基于IITD-WT的大地电磁噪声压制方法  

Magnetotelluric Noise Suppression Method Based on IITD-WT

作　　者：曾波[1] 宋毅[1] 苟其勇 徐尔斯 谢伟 周昊 张海杰 张贤 Zeng Bo;Song Yi;Gou Qiyong;Xu Ersi;Xie Wei;Zhou Hao;Zhang Haijie;Zhang Xian(Shale Gas Research Institute,PetroChina Southwest Oil&Gasfield Company,Chengdu Sichuan 610051,China;Sichuan Shale Gas Company,Southwest Oil and Gas Field,PetroChina,Chengdu Sichuan 610051,China;PetroChina Southwest Oil and Gas Field Sichuan Changning Natural Gas Development Limited Liability Company,Chengdu Sichuan 610051,China;Chongqing Shale Gas Company,Southwest Oil and Gas Field,PetroChina,Chongqing 401120,China;Hunan Key Laboratory of Financial Big Data Science and Technology,Hunan College of Finance and Economics,Changsha Hunan 410205,China;School of Information Technology and Management,Hunan College of Finance and Economics,Changsha Hunan 410205,China)

机构地区：[1]中国石油西南油气田分公司页岩气研究院,四川成都610051 [2]中国石油西南油气田四川页岩气公司,四川成都610051 [3]中国石油西南油气田四川长宁天然气开发有限责任公司,四川成都610051 [4]中国石油西南油气田重庆页岩气公司,重庆401120 [5]湖南财政经济学院“财经大数据科学与技术”湖南省重点实验室,湖南长沙410205 [6]湖南财政经济学院信息技术与管理学院,湖南长沙410205

出　　处：《工程地球物理学报》2024年第6期919-927,共9页Chinese Journal of Engineering Geophysics

基　　金：中国石油天然气集团有限公司西南油气田分公司院士合作项目(编号:XNS页岩院JS2021-39)。

摘　　要：矿集区采集的大地电磁信号极易受到各类噪声污染,导致其视电阻率-相位曲线在低频段出现紊乱现象或呈现出近源效应等。文中提出了一种优化固有时间尺度分解(Improved Intrinsic Time Decomposition,IITD)和小波阈值(Wavelet Threshold,WT)的大地电磁(Magnetotelluric,MT)去噪方法及应用。首先将含噪信号进行IITD分解得到若干阶旋转(Proper Rotation,PR)分量;然后对PR分量进行小波去噪,叠加小波系数重构得到MT去噪数据。通过计算机模拟出不同类型的强噪声,并对小波阈值法设置不同的分解层数、基函数对强噪声进行处理,总结出该算法面对不同噪声时的去噪性能。对模拟大尺度方波和三角波噪声去噪后,信噪比最高可达24dB和17dB,所提方法去噪性能显著。将所提方法应用至MT实测数据的降噪,结果显示该方法能够有效去除隐藏在MT数据中的强噪声。由去噪前后视电阻率曲线对比可知,相较于远参考法和原始曲线,所提方法获得的视电阻率曲线更为光滑、连续,低频段的数据质量明显改善。The magnetotelluric signals collected in the mining concentration area are easily polluted by various types of noise,resulting in the disorder of their apparent resistivity-phase curves in the low-frequency band or showing near-source effects,etc.We propose a magnetotelluric(MT)denoising method to improve intrinsic time scale decomposition(IITD)and wavelet thresholding(WT)and their applications.The noise-containing signal is firstly decomposed by IITD to obtain a number of order rotational(PR)components;then the PR component is denoised by wavelet,and the wavelet coefficients are superimposed to reconstruct the MT denoised data.Different types of strong noise are simulated by computer,and different decomposition layers and basis functions are set for WT method to remove the strong noise.The denoising performance of the algorithm in the face of different noises is summarized.After denoising the simulated large-scale square wave and triangular wave noise,the signal-to-noise ratio can reach up to 24 dB and 17 dB,and the proposed method has significant denoising performance.The proposed method can be applied to the noise reduction of MT measurement data,and the results show that the method can effectively remove the strong noise hidden in the MT data.From the comparison of the apparent resistivity curves before and after denoising,it can be seen that the apparent resistivity curves obtained with the proposed method are more smooth and more continuous,and the data quality in the lower frequency bands is higher compared with the far-reference method and the original curves.

关 键 词：大地电磁 优化固有时间尺度分解 小波阈值 去噪 

分 类 号：P631.3[天文地球—地质矿产勘探]