【摘要】 常规Vibroseis可控震源Chirp扫描的地震响应存在明显的旁瓣效应,二元m-序列伪随机扫描的解码地震剖面中存在严重的相关噪声,而基于伪随机编码的匹配扫描方法可有效压制解码地震剖面中的相关噪声,提高了地震记录的信噪比.为了将匹配伪随机编码方法应用到冲击式震源中,提出了基于脉冲编码震源的匹配冲击技术.以匹配扫描方法为理论基础给出了匹配冲击信号的编码与解码过程,以有限元差分法对匹配冲击技术和常规线性扫描冲击技术进行了地震数值模拟.结果表明,匹配冲击的综合解码地震剖面中,不存在线性扫描冲击解码地震剖面中能量较强的相关噪声干扰,剖面具有很高的信噪比和分辨率.地震波激发采集对比实验验证了匹配冲击技术在压制相关噪声及远偏移距地震道随机噪声方面相比线性扫描冲击技术所具有的优势.更多还原

【Abstract】 Seismic response of conventional Chirp sweeping for Vibroseis has obvious side-lobe effect and the decoded seismic section of binary m-sequence pseudorandom sweeping has serious correlation noises,while the matched sweeping method based on pseudorandom coding can suppress the correlation noises in the seismic section effectively and improve the SNR of seismic records.In order to apply the matched pseudorandom coding method to impact seismic sources,matched impact seismic technique for pulse-coded seismic sources was developed.The coding and decoding processes for matched impact signals were given with matched sweeping method as the rationale.Simultaneously,seismic numerical simulation for matched impact seismic technique and the conventional linear swept impact technique were conducted using finite difference method.The results show that the decoded seismic section for matched impact method has very high SNR and seismic resolution without the correlation noises in comparison with the linear swept impact method.The seismic excitation and acquisition experiments verify the superiority of matched impact seismic technique in suppressing the correlation noises and the random noises of large-offset seismic traces compared with the linear swept impact technique.更多还原