南海北部陆坡白云深水区浅层深水水道沉积

应用分辨率高的浅层三维地震资料,对白云深水区浅层深水水道沉积系统进行研究,以此指导地震分辨率降低的中深层勘探。在白云凹陷浅层的陆坡、陆坡底都发育大量深水水道,按成因可分为3类:侵蚀型、侵蚀/加积型和加积型。深水水道的几何形态随地形坡度的变化而变化,在上陆坡发育单一的深切供应水道,在坡度较缓的限制性环境内,多个较宽浅的水道垂向叠加,在盆底的非限制性环境,多个小型水道侧向迁移。在平面上,水道形态既有顺直型也有弯曲型。白云凹陷侵蚀/加积型水道垂向变化特征表现为粒度整体向上变细,底部为主水道,顶部为有堤水道。深水水道砂岩的勘探具有复杂性,因此找到厚度大、连通性好的水道砂岩尤为重要。 

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.