摘要
Abstract
With the breakthrough in deep coalbed methane(CBM),deep coal reservoirs with burial depths greater than 1 500 m have become a key successor domain for CBM exploration and development in China.However,the controlling mechanism of multi-scale pore structures on methane adsorption behavior remains unclear.Taking the No.Ⅱ1 coal seam in the Tongxu area of Henan Province as the research object,this study employs a combined characterization approach involving high-pressure mercury intrusion porosimetry,low-temperature N2 adsorption,low-temperature CO2 adsorption,and scanning electron microscopy(SEM)to characterize the multi-scale pore structure of coal reservoirs.Integrated with methane isothermal adsorption experiments,the controlling effect of pore structure on methane adsorption capacity and the dominant factors governing pore development in deep coal strata are revealed.The results show that the total pore volume of coal samples is 0.034 47 cm³/g,the total specific surface area is 50.941 86 m²/g,and the specific surface area of micropores accounts for up to 99.65%,which dominates the coal adsorption capacity,while mesopores and macropores contribute little.The average Langmuir volume of coal samples is 32.48 m³/t,and the average measured gas content of coal seams is 37.86 m³/t.Methane is mainly adsorbed with a certain proportion of free gas.In deep coal,micropores control adsorption capacity,mesopores act as connecting bridges,and macropores store free gas.High coal rank,high confining pressure and high geothermal temperature collectively result in the micropore-dominated pore structure of deep coal.The results can provide a theoretical basis for deep coalbed methane exploration,development and reservoir evaluation in this area.关键词
通许地区/深部煤储层/孔隙结构/多尺度表征/甲烷吸附Key words
deep coal reservoir/pore structure/multiscale characterization/methane adsorption/Tongxu area分类
能源科技
