The Sedimentary Characteristics And Reservoir Forming Law In The 9^th Member Of Lower Es3 Formation In Gubei Sub

The Shahejie Formation in Gubei Sag which having thick source rocks,sufficient oil source and developed fracture system,is easy to migrating oil and favorable to accumulate.The 9th member of lower Es3 formation is the main serie of Wuhaozhuang OilField,with a higher degree of exploration and development.It reported 14 million 650 thousand tons of proven reserves,which has accumulated 2 million 950 thousand tons of oil.The reservoir with 4-60 m thickness,17.25% average porosity,78.34 mD average permeability,belongs to the medium porosity and permeability structural-lithologic reservoir.The area in the process of exploration and development existes the problems such as the high position of the structure producing water and the low parts producing oil,no clear sedimentary model.Also,the 9 sand group of seismic response belonging the sedimentary phenomena or the structure phenomenon is not clear and the reservoir type and distribution is not fine to small layer research.On the basis of fully digested and absorbed the achievements and understandings on the previous research,according to the in-depth analysis of the basic geological and geophysical data,by carrying out the sequence division and small layer contrast,4 layers of fine structure,reservoir characteristics,sedimentary characteristics and reservoir types and distribution of 9 sand groups were studied.Two types of sedimentary strata in the 9 sand group,one is the positive cycle of sedimentary energy,and the other is the upward sedimentary energy.It is subdivided into I,II,III,IV,four sets of genetic stratigraphic,II and III small reservoirs in eastern sag common development,reservoir mainly concentrated in the I and II layer.The 9th member of lower Es3 formation is in deep water basin,developing of multi-period gravity flow sublacustrine fan from neighboring Qianshan,because reservoir types are turbidite channel sand bodies and progradational leafy sandbody.The turbidite channel sand bodies developed in the ascending half cycle of reduced energy deposition,and progradational leafy sandbody developed in the the descending half cycle of enhanced energy deposition.Turbidite channel migration changes caused by sand and sand mutually stacked.The 9 sand group mainly developed four types of reservoir such as lithologic reservoir and lithologic pinchout reservoir,fault block of lithology reservoir and structural reservoir.Most of the oil reservoir in the eastern sag of the reservoir is located in the fault block trap with a tectonic setting.On the West Wing of Gubei eastern Sag,the formation of the complex reservoir with double control of fault and lithology is pointed out.