东营凹陷沙河街组三段层序低位域砂体沉积特征

Depositional Characteristics of Lowstand Sand Bodies of the Third Member of the Shahejie Formation in the Dongying Depression and the Significance in Petroleum Geology

本文基于构造层序分析和基准面分析原理,利用测井曲线、岩相等资料,重点研究了东营凹陷沙三段3个层序的低位域砂体沉积特征、发育规律及其石油地质意义。应用构造坡折带的概念在该凹陷划分出了4种构造坡折带样式。研究表明:该凹陷沙三段层序低位域砂体发育下切水道充填、低位楔和低位扇。构造坡折带的发育特征和样式控制了低位域砂体的时空展布特征。构造坡折带控制下的低位域砂体发育在层序底部、构造坡折带附近,成藏条件优良,是隐蔽油气藏勘探的主要方向。

Based on the principles of tectonic sequence analysis and base-level analysis and high-resolution seismic sections , log curves and lithofacies data, this research is focussed on the depositional characteristics of the lowstand sand bodies of three sequences of the third member of the Shahejie Formation in the Dongying depression and their development rules and the significance in petroleum geology. The concept of structural break zone is used in this paper, and four structural break zone styles have been identified. The research shows that the lowstand sand bodies of the third member of the Shahejie Formation in the depression consist of incised channel deposits, lowstand wedges, and lowstand fan deposits. The development characteristics and styles of the structural break zones control the distribution of the lowstand sand bodies. The lowstand sand bodies controlled by structural break zones are developed in the lower part of the sequences and near the structural break zones. They are favourable for oil bearing, so that the lowstand sand bodies are prospect districts for subtle reservoirs.