Comparison of pore systems of clay-rich and silica-rich gas shales in the lower Silurian Longmaxi formation from the Jiaoshiba area in the eastern Sichuan Basin, China

Guo, Xiaowen; Qin, Zhejian; Yang, Rui; Dong, Tian; He, Sheng; Hao, Fang; Jiang, Yi; Shu, Zhiguo; Bao, Hanyong; Liu, Keyu

doi:10.1016/j.marpetgeo.2018.11.038

Cited by 83 publications

(63 citation statements)

References 31 publications

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“…This agrees well with coal cuttings identified under the scanning electron microscope (Figure 8), where no organic pores are developed. It is different from representative marine gas shales worldwide, where many organic pores are developed (mostly in solid bitumen) (Inan et al, 2018;Katz and Arango, 2018;Guo et al, 2019). However, XRD identification and SEM observation show no solid bitumen at high to over-high maturity stage in the study area.…”

Section: Factors Affecting Organic Pore Developmentcontrasting

confidence: 63%

Mineralogy and Pore Structure of Marine–Continental Transitional Shale: A Case Study of the Upper Carboniferous Keluke Formation in the Eastern Qaidam Basin, China

Guo

Fang

Wang³

et al. 2022

Front. Earth Sci.

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Organic-rich shale and associated fine-grained sedimentary rocks of marine-continental transitional facies were well developed in the Upper Carboniferous Keluke Formation in the Eastern Qaidam Basin, which is expected to be a set of potential shale gas exploration and development target. Mineralogy and pore structure of marine-continental transitional shale were investigated systematically based on thin-section identification, X-ray diffraction (XRD), helium porosity test and pressure-pulse permeability measurement, scanning electron microscopy (QEMSCAN), field emission scanning electron microscopy (FESEM), and high-pressure mercury injection (MICP) and nitrogen adsorption. Thin section, XRD, and QEMSCAN data suggest that marine–continental transitional shale has complex mineral compositions, resulting in mixed rocks and mixed sequences. FE-SEM images show that interparticle and intercrystalline pores are popular in the Keluke Shales, with minor dissolution pores and microfractures. No secondary organic matter pores occur in the Keluke Shales because organic macerals are dominated by vitrinite and inertinite, where only primary pores can be found among organic matter frameworks. MICP and nitrogen adsorption indicate that pore size distributions follow a bimodal pattern and proportions of micro-scale pores and macro-scale pores increase in an order: bioclastic limestone, argillaceous bioclastic limestone, silty mudstone, argillaceous siltstone. The differences in pore structure are caused by sedimentary facies and associated mineralogy and diagenesis. This study can provide a crucial theoretical guidance for sweet spots determination and deep understanding of transitional shale gas potential.

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Section: Factors Affecting Organic Pore Developmentcontrasting

confidence: 63%

Mineralogy and Pore Structure of Marine–Continental Transitional Shale: A Case Study of the Upper Carboniferous Keluke Formation in the Eastern Qaidam Basin, China

Guo

Fang

Wang³

et al. 2022

Front. Earth Sci.

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“…It has been proved that the shale reservoir pore structure affects both adsorbed and free gas storage capacities and, therefore, the total shale gas resource potential. − Compared with conventional hydrocarbon reservoirs, a shale reservoir is characterized by low porosity, permeability, and nanometer-scale pores. ,,− According to the pore size, shale reservoir pores are usually classified as micropores, mesopores, and macropores . The pore networks of many highly mature organic-rich shale reservoirs primarily consist of micropores and mesopores. ,, …”

Section: Introductionmentioning

confidence: 99%

The Influence of Analytical Particle Size on the Pore System Measured by CO₂, N₂, and Ar Adsorption Experiments for Shales

