基于共散射道集的叠前时间偏移/反偏移提高叠前数据质量

为了提高叠前数据质量,将叠前时间偏移/反偏移与共散射点道集相结合,提出了一种新的时间偏移/反偏移方法.利用改进的CRS参数建立精确的速度模型,提高偏移成像质量.将振幅映射到共偏移距顶点来生成共散射点道集,将偏移和中点上的多参数叠加,通过叠加数据,实现了叠前数据增强,道集的数量远高于传统叠前时间偏移的叠加数量.利用基于中点位移、半偏移距和偏移速度的算子进行反偏移处理,能量重新分配回时间域中的每个绕射同相轴,压制噪声,地震资料信噪比和成像精度均得到了提高.提高质量后的叠前数据可用于后续的速度分析、叠加、偏移等常规处理中,效果好于原始CMP道集.模型和实际数据的计算结果均验证了该方法的正确性和有效性,该方法在低信噪比资料的处理中将会有广阔的应用前景.

Prestack time migration/demigration based on common scattered gather improves the quality of prestack data

In order to improve the quality of pre-stack data,a new time domain migration/premigration method is proposed by combining the prestack time migration/premigration with Common Scatter points.The improved CRS parameters are used to establish an accurate velocity model,which improves the accuracy of time migration.By mapping the amplitude to the common offset vertex to generate the common scattering point trace set,the multiple parameters on the offset and midpoint are superimposed,and the prestack data is enhanced by superimposing the data.The number of trace sets is much higher than that of traditional pre-stack time migration.By using the operators based on mid-point displacement,half-offset and migration velocity,the energy is redistributed back to each diffraction in-phase axis in the time domain,the noise is suppressed,and the signal-to-noise ratio and imaging accuracy of seismic data are improved.The improved prestack data can be used in subsequent conventional processing such as velocity analysis,stack and migration,and the result is better than the original CMP data set.The correctness and validity of this method have been verified by the model and the calculation results of the actual data.