Quantification of the influences of radiolarian fossils on the pore structure of Wufeng-Lungmachi gas shales (Ordovician-Silurian) in the Sichuan Basin, South China

Hu, Ruining; Tan, Jingqiang; Dick, Jeffrey M.; Li, Lei; Wang, Wenhui

doi:10.1016/j.jngse.2020.103442

Cited by 8 publications

(6 citation statements)

References 42 publications

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“…The intergranular pores and interlayer pores are widely developed in minerals, which are the main sources for mesopores and macropores, respectively. The marine shale gas exploitation in South China shows that honeycomb-shaped organic pores are the main occurrence space for gas. − Dense pores are developed on the surface of several OMs in the samples (Figure a), and the adsorption capacity of coal measure shale is positively correlated with the TOC in the study area, indicating that organic pores provide partial storage space for shale gas. Compared with marine shale, organic pores in the samples are more dispersed and show strong heterogeneity (Figure ).…”

Section: Discussionmentioning

confidence: 95%

Geochemical Composition and Microstructure of Coal Measure Shale in the Upper Permian, Western Guizhou, China: Implications for Methane Generation and Storage

Zhang

Kang

et al. 2022

Energy Fuels

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Substantial coal measure gas is reserved in the Upper Permian shale in western Guizhou, China, but the mechanism of gas generation and enrichment remains unclear. In this study, rock-eval pyrolysis, stable carbon isotope, and low-temperature N2/CO2 adsorption (LN2/CO2A) experiments were conducted on coal measure shale collected from western Guizhou. The geochemical composition and pore morphology were clarified, and the shale gas generation and storage characteristics were ultimately revealed. The results show that the total organic carbon (TOC) contents of most samples exceed 2%, indicating a high organic matter (OM) abundance. The average R o and T max are 2.89% and 576 °C, respectively, corresponding to the overmature stage, leading to the poor current hydrocarbon generation potential. Unlike marine shale with dense organic pores, these pores are generally poorly developed and heterogeneous in the samples. Densely distributed microfractures are favorable methane migration channels. The pores are dominated by mesopores, with an average pore volume (PV) proportion of 53.55%, while the specific surface area (SSA) is mainly contributed by micropores. The LCO2A-SSA and LCO2A-PV show a positive correlation with the TOC, T max, and S1, but the LN2A-SSA and LN2A-PV are poorly correlated with these parameters, indicating that micropores are mainly derived from organic pores and that hydrocarbons generated by OM pyrolysis are mainly reserved in micropores. When δ13COM shows a negative anomaly, R o, T max, and S1 all show a negative drift in the vertical sequence, suggesting that the chemical parameters are closely related during thermal maturation. Accompanied by hydrocarbon generation, 12CH4 is preferentially separated from the OM, resulting in a higher δ13COM. Meanwhile, the generated methane is mainly reserved in the form of adsorption, and the micropores/mesopores provide a favorable place for shale gas storage.

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Section: Discussionmentioning

confidence: 95%

Geochemical Composition and Microstructure of Coal Measure Shale in the Upper Permian, Western Guizhou, China: Implications for Methane Generation and Storage

Zhang

Kang

et al. 2022

Energy Fuels

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“…The exploration and development of shale oil and gas is an intense research topic in the field of unconventional oil and gas, especially the pore structure characteristics of shale and the occurrence mechanism of shale oil and gas. − The Huadian shale is one of the significant unconventional resources in China; it is reported that there are 6–26 oil shale layers in the Huadian Basin . Several oil shale layers are mined for oil and gas reserves and can produce approximately 50 000 tonnes of oil each year .…”

Section: Introductionmentioning

confidence: 99%

“…Shale pores typically have a low porosity and permeability. Many scholars have conducted qualitative (such as field emission scanning electron microscopy (FE-SEM)) and quantitative (such as gas adsorption analyses, high-pressure mercury intrusion, and nuclear magnetic resonance) analyses on the characteristics of pore size and morphology. ,− According to compositional differences and differences in the formation conditions, shale pores can be divided into organic matter pores (OM pores), mineral matrix pores (including intergranular and intragranular pores), and microcracks. , Additionally, shale pores can be divided according to pore size into micropores (<2 nm), mesopores (2–50 nm), and macropores (>50 nm) …”

