珠江口盆地开平凹陷韩江组下段沉积体系

Sedimentary system of the Lower Hanjiang Formationin Kaiping Sag,Pearl River Mouth Basin

一直以来,开平地区缺少针对古珠江三角洲—深水扇沉积体系平面分布的研究。基于三维地震数据和钻井资料,使用地震沉积学方法,对开平凹陷韩江组下段开展沉积体系研究。结果表明,研究区主要发育陆架边缘三角洲—斜坡扇沉积体系,其内部发育河口坝、沿岸砂脊、陆架砂脊、席状砂、斜坡扇及深水泥等6类沉积单元。陆架区主要发育古珠江三角洲前缘远端沉积,主水流路径为近SN或NE-SW向;陆架边缘发育大量陆架砂脊,呈NW-SE向展布,单砂脊规模不大。斜坡区发育较大规模斜坡扇沉积,其以块状叠覆扇砂体为主,砂体扇形特征较典型。凹陷区主要为泥质沉积,砂体不发育。整体来看,SQ13.8发育较多厚层砂体,其易于形成岩性圈闭,具备油气储集层发育条件。研究成果可以为开平凹陷下中新统的储层分布预测提供依据。

For a long time,there has been a lack of research on the plane distribution of sedimentary system of the ancient Pearl River delta-deep water fan in Kaiping area.Based on 3D seismic data and drilling data,the sedimentary system of the Lower Hanjiang Formation in Kaiping Sag has been studied by using seismic sedimentology method.The study shows that the sedimentary system of shelf margin delta-slope fan is mainly developed in the study area,and six types of sedimentary units such as estuarine bar,coastal sand ridge,shelf sand ridge,sheet sand,slope fan and deep cement are developed in it.The shelf area mainly develops the far end deposits of ancient Pearl River delta front,and the main flow path is near north-south or NE-SW direction.A large number of shelf sand ridges are developed at the edge of shelf,distributed in NW-SE direction,and the scale of single sand ridge is small.Large scale slope fan deposits,which are mainly composed of massive overlapping fan sand bodies with typical fan-shaped characteristics,are developed in the slope area.The basin area mainly develops argillaceous deposits,and the sand body is not developed.Overall,a large number of thick sand bodies are developed in the sequence of SQ13.8.They are easy to form lithologic traps and have the conditions for the development of oil-gas reservoirs.The research results can provide a basis for the prediction of reservoir distribution of the lower Miocene in Kaiping Sag.