Nanopore Structure Evolution of Lower Cambrian Shale in the Western Hubei Area, Southern China, and its Geological Implications based on Thermal Simulation Experimental Results

Li, Gang; Xiao, Xia; Gai, Haifeng; Yuan, Feng; Lu, Chengang; Meng, Guangming

doi:10.1007/s11053-022-10149-1

Cited by 8 publications

(4 citation statements)

References 68 publications

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“…For the quartz crystallinity measurement, the scan angle, step length, and scanning speed differ from those employed in the X-ray diffraction test for the quantitative whole-rock mineralogical composition. , Consequently, this measurement underwent a dedicated test and analysis in this study. To ensure a smooth tablet surface during pressing and minimize the influence of crystal size and preferred orientation on the measurement results, the prepared shale sample was meticulously ground in an agate mortar until uniformly sized particles with less than 200 mesh were achieved.…”

Section: Database and Methodologymentioning

confidence: 99%

Quartz Crystallinity Characteristics and Their Effects on Shale Gas Reservoir Performance: A Case Study of the Deep Longmaxi Formation Shale in the Sichuan Basin, China

Feng,

Xiao,

Wang

et al. 2024

ACS Earth Space Chem.

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Quartz, as a pivotal constituent of shale, has garnered considerable attention in research. Nevertheless, prior studies on quartz in shale have concentrated on its influence on organic matter accumulation, pore development, and physical properties. The crystal morphology of quartz and its implications for shale reservoir performance have been largely overlooked. This study utilizes the Longmaxi (LMX) shale in the Sichuan Basin, China, as an example to conduct this work. We used X-ray powder diffraction, polarizing microscopy, scanning electron microscopy, and cathodoluminescence testing, characterizing the crystallinity and characteristics of quartz, revealing the influence of quartz crystallinity on shale reservoirs. The results indicate that the quartz crystallinity index (QCI) of the LMX shale ranges from 2.81 to 8.09, and a significant correlation between the QCI and the sources of quartz is observed. Shale samples with lower QCI values tend to exhibit a higher content of biogenic quartz, whereas the content of clay-transformed quartz and/or terrigenous detrital quartz increases. Furthermore, the pore structure parameters of shale exhibit synergistic variations with QCI, especially for shale with low crystallinity, despite showcasing differences for pores with different pore sizes. Notably, QCI exhibits the strongest negative correlation with micropores, followed by mesopores, while this correlation is less apparent in macropores. The influence of QCI on pore development is primarily ascribed to its synergistic interaction with organic matter enrichment and the constraints imposed on the development and preservation of organic-matter-hosted pores. Under the well-preserved geological conditions of the LMX shale reservoirs, a definite correlation exists between the QCI value and shale gas content/production. This correlation signifies that QCI could serve as a potential indicator for assessing shale reservoir quality, complementing conventional parameters, such as the contents of total organic carbon and quartz.

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Section: Database and Methodologymentioning

confidence: 99%

Quartz Crystallinity Characteristics and Their Effects on Shale Gas Reservoir Performance: A Case Study of the Deep Longmaxi Formation Shale in the Sichuan Basin, China

Feng,

Xiao,

Wang

et al. 2024

ACS Earth Space Chem.

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“…The studied 12 shale samples were collected from the middle and bottom of the Lower Cambrian Shuijingtuo Formation in Well YD4, which was deposited in deep-water shelf facies. ,,− Geological background of studied well, as well as TOC content, mineral composition, and equivalent vitrinite reflectance (EqRo) of studied whole-rock samples were described by Li et al The TOC content of studied whole-rock samples was 0.91–10.70% (average = 5.38%), the EqRo value was 3.14–3.26% (average = 3.23%), and the mineral compositions mainly included quartz, clay, and carbonates, with their contents in the ranges of 17.50–57.80% (average = 31.95%), 18.10–54.70% (average = 33.71%), and 11.70–39.10% (average = 20.86%), respectively …”

