Influential factors and model of shale pore evolution: A case study of a continental shale from the Ordos Basin

Wang, Feiteng; Guo, Shaohui

doi:10.1016/j.marpetgeo.2018.12.045

Cited by 55 publications

(34 citation statements)

References 55 publications

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“…The ye23-2 sample has the highest relative clay content of 81%.From the composition of clays, the most important components are the kaolinite, illite and illite-smectite mixed layer(I/S).The ye23-2 and ye23-5 are mainly composed of kaolinite, whose relative content is close to 60%, followed by I/S, which accounts for 25%-32%. The ye23-8, ye31-1 and ye31-2 samples are mainly kaolinite and illite, with a relative content of kaolinite less than 40%, but the content of illite is high at 38-50%.The relative content of kaolinite is lower in samples with high thermal evolution, while the relative content of illite and chlorite is higher ( Figure 2); this is because kaolinite is converted to illite in environments rich in K þ with high thermal evolution and converted to chlorite in environments rich in Fe 2þ and Mg 2þ (Wang and Guo, 2019a). Figure 3 shows the variation of the mercury intrusion-extrusion volume with the pressure of the samples, and the curves can be divided into two categories.…”

Section: Resultsmentioning

confidence: 99%

Pore characterization of marine-continental transitional shale in Permian Shanxi Formation of The Southern North China Basin

Yang

Guo

2020

Energy Exploration & Exploitation

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Organic-rich marine-continental transitional shale is widely developed in the Permian Shanxi Formation in the Southern North China Basin. In this study, shale samples from the southern and northern wells of the basin were characterized by X-ray diffraction, high-pressure mercury intrusion porosimetry, low-pressure gas adsorption (N2 and CO2) and argon ion polishing-field emissions scanning electron microscopy. The pore types and structures of shale micropores, mesopores and macropores are qualitatively described; their pore size distribution and volume are quantitatively characterized; and the influencing factors of the pore volume are analyzed. The results show that the marine-continental transitional shale pores exhibit an unbalanced multimodal distribution with four peaks at 0.4–0.8 nm, 2–4 nm, 10–50 nm, and >10 µm. The mesopore volume is dominant, accounting for 40–70% of pores. The mesopores of the samples are slit-shaped pores and ink bottle-shaped pores. Since there is a desorption hysteresis loop on the N2 adsorption-desorption curve, most of them belong to the H4 type, and ye23-8 belongs to the mixed H2 and H4 type according to the IUPAC classification scheme. The slit-shaped pores are mainly interlayer pores and interparticle pores in clays, and the ink bottle-shaped pores are tiny dissolved pores and organic matter pores. Ro has negative correlation with the volumes of the mesopores and macropores, but it does not affect the volume of micropores. TOC has a positive correlation with the macropore and micropore volumes, and it has a negative correlation with mesopore volume. The relative contents of kaolinite and I/S have a positive correlation with the mesopore and macropore volumes. The relative content of illite has a negative correlation with the mesopore and macropore volumes. The relative content of chlorite has a negative correlation with the mesopore volume.

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Section: Resultsmentioning

confidence: 99%

Pore characterization of marine-continental transitional shale in Permian Shanxi Formation of The Southern North China Basin

Yang

Guo

2020

Energy Exploration & Exploitation

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“…However, argon is present in shale characterization in other ways. It has been used for ion milling/polishing associated with imaging techniques as well as for permeability measurements [90][91][92][93][94][95]. Finally, if the purpose is to acquire a better description of the micropores, the most appropriate adsorbate is carbon dioxide.…”

Section: Adsorptive Capabilities and Selectionmentioning

confidence: 99%

Use of Gas Adsorption and Inversion Methods for Shale Pore Structure Characterization

