珠江口盆地番禺隆起东南缘断裂坡折带及其对低位域构造—岩性油气藏的控制作用

Fault Slope-Break Zone and Its Control over Structural Lithostratigraphic Traps of Lowstand System Tracts in Southeast Panyu Uplift of the Pearl River Mouth Basin

番禺隆起是珠江口盆地中南部的一个重要含油气区。区内新近系沉积期主要发育NW向和近EW向的同沉积断裂,它们的发育和分布控制着沉积充填和总体的古构造地貌特征。古隆起的东南和东北缘发育的主要同沉积断裂形成明显的古地貌突变带或断裂坡折带。东南缘的主控断裂是由裂陷期发育的缓坡反向断裂所形成的,构成了番禺隆起与白云深凹带的分界。地震相、地震属性等分析和追踪其分布范围揭示出,珠海组、珠江组中下部层序的低位域三角洲砂体沿断裂坡折带下斜坡呈裙带状分布。研究指出断裂坡折带下斜坡低位域具有形成构造—岩性油气藏的良好条件,并为该区近期的勘探突破提供了重要依据。

The Panyu Uplift is an important oil and gas-bearing district in central south Pearl River Mouth Basin. A series of northwest and east-west striking syndepositional faults were developed during Neogene, and their development and distribution controlled the paleo-structural framework and the sedimentary filling pattern. The main syndepositional faults along the southeastern and northeastern margins of the ancient uplift formed obvious geo- morphologic abrupt zones or fault slope-break zones. The main controlling faults in the southeastern part were formed by the antithetic faults in the hinge gentle slope which were developed during syn-rifting and formed the boundary between Panyu Uplift and Baiyun deep sag. An analysis of seismic facies and seismic attributes has shown that the lowstand system tract deltaic sandstones in the middle-lower part of Zhuhai and Zhujiang Formations were developed and distributed along the low slope of the fault slope-break zone. Researches indicate that the low slope lowstand system tracts along the fault slope-break zone constitute a favorable condition for the formation of lithostratigraphic or structural-stratigraphic traps. This study hence has offered an important basis for the recent exploration breakthrough in this area.