The characteristics of organic matter in coal-measure source rocks and coal-measure gas resource potential in eastern Henan Province

In order to evaluate the hydrocarbon generation potential of coal-measure source rocks in eastern Henan Province, based on the measurement results of organic carbon content, vitrinite reflectance and the identification of maceral and type of kerogen in source rocks, the organic geochemical characteristics and the resource potential of coal-measure gas in different blocks of eastern Henan Province were comprehensively analyzed, and favorable blocks for coal-measure gas exploration were designated. The results show that the organic carbon mass fraction of coal-measure source rocks presents low as a whole(less than 1.5%). Kerogen in coal-measures source rocks is mainly of type Ⅲ and Ⅱ₂ can be locally seen in the source rocks, so it can be concluded the source rocks are favorable for hydrocarbon generation. The coal-measure strata has undergone twice mass hydrocarbon generation stage(Middle Permian to Middle-Late Triassic and Late Jurassic to Early Cretaceous), the thermal evolution extent of source rocks is relatively high. The vitrinite reflectance ranges from 1.44% to 3.80% and 2.83% in average, so the organic matter is classified form the high mature to over high mature stage, hydrocarbon generation is adequate. As a whole, the hydrocarbon generation potential of source rocks in the area belongs to bad-medium standard, sandstone and mudstone reservoir property is relatively good, gas content is high. The coal measures are mainly fine sandstone, coal seam, mudstone with good sealing property, which have good preservation conditions. The study shows that the hydrocarbon source rocks in Suixi block are characterized by shallow burial depth, large effective thickness, high porosity, high gas content and high gas saturation, high maturity of organic matter, are favorable blocks for the exploration of coal-measure gas in eastern Henan Province.