文昌B凹陷脉动式构造演化及其与油气成藏关系

Pulsating tectonic evolution and its relationship with hydrocarbon accumulation in Wenchang B Depression

珠江口盆地西部文昌B凹陷构造复杂多样,应力场多变。新三维地震及探井等资料的日渐丰富,为研究该凹陷的构造及演化特征奠定了基础。文中运用板块构造理论和构造解析方法研究认为,文昌B凹陷具有伸展—反转—再伸展—再反转的脉动式演化特征。这种脉动式构造演化,不仅控制了文昌B凹陷烃源岩、储盖层的发育,而且导致珠海组二段和珠江组二段不同性质的圈闭在纵向上叠加,有利于形成复式油气藏聚集带。因此,对于文昌B凹陷的勘探,应结合构造演化特点,既要注重特定演化阶段圈闭的特殊性,也要分析不同演化阶段叠合造成的复式成藏效应,进行多层系勘探,从而提高勘探成功率。

The structure is complex and the tectonic stress field is diverse during different geologic epochs in Wenchang B Depression,western the Pearl River Mouth Basin.The study of structure characteristics and evaluation is imperative as the new 3D seismic data are acquired and the new well data are accumulated.Based on the plate tectonics theory and adopting the structural interpretation method,this paper considers that Wenchang B Depression has the characteristics of pulsating tectonic evolution with extension structure and inverse structure.This pulsating tectonic evolution not only controls the development of oil source rock and reservoir and cap beds,but also leads to the distinct trap overlap for the second intervals of Zhuhai Formation and Zhujiang Formation in column order,which is in favour of forming the hydrocarbon accumulation zones of compound reservoirs.The oil exploration should combine the structure evolution characteristics,attend the uniquely trap in the special evolution period and analyze the complicated structure overlay in different evolution periods.Multi-layer traps should be placed stress on in order to improve the exploration success rate.