The Origin of Deep-Water Sandbody in Well LW3-1-1 in the Zhujiang Formation of Baiyun Sag, Pearl River Mouth Basin

According to comprehensive researches on indicators of lithology，indicators of primary sedimentary structures，bioclasts and matrix, summarize sedimentary characteristics and origin for sandbody in the Zhujiang formation of the Well LW3-1-1. The main rock types are mid-coarse grained sandstone with heavy coloured mudstone at its top and bottom，followed by very coarse grained sandstone with fine gravel occurs locally. It is showed that the sandstones are well sorted with very low content of mud, and possess high compositional maturity and textural maturity. Massive bedding, typical inverse graded bedding and inverse-normal graded bedding occur in the sandstones. So in general, it is a set of sedimentation of grain flow and density-modified grain flow.