珠江口盆地惠州凹陷古近系油藏地质特征及成藏机理

摘要

珠江口盆地惠州凹陷油气勘探开发主要目的层序和探明储量集中在新近系,古近系油气藏由于埋藏深、钻井成本高等原因而导致勘探程度较低.HZ-A古近系文昌组低孔低渗砂岩岩性油藏位于惠州凹陷HZ26洼西次洼南部斜坡区,该油藏的储层物性较差,横向变化较大,具有"低孔低渗"特点,而且油水分布规律复杂,油、水层及干层共存,无统一的油水界面,给油藏的定量描述带来极大困难.本文以HZ-A古近系油藏为例,系统分析了区域地质特征、烃源岩特征、储集层特征、盖层特征、油藏地质特征、原油来源、成藏期与储层演化匹配关系和浮力成藏下限,提出了HZ-A古近系油藏是常规油藏和致密油藏的过渡类型的新认识,丰富了研究区油气成藏地质规律的认识,对于勘探珠江口盆地古近系自生自储油藏具有重要的指导意义.%The petroleum exploration and development targets are mainly focused in Neogene strata in Huizhou sag, Pearl River Mouth basin, while the exploration degree in Paleogene strata is relatively low due to the deep burial depth and high drilling cost, etc.HZ-A located in the southern slope area of HZ26 western sub-sag is a Paleogene low porosity and low permeability sandstone reservoir in Wenchang Formation.The reservoir has the characteristics of poor physical property with great lateral variation and complex oil and water distribution, such as the coexistence of water, oil and dry layers, and no uniform oil water interface, which cause great challenge for quantitative reservoir description.Taking HZ-A Paleogene reservoir as an example, the regional geological features, characteristics of source rock, reservoir, seal and structure, oil source, relationship between oil charging and reservoir evolution, and lower limit of buoyancy enforced oil accumulation are systematically analyzed.The study demonstrates that HZ-A Paleogene reservoir is the transitional type from conventional to tight sandstone reservoir, which enriches the knowledge of petroleum accumulation regulation in the research area and has important significance for petroleum exploration in Paleogene self-generating and self-storing reservoir in the Pearl River Mouth basin.