石油与天然气地质 ›› 2017, Vol. 38 ›› Issue (6): 1032-1042.doi: 10.11743/ogg20170603

• 油气地质 • 上一篇    下一篇

渤海湾盆地南堡凹陷3区多期叠加断裂体系形成机制

冯建伟1, 王志坤2, 商琳2   

  1. 1. 中国石油大学(华东) 地球科学与技术学院, 山东 青岛 266580;
    2. 中国石油 冀东油田分公司 勘探开发研究院, 河北 唐山 063004
  • 收稿日期:2015-08-03 修回日期:2017-08-10 出版日期:2017-12-28 发布日期:2018-01-08
  • 作者简介:冯建伟(1979-),男,副教授,构造地质学。E-mail:linqu_fengjw@126.com。
  • 基金资助:
    中央高校基本科研业务费专项资金项目(17CX05010);国家自然科学基金项目(41572124);国家科技重大专项 (2016ZX05047-003,2016ZX05014002-006)。

Genetic mechanisms of superimposed fault systems in Block 3 of Nanpu Sag,Bohai Bay Basin

Feng Jianwei1, Wang Zhikun2, Shang Lin2   

  1. 1. School of Geosciences, China University of Petroleum, Qingdao, Shandong 266580, China;
    2. Exploration and Development Research Institute, Jidong Oilfield Branch, PetroChina, Tangshan, Hebei 063004, China
  • Received:2015-08-03 Revised:2017-08-10 Online:2017-12-28 Published:2018-01-08

摘要: 针对渤海湾盆地南堡凹陷3区内广泛发育的多期叠加断裂体系形成机制及演化过程不清的问题,以构造地质学、地质力学理论为指导,采用三维地震解释、构造物理模拟、有限元数值模拟等综合、联合技术,梳理断裂几何特征及组合样式,恢复不同构造活动期的应力状态,分析平面上变应力场条件下的断裂形成演化规律,探讨垂向上断陷盆地深部先期构造对晚期断裂形成和演化的控制作用,建立研究区多期叠加断裂体系动力学模式。结果表明:以沙河街顶不整合为界分为上、下两套断裂系统,常呈现为“X”型叠加样式,中间具短期反转特征,上部为SN向伸展兼左旋走滑的复合断裂系统,力学机制为纯剪,下部为NW-SE向伸展断裂系统,力学机制为单剪。叠加断裂体系的发育主要受控于地质力学层分布、晚期应力强度、先期断裂与后期应力方向之间的夹角。先期断裂的存在影响着局部应力场的重新分布以及后期断裂的发育,晚期断裂要么继续扩展,要么产生新的断裂。以不整合面为主要特征的岩层界面作为一种力学薄弱面,受力作用时,容易发生“变形不协调或滑移”现象,使得断裂发育在垂向上具有明显的不连续性或间断性;区域上,多期叠加断裂系统的形成和发育直接受控于郯庐断裂古近纪以来构造应力场的转变。

关键词: 叠加断裂, 形成机制, 物理模拟, 数值模拟, 南堡凹陷, 渤海湾盆地

Abstract: This research focuses on investigating the genetic mechanisms and evolutionary processes of the superimposed multi-stage fault systems in Block 3 of Nanpu Sag,Bohai Bay Basin.The workflow herein adopted a variety of modern techniques such as 3-D seismic interpretation,physical simulation of structure and finite element numerical simulation,and took the theories of structural geology and geomechanics as guidance.We recognized the geometry and combination modes of faults,restored the paleostress state of different tectonic periods,analyzed the development and evolution patterns of faults under variable stress field,discussed the control of pre-existing structures on later fault formation and evolution,and established geodynamic models of the superimposed multi-stage fault systems in the study area.The results showed that,bounded by unconformity on the top of Shahejie Formation,the X-pattern normal faults could be divided into two vertically superposed fault systems with short-term inversion characteristics.The upper tone is a SN-trending composite extensional and sinistral strike-slip fault system with pure shear deformation being predominant,while the lower tone is a NW-SE-trending extensional fault system with single shear deformation being predominant.Distribution of geomechanical layers,later tectonic stress intensity,and angle between pre-existing fault strike and later principle stress direction were regarded as the three main factors controlling the development of superposed fault systems.The pre-existing faults could influence the redistribution of local stress field and the development of later faults,which either continued to expand along early faults,or created new faults.As a mechanical weak surface,the unconformity was easy to generate uncoordinated deformation or slipping,resulting in significant vertical discontinuous development of faults.Regionally,the formation and evolution of the superimposed fault system in Block 3 of Nanpu Sag was directly controlled by transition of tectonic stress field by Tan-Lu fault since the Paleogene.

Key words: superimposed faults, genetic mechanism, physical simulation, numerical simulation, Nanpu Sag, Bohai Bay Basin

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