惠州凹陷A断层转换带文昌组地震相特征及沉积相演化

Seismic Facies Characteristics and Sedimentary Facies Evolution of Wenchang Formation in Transfer Zone of Fault A in Huizhou Sag

惠州凹陷位于珠江口盆地北部坳陷带中部，是南海东部海域最富烃的凹陷之一。惠州凹陷古近系文昌组钻井资料少，勘探程度低，单纯依靠单井相分析来进行沉积相的平面研究比较困难。通过对三维地震剖面的精细对比分析，将惠州凹陷A断层转换带文昌组地层划分为SQ1～SQ4等4个地震层序。通过对A断层转换带地震相的研究，在地震剖面上识别出了楔状地震相、前积（侧积）地震相、席状平行～亚平行地震相和透镜状地震相，并确定了地震相在平面上的分布范围。在对单井钻遇文昌组地层的各层序沉积相进行深入研究的基础上，结合区域地质背景，将平面地震相转化为沉积相，对文昌组各层序沉积相分布及演化特征进行了分析。确定了本地区主要发育辫状河三角洲、扇三角洲、滨～浅湖及中～深湖相沉积，其中辫状河三角洲是本地区占主导地位的沉积相类型。

Huizhou sag locates in the middle of northern depression belt of the Pearl River Mouth Basin,which is one of the richest hydrocarbon-bearing research of the sedimentary facies through depressions in eastern South China Sea.It＇s difficult to make plane single well facies only for low exploration degree and few drilling information in the Wenchang formation of Huizhou sag.By analyzing and contrasting the 3D seismic sectio the Wenchang formation can be divided into SQ1-SQ4 four seismic sequences in transfer zone of fault A n, Huizhou sag.After the research of the seismic facies of the transfer zone of fault A ,wedge-shaped seismic fa- cies,foreset seismic facies,sill-like parallel-subparallel seismic facies and lens seismic facies are identified on the seismic sections.And the distribution range of the seismic facies on the plane is known.Based on the thorough research of the sedimentary facies in every sequence of Wenchang formation drilled by single well, the seismic facies may be inverted to sedimentary facies under the regional geological background.Distribution and evolution characteristics of the sedimentary facies in sequences of Wenchang formation are analyzed.It is found out that the sedimentary facies includes braided river delta,fan delta,shore-shallow lake and semideep-deep lake facies,among them the braided river delta is the most important sedimentary facies in this area.