Medina-Rodriguez

Alvarado

2021

Energies

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The analysis of porosity and pore structure of shale rocks has received special attention in the last decades as unconventional reservoir hydrocarbons have become a larger parcel of the oil and gas market. A variety of techniques are available to provide a satisfactory description of these porous media. Some techniques are based on saturating the porous rock with a fluid to probe the pore structure. In this sense, gases have played an important role in porosity and pore structure characterization, particularly for the analysis of pore size and shapes and storage or intake capacity. In this review, we discuss the use of various gases, with emphasis on N2 and CO2, for characterization of shale pore architecture. We describe the state of the art on the related inversion methods for processing the corresponding isotherms and the procedure to obtain surface area and pore-size distribution. The state of the art is based on the collation of publications in the last 10 years. Limitations of the gas adsorption technique and the associated inversion methods as well as the most suitable scenario for its application are presented in this review. Finally, we discuss the future of gas adsorption for shale characterization, which we believe will rely on hybridization with other techniques to overcome some of the limitations.

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“…The Soxhletextracted samples finer than 100 mesh were analyzed for IOC with a LECO CS230 carbon/sulfur analyzer [44]. The kerogen in the other ground aliquot of each sample, separated from the shale sample and polished into a thin section, was tested using a J&M TIDAS MSP 400 microspectrophotometer for vitrinite reflectance (Ro) [50]. Experiments were regarded to reach equilibration when the ratio of the pressure variation to the average pressure per time interval (60 s) was less than 0.01%.…”

Section: Microscopymentioning

confidence: 99%

Pore Properties of the Lacustrine Shale in the Upper Part of the Sha-4 Member of the Paleogene Shahejie Formation in the Dongying Depression in East China

et al. 2021

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Lacustrine shales hold a huge potential oil resource in China. Pore properties (pore volume, diameter, specific surface area, and fractal dimensions) and their relationships with geological factors (mineralogy, insoluble organic carbon, burial depth, and vitrinite reflectance) are critical for evaluating shale oil resource. However, the factors controlling pores for lacustrine shale oil remain unclear, as the relationships between pore properties of Soxhlet-extracted samples and geological factors have not been studied using multivariate analytical methods. In this paper, the samples from the lacustrine shale in the upper part of the Sha-4 Member of the Paleogene Shahejie Formation in the Dongying Depression were tested with a set of experiments including Soxhlet (solvent) extraction, X-ray diffraction mineral analysis, insoluble organic carbon, vitrinite reflectance, and low-pressure CO2 and N2 adsorption experiments. The micromesopore volume varies from 0.003 cm3/g to 0.045 cm3/g. The relationships of pore properties with geological factors were studied with partial least square regression analysis (PLSR analysis, a powerful multivariate regression analysis). The results of the PLSR analyses indicate that clay minerals and carbonates are two key factors affecting the pore properties of the lacustrine shale. Compared with marine shales, more clay minerals in the lacustrine shale make them become more important for controlling pores than organic matter. The PLSR results also illustrate that the shale with higher pore volume contains more clay minerals and fewer carbonates and thus is unfavorable for hydraulic fracturing. Therefore, the shale with high micromesopore volume may be unfavorable for shale oil production. The shale with the modest micromesopore volume (~0.036 cm3/g), relatively high content of brittle minerals (~71 wt%), and low clay mineral content (~29 wt%) is conducive to both oil storage and hydraulic fracturing for the development of the Es4U shale oil in the Dongying Depression in East China.

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Influential factors and model of shale pore evolution: A case study of a continental shale from the Ordos Basin

Cited by 55 publications

References 55 publications

Pore characterization of marine-continental transitional shale in Permian Shanxi Formation of The Southern North China Basin

Pore characterization of marine-continental transitional shale in Permian Shanxi Formation of The Southern North China Basin

Use of Gas Adsorption and Inversion Methods for Shale Pore Structure Characterization

Pore Properties of the Lacustrine Shale in the Upper Part of the Sha-4 Member of the Paleogene Shahejie Formation in the Dongying Depression in East China

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