摘要： 辽河盆地老第三系深层主要发育扇三角洲、湖底扇和泛滥平原沉积体系。依据其成因机制、古构造背景及其砂体形态将湖底扇划分为3种类型: ① 缓坡型湖底扇: 分布于辽河凹陷缓坡半深水至深水区, 有较长的供给水道, 砂体延伸方向与盆地长轴方向垂直,平面上相带展布及延伸明显受供给水道及古地形变化的控制。② 陡坡型湖底扇: 发育于陡岸坡脚深水区, 由陡坡扇三角洲向断阶下滑塌形成, 砂体多发育在断层下降盘, 前端进入地形相对开阔的洼陷区形成一套沿构造走向分布的扇带状砂体。③ 断槽型重力流水道沉积: 分布于两条断层夹持的断槽之中, 碎屑沉积物从东侧陡岸泻入湖盆后直接进入由东侧边界大断裂形成的断槽中成为轴向分布的重力流水道沉积。对深层储层的沉积特征及砂体展布规律作了深入研究, 认为沉积体系、沉积相决定了老第三系深层储层的发育规模和储集性能, 在相同或相近埋深情况下, 储集性能由好到差依次为扇三角洲砂体→湖底扇体→泛滥平原河道砂体;同一类型不同亚相、微相砂体储集性能也有显著差异, 如缓坡湖底扇砂体由中扇辫状沟道→扇中前缘→外扇亚相方向由好变差。对深部有利储层预测和勘探潜力分析认为, 湖底扇中扇、扇三角洲前缘以及泛滥平原河道砂体都有很大的勘探潜力, 寻找深层的有利储层应首先寻找有利的沉积相带, 再在有利的沉积相带中寻找具相对高孔、高渗带的有利砂砾岩体。

关键词: 辽河盆地, 老第三系, 深层, 碎岩储层, 沉积相, 湖底扇, 扇三角洲

Abstract: The fan-deltas, sublacustrine fans and flood plains constitute the main depositional systems of the Palaeogene of deep burial strata (below 3500m) in the Liaohe Basin. According to their forming mechanisms, palaeotectonic settings and sandbody distributions, the sublacustrine fans can be classified into three types, i. e. the gentle-sloped sublacustrine fan, the steep sloped sublacustrine fan and the gravity flow channels. The gentle sloped sublacustrine fan was formed in the deeper water area along the gentle slope side of the depression and was developed with sediment-supplying channels. Its sandbodies were distributed along the short axis. The sediment-supplying channels and the palaeomorphology controlled the distribution pattern of the sub-facies and sandbodies. The steep sloped sublacustrine fan was distributed in the deep-water area and was formed by the sliding of the fan deltas along the eastern boundary fault surface. It has been developed with sandbodies distributed along the long axis. The gravity flow channels was distributed along a fault trough and was formed by two eastern boundary faults Detrital sediments come from the eastern faulting cliff of the depression. This paper has especially studied the depositional characteristics and sandbody spatial distribution of deep reservoirs in the Liaohe Basin. It is indicated that the scales of the deep reservoirs and their petrophysical properties are controlled by the depositional systems and sedimentary facies. The petrophysical properties of the fan deltas are better than those of the sublacustrine fans and the flood plain fluvial channels at the same depth. Similarly, the petrophysical properties of different sub-facies in the same sedimentary facies are also notably different. For in stance, the petrophysical properties of the braided channel sandbody are better than those of the mid fan front and the outer fan of the sublacustrine fans. It is concluded that the petrophysical properties of the fan delta front sandbodies and the braided channel sandbodies of the sublacustrine fans are of the best exploration potential in the deep area of the Liaohe Basin.

Key words: Liaohe Basin, Palaeogene, deep burial strata, clastic reservoir, sedimentary facies, sublacustrine fan, fan delta

中图分类号: 

• TE1213