珠江口盆地番禺低隆起新生代断裂体系及油气成藏潜力

    Cenozoic fault characteristics and hydrocarbon accumulation potential of the Panyu Low Uplift in the Pearl River Mouth Basin

    • 摘要: 番禺低隆起的油气勘探潜力受新生代断裂体系控制,目前对其断裂特征和演化过程的研究较为匮乏。利用覆盖番禺低隆起的三维地震资料,对研究区的结构特征、断裂平面展布、断裂剖面变形样式等进行分析;定量计算了新生代以来各洼陷边界断裂的活动速率,划分了断裂活动期次;对研究区新生代演化过程进行了复原,分析了不同时期断裂发育的动力学成因。结果表明:番禺低隆起各洼陷均为“南断北超”结构,控洼断裂沿走向的不连续导致洼陷具有多个沉积中心;控洼断裂新生代活动可划分为初始裂陷期、加速裂陷期、裂后拗陷期、构造复活期和构造平静期;其中,文昌组沉积期和韩江组下段沉积期为断层活动的两大高峰期;番禺低隆起新生代断裂的发育受到基底先存断裂的严格控制,断裂走向自深到浅发生顺时针偏转,与南海区域应力场的偏转密切相关。裂陷期断裂活动强烈,使得番禺低隆起具备发育优质烃源岩的潜力。

       

      Abstract: The potential for oil and gas accumulation in the Panyu Low Uplift is strongly controlled by the development and activity of faults. At present, research on its fault characteristics and evolution process is relatively scarce. Using three-dimensional seismic data covering the Panyu Low Uplift, the structural characteristics, fault plane distribution, and the deformation styles at fault profile of the study area were analyzed. The activity rates of boundary faults in various sags since the Cenozoic were calculated based on the division of the fault activity periods. The evolution process of the Cenozoic in the research area was reconstructed and the dynamic causes of fault development in different periods were analyzed. Results show that all the sags in the Panyu Low Uplift are characterized by faulting in the south and stratigraphic overlapping in the north, and the discontinuous distribution of depression-controlling faults along the strike leads to multiple subsidence centers of depression. The Cenozoic activity of depression-controlling fault could be divided into periods from initial rift, accelerated rift, post rift, tectonic reactivation, to tectonic quiescence. The sedimentation periods of the Wenchang Formation and the lower Hanjiang Formation are two peak periods of faulting. The development of the Cenozoic faults in the Panyu Low Uplift is strictly controlled by the pre-existing faults in the basement, and the fault direction deviates clockwise from deep to shallow in depth, which is closely related to the deviation of the stress field of the South China Sea. The strong activity of faults during rifting in this area has given the low uplift the potential to develop high-quality source rocks.

       

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