扇三角洲前缘薄互层叠置砂体的敏感属性分析

地震属性与砂体厚度及砂体速度之间的敏感性关系一直是地球物理工作者研究的课题.针对苏北盆地高邮凹陷HJ地区戴南组扇三角洲前缘的沉积地质特征,本文设计了5个薄互层叠置砂体模型:4个不同位置处局部砂体速度变化模型及1个局部砂体累积厚度变化模型.采用褶积正演模拟方法,从正演剖面中提取了50种地震属性,优选振幅类和层序类的4种敏感地震属性.最后分析了这4个敏感地震属性与模型中局部砂体速度变化和局部砂体累积厚度变化之间的敏感性关系.结果表明:振幅类属性对薄互层砂体的局部累积厚度变化较为敏感,对薄互层砂体的局部速度变化敏感性要弱一些;层序类属性对薄互层砂体的局部速度、局部累积厚度变化以及砂体在纵向上的分布位置都较为敏感.

Sensitive seismic attribute analysis on thin interbed overlapped sandbodies in fan-delta front

The sensitivity relations among seismic attributes, sand thickness and sand velocity have always been key topics for geophysicists. In this article we analyze some seismic attributes sensitive to interbed sandbodies. For sedimentary geological features of fan-delta front in the Dainan Formation, Gaoyou Sag, Subei Basin, five models of overlapped thin interbed sandbodies are designed: four models with local sand velocity change, and one model with cumulative thickness change. Convolution forward modeling is utilized, and 50 kinds of different seismic attributes are extracted from seismic data, then four different sensitive seismic attributes are optimized from the amplitude class and sequence class. Finally, the sensitivity relations are analysised among four sensitive seismic attributes and local sands with velocity and cumulative thickness changes. The results show that amplitude attributes are relatively more sensitive to cumulative thickness change than velocity change. Sequence attributes are quite sensitive to sand velocity and cumulative thickness changes, and its longitudinal distribution.