摘要
信号去噪是海洋可控源电磁勘探(Marine Controlled-Source Electromagnetic,MCSEM)数据处理过程中的重要环节.在中、远收发距处,大地天然电磁信号(Magneto Telluric,MT)是影响MCSEM反演质量的主要噪声之一.尽管已有学者提出一些MT噪声降噪方法,但由于缺乏降噪效果的量化评价,导致这些方法的有效性亟待验证.针对上述问题,本文将信号和噪声一维正演、噪声降噪处理、电阻率一维反演相结合,提出一种MT噪声降噪效果评估方法.该方法利用电阻率反演结果与电阻率输入值的均方相对误差作为降噪效果的量化评价指标.为提高灵活性,既可以利用正演的手段生成MT噪声,也可以直接输入MCSEM发射机不开机时间段的实测数据作为MT噪声.利用该评估方法,验证了短时窗结合预白化滤波降噪方法的有效性.在所开展的实验中,实测数据的均方相对误差为231%.相比于不进行降噪处理的直接反演结果,均方相对误差减小了126%.本文所研究的评估方法可应用于MT噪声降噪方法有效性的量化评估,也可推广至其他类型噪声降噪效果的量化评估.
Marine Controlled-Source Electromagnetic(MCSEM)is a new technology that has emerged in recent years to explore marine oil and gas.Signal denoising is an important part of data processing procedure in MCSEM exploration.Main noise sources in MCSEM exploration include direct-path transmitted signal,the Magneto Telluric(MT)signal,noises caused by the movement of the sea,random noise,and etc.When the distance between transmitters and receivers are medium or long,MT signal is one of the main noise that affects the MCSEM inversion quality.Although some MT noise reduction methods have been proposed in published literature recently,the effectiveness of these methods needs to be verified due to the lack of quantitative evaluation of noise reduction effects.In order to solve the above problems,this paper proposes an evaluation method of MT noise denoising effect by combining one-dimensional forwarding for signals and noises,noise reduction processing and one-dimensional resistivity inversion.In our proposed method,the mean square relative error between the resistivity inversion results and the input values of the resistivity is adopted as the quantitative evaluation parameter to evaluating the denoising effect.The proposed approach can generate MT noise either by the forward model,or by real data sampled during the period when MCSEM transmitters are not powered on,and thereby the proposed approach has strong flexibility.The carried out experiments verify the effectiveness of the denoising method of short-time window combined with the pre-whitening filtering.In the performed experimentations,the mean square relative error of the real data is 231%.Compared with the direct inversion without noise reduction,the mean square relative error is reduced by 126%.The proposed evaluation method can be applied to the quantitative evaluation of the effectiveness of MT noise reduction methods,and can be generalized to the quantitative evaluation of the reduction effectiveness of other type noises.
作者
周文强
周鹏
戴永寿
孙伟峰
ZHOU Wen-qiang;ZHOU Peng;DAI Yong-shou;SUN Wei-feng(College of Information and Control Engineering,China University of Petroleum,Shandong Qingdao 266580,China)
出处
《地球物理学进展》
CSCD
北大核心
2019年第3期1268-1280,共13页
Progress in Geophysics
基金
中国石油集团东方地球物理勘探有限责任公司委托项目“海洋可控源电磁勘探中MT噪声的降噪方法研究”
国家海洋局海洋遥测工程技术研究中心创新青年基金(2017003)
国家留学基金(201706455032)联合资助
关键词
海洋可控源电磁勘探
MT噪声
降噪效果评估
正演
反演
Marine Controlled-Source Electromagnetic(MCSEM)
Magneto Telluric(MT)noise
Denoising effect evaluation
Forward
Inversion
