Characteristics of Deep Coal Seam and Occurrence State of Coalbed Methane in Nanchuan,Southeast Chongqing
This study,based on coalfield drilling data,coal-rock core samples,and microscopic observations,conducts a series of tests,including digital analysis of coal-seam reservoir cores,Liquid N2 adsorption,CO2 adsorption,high-pressure mercury intrusion tests,gas chromatography and isothermal adsorption experiments in Nanchuan,Chongqing.The study analyzes and discusses the characteristics of deep coal beds,the occurrence state of coalbed methane and its influencing factors.The research indicates:①The deep coal seam development in Nanchuan block provides good foundation for the formation of coalbed methane.② Micro-fractures serve as the primary reservoir space in coal reservoirs,controlling the permeability of gas.The existence of micropores is the main reason for gas adsorption,while throats control the microscopic flow of natural gas.③ The adsorption capacity of coal increases with the degree of metamorphism,positively correlated with pressure,and negatively correlated with temperature.In shallow and mid-deep layers(buried depth less than 1500 m),adsorption is pressure-sensitive,while in deep layers(buried depth more than 1500 m),adsorption is temperature-sensitive.④ Deep coal beds exhibit the characteristic of being"Meso-high evolution,micro fissure well developed,highly gas-bearing and rich in free gas",providing a substantial source of gas for coal rock desorption.
deep coalbed methanecoal bed characteristicsoccurrence statereservoir analysisNanchuan area
NETL
NSTL
万方数据
