Main Controlling Factors Of Tight Oil Accumulation For Chang 7 Oil Reservoir In Baibao Area,Ordos Basin

The deep-lake-semi-deep lake deposits of the Yanchang Formation in the Baibao area of the Ordos Basin develop a large-area distribution of turbidite sandstones due to gravity,which is a typical tight reservoir.The oil and water distribution in the study area is complex,and the main controlling factors of tight oil are not clear,This paper uses sedimentary petrology,petroleum geology and reservoir physics to combine experimental data with organic carbon analysis experiments,rock pyrolysis,cast thin sections,scanning electron microscopy,X-ray diffraction,high pressure mercury intrusion and constant velocity mercury intrusion,analyze and study the logging,core and other data collected in the study area.,summarize the important geological foundations required for the formation of Chang 7 tight oil in the Baibao area of the Ordos Basin,including high-quality source rocks,tight reservoirs formed by gravity-flowing sand bodies,close contact source and reservoir relationships,and strong transport mobility.Analyze the reservoir-forming environment of tight oil in the study area,clarify the main controlling factors of oil and gas enrichment in the study area,and predict and screen favorable areas.The source rock of the study area is well developed,and the chang 7₃“Zhangjiatan shale”is the best.The Chang 7 source rock is widely distributed,with high abundance of organic matter and is in the mature stage.It is the oil and gas foundation of Chang 7 tight oil and provides guarantee for the enrichment of tight oil.The main types of the Chang 7 tight sandstone reservoir rocks are lithic feldspathic sandstone and feldspar lithic sandstone.The interstitial content is high,the reservoir physical properties are poor,the average porosity is 7.61%,the permeability is 0.17mD and the pore type is mainly Intergranular pores and dissolved pores,the throat type is mainly tubular and flaky,the pore radius is mainly distributed between 80-200μm,and the throat radius is distributed between 0.18-0.6μm,which is a typical dense reservoir.The reason why the length 7 is dense is the strong compaction and cementation,and the dissolution holes generated by the erosion improve the reservoir physical properties.Due to the high-quality source rock of the Chang 7 lake basin environment,and the source of the lake basin accumulates to the lake center,the Chang 7 has both a source of oil and an oil storage space,and the two are in close contact with each other in the Chang 7 stratum.It constitutes a good source-storage configuration relationship,and the bottom source rock generates hydrocarbons and is transported into reservoirs.After the reservoir was densified,the oil and gas was filled in the Early Cretaceous,and the high-filling dynamics formed by the hydrogenation of hydrocarbons and under-compaction pressure moved to the adjacent tight reservoirs.Wide-cover high-quality source rocks,densely distributed reservoirs with large areas,close contact with source and storage,and continuous charging are the main controlling factors for tight oil accumulation.Combined with the effective source rock and the distribution of tight reservoirs,the favorable area of the Chang 7 tight oil in the Baibao area of Ordos is predicted.