基于模型的薄互层地震属性分析及其应用

Seismic attributes analysis based on model in thin interbedded layers and its application

反射振幅和瞬时频率是砂体厚度预测中常用的2个地震属性,但建立这2个基本属性与砂体厚度之间的关系所依据的实验模型是简单的单砂体楔形模型,不一定适用于薄互层情况。为此设计了2个薄互层地质模型,利用褶积算法产生合成地震记录,进而分析薄互层条件下反射振幅和瞬时频率与砂体累计厚度之间的关系。实验结果表明:在薄互层的累计厚度小于1/4波长的情况下,薄互层反射振幅和瞬时频率与单砂体模型具有类似的特征,砂体累计厚度越大,地震反射振幅越大,瞬时频率越小。以上结论在华北油田实际地震属性分析中得到了验证和应用。

Reflection amplitude and simultaneous frequency are two basic seismic attributes widely used to predict sand body thickness.However, the experimental model,from which the relationship between the two attributes and sand thickness were derived,is a simple wedge model of single sand body,which may not be applicable to thin interbedded layers.Therefore,two thin interbedded models were designed and synthetic seismic records were generated by using convolution method,then,the relationship between reflection amplitude and cumulative sand thickness,as well as the relationship between simultaneous frequency and cumulative sand thickness, was analyzed.The experimental result indicates that when the cumulative thickness of thin interbedded layers is less than a quarter wavelength,and the characteristics of reflection amplitude and simultaneous frequency in thin interbedded layers are similar to those in single sand body model.Larger cumulative thickness leads to stronger seismic reflection amplitude and smaller simultaneous frequency. The above conclusions were verified in seismic attribute analysis in Huabei oilfield.