Enrichment characteristics and main controlling factors of hydrocarbon in buried hill of Bohai Bay Basin

Key words:  buried hill reservoir  formation condition  enrichment characteristic  controlling factor  quantitative evaluation  Bohai Bay Basin

Abstract:

Based on exploration results and previous studies, the hydrocarbon accumulation conditions were summarized and the differences were compared in different sags of the Bohai Bay Basin. The results show that the pre-Cenozoic tectonic evolution created three types of basement. Evolution of the Cenozoic formed three types of sags:basin of early rift, basin of inheritance rift and basin of lately rift. Evolution differences controlled the distribution of source rock in the sag. The source rock gradually migrated to shallow depth from the periphery to the center of basin. The distribution of reservoir and transport condition became poor gradually from type Ⅰ basement to type Ⅲ basement. Hydrocarbon enrichment is controlled by the pre-Cenozoic and Cenozoic evolution. Hydrocarbon mainly gathered in those sags with type I or type II basement and also with evolution type of inheritance or early rift basin. The hydrocarbon enrichment is controlled simultaneously by the source rock horizon, the scale of high quality reservoir and the formation of oil supplying window. Our study quantifies different hydrocarbon accumulation conditions, and suggests that three factors, including "source-reservoir-migration" which couple with each other, control the mode of the buried hill reservoirs, and the reservoir conditions are the main controlling factors.