"Three History" Evolution And Gas-bearing Characteristics Of Coal Measure Stratum In Eastern Henan

Source rocks of the coal measures strata generate large amounts of hydrocarbon gase during the evolution of hydrocarbon generation,some of which migrates to coal measure stratum?Coal-bearing basins distribute widely in China and coal-bearing gas resources are abundant.It is necessary to study coal measures gas.Discussed the physical and gas-bearing characteristics of coal-bearing gas reservoirs,studied the occurrence patterns of coal measures gas resources,and integrated the hydrocarbongenerating evolution process of coal measure source rocks.The research results will provide some references for the study of the theory of coal measures gas generation,occurrence,accumulation,and exploration and development in the study area.Parameters and gas-bearing characteristics of coal measure stratum were tested,based on the geological background of Permian coal-bearing strata of the eastern Henan,combined with the ongoing exploration work and modern testing technology.The research of burial history,thermal history and maturity history of area were inverted by numerical simulation software of Petromod and test results of relead parameters.The differences of "Three histories" and physical property in each block were compared.The main factors controlling the occurrence of coal-bearing gas in different sections were revealed.The main study results are as follows:It was found that the main source rocks of the coal measures strata in the study area are coal and mudstone,through the pore structure parameters,maturity and organic matter content of rock samples,combined with the SEM observation.Coal adsorption was strong with high maturity.Shale adsorption was strong with high content of organic matter and shale source rock level was medium and above.The rank of source rocks is medium and above.The porosity and permeability of coal and sand and mudstones in the study area was low.Most sand and mudstone pore throat radius was less than 0.1?m,and the fractures of sand and mudstone reservoirs were few.Paleotemperature scales was used to recover the erosion thickness through the vitrinite reflectance of the mudstone.The evolution history of "Three History" were retrieved using the paleotemperature data in the adjacent area.The two major hydrocarbon generation periods of the source rocks were the rapid burial stage and uplift-erosion stage of Late Jurassic to Early Cretaceous.Since the western area entered the rapid burial stage earlier than the east,the source rocks matured earlier than the eastern.In the high temperature field formed by the thinner lithosphere and upwelling of the mantle heat flux during the Late Jurassic to Early Cretaceous,the west and the middle were earlier than the east,and the eastern area was accompanied by magmatic activity.High temperature made the maturity of source rocks rise again,the maturity of east and west were higher than the middle.By studying the gas-bearing in the study area,it is found that the gas content of coal-bearing gas in the study area generally shows a tendency of increasing from the east to the west.The top and bottom floor of the coal rock in coal-bearing strata are tight with gteat effective buried depth.They have a good preservation effect on the gas content of the coal,forming a higher gas content in the two wings of the fold.In the area affected by magmatic activity,the gas content was high only in the tight roof with poor permeability.The gas content of shale was mainly affected by the organic matter content,and the gas content was highe since it's strong adsorption.