地震波叠前逆时偏移——模型分析与应用

Abstract

根据地震波逆时偏移技术与常规克希霍夫和单程波深度成像技术的算法差异，开展了针对逆时偏移方法关键技术的若干问题分析。从理论模型的脉冲响应出发，理清了低频背景逆时噪声的成因机理，采用上下行波波场分离相关逆时成像条件实现有效压制；采用基于扩散滤波的拉普拉斯算子实现了低频背景逆时噪声的横向相对保幅压制处理，其效果要优于常规的高通滤波方法；对比分析了不同阶数声波方程1D逆时偏移处理的成像波形差异以及与克希霍夫结果的差异。计算结果表明，综合考虑逆时噪声和波形差异成因及其对应的解决方法，在实际陆地地震资料逆时偏移中取得了较好的应用效果。 According to the algorithmic difference between the seismic wave reverse-time migration technology and the conventional Kirchhoff integral method’s depth migration and one-way wave depth migration technology, we carry out several analyses of key problem on specific aspects of the reverse-time migration method. The paper starts from the theoretical model’s impulse response, and finds out the origin mechanisms of the low-frequency reverse-time noise, effectively weakening the low-frequency noise by using correlative reverse-time imaging condition with up/down going wave-field separation processing. The low-frequency reverse-time noise is eliminated afterward with relatively horizontal-amplitude preserved Laplacian operator based on diffusion filter, and this method’s processing effect is better than that of conventional high-pass filter method. What’s more, 1D reverse-time migration is carried out using different order acoustic wave equations together with 1D Kirchhoff depth migration. The computational results show that perfect application results are achieved in the reverse-time migration processing of practical land’s seismic data by considering the above factors.