Experimental investigations on the geometry and connectivity of pore space in organic-rich Wufeng and Longmaxi shales

Yang, Rui; Hao, Fang; He, Sheng; He, Chencheng; Guo, Xusheng; Jiang, Yi; Hu, Haiyan; Zhang, Shiwan; Hu, Qinhong

doi:10.1016/j.marpetgeo.2017.03.033

Cited by 108 publications

(79 citation statements)

References 109 publications

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“…These trends were consistent with many previous studies and rock types including coal [11], marine shale [14,57], continental shale [43] and marine-continental transitional shale [55]. Figure 10a shows the relationships between the SSA and PV of the shale samples, indicating that PV increased with increasing SSA, which is consistent with previous studies [48,58]. The negative relationship between average pore diameter and PV and SSA (Figure 10b,c) showed that PV and SSA increased when the average pore diameter decreased.…”

Section: Effect Of Mineral Composition On Pore Structuresupporting

confidence: 91%

“…Scanning electron microscopy (SEM) images of Niutitang shale samples in the study area: (a) quartz contained fewer pores and has smooth surfaces, sample 4, and (b) quartz has smooth surfaces and no pores can be observed, sample 4. Figure 10a shows the relationships between the SSA and PV of the shale samples, indicating that PV increased with increasing SSA, which is consistent with previous studies [48,58]. The negative relationship between average pore diameter and PV and SSA (Figure 10b,c) showed that PV and SSA increased when the average pore diameter decreased.…”

Section: Effect Of Mineral Composition On Pore Structuresupporting

confidence: 88%

“…The Ro values of the Niutitang shale from a different region of southern China are similar, ranging between 2.0% and 4.5%, typically 2.5% to 3.5% ( Figure 2); but the Ro values of the Niutitang Formation is obviously higher than that of typical shale gas plays from North America (Figure 2). The low hydrogen index (HI) and S2 values (Table 1) indicate that the shale has a poor hydrocarbon generation potential at present day, probably because of the high maturity [48]. Mandelbrot first proposed fractal concepts and geometry for evaluating the complex shapes of objects found in nature [35] and the geometry of coal or shale pores is a typical example of such shapes.…”

Section: Organic Geochemistrymentioning

confidence: 99%

“…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%

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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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Section: Effect Of Mineral Composition On Pore Structuresupporting

confidence: 91%

Section: Effect Of Mineral Composition On Pore Structuresupporting

confidence: 88%

Section: Organic Geochemistrymentioning

confidence: 99%

Section: Pore Structure Characterization Through Nitrogen Physisorptionmentioning

confidence: 99%

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Pore Structure and Fractal Characteristics of Niutitang Shale from China

Tang

Wang

et al. 2018

Minerals

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“…Among them, high resolution SEM-based imaging techniques, for example, field emission SEM (FE-SEM) [19,20,[22][23][24][25], broad ion beam SEM (BIB-SEM) [21,27,29], and focused ion beam SEM (FIB-SEM) [26][27][28][29][30][31]41], are commonly used in the field of visualized characterization of nanoscale pore systems of tight reservoir rocks such as gas shales and fine-grained sandstones due to their high resolution imaging advantages. For example, nanoscale pore structure characteristics of the organic-rich Wufeng-Longmaxi shale and the Lower Cambrian Niutitang shale were investigated by Yang et al [19] and Sun et al [24] using FE-SEM.…”

Section: Introductionmentioning

confidence: 99%

Nanoscale Pore Structure Characterization and Permeability of Mudrocks and Fine-Grained Sandstones in Coal Reservoirs by Scanning Electron Microscopy, Mercury Intrusion Porosimetry, and Low-Field Nuclear Magnetic Resonance

et al. 2018

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Porosity and permeability of two typical sedimentary rocks in coal bearing strata of underground coal mines in China, i.e., mudrocks and fine-grained sandstones, were comprehensively investigated by multiple experimental methods. Measured porosity averages of the helium gas porosity ( ), MIP porosity ( MIP ), water porosity ( ), and NMR porosity ( NMR ) of the twelve investigated rock samples range from 1.78 to 16.50% and the measured gas permeabilities ( ) range from 0.0003 to 2.4133 mD. Meanwhile, pore types, pore morphologies, and pore size distributions (PSD) were determined by focused ion beam scanning electron microscopy (FIB-SEM), mercury intrusion porosimetry (MIP), and low-field nuclear magnetic resonance (NMR). FIB-SEM image analyses showed that the mineral matrix pores including interparticle (interP) and intraparticle (intraP) pores with varied morphologies are the dominant pore types of the investigated rock samples while very few organic matter (OM) pores were observed. Results of the MIP and the full water-saturated NMR measurements showed that the PSD curves of the mudrock samples mostly present a unimodal pattern and nanopores with pore diameter less than 0.1 m are their predominant pore type, while the PSD curves of the fine-grained sandstone samples are featured by a bimodal distribution. Furthermore, comparison of the full water-saturated and irreducible-water-saturated NMR measurements indicated that pores in the mudrocks are solely adsorption pores (normally pore size < 0.1 m) whereas apart from a fraction of adsorption pores, a large part of the pores in the sandstone sample with relatively high porosity are seepage pores (normally pore size > 0.1 m). Moreover, the PSD curves of NMR quantitatively converted from the NMR 2 spectra by 2 and weighted arithmetic mean (WAM) methods are in good agreement with the PSD curves of MIP. Finally, the applicability of three classic permeability estimation models based on MIP and NMR data to the investigated rock samples was evaluated.

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Experimental Understanding of Pore Structure and Wettability of the Unconventional Reservoir

Kibria¹,

Hu²

2022

Handbook of Petroleum Geoscience

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Experimental investigations on the geometry and connectivity of pore space in organic-rich Wufeng and Longmaxi shales

Cited by 108 publications

References 109 publications

Pore Structure and Fractal Characteristics of Niutitang Shale from China

Pore Structure and Fractal Characteristics of Niutitang Shale from China

Nanoscale Pore Structure Characterization and Permeability of Mudrocks and Fine-Grained Sandstones in Coal Reservoirs by Scanning Electron Microscopy, Mercury Intrusion Porosimetry, and Low-Field Nuclear Magnetic Resonance

Experimental Understanding of Pore Structure and Wettability of the Unconventional Reservoir

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