The characterization and quantitative analysis of nanopores in unconventional gas reservoirs utilizing FESEM–FIB and image processing: An example from the lower Silurian Longmaxi Shale, upper Yangtze region, China

Jiao, Kun; Yao, Shuzhen; Li, Chun; Gao, Yanfang; Wu, Hui; Li, MiaoChun; Zhongyi, Tang

doi:10.1016/j.coal.2014.03.004

Cited by 242 publications

(137 citation statements)

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“…High-resolution images were firstly converted into binary images showing matrix and pore space. In order to reduce human error, the method where multiple independent parameters are averaged is used to analyze the porosity, which controls the recognition error of shale geometric factors to about 2% (Jiao et al, 2014). Then the number of pores as well as the area, perimeter, length, width, fractal dimension, form factor, and probability entropy of the pore can be obtained by this software.…”

Section: Fe-sem and Pcasmentioning

confidence: 99%

Pore characteristics of organic-rich shale in the Carboniferous-Permian coal-bearing strata in Qinshui Basin

Gao

Wei

Song

et al. 2017

Energy Exploration & Exploitation

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The study of shale pore has always been an important aspect of nonconventional shale reservoir analysis. However, there are relatively few studies on shale that is deposited in transitional environment in the Qinshui Basin. X-ray diffraction, field-emission scanning electron microscopy, N 2 , and CO 2 adsorption experiments were used for shale samples from the Taiyuan and Shanxi Formations. Sample pore characteristics based on field-emission scanning electron microscopic photographs were quantitatively characterized by pore fracture characteristics analysis software and fractal characteristics were discussed based on the nitrogen adsorption curve. Results show that sample pores were primarily composed of inter-granular and intra-granular pores. The proportion of micropores (<2 nm) is 25.84-91.65% of the total pore space, with an average of 58.65%. Micropores show three peaks, which occur near 0.38 nm, 0.5 nm, and 0.85 nm. Mesopores (2-50 nm) account for 6.74-56.11% of the total pore space, with an average of 31.20%. The ratio of macropores (>50 nm) less than 100 nm is 1.61-20.64% with an average of 9.17%. The volume of micropores increases with increase in the total organic carbon and clay mineral contents, decreases with the increase of carbonate and quartz mineral contents, and has weak correlation with other factors. The micropore volume per unit organic matter decreases with increase in maximum vitrinite reflectance (R o,max ) in a binomial relationship. The correlations between meso-macropore volume and each factor are rather weak. Form factor, fractal dimension, and probability entropy all correlate well with the depth. Pore structure complexity gradually increases with the increase in the burial depth. The deeper the rock layer increases with the pore size, the more slowly the pore complexity increases. The larger pore diameter, the more smooth journals.sagepub.com/home/eea the pore wall surface, and the rougher surface is more favorable for gas adsorption. The directionality of pore development increases first and then decreases with increase in the depth.

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Section: Fe-sem and Pcasmentioning

confidence: 99%

Pore characteristics of organic-rich shale in the Carboniferous-Permian coal-bearing strata in Qinshui Basin

Gao

Wei

Song

et al. 2017

Energy Exploration & Exploitation

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“…Using the shape of the curve to describe pore shape [48,52], Type H2 hysteresis occurs in pores with a narrow pore throat and wide bodies (defined as inkbottle-shaped pores) and Type H3 hysteresis indicates slit-shaped or wedge-shaped pores according to International Union of Pure and Applied Chemistry (IUPAC) classification. The shape of hysteresis loops of the samples indicated that the shape is somewhere between Types H3 and H2, which may be related to a combination of different pore types.…”

Section: Pore Structure Characterization Through Nitrogen Physisorptionmentioning