Dong

et al. 2021

Energy Fuels

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To investigate the analytical particle size impact on pore structure parameters of shale reservoirs measured by low-pressure gas adsorption (LPGA), shale samples with varying total organic carbon (TOC) contents and mineral compositions from the Lower Silurian Longmaxi Formation were selected and crushed into five different analytical particle size ranges. All samples with different analytical particle sizes were analyzed by CO2, N2, and Ar adsorption techniques, and the measured pore structure parameters were compared. Our results suggest that the analytical particle size has subtle influence on measured micropore structure parameters, whereas measured mesopore and macropore structure parameters are greatly affected by different particle sizes, especially the pores with a diameter greater than 10 nm. The average pore size (APS) and mesopore and macropore volume and surface area (V meso, S meso, V macro, and S macro) gradually increase with decreasing particle size, whereas the micropore volume and surface area (V micro and S micro) have subtle variation. With decreasing particle size, the contribution of V meso and V macro to the total pore volume (TPV) increases, while the contribution of V micro to TPV decreases. Meanwhile, the changing trend of fractal dimensions of the micropore (D micro), mesopore (D meso), and macropore (D macro) with decreasing particle size indicates that the micropore still maintains strong heterogeneity, whereas the mesopore and macropore gradually become homogeneous, and the pore surface gradually becomes smooth. The changing rates of APS (ΔAPS), V meso (ΔV meso), S meso (ΔS meso), V macro (ΔV macro), S macro (ΔS macro), D meso (dD meso), and D macro (dD macro) with decreasing particle size were defined, and the changing rates show negative correlations with TOC, quartz content, and positive relationships to clay content. The LPGA experiments should adopt unified particle size so as to eliminate the particle size impact on measured pore structure parameters. This study suggests that the particle size range of 250–180 μm (60–80 mesh) used by most previous studies is recommended for LPGA experiments in shales, and the finer particle size (e.g., 106–75 μm) should be used with caution.

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“…The isotherm curves for N 2 adsorption and desorption were obtained, and all the samples were belong to types III and IV according to IUPAC (Figure 3) [46]. The capillary hysteresis loops were distinct and similar to those of H3 types, suggesting that slit-shaped pores were the main pore types in C7 shale, corresponding to the SEM images [47][48][49].…”

Section: Geochemistry Parametersmentioning

confidence: 83%

Characterization of Shale Pore Structure by Multitechnique Combination and Multifractal Analysis and Its Significance

et al. 2020

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Understanding pore structure would enable us to obtain a deeper insight into the fluid mechanism in porous media. In this research, multifractal analysis by various experiments is employed to analyze the pore structure and heterogeneity characterization in the source rock in Ordos Basin, China. For this purpose, imaging apparatus, intrusion tests, and nonintrusion methods have been used. The results show that the objective shale reservoir contains complex pore network, and minor pores dominant the pore system. Both intrusion and nonintrusion methods detected pore size distributions show multifractal nature, while the former one demonstrates more heterogeneous features. The pore size distributions acquired by low temperature adsorption and nuclear magnetic resonance have relatively good consistence, indicating that similar pore network detection method may share the same mechanism, and the full-ranged pore size distributions need to be acquired by multitechniques. Chlorite has an obvious impact on the heterogeneity of pore structure in narrow pore size range, while illite and I/S mixed layer influence that in wide range. Kerogen index is the fundamental indicators of geochemical parameters. With the decrease of averaged small and middle/large pore radius, the heterogeneity of pore structures increase in narrow and wide ranges, respectively. This work employed a comprehensive methodology based on multitechniques and helps to explore how pore networks affect reservoir quality in shale reservoirs.

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Comparison of pore systems of clay-rich and silica-rich gas shales in the lower Silurian Longmaxi formation from the Jiaoshiba area in the eastern Sichuan Basin, China

Cited by 83 publications

References 31 publications

Mineralogy and Pore Structure of Marine–Continental Transitional Shale: A Case Study of the Upper Carboniferous Keluke Formation in the Eastern Qaidam Basin, China

Mineralogy and Pore Structure of Marine–Continental Transitional Shale: A Case Study of the Upper Carboniferous Keluke Formation in the Eastern Qaidam Basin, China

The Influence of Analytical Particle Size on the Pore System Measured by CO₂, N₂, and Ar Adsorption Experiments for Shales

Characterization of Shale Pore Structure by Multitechnique Combination and Multifractal Analysis and Its Significance

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Comparison of pore systems of clay-rich and silica-rich gas shales in the lower Silurian Longmaxi formation from the Jiaoshiba area in the eastern Sichuan Basin, China

Cited by 83 publications

References 31 publications

Mineralogy and Pore Structure of Marine–Continental Transitional Shale: A Case Study of the Upper Carboniferous Keluke Formation in the Eastern Qaidam Basin, China

Mineralogy and Pore Structure of Marine–Continental Transitional Shale: A Case Study of the Upper Carboniferous Keluke Formation in the Eastern Qaidam Basin, China

The Influence of Analytical Particle Size on the Pore System Measured by CO2, N2, and Ar Adsorption Experiments for Shales

Characterization of Shale Pore Structure by Multitechnique Combination and Multifractal Analysis and Its Significance

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The Influence of Analytical Particle Size on the Pore System Measured by CO₂, N₂, and Ar Adsorption Experiments for Shales