Study on hydrocarbon migration of flower-like structure and exploration of rich hydrocarbon reservoirs in central and southern Bohai Sea
Flower-like structure is a typical Cenozoic structure in the central and southern Bohai Sea,exerting a significant control on hydrocarbon migration and accumulation.Based on the exploration practice in Bohai Sea,this study systematically summarizes the characteristics of oil and gas accumulation in the flower-like structural belt of the central and southern part of Bohai Sea by leveraging on drilling,seismic and analytical data.It also provides a detailed analysis of the controlling process of oil and gas migration This study concludes that the differential enrichment of oil and gas in flower-like structures is controlled by the deep primary convergence and shallow secondary convergence as well as their superimposed relations.The deep primary convergence consists of two media:buried hill weathering crust and Shahejie Formation fan body.The area of weathering crust,fan body area and thickness are the main controlling factors of the initial convergence volume.The shallow secondary convergence refers to the accumulation of oil and gas in Guantao Formation structural traps,where the trap morphology and caprock conditions are the main factors affecting secondary convergence volume.The superposition relationship between deep and shallow convergence centers determines the oil-gas enrichment location within flower-like structure:in the escape model,oil and gas accumulate at the high updip positions;in the through model,oil and gas are enriched near the main faults;and in the eccentric model,oil and gas are concentrated near the secondary faults.Guided by the above research,successful discoveries have been made,including the Kenli 6-1 oilfield,Kenli 3-2 oilfield and large-scale oil and gas reservoirs,providing valuable insights for hydrocarbon exploration in other source-adjacent strata.
Central and southern Bohai SeaNeogenePrimary convergenceSecondary convergenceHigh abundance reservoir
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