渤海海域大型伸展-走滑复合断裂特征与控藏作用

Characteristics and reservoir controlling of large-scale extension-strike slip composite faults in Bohai sea area

渤海海域受伸展-走滑“双动力源”的控制发育众多大型伸展-走滑复合断裂,但是长期以来,对伸展-走滑复合断裂的发育特征、控盆差异性和控藏作用不明确。本文基于渤海海域满覆盖三维地震资料和众多油田勘探实践成果,对大型伸展-走滑复合断裂进行了深入分析和总结,研究认为:(1)板块俯冲作用为渤海海域伸展-走滑复合断裂体系的根本动力;(2)在走滑作用控制的构造样式中,依据主控走滑断层的强度,分为强走滑、中等走滑、弱走滑和隐性走滑(极弱走滑)四种,控制着不同的断裂类型结构模式;(3)伸展-走滑复合断裂构造样式可分为似花状构造、多级Y字形构造、无根花状构造和复杂X型构造四种;(4)伸展-走滑复合断裂体系和构造样式及其控盆作用,在渤海具有明显的时空差异性,可划分为辽东湾、渤东、渤中—渤西和渤南四大分区;(5)伸展-走滑复合断裂体系对油气成藏的控制作用主要表现在对圈闭、沉积体系和油气运移的控制;(6)基于伸展-走滑复合断裂体系的差异性,建立了渤海海域“S”型走滑带古富-新贫型、帚状走滑带古贫-新富型、花状走滑带古贫-新富型、反转区双重走滑带古贫-新富型、共轭走滑带多层互补富集型和走滑斜坡带古贫-新富型富集模式。

Many large-scale extension-strike slip composite faults are developed in the Bohai sea area under the control of “double power sources” of extension-strike slip stress. However, for a long time, the development characteristics, the differences of basin controlling and reservoir controlling of extension-strike slip composite faults have not been clear. Based on the full coverage of 3 D seismic data in the Bohai Sea area and the exploration practices of many oil fields, this paper deeply analyzes and summarizes the characteristics of large-scale extension-strike slip composite faults. The research shows that:(1)The fundamental driving force of the formation of extension-strike slip composite fault system is plate subduction in the Bohai sea;(2)Among the structural styles controlled by strike slip, the strength of the main strike slip fault, including strong strike slip, medium strike slip, weak strike slip and subtle strike slip(very weak strike slip), controls the structural patterns of different fault types;(3)The structural styles of the extension-strike slip composite faults can be divided into four types: flower like structure, multilevel Y structure, rootless flower structure and complex X type structure;(4)The extension-strike slip composite fault system, structural style and its basin controlling effect have obvious temporal and spatial differences in the Bohai sea, which can be divided into four sub regions: Liaodong Bay, Bodong, Bozhong-Boxi and Bonan;(5)The control of extension-strike slip composite fault system on hydrocarbon accumulation is mainly manifested in the trap formation, sedimentary system and hydrocarbon migration;(6)Based on the differences of extension-strike slip composite fault system in the Bohai sea, the accumulation models of rich Paleogene and poor Neogene in “S” type strike slip zone, poor Paleogene and rich Neogene in broom type strike slip zone, poor Paleogene and rich Neogene flower type strike slip zone, poor Paleogene and rich Neogene in inverted dual strike slip zone, multi-layer complementary accumulation in conjugate strike slip zone, poor Paleogene and rich Neogene accumulation in strike slip slope zone are established.