Image-based quantitative probing of 3D heterogeneous pore structure in CBM reservoir and permeability estimation with pore network modeling  

作　　者：Peng Liu Yulong Zhao Zhengduo Zhao Huiming Yang Baisheng Nie Hengyi He Quangui Li Guangjie Bao 

机构地区：[1]State Key Laboratory of Coal Mine Disaster Dynamics and Control,Chongqing University,Chongqing 400030,China [2]State Key Laboratory of Gas Disaster Detecting,Preventing and Emergency Controlling,Chongqing 400037,China [3]College of Resources and Safety Engineering,Chongqing University,Chongqing 400030,China [4]China Coal Technology Engineering Group Chongqing Research Institute,Chongqing 400037,China

出　　处：《International Journal of Coal Science & Technology》2024年第5期121-141,共21页国际煤炭科学技术学报(英文)

基　　金：This work was supported by the National Natural Science Foundation of China(52204206,52274246);the Open Fund Project Funded by State Key Laboratory of Gas Disaster Detecting,Preventing and Emergency Controlling(2021SKLFF03);the Natural Science Foundation of Chongqing(cstc2021jcyj-msxmX1149).

摘　　要：Coalbed methane(CBM)recovery is attracting global attention due to its huge reserve and low carbon burning benefits for the environment.Fully understanding the complex structure of coal and its transport properties is crucial for CBM development.This study describes the implementation of mercury intrusion and μ-CT techniques for quantitative analysis of 3D pore structure in two anthracite coals.It shows that the porosity is 7.04%-8.47%and 10.88%-12.11%,and the pore connectivity is 0.5422-0.6852 and 0.7948-0.9186 for coal samples 1 and 2,respectively.The fractal dimension and pore geometric tortuosity were calculated based on the data obtained from 3D pore structure.The results show that the pore structure of sample 2 is more complex and developed,with lower tortuosity,indicating the higher fluid deliverability of pore system in sample 2.The tortuosity in three-direction is significantly different,indicating that the pore structure of the studied coals has significant anisotropy.The equivalent pore network model(PNM)was extracted,and the anisotropic permeability was estimated by PNM gas flow simulation.The results show that the anisotropy of permeability is consistent with the slice surface porosity distribution in 3D pore structure.The permeability in the horizontal direction is much greater than that in the vertical direction,indicating that the dominant transportation channel is along the horizontal direction of the studied coals.The research results achieve the visualization of the 3D complex structure of coal and fully capture and quantify pore size,connectivity,curvature,permeability,and its anisotropic characteristics at micron-scale resolution.This provides a prerequisite for the study of mass transfer behaviors and associated transport mechanisms in real pore structures.

关 键 词：CT image Heterogeneous pore structure Pore network model Coal permeability Coalbed methane 

分 类 号：TE82[石油与天然气工程—油气储运工程]