Study On Reservoir Features And Oil Pool Forming Regularity Of Paleogene In The South Slope Of Dongying Depression

Based on the study of the sequence stratigraghy and depositional system, and supported by the analysis of core, well logging, geological logging and seismic data, fluvial, braided delta and lacustrine depositional system are identified in the study area. Furthermore, we conclude that braided delta front distributary channel and channel mouth bar sandbodies are the main reservoir sandstones, while beach-bar in shallow lake, fluvial sandbodies and a small amount of turbidite bodies are the secondary reservoir sandstones. Braided delta and fluvial sand reservoirs are developed in the margin of basin, while beach-bar sandstone and turbidite sandstone reservoirs are developed in the inner of basin.On the basis of the identification of rock thin sections, casting thin sections , and various of analysis and chemical examination data, we conclude that compaction and cementation are primary diagenesis in Paleogene reservoir, while dissolution and replacement can just be found in the third member of Shahejie Formation. By the analysis of Ro value, S content in I/S, cement type, clay mineral and pore characteristics, we propose that the Paleogene System's Strata(Es3～Ed) in the Southern Slope of Dongying Depression are mainly in B period of early diagenesis and A period of middle diagenesis. The reservoir spaces are mainly composed of primary porosity, while secondary porosity is not developed. The reservoir pore structure is characterized by middle-high porosity and middle-high permeability. According to the study of sedimentary facies, pore structure, diagenesis, the evaluation of reservoir development conditions in different sequence stratigraphy is made. On the vertical, typeⅡ-Ⅲreservoirs are developed in SQ1 and SQ2. And typeⅠ-Ⅱreservoirs are mainly developed in SQ3, SQ4 and SQ5. In the plane, the reservoirs developed in the margin of basin are mainly composed of braided delta distributary channel, channel bar and fluvial sandstone which are characterized by typeⅠ-Ⅱr eservoir, While the reservoirs developed in the inner basin are mainly composed of beach-bar sandstone and turbidite sandstone which are characterized by typeⅡ-Ⅲreservoir. According to the above studies, the oil reservoir types and distribution discipline can be summarized. Laterally, stratigraphic oil reservoir and lithologic oil reservoir which consist of braided delta distributary channel and channel bar sandstone are mainly developed in the margin of basin. Whereas structural -lithologic oil reservoir is easily formed in beach-bar sandstone. Vertically, lithologic oil reservoir, structural-lithologic oil reservoirs are mainly developed in SQ1, SQ2 and SQ3, while stratigraphic oil reservoir and lithologic oil reservoir are mainly developed in SQ4 and SQ5.This paper also analyzes the discipline of oil reservoir types and distribution , then points out that sedimentary facies distribution and tectonics movement are the dominant factors influencing the reservoir distribution. And finally the prediction of favorable oil reservoir is made which will provide valuable reference and foundation for further exploration.