Section: Samples and Methodsmentioning

confidence: 99%

“…Kerogen Isolation. Kerogen fraction was isolated from whole-rock samples using the chemical digestion method, as suggested by Li et al 18 First, 20 g of shale samples was crushed into 0.074 mm, and the powdered samples were treated with hydrochloric acid (6 mol/L) to remove carbonates. The residues were washed with deionized water several times.…”

Section: Samples and Methodsmentioning

confidence: 99%

“…Conventional pore structure parameters of shales mainly include pore size, pore size distribution (PSD), pore types, pore-specific surface area (SSA), and pore volume (PV). − A variety of techniques and methods has been applied to quantitatively characterize the shale pore structure, such as low-pressure CO 2 and N 2 adsorptions (LPCA and LPNA), high-pressure mercury injection (MICP), small and ultrasmall angle neutron scattering (SANS/USANS), and nuclear magnetic resonance (NMR). ,− In these methods, LPCA and LPNA experiments are usually applied to obtain PSD, SSA, and PV, which are effective in characterizing the shale pore structure. ,,− …”

Section: Introductionmentioning

confidence: 99%

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Fractal Characteristics of Nanopores and Their Controlling Factors of the Lower Cambrian Shale in the Western Hubei Area, South China

Li,

Gao,

et al. 2023

Energy Fuels

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The Lower Cambrian shale is one of the most important marine shale reservoirs in South China, which has huge potential for shale gas resources. However, the Lower Cambrian shale displays strong pore heterogeneity, influencing shale gas exploration. Based on the low-pressure N2 adsorption (LPNA) of the Lower Cambrian shale samples and their isolated kerogens in the western Hubei area, South China, fractal dimensions and their controlling factors of shale nanopores have been investigated. In this study, the pore specific surface area (SSA) and pore volume (PV) of isolated kerogen samples are mainly contributed from micropores and non-micropores, respectively, which are consistent with those of whole-rock samples. The average fractal dimensions of whole-rock samples are higher than those of isolated kerogen samples, suggesting that organic matter (OM) controls the shale pore structure and exerts major influences on fractal characteristics of nanopores and inorganic mineral (IM) enhances the complexity of shale nanopores. The correlations between fractal dimensions and total organic carbon (TOC) and IM contents of whole-rock samples further indicate that the OM simultaneously affects the heterogeneities of the pore surface and structure, while the IM mainly affects the heterogeneity of the pore structure. They both control the fractal characteristics of nanopores in the Lower Cambrian shale. Compared with the Upper Carboniferous–Lower Permian marine-continental transitional (MCT) shale and the Lower Silurian marine shale, the D 1 and D 2 of the studied marine shale display relatively lower and higher values, respectively, revealing that the Lower Cambrian shale has relatively weak adsorption capacity, as well as poor permeability and connectivity.

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Evolution Mechanism of Pore Structures of Organic-Rich Shale Under Tectonic Deformation: A Comparative Study Between Whole Rock and Kerogen Samples

Cheng,

Jiang,

et al. 2023

Nat Resour Res

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Nanopore Structure Evolution of Lower Cambrian Shale in the Western Hubei Area, Southern China, and its Geological Implications based on Thermal Simulation Experimental Results

Cited by 8 publications

References 68 publications

Quartz Crystallinity Characteristics and Their Effects on Shale Gas Reservoir Performance: A Case Study of the Deep Longmaxi Formation Shale in the Sichuan Basin, China

Quartz Crystallinity Characteristics and Their Effects on Shale Gas Reservoir Performance: A Case Study of the Deep Longmaxi Formation Shale in the Sichuan Basin, China

Fractal Characteristics of Nanopores and Their Controlling Factors of the Lower Cambrian Shale in the Western Hubei Area, South China

Evolution Mechanism of Pore Structures of Organic-Rich Shale Under Tectonic Deformation: A Comparative Study Between Whole Rock and Kerogen Samples

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