南堡凹陷3号构造带中深层层序地层特征与油气关系

地层划分问题一直制约了南堡凹陷3号构造带中深层(沙三段—东一段)的后续油藏评价研究。本文基于层序界面在地震反射结构特征、岩性突变以及电测曲线等方面的特征变化,共识别出该带4个二级层序界面,8个三级层序界面,并将该带沙三段—东一段划分出3个二级层序和7个三级层序。研究表明,南堡凹陷3号构造带中深层层序发育样式受湖盆结构及构造坡折带影响,三级层序厚度由南西至北东方向总体呈增厚趋势,由北西至南东方向总体呈厚—薄—厚的发育特征。在对层序地层特征研究的基础上,分析了层序地层与油气的关系,认为研究区沙一段中层序存在构造与地层控制的油气藏,而在东营组层序存在构造与岩性共同控制的油气藏,并且在南堡凹陷3号构造带中深层存在有利的构造与岩性、构造与地层共同控制的复杂油气藏发育带。

Sequence stratigraphy and oil reservoirs in the medium-deep strata within No. 3 Structure, Nanpu depression

The medium-deep strata within No. 3 Structure consist of the third member of the Shahejie Formataion to the first member of the Dongying Formation in the Nanpu depression, and are divided, in terms of seismic reflection configuration, lithology and electric logs, into four second-order sequence boundaries, i. e., three second-order sequences and eight third-order sequence boundaries, i. e., seven third-order sequences. Constrained by the lake basin structures and structural break, the thickness of the third-order sequences generally increases from the southwest to the northeast, and display thick-thin-thick patterns from the northwest to the southeast of the study area. There occur the structurally-or stratigraphically-controlled oil reservoirs in the central part of the first member of the Shahejie Formation, and mixed structurally-and lithologically-controlled oil reservoirs in the Dongying Formation. On the whole, the favourable oil reservoirs are controlled by mixed structures and lithology and structures and stratigraphy in the medium-deep strata within No. 3 Structure in the Nanpu depression.