辽河坳陷沉积体系与油气分布

DEPOSITIONAL SYSTEMS AND OIL/GAS DISTRIBUTION IN THE LIAOHE DEPRESSION

辽河动陷是渤海湾盆地油气资源丰度很高的一个断陷，发育各种类型的沉积体系和它们的组合类型，以缓坡辫状河三角洲、陡坡扇三角洲和缓被远岸水下扇、陡坡近岸水下扇含油性最佳；在各类沉积体系中，技含油丰度由高到低排序，依次为辫状河三角洲、扇三角洲、缓坡水下扇、陡坡水下扇、曲流河三角洲、滩坝和河流。该协陷经过30年的勘探、开发，已建成中国第三大油田。80年代以来，在其滩海地区（面积约占全场陷的1／5）、陆上各凹陷的深层（埋深大于3km）和古潜山的油气勘探又有新进展，是今后辽河动陷最重要的勘探领域。进一步研究辽河坳陷沉积体系类型及其组合型式、分布规律和含油性，并与圈闭分析相结合，对其深层和滩海的评价及有利勘探目标的预测有重要价值；要针对勘探目标特点，加强多学科综合分析工作，以达到少打井多拿储量的目的；要注意各级湖泛面之间砂体的类型和分布，进一步寻找老性和地层油气藏。

The Liaohe depression has a fairly high hydrocarbon abundance in the Bohai Gulf basin. There are various depositional systems and assemblage types of depositional systems. Among them, gentle-slope braided-delta, steep-slope fan-delta, fandelta, gentle-slope distal subaqueous fan are the best for bearing oil. According to oil abundance, from high to low, these depositional systems are successively braided-delta, fan-delta, gentle-slope subaqueous fan, steep-slope subaqueous fan,meandering-delta, shoal bar and fluvial systems. The Liaohe oil field has experienced exploration and development for more than 30 years, and has become the third biggest oil field in China. Since 1980s, new development in oil exploration has been made in some locations, such as: beach (taking up 1/5 of whole depression in area ), deep-set reservolrs of nonmarine sags (deeper than 3 km),and buried hill, which will be the top exploration targets of Liaohe in the future. It has important value for the evaluation of deep-set reservoirs and beach and for the prediction of prospective districts, to research depositional systems, assemblage types, distribution and oil-bearing properties and to combine with analysis of traps. To reach the destination of gaining more reserve by drilling fewer wells, we should better be aimed at the exploratory targets to strengthen comprehensive analysls of many disciplines. And we should better notice sand types and distribution among different-order lacustrine flooding surfaces to find lithological and stratigraphic oil/gas accumulations.