冀中坳陷牛驼镇凸起潜山内幕勘探成藏条件研究

Research on Hydrocarbon Accumulating Conditions of Internal Buried Hills Exploration in Niutuozhen Uplift in Jizhong Sag

近几年,冀中坳陷潜山内幕油气藏勘探取得了重大突破,实现了潜山勘探由相对简单、明显的类型向更复杂、更隐蔽类型的转变。但这些发现的潜山内幕油藏均位于坳陷的负向构造单元内,从成藏条件分析,凹陷内内幕潜山成藏与凸起相比往往具备一定的优势。通过对牛驼镇凸起潜山及内幕地层、构造特征、储盖组合、供油条件、保存条件等方面的研究,认为牛驼镇凸起夹持于两个富油气凹陷之间,油源供给充足,油气运移通道畅通,并且存在下古生界至新元古界、中古元界3套内幕储盖组合。由于下古生界寒武系(府君山组除外)、中元古界蓟县系洪水庄组为盖层,蓟县系雾迷山组为储层的储盖组合分布范围局限,蓟县系杨庄组、长城系串岭沟组能否起盖层(隔层)作用,是凸起形成潜山内幕油藏的关键。

In recent years, great breakthrough has been made in the exploration of internal reservoir of buried hill, buried hill exploration targets have been shifted from simple and obvious reservoirs to relatively more complex ones. But the internal reservoirs of buried hill that have been discovered mostly lie in the negative structural unit of Jizhong Depression. The accumulation condition of internal reservoirs of buried hill located in sags is usually superior to that of uplifts. By the study on the buried hill and internal strata, structural features, reservoir-capping-assemblages, condition of hydrocarbon supply and preservation in Niutuohzhen uplift, it is regarded that the uplift located between two oil-rich subsags is abundant of resources, open channels for oil migration, and there are three internal source-reservoir-assemblages consisting of lower Palaeozoic, upper and intermediate Proterozoic. Because the Cambrian system of Palaeozoic (except for Fujunshan Formation) and Hongshuizhuang Formation of Jixian system of middle Proterozoic are capping formations, and the Wumishan Formation of Jixian system is reservoir bed, which consists of reservoir-capping-assemblages and it's partly distributed, whether the Yangzhuang Formation of Jixian system and the Chuanlinggou Formation of Changcheng system can serve as capping formations is the key to develop internal reservoir of buried hills.