一个深水区深层沉积相早期预测方法——以南海北部深水区D凹陷渐新统为例

深水区钻井稀少，且钻探深度浅，仅利用少量的钻井资料无法完成深水区深层砂泥岩分布以及沉积相分布预测，影响烃源岩及深层有利储集相带预测。以中国南海北部深水区D凹陷渐新统为对象，利用地震速度谱和钻井资料，通过速度岩性分析，预测砂泥岩分布特征，并综合分析地震相与单井沉积相、凹陷砂泥岩分布的匹配关系，划分D凹陷渐新统沉积相。结果表明：L组为海陆过渡沉积，Y组为滨浅海沉积。整个渐新统在凹陷中部和南部的浅海相以及Y组在凹陷边缘局部发育的海岸平原相等富泥沉积相，为有利的烃源岩发育相带，而Y组在凹陷边缘的扇三角洲相、滨海相以及L组在凹陷北部的三角洲相、扇三角洲相和滨海相等富砂沉积相为有利的储集相带。该方法克服资料不足的困难，降低传统地震相转沉积相预测方法的多解性，为深水区深层烃源岩以及有利储集相预测提供依据。

Early Sedimentary Facies Prediction of Deep Layers in Deep-water Area:An Example of Oligocene of D Sag in the Deep-water Area of Northern South China Sea

Owing to the few wells and shallow well depth,it is impossible to predict the distribution of sand and shale and sedimentary facies of deep layers in deep water area by few drilling data.Aimed at the Oligocene of D Sag in the deep-water area of northern South China Sea,this study predicted the distribution of sand and shale based on seismic velocity-lithology analysis by using seismic velocity spectrum and drilling data.Further,the Oligocene sedimentary facies of D Sag was predicted based on the comprehensive analysis about seismic facies and its relationship to single well sedimentary facies and sand and shale distribution.The result showed that the L Group is transitional facies and the Y Group is littoral neritic facies.Neritic facies in the central and southern of the sag in the whole Oligocene,and the local coastal plain on the edge of the sag in the Y Group are rich in shale.While the fan delta and littoral facies on the edge of sag in the Y Group and the delta,fan delta and littoral facies in the northern of the sag in the L Group are rich in sand.