%0 Journal Article
%T Structural and fractal characterization of adsorption pores of middle每high rank coal reservoirs in western Yunnan and eastern Guizhou: An experimental study of coals from the Panguan syncline and Laochang anticline
%A Chongtao Wei
%A Gaoyuan Yan
%A Guanwen Lu
%A Junjian Zhang
%J Energy Exploration & Exploitation
%@ 2048-4054
%D 2019
%R 10.1177/0144598718790319
%X To better understand the structural characteristic of adsorption pores (pore diameterˋ<ˋ100 nm) of coal reservoirs around the coalbed methane production areas of western Yunnan and eastern Guizhou, we analyzed the structural and fractal characteristics of pore size range of 0.40每2.0 nm and 2每100 nm in middle每high rank coals (Ro,maxˋ=ˋ0.93每3.20%) by combining low-temperature N2/CO2 adsorption tests and surface/volume fractal theory. The results show that the coal reservoirs can be divided into three categories: type A (Ro,maxˋ<ˋ2.15%), type B (2.15%ˋ<ˋRo,max <2.50%), and type C (Ro,maxˋ>ˋ2.15%). The structural parameters of pores in the range from 2 to 100 nm are influenced by the degree of coal metamorphism and the compositional parameters (e.g., ash and volatile matter). The dominant diameters of the specific surface areas are 10每50 nm, 2每50 nm, and 2每10 nm, respectively. The pores in the range from <2 nm provide the largest proportion of total specific surface area (97.22%每99.96%) of the coal reservoir, and the CO2-specific surface area and CO2-total pore volume relationships show a positive linear correlation. The metamorphic degree has a much greater control on the pores (pore diameter less than 2 nm) structural parameters than those of the pore diameter ranges from 2 to 100 nm. Dv1 and Dv2 can characterize the structure of 2每100 nm adsorption pores, and Dv1 (volume heterogeneity) has a positive correlation with the pore structural parameters such as N2-specific surface area and N2-total pore volume. This parameter can be used to characterize volume heterogeneity of 2每10 nm pores. Dv2 (surface heterogeneity) showed type Aˋ>ˋtype Bˋ>ˋtype C and was mainly affected by the metamorphism degree. Ds2 can be used to characterize the pore surface heterogeneity of micropores in the range of 0.62每1.50 nm. This parameter has a good correlation with the pore parameters (CO2-total pore volume, CO2-specific surface area, and average pore size) and is expressed as type Cˋ<ˋtype Bˋ<ˋtype A. In conclusion, the heterogeneity of the micropores is less than that of the meso- and macropores (2每100 nm). Dv1, Dv2, and Ds2 can be used as effective parameters to characterize the pore structure of adsorption pores. This result can provide a theoretical basis for studying the pore structure compatibility of coal reservoirs in the region
%K Adsorption pores
%K structural heterogeneity
%K micropores
%K structural compatibility
%U https://journals.sagepub.com/doi/full/10.1177/0144598718790319