摘要
利用可控震源进行地震勘探时,通常都需要进行相关滤波,相关滤波结果的好坏取决于所选取的子波与有效反射波的相关性.海洋地震勘探常用的电火花震源激发能量通常可以调控,理论上,同一激发能量产生的震源子波应当是一致的,因此可以仿效可控震源资料的处理手段,对单道地震资料进行相关处理.但在复杂多变的海洋环境下,震源参数也要随勘探条件的变化而改变,采用理论计算或实验环境下获得的子波模型进行相关滤波往往难以达到预期的效果,需要寻找与实际勘探中激发的地震波相似度更高的地震子波.单道地震记录中直达波的能量较强,波形畸变较小,与震源子波较为接近.本文建立了一种利用直达波提取地震子波的方法,并应用到实际资料.实际资料的地震子波提取和相关滤波处理结果显示,利用直达波提取地震子波进行相关滤波能够有效地压制干扰波、突出有效波,提高了地震记录的信噪比.需要注意的是:1)提取子波的过程中要降低环境因素的影响,可利用统计平均的方法来实现;2)相关滤波时要根据实际处理效果的改善程度选择相关子波长度.
Correlation Filtering suppress noises and enhances the reflection waves based on the source wavelet, which correlates with the reflected waves instead of the noise,and is very useful in the marine seismic exploration.The performance of correlation filtering depends on the coherence of the wavelet and the reflected wave.Most of sparkers used in the singlechannel exploration are energy-controlled seismic sources.Theoretically,seismic wave produced by sparker at the same mode each time should be consistent.So we can apply correlation filtering to single-channel seismic data processing.However,few of the sources provide the reference source wavelet for correlation filtering in seismic data processing.Furthermore,the parameters of vibroseis will induce the changes of the source wavelet due to the viriation of environment or exploration target.So we have to estimate the source wavelet for correlation filtering based on the real acquisition environment.The direct wave on single-channel seismic record seems to be most similar to the source wavelet with maximal energy and minimal wave form change thanks to the sea water have a relative weak absorption effect to seismic wave.So we can extracting the wavelet utilized the direct wave on seismic record.The result of correlation filtering utilized the source wavelet extracted from direct wave on original seismic data shows that：Extracting seismic wavelet from the direct wave and make it to do the correlation filtering with seismic record can suppress noises and enhance the reflected wave,and improve the Signal-to-Noise Ratio.There are two tips must be noticed：1）suppressing the effect caused by environment during extracting source wavelet;2）the length of correlation wavelet should be chosen on the basis of the improvement of the correlation filtering result.
出处
《地球物理学进展》
CSCD
北大核心
2015年第6期2878-2884,共7页
Progress in Geophysics
基金
海洋公益专项(201005029
201305038)
极地专项(CHINARE2014-04-01
CHINARE2014-01-03)
国家海洋局第三海洋研究所基本科研业务专项(海三科2009058)联合资助
关键词
单道地震勘探
地震资料处理
直达波
地震子波
相关滤波
single-channel seismic exploration
seismic data processing
direct wave
source wavelet
correlation filtering
