多次波贡献道集优化在波场延拓压制多次波中的应用

Application of Optimized MCG to Multiple Attenuation Based on Wavefield Extrapolation

基于波场延拓的多次波预测和减去技术是压制水层多次波的有效手段。常规波场延拓方法中,由已知的原始波场通过与水底各点的格林函数褶积来预测地震数据中的多次波,但在进行褶积相加时只有稳相点附近的能量才对求和结果有影响。提出了一种基于高精度拉东变换的稳相点拾取方法,是利用拉东域中的低曲率信息提取稳相点附近的同相轴,利用KL变换突出水平同相轴,得到优化的多次波贡献道集,对其进行叠加,能够很好地解决波场延拓预测的多次波存在假象的问题,并采用贝叶斯匹配减去技术将预测的多次波去除,提高了预测的多次波的精度,在同相轴两端出现的假象得到了很好的消除,理论和实际数据的应用结果验证了该方法的有效性和可行性。

Multiple prediction and subtraction techniques based on wavefield extrapolation are effective for suppressing multiple of water layers. In the conventional wavefield extrapolation method, the multiples of the seismic data are predicted from the known total wavefield by the Green function convoluted with each point of the bottom. However, only the energy near the stationary phase point has an effect on the summation result when the convolutional gathers are added. We proposed a stationary phase point extraction method based on high-resolution Radon transform and K-L transform. Low curvature information can be extracted in the radon domain, which represents the energy near the stationary phase point and then use K- L transform to flatten the events in MCG. Finally, the multiple can be predicted by summing the optimized MCG to satisfy the stationary phase assumption. The matching subtraction technique based on Bayesian estimation is used to remove the multiple, which improved the accuracy of the multiple predicted by the wavefield extrapolation and the artifacts appearing around the events of the multiple are well eliminated. The validity and feasibility of the proposed method are verified by the theoretical and practical data.