Study On The Characteristics Of Upper And Lower Tight Sandstone Reservoirs In The Coal Seam Of Daji 6 Well In Linyi, Shanxi

Coal seam gas in Ordos Basin in recent years made significant development, it found that there was good gas logging response in the tight sandstone near the coal seam.However, the characteristics of tight sandstone reservoir was not detailed and systematic. Therefore, this paper chose Linfen Daji 6 well area as the study object to carry out the study of tight sandstone gas reservoir's characteristics in detail. By means of core observation and description and casting lamella, scan electron microscope and X-ray diffractions, in combination with regional geological background, the characteristics of sedimentary, reservoir pore structures, physical properties and the main control factors of the reservoir charateristics can be explainer fully. Eventually based on the classification and evaluation of tight sandstone reservoir, it would be a favorable reservoir prediction.The study found that the sedimentary facies of Taiyuan formation, Shanxi formation and Xiashihezi formation is the transitional facies, Lake delta and delta plain; the sandstone types of Taiyuan formation are fine grain quartz sandstone, argillaceous siltstone and silty mudstone, the sandstone types of the Shanxi formation is mainly fine quartz sandstone, the sandstone types of Xiashihezi Formation is lithic sandstone and lithic quartz sandstone.Sandstone diagenesis stage belonged to the stage B of late diagenetic. Through the comprehensive analysis of reservoir petrology, sedimentary environment and diagenesis on reservoir properties, there was a conclusion that the regoin where the reservoir characteristics is high maturity, high energy environment and strong dissolution did good to high quality reservoir relatively. Finally,all the geological factors considered,the reseervoir of Shanxi formation was belong to the types of II-III reservoir, Taiyuan formation and Shihezi formation was belong to III reservoir. The sand flat and sand bar of Taiyuan formation, the distributary channel and mouth bar of Shanxi Formation and Shihezi formation would be the best advantaged reservoir.