西沙海槽盆地古近系沉积特征

西沙海槽盆地位于琼东南盆地东部,是南海北部陆坡深水区的有利油气勘探区域。该盆地古近系发育有始新统、渐新统两套主要地层层序。始新统主要发育平行-亚平行地震相、杂乱反射地震相以及前积地震相,渐新统主要发育一套平行-亚平行反射地震相。利用地震资料对西沙海槽盆地的地层砂岩百分含量(Ps)进行了计算,结合地震相分布特点以及区域构造-沉积背景对该盆地的沉积特征进行了分析。结果表明,西沙海槽盆地始新世为陆相湖盆沉积体系,神狐隆起区以及西沙隆起区成为始新统主要物源区;渐新世主要接受滨、浅海相沉积,主要物源区为北部的神狐隆起区。

Sedimentary Characteristics of Paleogene in Xisha Trough Basin

Xisha Trough Basin located in the Eastern Qiongdongnan Basin was the advantageous oil and gas exploration area of the northern continental slope of the South China Sea.Xisha Trough Basin developed Eocene and Oilgocene stratigraphic sequenses.Eocene included parallel-subparallel seismic facies,untrimmed seismic facies and foreset seismic facies.Oilgocene mainly included parallel-subparallel seismic facies.The sand-ground proportion was researched on the basis of seismic data,in combination with seismic facies distribution and structural sedimentary background,the sedimentary characteristics of the basin were analyzed.The result indicates that Eocene developes a land lake depositional system,Shenhu uplifted area in the north of the basin and Xisha uplifted area in the south of the Basin are the main source areas;Oilgocene developes offshore and shelf sea sediment,Shenhu uplifted area in the north of the basin is the main source area.