Pore Structure and Its Fractal Dimension: A Case Study of the Marine Shales of the Niutitang Formation in Northwest Hunan, South China by Wei Jiang, Yang Zhang, Tianran Ma, Song Chen, Yang Hu, Qiang Wei, Dingxiang Zhuang

“…The pores have a large specific surface area (SSA), primarily consisting of mesopores. The fractal dimensions are calculated using the FHH model and the XS model. …”
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Storage and permeation space development characteristics and water production capacity evaluation of deep coal reservoirs in Linxing-Shenfu area of Ordos Basin by Jinwei WANG, Hao XU, Yinan LIU, Bing ZHANG, Yanyong XU, Ding LIU, Peng ZONG, Yajuan WANG, Xuejing SONG

“…The results show that deep coal reservoirs in the Linxing-Shenfu area exhibit well-developed micropores, macropores, and fractures, with relatively underdeveloped mesopores. As coal rank increases, the total pore volume first decreases and then increases. …”
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Combined multi-scale characterization of pores in ultra-thick coal seams of Jurassic Xishanyao Formation, Tiaohu-Malang sags, Santanghu Basin by Yue CHEN, Qiqi LEI, Dongmin MA, Xin WANG, Xinggang WANG, Diefang HUANG, Gaoxiang RONG

“…Macropores have the largest volume proportion, accounting for 47.97% and 44.48%, respectively, followed by mesopores and small pores, and the proportion of micropores is the smallest. …”
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Key experimental technologies and their development directions for the exploration and production of deep coalbed methane by Xia YAN, Fengyin XU, Xianyue XIONG, Feng WANG, Chunhu LI, Jiyuan ZHANG, Borui XU, Qianhui CHENG, Xiong HU, Xueguang ZHU, Wei LIANG, Pu YUAN, Yanqing FENG, Zhenji WEI

“…ProspectsThis study posits seven development directions for deep CBM production and in-situ coal conversion experiments: (1) Clear, direct observation techniques for micropores (< 2 nm) in deep coal seams with ultra-low porosity and permeability, full-scale pore size splicing technology for multiscale pore structure characterized by abundant micropores, a few mesopores, and many macropores, and assessment techniques for pore-fracture connectivity. (2) Isothermal adsorption test technologies for raw coals considering the effects of deep coal seam wettability, fracturing fluid invasion, and high total dissolved solids (TDS) under high-temperature, high-pressure in-situ conditions; (3) Sealed coring devices and in-situ pressure-retaining coring technologies featuring high pressure retaining success rates, heat preservation rates, and traceable gas volume. (4) Nanoscience-based assessment technologies for gas and water occurrence in micropores in deep coal seams under high-temperature and high-pressure multi-field coupling, and experimental technologies for desorption, diffusion, and seepage across nano-micro-millimeter scales. (5) Techniques for developing and testing multifunctional mechanical experiment equipment applicable to in-situ conditions of deep coal seams featuring high stress, low modulus of elasticity, and high Poisson's ratio. (6) Experimental techniques for the purpose of enhancing CBM recovery of deep coal seams, including reservoir stimulation (microwaves, laser, and electric heating), stimulation for permeability enhancement (electromagnetic pulses, pulsed ultrasonic waves, and controlled shockwaves), displacement via CO2 injection, and mechanical pulsation with supercritical CO2. (7) Experimental techniques for in-situ coal conversion and utilization, including pyrolysis, underground coal gasification (UCG), geothermal utilization, and CO2 geological storage. …”
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