白云凹陷陆架坡折带识别方法

Identification Method of the Shelf Break Zones in Baiyun Depression

珠江口盆地深水区的油气勘探已获得战略性突破,为提高勘探成功率及降低勘探开发成本,需要运用层序地层学,对深水沉积体系进行研究。深水沉积体系研究发现,陆架坡折带为重力流发生的主要区域,其连接着物源与深水扇,控制高位域砂体的分布与深水扇的发育。陆架坡折带的识别,在低位域深水扇的分析中具有承上启下的作用。本文阐述了陆架坡折带在深水沉积体系研究中的意义,并以白云凹陷为靶区,总结了进行陆架坡折带识别的多种方法。当海退规模较大、陆源充足时,三角洲前积最后一个顶超点就是陆架坡折带;当海退规模较小,或陆源供给不足时,需要结合地层侵蚀、海侵期地层初始上超点、三角洲前积、层序界面之上深切谷出现位置、地震属性图变化特征、沉积水道指向突变、钻井岩性-电性组合及横向对比变化等多种因素,进行综合判断。

Oil and gas exploration of the deep-water area in Pearl River Mouth Basin has been a strategic breakthrough.In order to improve the success rate of exploration and reduce the cost of exploration and de- velopment,sequence stratigraphy is applied to the study of the deep-water sediment system.Gravity flow main- ly occurs in the shelf break zones ,which connect the provenance and deep water fan and control the distri- bution of high-stand sandbodies and growth of the deep water fan.The identification of the shelf break zones has a connecting role for the research on the low-stand deep water fan.The significance of the shelf break zones in the deep-water sedimentary system is stated.The identification methods for the shelf break zones in Baiyun depression are summed up.When regressive scale is larger and terrigenous sources are sufficient,the last toplap point of the delta foreset is the shelf-break zone ;when regressive scale is smaller scale or ter- rigenous sources are insufficient,various factors are required for judgment,such as stratigraphic erosion,the first onlap point of transgression stratigraphy ,the delta foreset,the location of incised valley above stratigraphic sequence ,various features of seismic attribute map ,the change of channel direction,the lithology and electric nature of drilling and the change of lateral correlation