Hydrocarbon migration, accumulation and adjustment of strike-slip inversion structure zone in Bohai sea:Taking Lvda 22-27 Area as an example

Lvda 22-27 strike-slip inversion structure zone which is located in south Liaodong Bay of Bohai sea is one of the areas with the highest exploration degree in Bohai Oilfield. Influenced by Tan-Lu fault compression, typical strike-slip inversion structure is formed and is always in high position in the course of tectonic evolution, which is the favorable area for hydrocarbon accumulation. To identify the rules of hydrocarbon accumulation in this area, through analyzing the hydrocarbon accumulation period and time, and based on the geochemistry, drilling and seismic data, ancient reservoir and present reservoir of Dongying Formation are proved: ancient reservoir is formed in Late Miocene and present reservoir is formed since Late Pliocene. At the same time, this paper analyzes the hydrocarbon accumulation events and conditions, and defines the controlling role of Himalayan movement on hydrocarbon accumulation. It also sums up the hydrocarbon effusion and enrichment mechanism in this area, reappears the oil and gas accumulation process. At last, it is pointed out that the shallow layer such as the lower section of Minghuazhen Formation and Guantao Formation are considered as the favorable hydrocarbon accumulation layers, which are next step prospecting directions.