利用波动方程预测减去法压制海洋地震资料中的多次波

Using wave-equation-predicted minus approach to suppress multiple of marine seismic data

多次波是影响海洋地震资料处理效果的最突出问题之一。多次波的压制方法主要有两大类:基于多次波与一次波属性差异的滤波方法和基于波动方程的多次波预测减去法(如SRME)。滤波方法由于其实用性,是生产中的首选,但也受到使用前提的限制,往往具有一定的局限性。当使用条件不适合时,压制多次波效果不好。SRME法采用迭代法消除与自由界面有关的多次波,该法将地震记录中的任意一个反射轴看作是与自由界面有关多次波的某个子反射,利用数据一致性原理,将原始叠前数据与自身沿自由界面进行时间与空间域褶积。在此基础上,对每个炮检对,分别从原始数据中抽取相应炮点位置的共炮点道集,并从多次波预测算子中抽取相应检波点位置处的共检波点道集,再依据数据一致性原理,沿自由界面将上述共炮点道集与共检波点道集进行组合,使得炮点位置与检波点位置一致。然后,将所有满足该组合条件的地震道两两褶积并求和,即可预测出上述炮检对地震道的自由界面多次波。最后,将多次波从输入数据中减去。本文通过实例,重点介绍了SRME方法的原理及其在海洋地震资料处理中的应用效果。

The multiple is the most troubling issue affecting the marine seismic data processing effects. The multiple-suppressed approaches mainly can be divided into two categories; the filtering approach based on the difference between multiple and primary attributes and multiple-predicted minus approach based on wave equation (such as surface-related multiple elimination-SRME). The filtering approach is primary selection in the production because of practicality, but limited in used precondition that often has some limitation. The multiple-suppressed effects are poorer when the used condition is inappropriate. The SRME approach is using iteration to eliminate the free interface-related multiple, which sees any reflection event on seismic records as a certain sub-reflection of free interface-related multiple,using data-consistent principle for convolution of raw prestack data with itself along free interface in time and space domains. On that basis,for each shot-receiver pair,the common shot gathers are sorted from raw data at relevant shot points respectively and common receiver gathers are sorted from multiple-predicted operators at relevant receiver points, and again according to data-consistent principle to composite abovementioned common shot gathers with common receiver gathers along the free interface, making consistence of position of shot points with that of receiver points. Then,the all seismic traces meeting the composition condition are convolved and summed two by two,which can predict free interface-related multiple of seismic traces of abovementioned shot-receiver pair. Finally, minus of multiple from input data is implemented. The paper emphatically introduced the principle of SRME approach and illustrated the application effects of marine seismic data processing by cases.