渤海海域构造应力场演化及其在油气聚集中的作用

EVOLUTION OF THE STRUCTURAL STRESS AND ITS FUNCTION DURING OIL/GAS ACCUMULATION IN BOHAI SEA

  • 摘要: 渤海海域位于渤海湾盆地东部,在盆地区域动力学背景下,形成了渤海海域特征的沉积和构造环境。渤海海域新生代具有早期断陷、后期拗陷的特点,断裂以NE-NNE走向为主,其次是EW走向,再次是NW走向。通过区域构造演化和沉积体系的深入研究,将海域新生代地质构造活动按构造应力的方向、大小和其他构造形变参数划分为4个期次:①古新世;②始新世-渐新世;③中新世-早更新世;④晚更新世至今。在一系列构造演化过程中,构造应力场的变化对海域内的3组主要断裂具有重要的影响。不同方向的断裂在不同阶段应力场的作用下,所表现的特征和对油气的控制作用是不同的,尤其是NNE-NE向断裂在构造演化过程中多次具有走滑活动,油气主要聚集在走滑作用所派生的局部圈闭或附近存在的构造弱化带中。

     

    Abstract: Bohai Sea area covers Bozhong depression and the offshore part of Xialiaohe, Jiyang, Huanghua depressions and Chengning uplift. Unique sediments and structures of Bohai Sea were formed under regional dynamic setting in Bohai Bay basin. Its evolution has experienced early rifting stage and late down warping depression since Cenozoic. The main faults are NE-NNE trending,and then are EW and NW trending in the area. Based on the direction, magnitude and deformation parameters of structural stress, four structural successions are recognized in the Bohai Sea that are Paleocene, Eocene-Oligocene, Miocene-early Pleistocene, late Pleistocene-present. These four structural stages played an important role in the fault-controlling oil/gas in the Bohai Sea, especially for NNE-NE trending faults. After strike-slip activities, NNE-NE trending faults induced local traps and unsubstantial structure zone, which provide pathways for oil/gas migrating or accumulating.

     

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