南海北部小型海陆过渡相断陷地震相分析及沉积充填演化史研究——以琼东南盆地崖南凹陷崖城组为例

SEISMIC FACIES ANALYSIS AND FILLING HISTORY RECONSTRUCTION OF SMALL FAULTED DEPRESSIONS IN NORTHERN SOUTH CHINA SEA——A HISTORICAL CASE ON YACHENG FORMATION IN YANAN DEPRESSION OF THE QIONGDONGNAN BASIN

南海北部琼东南盆地众多凹陷存在有海陆过渡相沉积,选取浅水区井孔资料相对较多的小型断陷即崖南凹陷作为研究对象,在等时地层格架内,对该凹陷海陆过渡期崖城组地震相进行深入解剖;并综合利用经典沉积模式以及凹陷周缘浅水地区井孔资料来建立地震相与沉积相之间的关系,赋予地震相以地质意义,进而预测了凹陷无钻井资料地区各种沉积相的展布,再现了崖城组不同历史时期的沉积演化。同时,借鉴国内外断陷盆地经典模式,以崖南凹陷为原型建立了小型海陆过渡相断陷地震相模式和沉积充填模式,这对研究该凹陷与深水区类似凹陷具有重要意义,也为今后向深水勘探区纵深挺进提供了有力保障。

The Yanan Depression, a depression located in shallower water of the Qiongdongnan Basin, was selected as a case to study the seismic facies and the filling history of a depression contains transitional facies for relatively more logging data are available there. The seismic facies of the Yacheng Formation is carefully studied in an isochronous stratigraphic framework, and the relations between seismic facies and sedimentary facies were established upon the existing stratigraphic framework, classic depositional models and logging data in shallow water. The relations make it possible to predict the distribution of sedimentary facies in the areas without logging data. Referring to the classic model of a faulted basin and using Yanan Depression as the prototype, this paper established the seismic facies and depositional infilling model of a small faulted depression of transitional facies. The results are significant not only for this depression, but also for similar depressions in deep water. The model could be used as a powerful weapon for future exploration in deep water.