地表多次波应用研究

Surfacerelated multiple migration

（斯坦福大学地球物理系, 美国加利福尼亚CA94305）

Geophysics department, Stanford University, Palo Alto, CA 94305, USA

在地震资料处理中，多次波通常作为噪声被压制和消除。但和一次波类似，多次波是地下反射层的多次反射，因此也蕴含了地层结构信息。如果把一次反射波当作震源（准震源），把多次反射波当作接收点波场，就可以像处理一次波一样对多次波进行偏移成像。首先通过互相关技术将多次波转化成准一次波；然后以一次反射波地表接收点作为准震源，对准一次波进行偏移成像。准一次波的运动学特征与一次波的相似，因此可以用准一次波来弥补一次波记录中缺失的近炮检距数据，以及在有陡倾角构造的情况下，有可能弥补缺失的远炮检距数据。数值模拟表明，多次波偏移能得到和一次波相似的成像结果。

In seismic processing, multiples are usually suppressed and removed as the noise. However, similar to primaries, multiples also record multiple reflections from the subsurface and so contain the reflectivity information of the subsurface. Regarding the primary as the source wave field and the multiple as the receiver wave field, multiples can also be imaged like the processing of primary. Firstly, cross correlation technique is used to transform multiples into pseudo-primaries. Then, by taking the surface receiving points as pseudo source, the pseudo-primary is imaged as primary migration. The kinematics features of pseudo-primary is similar to that of primary, so the pseudo-primary can be used to compensate the absent of near offset data in primary record. Sometimes they can also be used to fill far-offset gaps with the existence of steeply dipping reflectors. Synthetic data examples show that the image result obtained by multiple migrations is similar to that from primary migration.