Section: Introductionmentioning

confidence: 99%

Pore Evolution of Lacustrine Organic-Rich Shales: Insights from Thermal Simulation Experiments

Tan

Luo

et al. 2021

Energy Fuels

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The pore structure characteristics of shale reservoirs are an intense research topic in unconventional oil and gas exploration and development. To explore the evolution of the shale pore structure at different maturity stages, the immature organic-rich shale (Ro = 0.27%, TOC = 26.27%) of the Paleogene Huadian Formation is selected for a series of thermal simulation experiments in a closed system from the immature to overmature stages. The N2/CO2 adsorption experiment and the Frenkel–Halsey–Hill (FHH) model are used to characterize the pore development and fractal dimensions of the thermal simulation samples before and after Soxhlet extraction. The results show that most of the oil-generating stage occurs between 300 and 400 °C. With an increase in temperature, abundant liquid hydrocarbons will undergo secondary cracking to generate wet gas. The thermal simulation samples mainly develop wedge-shaped or slit-shaped pores. The pore size distribution mainly exists within the bimodal distributions 0.5–0.8 and 30–100 nm. The residue of liquid hydrocarbons can block some mesopores and macropores, which is shown by comparing the pore volume before and after Soxhlet extraction. Moreover, the pore structure of the samples is more complex than the pore surface during the hydrocarbon evolutionary process. The pore evolution of shale can be divided into three stages: the complex development stage of pores in the low-maturity stage, the massive development stage of pores in the middle maturity to high-maturity stage, and the uniform development stage of pores in the overmature stage. Additionally, during the entire thermal evolution of shale, residual oil and diagenesis are the main factors affecting the differential development of pores and the variation in the fractal dimension.

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“…On the other hand, radiolarians and spicules are considered as the siliceous component of shale, which could increase the brittleness of reservoir rocks (Tan et al, 2020;Xu et al, 2021). In addition, siliceous microfossils also develop abundant biological pores, enhancing the heterogeneity of the shale pore network (Hu et al, 2020). Studies have shown that the disparity and abundance of radiolarians in various geological periods are highly similar to the distribution of giant oil and gas fields in the world (De Wever et al, 2002;Khan et al, 2019, Fig.…”

Section: Introductionmentioning

confidence: 99%

“…1c) were studied. The sequence stratigraphy and TOC contents of well LCA were obtained based on previous work (Hu et al, 2020;Tan et al, 2020). The analysis was augmented with data for four previously investigated auxiliary drillcore sections named 3-JYD (Khan et al, 2019), 4-JYB (Guo, 2013;Jin et al, 2020b;Wu et al, 2018), 5-JYA (Wang et al, 2019), and 6-WYA (Wu et al, 2019, Fig.…”

Section: Introductionmentioning

confidence: 99%

Depositional conditions of siliceous microfossil-rich shale during the Ordovician–Silurian transition of south China: Implication for organic matter enrichment

Tan

Dick

et al. 2023

Marine and Petroleum Geology

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Quantification of the influences of radiolarian fossils on the pore structure of Wufeng-Lungmachi gas shales (Ordovician-Silurian) in the Sichuan Basin, South China

Cited by 8 publications

References 42 publications

Geochemical Composition and Microstructure of Coal Measure Shale in the Upper Permian, Western Guizhou, China: Implications for Methane Generation and Storage

Geochemical Composition and Microstructure of Coal Measure Shale in the Upper Permian, Western Guizhou, China: Implications for Methane Generation and Storage

Pore Evolution of Lacustrine Organic-Rich Shales: Insights from Thermal Simulation Experiments

Depositional conditions of siliceous microfossil-rich shale during the Ordovician–Silurian transition of south China: Implication for organic matter enrichment

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