Research On Sedimentary Facies And Distribution Of Oil&gas In 19th Well Area Chang 3 Reservoir Group In Ansai Oilfield

Ordos Basin is a polycyclic superposition basin as well as the largest sedimentary basin on land in China which possesses abundant oil&gas resources and has bright prospects in oil&gas exploration. It has been becoming one of the important tactical areas in oil&gas exploration and exploitation in China. The amount of oil&gas resources and the degree which it is proven will directly influence the development of China petroleum industry. Ansai oilfield is one important generative area of oil of Ordos basin. As two primary oil beds in Ansai oil field, Exploration and exploitation of Chang3 oil beds are significant. For the sake of deeply researching the rules of hydrocarbon accumulation and distribution, it is necessary to study sedimentary facies and distribution oil&gas in the Chang3 oil beds of Ansai oilfield.On the basis of the theories of sedimentary facies and petroleum geology, by means of geology investigations in the field and research indoors, combined with the data of geological background, lithological association, sedimentary structure, construction, geochemistry, reservoir, oil&gas testing and chemical analysis of organic compound, the paper research Chang3 oil beds rules of sedimentary subfacies, rules of distribution of stratum and sandstone, oil resources, the rules of accumulation and the distribution of oil and gas.Used the marker formation in the study area,combined with sedimentary cycle and the principle of the thickness of strata, according to the traditional division method,this study divided Chang3 into four sections: Chang311,Chang312, Chang32, Chang33. Confirming the boundary of each stratum and elaborating the litho-electric feature of each stratum in order to enable thin layer division more reasonable,accurate and lay a favorable basis for the sedimentary facies and disciplinarian of accumulation oil&gas of research district.Chang3 reservoir is inner sediment in term of analytic result of plane configuration of sandstone, characteristics of lithology and log displays of all substratums, rate between sand and mud, the types of construction, sedimentary facies sequence of single well and granularity analysis.The watercourse sand is dominating zones of hydrocarbon accumulation and distribution. The better combination between local construction and mud sediment in up-dip direction is the guarantee of oil and gas accumulation. The better the combination is, the higher the degree of enrichment is. The oil and gas resource has an effect on the degree of enrichment of oil and gas in Ansai area.On the basis of the above research and analysis of tectonic, sedimentary and diagenesis and source reservoir cap rock and oil and gas distribution relationship, combined with the reservoir control factors and distribution rules, combining through division of flow unit and oil production test data, determine the favorable accumulation area.