珠江口盆地番禺低隆起韩江组高精度层序格架和沉积样式与岩性地层圈闭的发育分布

番禺低隆起是珠江口盆地重要的含油气区。区内的韩江组可划分为3个三级层序,其顶底界面均以削蚀和上超不整合及其对应的整合为界;依据四级旋回的海泛面可进一步划分出11个四级层序或体系域。三级层序SQhj1上部的2个四级层序发育两套具有前积结构的三角洲沉积,SQhj2的低位域广泛发育下切谷充填和低水位楔。结合钻井约束的地震沉积学和古地貌学分析,揭示了四级层序沉积相的平面分布和演化。高位域三角洲前缘砂坝和水下水道、低位下切水道及低位楔三角洲、海滩砂坝砂体等为区内主要的储集砂体,它们与其上覆的海进泥岩形成良好的储盖组合,沿上超斜坡带、下斜坡或坡折带可形成岩性地层圈闭。

High Resolution Sequence Framework,Depositional Pattern and Litho-Stratigraphic Traps of Hanjiang Formation in Panyu Uplift,Pearl River Mouth Basin

Panyu uplift is an important oil and gas-bearing district of the Pearl River Mouth Basin.Hanjiang Formation in the area can be divided into three third-order sequences,which are bonded by unconformities characterized by truncation or onlap contacts and its relevant conformity surfaces.Based on the flooding surfaces of the forth-order cycles,they can be subdivided into eleven forth-order sequences or systems tracts.The upper two forth-order sequences of the SQhj1 sequence consist of two sets of deltaic deposits showing progradational foresets.The lowstand systems tracts of the SQhj2 mainly include incised valley fills and lowstand wedges.Seismic sedimentology and paleo-geomorphology analysis,based on the 3D seismic data and combined with logging-restricted data,has revealed the facies distribution and revolution of important forth-order sequences in the area.The deltaic mouth bar and underwater distributary channel sandstones of the highstand systems tracts,incised channel and lowstand wedge deltaic sandy bodies and shoreline or beach sandbars comprise the major reservoirs in the study area.They are capped by overlying transgressive mudstones,so favorable reservoir and seal assemblages are formed.The economically important litho-stratigraphic traps could be formed around the onlap slope belts and the low slope or slope-break zones.