Accumulation Conditions And Favorable Area Prediction In The Deep Layers Of Chenghai Fault Slope Area In Qikou Sag

The Chenghai fault slope area of Qikou sag is an inherited multi-step fault slope.It has the characteristics of complex geological conditions,various trap types,low abundance of discovered reserves and it is difficult to generate hydrocarbon in fault steps.In this paper,we regard the Paleogene of Chenghai fault slope area as the main research layer.,comprehensively applies the source rock distribution,hydrocarbon generation and expulsion characteristics,sedimentary system and other models to analyze the main controlling factors of oil and gas accumulation and predict favorable reservoir formation zones,and obtain the following research results:(1)The Es₁ and Es₃ of Paleogene Shahejie Formations are the main hydrocarbon generation layers.Es₁ is the main source of oil,Es₃ is the source of oil and gas,and Es₂is the reservoir.Sandstones of the Es₂ Formation,mainly composed of braided river delta sedimentary and connected sand bodies,are important transmission conductors for lateral migration of oil and gas.(2)Through Research,it is considered that two periods of accumulation occurred in Chenghai fault slope area and the oil and gas filling time of two stages above is 24Ma±and 5Ma±.(3)Based on the analysis of the oil and gas geological background and the evolution of hydrocarbon accumulation,the accumulation model of"dual stove supply,transport system determines migration path,faults determine the location of accumulation,and late formation of oil and gas reservoir was proposed,confirming the phenomenon of dominant channel effect increases with the increase of oil and gas migration distance.(4)Based on the analysis of the oil and gas accumulation conditions,accumulation process and main controlling factors of the Chenghai fault slope area,the rules of oil and gas accumulation and accumulation in the study area are summarized:oil and gas are distributed stepwise along the fault;reservoir thickness and physical properties and sand bodies The type controls the degree of oil and gas enrichment;the position of the trap and the shape of the sand body control the thickness and range of the oil and gas reservoir;the mudstone caprock controls the oil and gas enrichment layer;the unconformity is favorable for the accumulation of oil and gas.Finally,the above multiple factors are superimposed to predict the compound oil and gas accumulation area.