic stage, the intergranular and intragranular pores of clay minerals were altered by mechanical and chemical compaction, and V L (Langmuir volume) shows a positive linear correlation with clay content. In period B of the middle diagenetic stage and late diagenetic stage, intergranular pores almost disappeared, clay adsorption capacity significantly decreased, and there was a lack of apparent correlation between V L and clay content. Experimental and molecular simulations of clay adsorption capacity in shale are limited due to several drawbacks. (i) Shale samples in different diagenetic stages were characterized by strong heterogeneity, which affected the reliability of the evolution results of clay adsorption capacity. (ii) The method of selecting clay-rich shale samples, extracting clay minerals from shale, or applying pure clay minerals ignored the difference of diagenetic background, the damage of pores and structure of clay minerals, or the support of brittle minerals to shale pore system. (iii) Molecular simulation mostly employed a simplified plate model or single clay mineral model, which oversimplified the structure and diversity of clay minerals in real shale gas reservoirs. Therefore, innovative experimental simulations on the effect of diagenetic evolution on pore structure and adsorption capacity of clay minerals are necessary, which need to comprehensively weigh the combined effect of time and space on the reservoir diagenetic evolution. Besides, the visualization of shale structure, adsorption process, and CH 4 adsorption behavior of the shale constituents may help our understanding. Furthermore, a more accurate model of the molecular structure of clay minerals is indispensable, especially the dynamic evolution model with different water contents.

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Modeling of the Correlation Between Mineral Size and Shale Pore Structure at Meso- and Macroscales

Cited by 6 publications

References 32 publications

A Review of Molecular Models for Gas Adsorption in Shale Nanopores and Experimental Characterization of Shale Properties

A Review of Molecular Models for Gas Adsorption in Shale Nanopores and Experimental Characterization of Shale Properties

Study on the Fracture Extension Pattern of Shale Reservoir Fracturing under the Influence of Mineral Content

Review of the Effect of Diagenetic Evolution of Shale Reservoir on the Pore Structure and Adsorption Capacity of Clay Minerals

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