伪随机编码震源信号的地震响应
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摘要
常规的可控震源Chirp扫描信号的地震响应存在着相关信号旁瓣大、分辨率低的缺点.本文利用数值模拟技术研究可控震源伪随机编码信号地震响应的规律和特点.伪随机编码信号的地震响应剖面的旁瓣电平与常规的Chirp扫描信号情形相比有明显地降低,但是伪随机编码信号地震响应剖面的相关噪声仍然没有得到有效地压制.利用伪随机编码信号的周期性特点把一个长地震记录以信号周期为间隔进行分时叠加可以提高地震记录的信噪比和地震数据的利用率.
Seismic response to conventional Chirp sweeping vibrator signal has the shortcomings of high side lobs and low resolution.In this paper,the characteristic of seismic response to pseudorandom coded vibrator signal is discussed with numerical simulation technique.The side lobe levels of the seismic section from pseudorandom coded vibrator signal are obviously lower than those from Chirp sweeping vibrator signal.But the correlation noises in the seismic section from pseudorandom coded vibrator signal are not effectively suppressed yet.Making use of the periodicity of pseudorandom coded vibrator signal,we can divide a long seismic recording into several segments according to the signal period and stack the segments onto one period segment by time-sharing so as to enhance the signal to noise ratio of seismic section and utilization rate of seismic data.
Seismic response to conventional Chirp sweeping vibrator signal has the shortcomings of high side lobs and low resolution.In this paper,the characteristic of seismic response to pseudorandom coded vibrator signal is discussed with numerical simulation technique.The side lobe levels of the seismic section from pseudorandom coded vibrator signal are obviously lower than those from Chirp sweeping vibrator signal.But the correlation noises in the seismic section from pseudorandom coded vibrator signal are not effectively suppressed yet.Making use of the periodicity of pseudorandom coded vibrator signal,we can divide a long seismic recording into several segments according to the signal period and stack the segments onto one period segment by time-sharing so as to enhance the signal to noise ratio of seismic section and utilization rate of seismic data.
引文
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[2]王忠仁,陈祖斌,姜弢,等.可控震源地震勘探的数值模拟[J].吉林大学学报(地球科学版),2006,36(4):627~630.
[3]王忠仁,林君,冯声涯.地震勘探中相控阵震源的方向特性研究[J].地球物理学报,2006,49(4):1191~1197.
[4]Goupillaud P L.Signal design in the“Vibroseis”technique[J].Geophysics,1976,41(6):1291~1304.
[5]王忠仁,陈祖斌,张林行,等.可控震源非线性扫描地震响应的数值模拟[J].地球物理学进展,2006,21(3):756~761.
[6]Cunningham A B.Some alternate vibrator signals[J].Geo-physics,1979,44(12):1901~1921.
[7]万哲先.代数和编码[M].北京:科学出版社,1980.
[8]冯重熙,钱亚生,姚彦,等.现代数字通信技术[M].北京:人民邮电出版社,1987.
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