复杂海底自由表面多次波预测方法

针对崎岖海底多次波路径复杂、绕射波及绕射多次波发育等情形，自由表面多次波压制技术（SRME）预测多次波模型存在数据信噪比低、动力学和运动学信息欠准确等不利因素，提出了基于单程波及双程波波动方程延拓的多次波预测方法。即基于波动方程并联合SRME技术，利用岩石物理模型对地震记录进行波场延拓，得到预测的多次波模型；同时采用自适应匹配相减方法提高复杂海底多次波压制效果。理论模型及实际数据试验表明：相对于单一的SRME多次波预测法，所提方法预测的多次波模型具有更高信噪比、与实际多次波在大多情况下的运动学和动力学特征吻合度更高。该方法理论上需已知准确岩石物理模型，由于海洋地震资料多次波主要是自由表面相关多次波，因此在仅已知海水及海底岩石物理参数情况下，该方法也能预测大部分与自由表面相关的多次波。

Free-surface-related multiple prediction for complex seafloor

For complex seafloor with complex wavepath,diffracted wave and diffracted multiples,multiple model predicted by SRME method has low signal-to-noise ratio,incorrect dynamic and kinematic information.Multiple prediction method based on the extrapolation of one-way and two-way wave equation was proposed in this paper.Based on wave equation and SRME method,it uses rock physics model to extrapolate the received wavefield,to derive the predicted multiple model.It also uses adaptive subtraction to improve multiple elimination effect for complex seafloor.Model tests and the application in real data demonstrate that multiple model predicted by the method proposed in this paper has higher signal-to-noise ratio and matches better with real multiples in dynamic and kinematic characteristics,compared with that predicted by individual SRME method.Theoretically,it is nece-ssary to know accurate rock physics model when using this method.For the majority of multiples in marine seismic data are free-surface-related multiples,given seawater and seafloor rock physics parameters,the method proposed in this paper can predict the majority of free-surface-related multiples.