花海凹陷白垩系含油气系统勘探潜力评价

Potential Evaluation of Exploration in Cretaceous Petroleum System in Huahai Sag

花海凹陷是一个小型的中新生代沉积断陷,其油气成藏条件在中小型盆地中具有代表性。含油气系统地质要素分析表明,花海凹陷南部沉积中心白垩系具有较好的生烃条件和封盖条件,储层物性总体较差,凹陷边缘则缺乏生油和保存条件。从各成藏要素的时间配置关系来看,早白垩世后期是凹陷中心油气运聚成藏的主要时期,以近距离小规模聚集为主;第三纪油气受构造影响再次运聚成藏和局部调整。分析认为该凹陷勘探潜力较小,建议该凹陷立足于寻找小型油藏,以位于生烃中心的中央断裂构造带为主要勘探对象。

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 hydrocarbon- generating 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.