保幅型裂步傅里叶叠前深度偏移方法探讨

利用地震资料进行岩性分析,要求叠前深度偏移成像结果不但包含走时信息,还要包含振幅信息。但是应用传统的单程波方程偏移算子只能得到地震波的运动学特征,无法得出其动力学特征。裂步傅里叶叠前深度偏移方法是基于单程波方程的一种快速稳定的叠前深度偏移方法,它遵循速度场分裂的思想,分别通过频率-波数域的相移处理和频率2空间域的时移处理来实现。但是传统单程波方程在保幅性方面的缺陷制约了该方法在岩性成像中的应用。文中引入了裂步傅里叶保幅偏移算法,分别通过频率2波数域的相移保幅校正算子和频率-空间域的保幅时移校正算子实现了保幅偏移。文中针对Marmousi 模型的炮点照明分析结果及其叠前深度偏移成像结果的对比表明了该方法的正确性和有效性。

Research and application of amplitude-preserved split-step Fourier prestack depth migration

Both the travel-time information and amplitude information are required to be contained in the prestack depth migration imaging results in the lithology analysis. Based on one-way wave equation , split step Fourier prestack depth migration method is fast and steady. It is carried out by phase shift processing in frequency-wave number domain and time shift processing in f requency-space domain according to the idea of velocity field split . The disadvantages of conventional one-way wave equation in amplitude preserved migration restrict the application of this method in lithology imaging. So split-step Fourier amplit ude-preserved migration operator was put forward. It carries out the amplitude-preserved migration with the phase shift amplitude-preserved correction operator in frequency-wave number domain and time shift amplitude-preserved correction operator in f requency-space domain. The comparison of the shot illumination analysis result s and the prestack depth migration imaging results aiming at Marmousi model indicated the validity and effectiveness of this method.