渤海海域辽中凹陷南洼断裂体系及走滑控圈模式

Development characteristics of fault system and trap-controlling effect of strike-slip faults in south of Liaozhong Sag, East China

以渤海海域辽东湾坳陷辽中凹陷南洼为研究对象,运用连片三维地震资料,将剖面分析与平面分析相结合,综合精细地震解释与时间-方差切片,建立了区域断裂体系发育模式,总结了走滑断裂的控圈模式。研究结果表明,辽中凹陷南洼新生代走滑断裂体系主要包括6条右旋走滑断裂。根据断裂性质及发育位置的差异,将断裂分为控洼走滑断裂和洼中走滑断裂2种类型;走滑断裂将辽中凹陷南洼分为西部斜坡带、中部走滑带和东部反转带;同时由北向南存在分段特征,北段整体表现为东断西抬的箕状断陷特征,中段为大型宽缓凸起,南段发育西高东低的小型凸起;走滑断裂的不同连接形式形成了区内多个构造变换带,依据对圈闭发育的控制作用可分为"S"型走滑控圈、走滑拉分控圈和多走滑复合控圈;受走滑断裂作用形成的挤压应力区易形成背斜或断鼻型圈闭,油气保存条件较好,而受走滑断裂作用形成的伸展应力区普遍发育断块型圈闭,单块圈闭面积相对较小,但油气运移条件好,对浅层油气成藏较为有利。

Based on combined analyses of the detailed description of seismic interpretation sections and time slice characteristics, this paper established the development patterns of fault system and its effect on the development of structural traps in the south of Liaozhong Sag by using block-jointed seismic data. Results show that the Cenozoic strike slip fault system in the south of Liaozhong Sag is mainly composed of 6 dextral strike-slip faults. According to the difference of fracture property and development position, faults can be divided into two types： sag-controlling strike-slip faults and sag-in strike-slip faults, which divide the south of Liaozhong Sag into the western slope zone, central strike-slip zone and eastern inversion zone. Meanwhile, the strike-slip fault system can also be divided into 3 zones from north to south： the northern part is characterized by dustpan shaped faulted features, the middle part with large wide slow uplift, and the southern part developed small uplift. It is the reason of strike-slip faults connection forms why there are many structural transfer zones in this region, and faults can be subdivided into S-type, pull-apart and multi-strike-slip composite faults based on the controlling role that strike-slip faults played on trap development. It is recognized that the traps controlled by restraining strike-slip transform structure are mainly anticline traps and the nose shaped high traps which have better oil and gas preservation conditions, while the traps controlled by releasing strike-slip transform structure are mainly block traps. Single block trap in the area is relatively small, but has better migration conditions, which is beneficial to the shallow oil and gas accumulation.