地震绕射波波场分离与成像方法综述

A review of seismic diffraction wavefield separation and imaging methods

地震资料中的绕射波携带了小尺度地质异常体信息,可以更加清晰地刻画断层、边界以及缝洞储集体等非均质体构造,但在常规地震资料处理中,绕射波往往作为噪声被压制掉。对分离地震绕射波和反射波的方法以及绕射体单独成像方法进行了研究。首先,从理论上阐述了地震绕射波的产生机制及地震特征;然后,从绕射波与反射波分离的角度出发,利用两者在不同域的形态差异,通过平面波分解技术、多聚焦叠加技术和聚焦切除反聚焦技术对绕射波与反射波进行分离;最后,应用高精度偏移方法对分离后的绕射波进行偏移成像。基于剖析和总结典型地区的应用实例,发现绕射目标单独成像可以实现小尺度异常体的识别,非均质地质体的成像精度显著提高,对高精度地震解释具有重要意义。由于绕射波本质上是三维现象,在三维情况下实现绕射波与反射波的分离并成像具有重要意义,也是未来研究与应用的发展方向。

The diffracted wave in seismic data carries the information of small-scale geological anomalies,which can assist in enhancing the accuracy of describing heterogeneous structures,such as faults,boundaries,and fracture cave reservoirs.However,in conventional seismic data processing,the diffraction wave is often suppressed as noise.In this study,the seismic diffraction and reflection waves separation method and the separate imaging method of diffractor are studied.First,the generation mechanism and seismic characteristics of seismic diffracted wave were developed theoretically.Then,from the perspective of the separation of diffracted wave and reflected wave using their morphological differences in different domains diffracted and reflected waves were separated using plane wave decomposition technology,multi-focus superposition technology,and focusing-mute-defocusing technology.Finally,the high-precision migration method was used to migrate and image the separated diffracted wave.By dissecting and summarizing the application examples in typical areas,results showed that the diffraction target imaging alone can achieve the identification of small-scale abnormal bodies.Additionally,the imaging accuracy of heterogeneous geological bodies significantly improved,which is critical for accurate high-precision seismic interpretation.