关键词: 花海凹陷, 白垩系, 含油气系统, 油气成藏, 勘探潜力

Abstract: Huahai sag is a small sedimentary fault-depression basin formed during Mesozoic-Cenozoic periods, its accumulation conditions of oil and gas represent the characteristics of medium-small basins.Through analysis on the geological factors of petroleum system, the results indicate that the Cretaceous source rock,deposited in the depocenter of southern Huahai sag, has a potential of hydrocarbongenerating and capping ability , the physical property of reservoirs are bad in general,but the margin of the sag lack oil-generating and conservation conditions . As seen from the time configuration of various reservoiring factors , the later of early Cretaceous is the principal phase of petroleum migration and accumulation in the sag centre ,mainly forming small oil reservoirs by short distance accumulating.In Tertiary,oil and gas migrated and accumulated again, as well as locally regulated ,being affected by structure activity. The analysis result reflects that Huahai sag has a less potential of exploration, it is ,therefore,suggested that the further exploration should be focused on looking for small oil reservoir in the sag ,and the central tectonic belt ,located in hydrocarbon-generating center , will be seen as the major targets to be explored.

Key words: Huahai sag, Cretaceous, petroleum system,oil and gas accumulation, exploration potential