莺歌海盆地D13区新近系黄流组大型海底扇地震识别及含气性预测

通过层序地层学和地震沉积学方法，对莺歌海盆地D13区新近系黄流组大型海底扇逐级解剖，并通过多属性融合地震切片技术对海底扇内水道进行雕刻识别，利用地震剖面上的“平点”反射特征预测含气甜点。研究结果表明：①研究区大型海底扇为古蓝江三角洲再次搬运而形成，发育了自南东向北西依次退积的4期扇体，并识别出11期砂体，早期扇的顶部地层被晚期扇不同程度侵蚀，相邻扇砂体间纵向局部连通。②海底扇中优质储层主要分布在沉积能量强、高水动力条件下形成的海底扇水道中，扇体内发育串珠状、复合型、曲流河形等类型的水道，其中“大、厚、宽”的水道为厚层优质“甜点”储层发育区；③地震剖面上的“平点”反射特征可用于识别水道沉积中的含气甜点，莺歌海盆地D13区平点具有水道内部近水平反射、水道底面反射能量变弱、平点向构造低部位略倾斜等基本特征。

Seismic identification and gas-bearing prediction of large-scale submarine fans of Neogene Huangliu Formation in D13 area of Yinggehai Basin

Through the methods of sequence stratigraphy and seismic sedimentology,the large-scale submarine fans of Neogene Huangliu Formation in D13 area of Yinggehai Basin were dissected step by step,the channels in the fans were characterized and identified by multi-attribute fusion seismic slicing technology, and the gas-bearing sweet spots were predicted by the flat point reflection characteristics on seismic sections. The results show that:(1)The large-scale submarine fans in the study area were formed by the re-transportation of the paleo Lanjiang delta. Four stages of fan bodies retrograde successively were developed from southeast to northwest,and 11 stages of sand bodies can be identified. The top strata of the earlier fans were eroded by the later fans,and the sand bodies of the adjacent fans were connected vertically and locally.(2)The high-quality reservoirs in the submarine fans are mainly distributed in the submarine fan channel formed under strong sedimentary energy and high hydrodynamic force. The channel types such as bead-shaped channels,composite channels and meandering river shaped channels are developed in the fan,among which the large,thick and wide channels are the development areas of thick and high-quality sweet spot reservoirs.(3)The flat spot reflection characteristics on the seismic sections can be used to identify gas-bearing sweet spots in the channels. The flat spots in D13 area have the basic characteristics of near horizontal reflection in the channel,weakening reflection energy at the bottom of the channel, and slight inclination of the flat spot to the lower part.