Abstract:

An integration of seism ic，drilling and logging datawith sequence stratigraphic theories reveals that the oil-bearing argillaceous siltstones of low-resistivity at the upper part of the firstmember of the Zhujiang Formation in western Zhujiangkou Basin are tidal sand ridges.This paper studies their geometry and planar distribution，and discusses their hydrodynam ic features and form ingmechanism.Four stages ofwater channels are identified in the upper part of the firstmember of the Zhujiang Formation，and their distribution aswell as logging and seism ic characteristics are also analyzed.It is suggested that there are two kinds of potential subtle traps:intrachannel tidal sand ridge structural-stratigraphic traps and channel lateral-sealing structural-stratigraphic traps.

Key words: low-resistivity oil layer, tidal sand ridge, Zhujiang Formation, Wenchang Sag, Zhujiangkou Basin