渤海湾盆地西部浊积岩沉积模式及地质意义

Depositional Model and Geological Significance of Turbidite in Western Bohai Bay Basin

在渤海湾盆地歧口凹陷东部歧南断裂带下盘发育了一系列典型的深湖相滑塌浊积扇,成为该地区油气勘探的重要领域。根据岩相、测井相以及粒度特征,将研究区浊积扇划分为内扇、中扇、外扇亚相。断层的幕式活动、洪水事件、古地形是影响浊积扇形成和分布的主要因素。单个浊积扇体分布面积小,但沿同生断层下降盘会形成一系列的浊积扇群;单期砂体厚度薄,但继承性好,多期叠置,累计砂层厚度大;生、储、盖配置关系好,油气充满度高。

There are a series of typical slump turbidite fans in the deep lake of the downthrown block in Qinan fault zone of the eastern Qikou sag in Bohai Bay basin,which have been major domains for oil-gas exploration in this area.According to the lithofacies,electrofacies and grain size features,the turbidite fans here can be divided into inner-fan,mid-fan and outer-fan subfacies.Fault episodic activity,flood events and the paleotopography are the main factors affecting the formation and distribution of the turbidite fans.These turbidite fans are characterized by the small area distribution of a single fan,a series of turbidite fans along the contemporaneous fault downthrown block; thin single-phase sand body,good inheritance,multi-phase superimposition and big cumulative sand thickness; good assemblage of source-reservoir-cap rock and high fullness of oil and gas.