摘要
本文深入分析了多次波逆时偏移的成像原理和串扰假象产生机制,并提出了多次波分阶逆时偏移策略,即首先应用自由界面多次波衰减方法对原始炮集记录中的多次波进行剔除得到一次波记录,然后应用一次波记录预测获得各阶多次波记录,最后将各阶多次波记录分别进行逆时偏移成像.模型实验结果表明,多次波分阶逆时偏移其各阶多次波成像剖面均可对真实界面正确成像且其能够有效压制串扰假象,其中一阶多次波逆时偏移剖面的成像精度最高,其深层成像质量明显优于常规多次波逆时偏移.
Imaging based on primaries encounters difficulties in the regions of low illumination and shadow areas where primaries cannot reach.Compared with the primaries,multiples have longer wave propagation paths,wider coverage and more balanced underground illumination.Theoretically,imaging based on multiples can compensate for the weakness of that based on primaries and enhance the quality of the imaging.However,the current reverse time migration（RTM）of multiples usually treats the original seismic record（including primaries and multiples）and the forecasted multiples record（including multiples of all orders）as the forward time disturbance and the reverse time disturbance respectively,which will cause some ＂unmatched＂multiples to generate serious crosstalk artifacts that reduce the imaging quality and reliability.Therefore,it has important scientific significance and application value to develop new methods or strategies of migration with multiples.We analyze each term in imaging conditions of reverse time migration of multiples and draw the following conclusions：only the correlation of the Nth（N≥0）order multiples（primaries are regarded as the 0th-order multiples）and the（N＋1）th order multiples can image the interfaces correctly.The correlation of the Nth order multiples and the（N＋i）th（i〉1）order multiples will generate crosstalk artifacts and the correlation of the Mth（M≥1）order multiples and theLth（1≤L≤M） order multiples will generate background noises. Based on the above conclusions,we propose a strategy of reverse time migration of divided-order multiples.Firstly,the primaries are acquired with multiples attenuation in the original record using the surface related multiples elimination（SRME）method.Secondly,based on the primaries,the first-order multiples are forecasted with the feedback loop theory,and then each order of multiples is forecasted in turn.Finally,each pair of the Nth order multiples and the（N＋1）th order multiples are used to image,resp
出处
《地球物理学报》
SCIE
EI
CAS
CSCD
北大核心
2015年第10期3791-3803,共13页
Chinese Journal of Geophysics
基金
中央高校基本科研业务费专项(201513005)
国家自然科学基金(41574105)联合资助
关键词
多次波
分阶
逆时偏移
串扰
Multiples
Divided-order
Reverse time migration
Crosstalk
