琼东南盆地南部深水区中新统层序地层地震相与沉积演化特征

根据高分辨率地震资料的反射和结构特征,结合地震剖面振幅旋回性变化,将研究区中新统划分为3个层序组及6个三级层序。三个层序组自下而上分别对应三亚组、梅山组及黄流组三个地层组。在层序格架内识别出六种典型的地震相类型:丘状地震相、前积地震相、水道充填地震相、杂乱地震相、波状地震相以及平行—亚平行地震相。三亚组以波状反射和平行—亚平行反射为主;梅山组以丘状反射和波状反射为主,梅山期是生物礁发育的繁盛期;黄流组仍以丘状反射和波状反射为主,但丘状反射规模较梅山组明显减小。中新统整体上表现为一个水进的过程,从滨浅海环境过渡到浅海环境再逐渐过渡到半深海环境,发育有扇三角洲、生物礁滩以及水道沉积体系,而地震相的分布和演化明显受沉积体系演化的控制。生物礁和水道沉积可能是该区的有利储层。

Seismic Facies and Sedimentary Evolution Characteristics of Miocene Sequence Strata in the Deep-water Region,Southern Qiongdongnan Basin

Based on the reflection and architectural characteristics of the high resolution seismic data,and combined with the cyclic variations of seismic attribute,the Miocene sedimentary sequence can be divided into three sequence groups and six 3rd-order sequences in the deep-water region,Southern Qiongdongnan Basin.From bottom to top,three sequence groups correspond to Sanya,Meishan and Huangliu Formations respectively.In the sequence framework,six types of typical seismic facies are indentified,which include moundy seismic facies,progradational seismic facies,channel-filled seismic facies,chaotic seismic facies,wavy seismic facies as well as parallel and sub-parallel seismic facies.Wavy reflection and parallel and sub-parallel reflection mainly develop in Sanya Formation while the moundy and wavy reflections dominates in Meishan Formation.Reefs thrived rapidly during Meishan age.Moundy and wavy reflections remained dominant but the scale of the moundy reflection was obviously minishing in Huangliu Formation compared with that in Meishan Formation.The whole Miocene sequence displayed a transgression progress in which the sedimentary environments changed from littoral and neritic to shallow marine and then gradually transited to bathyal so that fan deltas,reef shoals and channel sedimentary systems developed.It is known that the distribution and evolution of seismic facies are obviously controlled by the evolution of the sedimentary systems.It is suggested that the reefs and channel sediments may be the favorable hydrocarbon reservoirs.