Reservoir formation characteristics as well as co-exploration and co-mining orientation of Upper Permian coal-bearing gas in Liupanshui Coalfield

In the Upper Permian coal bearing strata of Liupanshui Coalfield,there were coal seam,shale and sandstone overlaid frequently. In order to have an overall plan and exploration on the natural gas in different reservoir and to fa- vorably reduce the resources wasted and improve the development benefit,with the study on the lithofacies,thickness and source rock geochemistry of the coal measure gas reservoir,the reservoir physical property and the spatial occur- rence law,this paper analyzed the reservoir formation potential of the coalbed methane,coal measure shale gas and the coal measure tight gas in Liupanshui Coalfield and discussed the space overlaid relationship and exploration prospects of the coal measure gas. The study results showed that within the coalfield,the coal rank of late Permian coal seam was complete,the thickness was high,the metamorphic grade was generally higher,and the gas content was good. The gross thicknesses of the shale and the sandstone were high,the organic geochemistry and reservoir physical parameters were good. The difference was high in regional and horizon distribution of different lithology,the lithological combination types varied,and the space disposition was beneficial to the development of many vertical natural gas reservoirs. The favorable exploration horizon of the coal measure shale gas was the lower section of the Longtan Formation and the fa- vorable horizon of the coalbed methane and the coal measure tight gas was the Wangjiazhai Formation and the up sec- tion of Longtan Formation. Based on the circumstances,totally three major gas reservoir types,including the “resources and storage integration” independent coal measure shale gas reservoir,“ resources and storage closed neighbor type” coal measure “three gas combined gas reservoirs” and “bottom resources and top storage type” coal measure “two ga- ses combined gas reservoirs” were summarized and provided. The paper preliminarily concluded that Qinglong Syn- cline deep section would be the priority exploration zone of the coal measure shale gas,Qingshan Syncline deep section would be favorable to the co-exploration and co-mining of the coalbed methane and the coal measure shale gas,Pan- guan Syncline and Gemudi Syncline deep section would be favorable to the co-exploration and co-mining of the coal- bed methane and the coal measure tight sandstone gas.