波动方程保幅地震偏移成像方法

Preserved amplitude seismic migration imaging method based on wave equation

地震数据中饱含有丰富的旅行时信息和振幅信息。传统的波动方程地震偏移成像方法忽略了介质参数变化对地震波振幅的改造,不能准确描述地震波传播的动力学特征。为此,基于严格的解耦理论,从全声波方程出发,进行单程波保幅分解,得到直观、高效率的的单程波动方程,直接面对地震波传播波场的压力分量进行延拓,从而将振幅误差补偿作为偏移的一部分在偏移过程中进行,实现地震偏移成像在获取正确位置的同时也获取真实振幅的信息。数值试算表明,该方法可使散射能量聚焦、归位,提高成像精度;可输出正确反映地下反射系数的振幅信息。

Seismic data include rich travel-time and amplitude information. Based on strict decoupling theory, and started from full acoustic wave equation ,we derive the high efficient and direct-viewing one-way wave equation through one-way wave＇s preserved-amplitude decomposition. So we can realize amplitude error compensation as one part of migration during migration period. Further more, this method has a special function that can give true amplitudes as well as the correct locations at the same time. Numerical value testing indicates that this method can not only make the scattering energy to be focused and migrated to a correct position for improving the imaging accuracy, but also output the amplitude information which reflects the correct subsurface reflection coefficients. So this method can provide more real seismic data for following seismic attribute analysis, such as AVO/AVA.