基于经验模态分解的核磁共振测井信号去噪新方法
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摘要
核磁共振的信噪比在T2谱反演中起着重要作用,信号噪声容易造成解的偏离,这种情况在信噪比小的核磁共振测井中更加突出。把最新发展的经验模态分解方法引入到核磁共振测井信号处理中来,对实测信号进行了去噪和对比分析,结果表明,该方法具有自适应和高效的特点,能反映原始信号的固有特性,经验模态分解方法对消除测井信号的噪声是有效的,与传统的多点平滑结果相比:SNR从18dB左右提高到68dB左右,为T2谱的精确反演奠定了良好的基础。
The SNR plays an important role in the inversion of NMR' s T2 spectrum.The noises easily cause the solution of deviate from the truth,and it is a more prominent situation in the small signal to noise ratio of nuclear magnetic resonance logging.The empirical mode decomposition(EMD) was firstly proposed to the processing of NMR logging signals in the paper.The EMD can reflect the intrinsic physical characteristics of original data and the method can adapt to the variations of signals.The results showed that the result after noise filtering by EMD was satisfactory.Comparing with some points smoothing,the SNR is improved from 18 dB to 68dB.It makes the inversion of NMR' s T2 spectrum more representative and robust.
The SNR plays an important role in the inversion of NMR' s T2 spectrum.The noises easily cause the solution of deviate from the truth,and it is a more prominent situation in the small signal to noise ratio of nuclear magnetic resonance logging.The empirical mode decomposition(EMD) was firstly proposed to the processing of NMR logging signals in the paper.The EMD can reflect the intrinsic physical characteristics of original data and the method can adapt to the variations of signals.The results showed that the result after noise filtering by EMD was satisfactory.Comparing with some points smoothing,the SNR is improved from 18 dB to 68dB.It makes the inversion of NMR' s T2 spectrum more representative and robust.
引文
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[6]何峰江,陶果,罗辱义.应用小波分析估计核磁共振测井信噪比[J].核电子学与探测技术,2005,25(5):471-474.
[7]HUANG N E.The empirical mode decompositionand the Hilbert spectrum for nonlinear and non-sta-tionary time series analysis[J].Procedures of theRoyal Society of London,1998,A454(3):903.
[8]HUANG N E,SHEN Z,LONG S R.A new viewof nonlinear water waves:the Hilbert spectrum[J].Annu Rev Fluid Mech,1999,31:417-457.
[9]Bradley M B,Camelia K.Application of the em-pirical mode decomposition and Hilbert-Huangtransform to reflection seismic data[J].Geophys-ics,2007,72(3):H29-H37.
[10]王希武,董光波,谢桂海.基于小波变换的核磁共振FID信号的去噪方法研究[J],核电子学与探测技术,2008,28(2):365-370.
[11]石春香,罗奇峰.时程信号的Hilbert-Huang变换与小波分析[J].地震学报,2003,25(4):398-405.
[2]肖立志,等.核磁共振测井资料解释与应用导论[M].北京:石油工业出版社,2001.
[3]翁爱华,李舟波,等.核磁共振测井数据高分辨率反演方法研究[J].测井技术,2002,26(6):455-459.
[4]翁爱华,李舟波,莫修文,等.低信噪比核磁共振测井资料的处理技术[J].吉林大学学报(地球科学版),2003,33(2):232-235.
[5]Edwards C,et al.Improved NMR well logs fromtime-dependent echo filtering[C].in 37th annuallogging symposium transactions:Society of Profes-sional Well Log Analysts,1996:12.
[6]何峰江,陶果,罗辱义.应用小波分析估计核磁共振测井信噪比[J].核电子学与探测技术,2005,25(5):471-474.
[7]HUANG N E.The empirical mode decompositionand the Hilbert spectrum for nonlinear and non-sta-tionary time series analysis[J].Procedures of theRoyal Society of London,1998,A454(3):903.
[8]HUANG N E,SHEN Z,LONG S R.A new viewof nonlinear water waves:the Hilbert spectrum[J].Annu Rev Fluid Mech,1999,31:417-457.
[9]Bradley M B,Camelia K.Application of the em-pirical mode decomposition and Hilbert-Huangtransform to reflection seismic data[J].Geophys-ics,2007,72(3):H29-H37.
[10]王希武,董光波,谢桂海.基于小波变换的核磁共振FID信号的去噪方法研究[J],核电子学与探测技术,2008,28(2):365-370.
[11]石春香,罗奇峰.时程信号的Hilbert-Huang变换与小波分析[J].地震学报,2003,25(4):398-405.
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