论湖相滩与坝的成因差异

滩坝是滨浅湖地区常见的一种沉积体系类型,自20世纪90年代起,滩坝作为良好的油气储集体受到人们重视。本文在国内外大量文献资料查阅以及现代沉积考察的基础上,追溯滩坝定义来源,并从水动力搬运和沉积方式上对湖相滩与坝的差异进行重新讨论,将滩与坝划分为两种能够完全区分的沉积体。滩是自浪基面至最大湖泛面范围内,碎屑物质在波浪作用下垂直于湖岸搬运和沉积的、与岸大致平行的席状(或条带状)沉积体,向陆地方向直接与湖岸平原相连。滩可以呈大面积席状展布,也可以呈滩脊、滩槽状相间分布,沿岸沙坝本质是形成于水下的滩脊。坝是在沿岸流作用下,碎屑物质平行湖岸搬运并沉积于岸线向陆弯折处、一端与岸相连、另一端向湖区自由伸展的沉积体,坝与湖岸平原常有湖湾或泻湖相隔。滩与坝的形成水动力条件不同,平面上无法共生,不应该将坝砂作为滩砂的特殊类型进行研究。厘清滩与坝的成因和差别,将有助于陆相含油气盆地滩坝砂储层的精确勘探与开发。

Discussion on Genesis Difference of Lake Beach and Bar

A beach and bar is one of the common shore shallow lake sedimentary system.Since 1990 s,the beach and bar has drown an increasing attention because of being good reservoir of hydrocarbon. Based on a great amount of domestic and broad references and modern sedimentary study,this article gives definition and classification to loch beach and loch bar according to the hydrodynamics and deposition pattern.Beach is the banded (or sheeted)sedimentary body because of the migration of clastic sediments of perpendicular to the shore which is roughly parallel to shore.Beach is connected to the shore plain,where a beach ridge or beach trough interphase is distributed.A underwater beach ridge is customarily referred to an offshore bar.Bar is the sedimentary body formed by littoral current;and one end of which is connected to the shore,while the other end freely extends.There should be a bay or lagoon between shore and bar.Beach and bar are different in hydrodynamic condition.They cannot be symbiosis in the plane.It is impossible that bar is one special type of beach.