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Open AccessArticle

Pore Structure and Fractal Characteristics of Niutitang Shale from China

by 1,2,3, 1,2,3,*, 1,2,3, 4, 1,2,3 and 1,2,3
1
School of Energy Resource, China University of Geosciences (Beijing), Beijing 100083, China
2
Key Laboratory of Marine Reservoir Evolution and Hydrocarbon Enrichment Mechanism, Ministry of Education, Beijing 100083, China
3
Key Laboratory of Strategy Evaluation for Shale Gas, Ministry of Land and Resources, Beijing 100083, China
4
China Metallurgical Geology Bureau, Institute of Mineral Resources Research Beijing, Beijing 100083, China
*
Author to whom correspondence should be addressed.
Minerals 2018, 8(4), 163; https://doi.org/10.3390/min8040163
Received: 14 March 2018 / Revised: 9 April 2018 / Accepted: 12 April 2018 / Published: 17 April 2018
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. View Full-Text
Keywords: Hunan province; shale gas; fractal dimension; nitrogen adsorption; permeability; adsorption capacity Hunan province; shale gas; fractal dimension; nitrogen adsorption; permeability; adsorption capacity
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MDPI and ACS Style

Xi, Z.; Tang, S.; Wang, J.; Yi, J.; Guo, Y.; Wang, K. Pore Structure and Fractal Characteristics of Niutitang Shale from China. Minerals 2018, 8, 163. https://doi.org/10.3390/min8040163

AMA Style

Xi Z, Tang S, Wang J, Yi J, Guo Y, Wang K. Pore Structure and Fractal Characteristics of Niutitang Shale from China. Minerals. 2018; 8(4):163. https://doi.org/10.3390/min8040163

Chicago/Turabian Style

Xi, Zhaodong; Tang, Shuheng; Wang, Jing; Yi, Junjie; Guo, Yingying; Wang, Kaifeng. 2018. "Pore Structure and Fractal Characteristics of Niutitang Shale from China" Minerals 8, no. 4: 163. https://doi.org/10.3390/min8040163

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