Study On The Accumulation Characteristics Of Tight Oil In The Fourth Member Of Shahejie Formation In The Western Sag Of Liaohe River

This thesis focused on the tight oil of the fourth member of Shahejie Formation western sag of Liaohe depression,and guided by the theory of sedimentology,oil and gas exploration geochemistry,unconventional oil and gas geology,and hydrocarbon accumulation theories,etc.On the basis of the results of previous research in the study area and drilling,logging,seismic etc.Combined all kinds of analytical tests and technical means,identified the characteristics of source rocks,tight reservoirs,migration and aggregation,and then analyzed the main controlling factors of tight oil accumulation in the fourth member of the Shahejie Formation and summarized the model of hydrocarbon accumulation,optimized the favorable zone of the tight oil.The analysis of the reservoirs found in the fourth member of Shahejie Formation shows that the fourth member of Shahejie Formation is dominated by unconventional tight reservoirs,and conventional reservoirs are only locally developed in the high-rise areas with a small surface area.Study on the characteristics of accumulation in the tight reservoir of the fourth member of Shahejie Formation shows:CDoil and gas in the fourth member of the Shahejie Formation comes from itself;?Accumulated thickness of source rock,up to several hundred meters,the organic matter type is good and dominated by Type ?,Type ?1 followed,the organic matter abundance of the source rocks in the fourth member of the Shahejie Formation is high,with a moderate degree of evolution and better hydrocarbon expulsion;?Types of the tight reservoir rocks are dominated by argillaceous volcanic rocks,the brittleness of rocks is high,the reservoir properties are poor,the pore throats are fine and pore connectivity are poor,so the reservoir heterogeneity is strong,the reservoir spaces are dominated by micropore,microfractures and macrofractures,the types of reservoir are mainly fracture type and fracture-porosity type;?Corrosion and fracturing have a constructive effect on tight reservoirs,and compaction is the main reason for reservoir densification;?The capillary resistance is the migration resistance,the hydrocarbon generation pressurization is the transport moving force,and the crack is not only the migration channel,but also the oil and gas storage space;?Source rocks and tight reservoirs are superimposed on each other in layers;?The main controlling factors of tight oil accumulation are distribution and thickness of source rock and reservoir,the development of crack,source rock and reservoir relations;?The tight oil distributed in the fourth member of the Shahejie Formation is contiguous and large area,and is mainly developed in the depression area and the middle of the depression during the Shahejie period.