Three-dimensional modeling and porosity calculation of coal rock pore structure

Coal rock is a type of dual-porosity medium, which is composed of matrix pores and fracture-cutting matrix. They play different roles in the seepage and storage capacity of coal rock. Therefore, constructing the micropore structure of coal rock is very important in the exploration and development of...

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Bibliographic Details
Published in:Applied geophysics Vol. 19; no. 2; pp. 161 - 172
Main Authors: Li, Qiong, Chen, Zheng, Yue, Lin, Zhang, Yu, He, Jian-Jun, Li, Yong
Format: Journal Article
Language:English
Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.06.2022
Springer Nature B.V
College of Geophysics,Chengdu University of Technology,Chengdu 610059,China
Key Laboratory of Earth Exploration and Information Technology of Ministry of Education(Chengdu University of Technology),Chengdu 610059,China%College of Geophysics,Chengdu University of Technology,Chengdu 610059,China%College of computer Science & Cybersecurity Security Technology(OXFORD BROOKES University),Chengdu University of Technology,Chengdu 610059,China
Subjects:
Aspect ratio
Borehole Geophysics and Rock Properties
Coal
Coalbed methane
Compression
Diameters
Earth and Environmental Science
Earth Sciences
Geophysics/Geodesy
Geotechnical Engineering & Applied Earth Sciences
Methane
Modelling
Pores
Porosity
Rock
Rocks
Seepage
Statistical analysis
Statistical methods
Storage capacity
Storage conditions
Three dimensional models
Two dimensional analysis
nonlinear-fitting relationship
random-packing method
pore aspect ratio
3D model of pore structures
Coal rock
porosity
ISSN:1672-7975, 1993-0658
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Summary:Coal rock is a type of dual-porosity medium, which is composed of matrix pores and fracture-cutting matrix. They play different roles in the seepage and storage capacity of coal rock. Therefore, constructing the micropore structure of coal rock is very important in the exploration and development of coalbed methane. In this study, we use a coal rock digital core and three-dimensional modeling to study the pore structure of coal rock. First, the micropore structure of coal rock is quantitatively analyzed using a two-dimensional thin-section image, and the quantitative information of the pore and fracture (cleat) structure in the coal rock is extracted. The mean value and standard deviation of the face porosity and pore radius are obtained using statistical analysis. The number of pores is determined using dichotomy and spherical random-packing methods based on compression. By combining with the results of the petrophysical analysis, the single-porosity structure model of the coal rock is obtained using a nonequal-diameter sphere to represent the pores of the coal rock. Then, an ellipsoid with an aspect ratio that is very much lesser than one is used to represent the fracture (cleat) in the coal rock, and a dual-pore structure model of the coal rock is obtained. On this basis, the relationship between the different pore aspect ratios and porosity is explored, and a fitting relationship is obtained. The results show that a nonlinear relationship exists between them. The relationship model can provide a basis for the prediction of coal rock pore structure and the pore structure parameters and provide a reference for understanding the internal structure of coalbed methane reservoirs.
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ISSN:1672-7975
1993-0658
DOI:10.1007/s11770-022-0935-5