编码与解码框架下的局部平面波域浅水多次波压制方法  

Shallow water multiple suppression method in local planar wave domain based on coding and decoding framework

作　　者：徐鹏 刘亚辉 王华忠[1] XU Peng;LIU Yahui;WANG Huazhong(Wave Phenomena and Intelligent Inversion Imaging Group (WPI),School of Ocean and Earth Science,Tongji University,Shanghai 200092,China;School of Geosciences,China University of Petroleum,Qingdao 266580,China)

机构地区：[1]波现象与智能反演成像研究组(WPI),同济大学海洋与地球科学学院,上海200092 [2]中国石油大学(华东)地球科学与技术学院,山东青岛266580

出　　处：《石油物探》2019年第3期346-355,403,共11页Geophysical Prospecting For Petroleum

基　　金：国家自然科学基金(41774126);国家科技重大专项(2016ZX05024-001,2016ZX05006-002)共同资助~~

摘　　要：多次波压制是提高地震数据品质与成像结果分辨率的重要手段之一,浅海环境给多次波压制引入了额外的难点。浅海环境中主要的多次波是水体相关多次波,由于海底海面路径短,且海面、海底都是强反射界面,因此该类多次波周期短、能量强,对有效波的干扰严重,采用常规多次波压制方法不能将其很好地压制。提出了针对浅水多次波的有效压制方法:将多次波的产生与压制用线性编码解码系统进行描述,即将上行波在水层震荡产生多次波的过程视为编码过程,将剥离多次波的过程视为解码过程,并从线性系统求解角度给出了平面波域多次波压制算法。首先将水体相关多次波的预测转移到局部平面波域,利用稀疏τ-p变换减弱了采样不规则、近偏移距缺失造成的影响;然后利用射线理论描述水体介质中的地震波传播,高效生成多次波模型;最后在τ-p域进行匹配相减,并利用一次波与多次波的视速度差异,提高匹配精度。利用浅海OBC数据和拖缆数据验证了方法的有效性和实用性,通过对比压制浅水多次波前后的地震剖面和自相关结果,展示了方法压制浅水多次波的效果和应用前景。The occurrence of multiples can affect the quality of seismic data and the resolution of imaging results.In a shallow-water environment,the suppression of multiples can be problematic.The dominant multiples in a shallow-water environment are the water-related multiples.They have a short period,strong energy,and strong interference due to the short seabed-surface path and the strong-reflectivity of the sea surface and floor interfaces.This paper presents an effective method for the suppression of shallow-water multiples.The generation and suppression of multiple waves are described here by a linear coding-decoding system,which regards the process of the upgoing wave generating multiples as a coding process,and the suppression of multiples as a decoding process.A multiple suppression algorithm in the plane wave domain is proposed,which is based on solving linear systems.First,the water-related multiples are transformed in the local plane wave domain,and a sparse τ-p transform is used to alleviate the effect of irregular and missing samples near the offsets.Second,ray theory is used to describe the wave propagation in the water medium,and to generate a multiples model.Finally,a matching subtraction in the τ-p domain is carried out,which can improve the matching accuracy by exploiting the difference between the apparent velocities of the primary waves and the multiple waves.The method was validated using tests on the field data of OBC and towed-streamer in shallow water.The comparison of the seismic profiles and the autocorrelation before and after the suppression of the shallow-water multiples showed that the method is effective in suppressing shallow-water multiple waves.

关 键 词：多次波压制 多次波预测 编码与解码 稀疏求解 Τ-P变换 局部平面波 反射射线追踪 匹配相减 

分 类 号：P631[天文地球—地质矿产勘探]