Shallow deepwater channels in Baiyun deepwater region of northern continental slope, South China Sea

Based on shallow 3D seismic data with high resolution,shallow deepwater channels in the Baiyun deepwater region are studied so as to guide medium and deep explorations with lower seismic resolution.Large amounts of deepwater channels generate in the slope and the slope base of Baiyun Sag.The channels are classified into 3 types:erosional,erosional/aggradational and aggradational.The geometries of deepwater channels change along with gradient.On the upper slope,single deep feeding channel develops.On the gentle slope with restrictive environment,shallow and broad channels stack vertically.On the basin floor with unconfined environment,small channels spread laterally.In plane view,channel shapes may be straight or bended.The vertical changing characteristics of erosional/aggradational channels in the Baiyun Sag are concluded as follows.Grain size decreases upwards.Mastering channels are found at the bottom and leveed channels are found at the top.The explorations of deepwater sandstones are complicated;hence it is necessary to find deepwater sandstones with big thickness and good communication.