confidence: 99%

Pore Structure and Fractal Characteristics of Niutitang Shale from China

Tang

Wang

et al. 2018

Minerals

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A suite of shale samples from the Lower Cambrian Niutitang Formation in northwestern Hunan Province, China, were investigated to better understand the pore structure and fractal characteristics of marine shale. Organic geochemistry, mineralogy by X-ray diffraction, porosity, permeability, mercury intrusion and nitrogen adsorption and methane adsorption experiments were conducted for each sample. Fractal dimension D was obtained from the nitrogen adsorption data using the fractal Frenkel-Halsey-Hill (FHH) model. The relationships between total organic carbon (TOC) content, mineral compositions, pore structure parameters and fractal dimension are discussed, along with the contributions of fractal dimension to shale gas reservoir evaluation. Analysis of the results showed that Niutitang shale samples featured high TOC content (2.51% on average), high thermal maturity (3.0% on average), low permeability and complex pore structures, which are highly fractal. TOC content and mineral compositions are two major factors affecting pore structure but they have different impacts on the fractal dimension. Shale samples with higher TOC content had a larger specific surface area (SSA), pore volume (PV) and fractal dimension, which enhanced the heterogeneity of the pore structure. Quartz content had a relatively weak influence on shale pore structure, whereas SSA, PV and fractal dimension decreased with increasing clay mineral content. Shale with a higher clay content weakened pore structure heterogeneity. The permeability and Langmuir volume of methane adsorption were affected by fractal dimension. Shale samples with higher fractal dimension had higher adsorption capacity but lower permeability, which is favorable for shale gas adsorption but adverse to shale gas seepage and diffusion.

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“…Mainly by means of probe gas adsorption techniques to quantitatively characterize the pore size and pore structure, including neutron scattering, high pressure mercury intrusion, low pressure gas adsorption and so on (Mastalerz et al, 2012(Mastalerz et al, , 2013Clarkson et al, 2013;Cao et al, 2015;Hu et al, 2015). Due to the complexity of sample preparation and limited observation area, microscopic observation method has a certain limit and generally only be used for qualitative analysis (Jiao et., 2014;Yang et al, 2016a,b;Zeng et al, 2016). High pressure mercury intrusion method provides both porosity value and the distribution characteristics of pores (Clarkson et al, 2013), however, pressure resistance of shale is much worse than sandstone and the pores in shale mainly consist of nanoscale pore, it will lead to some secondary macropores (Giesche, 2006).…”

Section: Introductionmentioning

confidence: 99%

Quantitative characterization of micropore structure for organic-rich Lower Silurian shale in the Upper Yangtze Platform, South China: Implications for shale gas adsorption capacity

Chen

Jiang

Liu

et al. 2017

Adv. Geo-Energ. Res.

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The pores in shales are mainly of nanometer-scale, and their pore size distribution is very important for shale gas storage and adsorption capacity, especially micropores having widths less than 2 nm, which contribute to the main occurrence space for gas adsorption. This study is focused on the organic-rich Lower Silurian black shale from four wells in the Upper Yangtze Platform, and their total organic carbon (TOC), mineralogical composition and micropore characterization were investigated. Low pressure CO2 adsorption measurement was conducted at 273.15 K in the relative pressure range of 0.0001-0.03, and the micropore structure was characterized by Dubinin-Radushkevich (DR) equation and density functional theory (DFT) method and then the relationship between micropore structure and shale gas adsorption capacity was discussed. The results indicated that (1) The Lower Silurian shale have high TOC content in the range of 0.92-4.96%, high quartz content in the range of 30.6-69.5%, and high clays content in the range of 24.1-51.2%. The TOC content shows a strong positive relationship with the quartz content which suggests that the quartz is mainly biogenic in origin. (2) The micropore volume varies from 0.12 cm 3 /100 g to 0.44 cm 3 /100 g and micropore surface area varies from 4.97 m 2 /g to 17.94 m 2 /g. Both of them increase with increasing TOC content, indicating TOC is the key factor to control the micropore structure of the Lower Silurian shale. (3) Low pressure CO2 adsorption measurement provides the most suitable detection range (0.3-1.5 nm) and has high reliability and accuracy for micropore structure characterization. (4) The TOC content is the key factor to control gas adsorption capacity of the Lower Silurian shale in the Upper Yangtze Platform.

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The characterization and quantitative analysis of nanopores in unconventional gas reservoirs utilizing FESEM–FIB and image processing: An example from the lower Silurian Longmaxi Shale, upper Yangtze region, China

Cited by 242 publications

References 40 publications

Pore characteristics of organic-rich shale in the Carboniferous-Permian coal-bearing strata in Qinshui Basin

Pore characteristics of organic-rich shale in the Carboniferous-Permian coal-bearing strata in Qinshui Basin

Pore Structure and Fractal Characteristics of Niutitang Shale from China

Quantitative characterization of micropore structure for organic-rich Lower Silurian shale in the Upper Yangtze Platform, South China: Implications for shale gas adsorption capacity

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