埕岛东斜坡下第三系层序地层与油气分布规律

Sequence stratigraphy and hydrocarbon distribution of the Eogene in the eastern slope of Chengdao area.

埕岛油田位于渤海湾盆地南部的浅海、极浅海海域 ,其东斜坡地区是拓展勘探的新区带 ,主要勘探目标是东营组三段和沙河街组一段的非构造型圈闭。应用层序地层学原理研究东三段、沙一段的砂体分布规律 ,对东斜坡的继续勘探具有指导意义。根据对地震、钻井、测井资料的综合分析 ,结合邻区的研究 ,将东斜坡地区下第三系划分为 2个层序和 7个体系域。该地区发育 5套含油砂体 ,层序边界附近的低水位体系域、下降体系域及高水位体系域上部沉积砂体最为发育 ,主力含油砂体位于层序Ⅰ与层序Ⅱ之间的层序界面附近。埕岛东斜坡地区下第三系广泛发育在斜坡背景上形成的岩性尖灭型、不整合面遮挡型、超覆尖灭型油气藏 ,层序界面附近往往是油气聚集的有利层段。图 4参

The Eogene in the eastern slope of Chengdao is divided into two sequences and seven system tracts according to the synthetical analysis of seismic, well logging and drilling data. It is demonstrated by the analysis results of stratum and its oilness that the lower stand system tracts, falling stage system tracts and upper high stand system tracts developed more sand bodies, at the same time they are the richest oil bearing formations. In this area, the main oil bearing sand bodies distributed over the formations near the sequence boundary between sequence II and sequence I. It shows that many types of hydrocarbon reservoir exist in this area, such as lithologic pinch out, unconformity and stratigraphic onlap. In this study, the affection of sequence boundaries to the oilness of sand bodies and the inner relationships between them are analyzed. Consequently, a hydrocarbon distribution model based on the sequence stratigraphy is built up.