基于SSEC-EWT的地震资料噪声压制算法  

Noise suppression algorithm for seismic data based on SSEC-EWT

作　　者：孟娟 高琴 李亚南 MENG Juan;GAO Qin;LI Ya'nan(School of Electronic Science and Control Engineering,Institute of Disaster Prevention,Sanhe,Hebei 065201,China;Hebei Key Laboratory of Seismic Disaster Ins-trument and Monitoring Technology,Sanhe,Hebei 065201,China)

机构地区：[1]防灾科技学院电子科学与控制工程学院,河北三河065201 [2]河北省地震灾害监测仪器与监测技术重点实验室,河北三河065201

出　　处：《石油地球物理勘探》2021年第5期1010-1021,I0009,I0010,共14页Oil Geophysical Prospecting

基　　金：河北省教育厅高等学校科学研究计划项目“城市地震预警系统关键技术研究”(QN2020527);国家重点研发计划项目“重大自然灾害监测预警与防范重点专项——超小型绝对重力仪研发”(2018YFC1503801)联合资助。

摘　　要：高信噪比地震资料是开展油气勘探的可靠基础。针对现行去噪方法大多难以同时压制地震资料中普遍存在的面波和随机噪声,且在去噪的同时易损害有效波的不足,提出基于S谱能量曲线(S-Transform spectrum energy curve,SSEC)与改进经验小波变换(Empirical wavelet transform,EWT)的地震资料噪声压制算法。先对地震记录进行S变换,根据S谱求取各频点能量,以能量曲线极大值点频率及ε邻域法确定频谱分割边界,完成改进的EWT;再通过SSEC确定面波所在本征模函数(Intrinsic mode function,IMF),并构造带通滤波器对面波IMF进行滤波,以保护有效波,实现精准的面波压制;然后计算其余IMF主频,根据有效波频率阈值去除随机噪声IMF,得到最终去噪后记录。仿真测试显示,改进的EWT能精确地根据地震信号的频率和能量自适应地对其进行分解,实现面波与随机噪声的提取与分离,尤其在强噪声背景下仍能精准实现面波与随机噪声的同步分离;实际地震资料处理结果表明,该算法在压制面波和随机噪声的同时能兼顾保护有效波,提高地震资料的信噪比。Seismic exploration data with high a signal-to-noise ratio is a solid basis for oil and gas exploration.Most existing de-noising methods cannot suppress the ubiquitous ground roll and random noise in seismic data at the same time and can easily damage the effective wave.In this regard,we proposed a noise suppression algorithm for seismic data,which was based on the S-transform spectrum energy curve(SSEC)and empirical wavelet transform(EWT).Firstly,seismic records were processed by S-transform,and the energy of each frequency point was calculated according to the S-spectrum.Secondly,the maximum point frequency of the energy curve and theε-neighborhood method were used to determine the spectral segmentation boundary to improve the traditional EWT.Thirdly,the intrinsic mode function(IMF)of the ground roll was determined according to the SSEC,and a band-pass filter was constructed to filter the ground roll IMF to protect the effective wave and achieve accurate ground roll suppression.Finally,dominant frequencies of the remaining IMF were calculated,and the random noise IMF was removed according to the frequency threshold of the effective wave to obtain the denoised record.The simulation test shows that the improved EWT can decompose the seismic signal adaptively according to frequency and energy,thereby separating the ground roll and random noise accurately.Especially in a strong noise environment,the proposed algorithm can separate ground roll and random noise accurately and synchronously.The processing results of actual seismic data reveal that the algorithm can protect the effective wave while suppressing the ground roll and random noise,thus improving the signal-to-noise ratio of the seismic data.

关 键 词：经验小波变换 改进经验小波变换 面波压制 地震勘探 去噪 

分 类 号：P631[天文地球—地质矿产勘探]