Effect of Organic Matter and Maturity on Pore Size Distribution and Gas Storage Capacity in High-Mature to Post-Mature Shales

Tang, Xianglu; Jiang, Zhenxue; Jiang, Shu; Wang, Pengfei; Xiang, Caifu

doi:10.1021/acs.energyfuels.6b01499

Cited by 82 publications

(43 citation statements)

References 50 publications

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“…In addition, hydrothermal activity is relatively developed at this time, which is beneficial to the improvement of biological productivity and the preservation of organic matter, and thus the accumulation of organic matter. Shale gas is mainly stored in organic matter pores, and organic matter pores provide natural gas main flowing channels [62][63][64][65][66]. The content of TOC in SQ4 and SQ5 is much lower than that of SQ2 and SQ3, and the gas content is low.…”

Section: Discussionmentioning

confidence: 99%

Division of shale sequences and prediction of the favorable shale gas intervals: an example of the Lower Cambrian of Yangtze Region in Xiuwu Basin

Zhang

Song

et al. 2019

Open Geosciences

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It is a common method to use sequence stratigraphic theory to identify favourable intervals in hydrocarbon exploration. The Lower Cambrian shale of Well Jiangye-1 in Yangtze Region in Xiuwu Basin was chosen as the research object. The content of excess silicon of siliceous minerals in shale was calculated quantitatively, and the concentration distribution of Al, Fe, Mn showed that the excess silicon is of hydrothermally origin and the shale deposited in an environment with hydrothermal activity. Using U/Th values in the study, combined with lithology and logging data, in order to divide sequences of the Lower Cambrian shale in Yangtze Region in Xiuwu Basin. The result shows that the shale of the Lower Cambrian shale is recognized as 1 2nd sequence (TST-RST, TST = Transgressive systems tract; RST = Regressive systems tract) and then further subdivided into 5 3rd sequences (SQ1-SQ5). During the deposition of SQ2 and SQ3, hydrothermal activity was active, and their excess silicon content was generally above 20%-30%. Rising sea level and active hydrothermal activity were beneficial for the enrichment of siliceous minerals and organic matter. Based on the comparison of the reservoir parameters, it tells that SQ2 and SQ3 have relatively higher content of TOC, higher content of brittle minerals (such as siliceous minerals, carbonate minerals and so on), larger effective porosity and higher content of gas, which make it as the most favourable intervals of the Lower Cambrian in Xiuwu Basin.

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Section: Discussionmentioning

confidence: 99%

Division of shale sequences and prediction of the favorable shale gas intervals: an example of the Lower Cambrian of Yangtze Region in Xiuwu Basin

Zhang

Song

et al. 2019

Open Geosciences

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“…According to IUPAC (1972), pores can be classified as micropores (< 2 nm), mesopores (2-50 nm), and macropores (> 50 nm). The categorization was initially applied to chemical products and has been widely used for shale and mudstone reservoirs worldwide (Jiang et al, 2016a;Tang et al, 2017). In the actual pore size distribution curve, different peaks are bound to correspond to internal control factors and have different effects on fluid flow.…”

Section: Pore Structure Characteristicsmentioning

confidence: 99%

Effect of Shale Reservoir Characteristics on Shale Oil Movability in the Lower Third Member of the Shahejie Formation, Zhanhua Sag

Ning

Jiang

et al. 2020

Acta Geologica Sinica (Eng)

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To reveal the effect of shale reservoir characteristics on the movability of shale oil and its action mechanism in the lower third member of the Shahejie Formation (Es3l), samples with different features were selected and analyzed using N2 adsorption, high‐pressure mercury injection capillary pressure (MICP), nuclear magnetic resonance (NMR), high‐speed centrifugation, and displacement image techniques. The results show that shale pore structure characteristics control shale oil movability directly. Movable oil saturation has a positive relationship with pore volume for radius > 2 μm, as larger pores often have higher movable oil saturation, indicating that movable oil is present in relatively larger pores. The main reasons for this are as follows. The relatively smaller pores often have oil‐wetting properties because of organic matter, which has an unfavorable effect on the flow of oil, while the relatively larger pores are often wetted by water, which is helpful to shale oil movability. The rich surface provided by the relatively smaller pores is beneficial to the adsorption of immovable oil. Meanwhile, the relatively larger pores create significant pore volume for movable oil. Moreover, the larger pores often have good pore connectivity. Pores and fractures are interconnected to form a complex fracture network, which provides a good permeability channel for shale oil flow. The smaller pores are mostly distributed separately; thus, they are not conducive to the flow of shale oil. The mineral composition and fabric macroscopically affect the movability of shale oil. Calcite plays an active role in shale oil movability by increasing the brittleness of shale and is more likely to form micro‐cracks under the same stress background. Clay does not utilize shale oil flow because of its large specific surface area and its block effect. The bedding structure increases the large‐scale storage space and improves the connectivity of pores at different scales, which is conducive to the movability of shale oil.

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“…The qualitative techniques include polarized light microscopy, field emission scanning electron microscopy (FE-SEM), and atomic force microscopy [21][22][23]. The quantitative techniques include low pressure gas adsorption (N 2 and CO 2 ), high-pressure MIP, small angle and ultra-small-angle neutron scattering (SANS and USANS), and nano-CT [24][25][26]. It is generally necessary to comprehensively use a variety of methods to characterize the pore structure due to the complexity of pore structure [27].…”

Section: Introductionmentioning

confidence: 99%

Micropore Structural Heterogeneity of Siliceous Shale Reservoir of the Longmaxi Formation in the Southern Sichuan Basin, China

Tang

Zheng

2019

Minerals

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In recent years, the shale gas in the southern Sichuan Basin has achieved great commercial development, and the Silurian Longmaxi Formation is the main development stratum. In order to solve the problems of great difference production and inaccurate gas content of the Longmaxi Formation shale gas field in the southern Sichuan Basin, based on thin section identification, argon ion polishing-field emission scanning electron microscopy, high pressure mercury injection, low temperature nitrogen adsorption and the fractal method, the micropore structural heterogeneity of the siliceous shale reservoir of the Longmaxi Formation has been studied. The results show the following: The pores of siliceous shale are mainly intergranular pores and organic pores. Image analysis shows that there are obvious differences in size and distribution of shale pores among different types. The micropore structural heterogeneity is as follows: intragranular pore > intergranular pore > organic pore. In the paper, the combination of low temperature nitrogen adsorption method and high-pressure mercury injection method is proposed to characterize the micropore size distribution and fractal dimension, which ensures the credibility of pore heterogeneity. The shale pores are mainly composed of mesopores (2–20 nm), followed by macropores (100–300 nm). For different pore sizes, the fractal dimension from large to small is mesopore, micropore and macropore. Shale pore structure and fractal dimension are correlated with mineral composition and total organic carbon (TOC) content, but the correlation is significantly different in different areas, being mainly controlled by the sedimentary environment and diagenesis.

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Effect of Organic Matter and Maturity on Pore Size Distribution and Gas Storage Capacity in High-Mature to Post-Mature Shales

Cited by 82 publications

References 50 publications

Division of shale sequences and prediction of the favorable shale gas intervals: an example of the Lower Cambrian of Yangtze Region in Xiuwu Basin

Division of shale sequences and prediction of the favorable shale gas intervals: an example of the Lower Cambrian of Yangtze Region in Xiuwu Basin

Effect of Shale Reservoir Characteristics on Shale Oil Movability in the Lower Third Member of the Shahejie Formation, Zhanhua Sag

Micropore Structural Heterogeneity of Siliceous Shale Reservoir of the Longmaxi Formation in the Southern Sichuan Basin, China

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