基于全方向波束定向的地震记录信噪比改善方法  

The SNR improvement method based on omnidirectional beam-forming for vibrator seismic record

作　　者：贾海青[1,2] 姜弢[1,2] 徐学纯[3] 林君[1,2] 

机构地区：[1]地球信息探测仪器教育部重点实验室(吉林大学),吉林长春130026 [2]吉林大学仪器科学与电气工程学院,吉林长春130026 [3]吉林大学地球科学学院,吉林长春130026

出　　处：《石油物探》2015年第5期521-530,共10页Geophysical Prospecting For Petroleum

基　　金：深部探测技术与实验研究专项SinoProbe-09-06(201311197和201011083);SinoProbe-09-04(201011081);高等学校博士学科点专项科研基金(20110061110053)联合资助

摘　　要：常规波束定向方法利用多炮地震记录、采用恒定延时差实现目标方向上地震波场的加强,所用的地震记录是由相同震源在不同位置激发得到的,由于不同地震记录的震源与大地的耦合程度不同,即震源的一致性存在差异,因而降低了波束定向的质量,同时,该方法未能实现全方向波束加强,波束定向结果的整体信噪比仍较低。为此,提出了一种全方向波束定向方法(Omnidirectional Beam-forming,OB),该方法基于波场叠加原理,通过不同方向有效波场的叠加,实现地震记录全方向有效信号的增强。其具体实现包括5个步骤:单炮记录的复制、角度域划分、延时参数计算及波束定向、有效波场的提取和有效波场的合并。利用数值模拟的含随机噪声单炮记录,验证了OB方法的正确性和有效性。将OB方法应用于某地区实际地震资料处理,使地震资料中的随机噪声得到明显压制,信噪比提高了6.75dB。Conventional beam-forming method is applied to strengthen the seismic wavefield in target directions by adopting multi seismic records and constant delay difference. Since the multi vibrator seismic records were achieved by the same vibra- tor vibrating at different positions, the coupling between the vibrator and the ground is different, which causes the difference on the consistency of vibrators and eventually decreases the quality of beam-forming. Meanwhile, the method cannot realize beam strengthened in all directions and the overall SNR of the result is low. Therefore, we propose an omnidirectional beam- forming （OB） method, which is based on wavefield superposition principle by the superposition of effective wavefield in dif- ferent directions to strengthen the effective signals in all directions. The workflow includes single shot record copying, angle- domain division, time-lapse parameters calculation and omnidirectional beam-forming, effective wavefield extraction and merge. The correctness and effectiveness of the OB method are proved by the processing on the single shot with random noise. Moreover, the OB method is applied on the actual seismic data, and the random noise is obviously suppressed and the SNR is increased by 6.75 dB.

关 键 词：全方向波束定向 单炮记录 信噪比 随机噪声压制 

分 类 号：P631[天文地球—地质矿产勘探]