Source Rock Evaluation Of The Upper Palaeozoic In Eastern Ordos Basin

Based on a great deal of geology、geo-chemical data and combines with the logging data, this paper analysis the distribution of the source rock and organic matter abundance、type、 maturity of the Upper Palaeozoic in Eastern Ordos Basin; meanwhile, combines with hydrocarbon generation history and evolution history, we calculate the gas generation intensity and gas generation amount. Finally, study on the control action of hydrocarbon source rock condition to shale gas reservoir forming and the gas generation intensity to shale gas and tight sandstone gas reservoir forming. Our research shows that:The coal and shale was distributed in benxi、taiyuan and shanxi formation of our study area, which belongs to marine and continental facies. The total thickness of the coal is mean10-12m, mainly distributed in north and east of our study area, among them, the thickness of benxi formation is biggest. The total shale thickness with an average of40-60m, and the maximum thickness is upto80-100m, mainly distributed nearby Jiaxian, among them, the thickness of shanxi formation is biggest, with an average of30-40m; in vertically, the coal and shale of shanxi-benxi formation is widely distributed in our study area, which formed the good hydrocarbon source condition.According to the test data, we can found that the mean TOC of coal in benxi and taiyuan formation is63.13%, shanxi formation is mean53.48%, the Upper Palaeozoic total average values is59.01%; the mean TOC of shale in benxi and taiyuan formation is2.09%, shanxi formation is mean1.92%, the Upper Palaeozoic total average values is2.02%; which all belongs to1.0～2.5%. The organic matter type is mainlyⅢ, gas yields isobviously.Ro in study area is1.0～2.5%, beneficial to natural gas generation.The gas generation intensity in study area is bigger than16×108m3/km2, some areas is upto40×108m3/km2, and the total gas generation amount is601342×108m3.The shale gas reservoir in our study area is mainly controlled by shale thickness and buried depth, organic matter abundance, maturity, and gas generation intensity; mean while, under the background of tight sandstone gas, the gas production is not only controlled by the gas generation intensity.