Deposition features of unconventional natural gas in Upper Paleozoic coal measures of Ordos Basin

Based on the close relationship between the natural gas deposition features and the exploration development, in order to provide the theoretical support to the high efficient development of the unconventional natural gas in Ordos Basin, with the comprehensive analysis method of the Upper Paleozoic sedimentary evoluti on in Well U-1, the organic matter thermal evolution, hydrocarbon source rock condition, reservoir types, reservoir material condition and gas, the paper discussed the u nconventional natural gas deposition features of the coal measures in Well U-1. The results showed that the Upper Paleozoic coal measure strata in the study area wer e mainly developed the tidal flat-delta sedimentary, the basin sustainable sedimentation formed the gas reservoir and the in source and near source formation combined structure formed the many vertical natural gas reservoirs. In the study area, three deposition modes of the shale-sandstone-shale, shale-coal-shale and shale-coal-sand stone-shale were developed. Among the three modes, the total gas content of the shale-coal-shale mode would be higher and would be suitable for the coal bed metha ne mining. The shale-coal-sandstone-shale mode would be second and would be suitable for the coal bed methane, compact sandstone gas and shale gas comprehensi ve mining. The shale-coal-shale mode would be suitable for the compact sandstone gas reservoir mining.