基于Marchenko理论压制自由表面多次波方法研究

常规虚源点Marchenko自聚焦多次波预测方法只适用于预测不含自由表面的多次波模型,局限于压制层间多次波,该方法在构建上下行格林函数场前,必须从反射响应中去除所有与表面相关的多次波.本文对构建上下行Marchenko格林函数方程进行改进,得到了包含一次波、层间多次波和自由表面多次波的格林函数,利用改进的Marchenko自聚焦预测方法预测自由表面多次波.本文利用水平层状模型数据及SMARRT模型数据证明,改进后的Marchenko法预测海底相关的自由表面多次波效果较为理想,该方法避免了常规SRME自由表面多次波预测方法需要近道重构的缺陷,能够有效提高地震资料的信噪比和分辨率.

Research on suppressing free surface multiples based on Marchenko theory

The conventional multiple prediction method based on virtual source position Marchenko autofocusing is only applicable to the multiple models without free surface and is limited to the suppression of interlayer multiples.This method must remove all surface-related multiples from the reflection response before retrieving the up and downgoing Green′s function fields.This work improved the Marchenko equation to compute up and downgoing Green′s function,and obtained the Green′s function including primaries,internal multiples,and surface-related multiples.The modified Marchenko autofocusing prediction method can predict surface-related multiples.Using a horizontally layered model data and model data with dip,it was proved that the modified Marchenko method can yield relatively ideal results in prediction of surface-related multiples and interlayer multiples of seafloor,and avoids the defect that the conventional SRME surface-related multiple attenuation method needs a near route to reconstruct,thus can effectively improve the signal-to-noise ratio and resolution of seismic data.