Tectonic evolution and hydrocarbon accumulation of Laizhouwan depression in southern Bohai Sea

Niu Chengmin

doi:10.11743/ogg20120312

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Tectonic evolution and hydrocarbon accumulation of Laizhouwan depression in southern Bohai Sea
Vol. 33, Issue 3, Pages: 424-431(2012)
Online First：28 June 2012，

Published：2012
DOI： 10.11743/ogg20120312
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DOI：

Niu Chengmin. Tectonic evolution and hydrocarbon accumulation of Laizhouwan depression in southern Bohai Sea[J]. 2012, 33(3): 424-431. DOI： 10.11743/ogg20120312.

摘要

莱州湾凹陷位于渤海南部海域

勘探程度较低

油气成藏特征复杂。在近期勘探获得亿吨级油气发现的基础上

通过凹陷构造特征分析

揭示莱州湾凹陷同时具有断陷和走滑反转的双重构造特点;根据断裂活动特点和强度

将凹陷内断层划分为3类

它们分别对凹陷格局形成、沉积体系与输导系统具有不同的控制作用

并将莱州湾凹陷演化进一步划分为3个阶段:孔店组(Ek)至沙河街组三段(Es

)的早期断陷、沙河街组一、二段(Es

1+2

)至东营组(Ed)的中期走滑和晚期活化阶段(新近纪以来)。构造演化对凹陷内油气成藏具有重要的控制作用:构造演化控制了各种类型圈闭的形成;控制了凹陷沉积充填、沉降中心迁移以及烃源岩形成演化;另外

由于晚期强烈的构造和火山活动

对莱州湾凹陷的晚期成藏起到了重要的促进作用。

Abstract

Laizhouwan depression in the southern Bohai Bay is complicated in hydrocarbon accumulation and is low in exploration maturity.An oil discovery with reserves around hundred millions of tons was obtained recently.Laizhouwan depression is characterized by fault depression and strike-slip inversion.According to the feature and strength of fault activity

the faults were divided into three types which have different control on depression pattern

sedimentary system and hydrocarbon migration system.Furthermore

the tectonic evolution of Laizhouwan depression was divided into three stages:the early rifting stage during deposition of the Kongdian Formation to the Member Ⅲ of Shahejie Formation

the strike-slip stage during deposition of the Member Ⅱ of Shahejie Formation to Dongying Formation and the late activation stage since the Neogene.The tectonic evolution controls trap formation

sediment filling

subsidence center migration

and source rock formation and evolution.The late strong tectonic and volcanic activities are helpful for late hydrocarbon accumulation in Laizhouwan depression.