核磁共振测井回波信号小波阀值去噪方法

Wavelet Threshold Denoising Method for NMR Logging Echo Signal

MRT6910核磁共振测井仪采集的信号属于微弱信号,在高背景噪声下回波信号信噪比低、信号强度弱,影响反演效果及测井解释准确性。通过仿真分析,考察小波去噪方法和小波分解层数对去噪效果的影响,引入去噪效果评价指标,提出一种适合于核磁共振测井回波信号的小波阀值自动去噪法。模拟结果表明,小波去噪后信噪比增强,T2谱反演精度大幅度提高。

The signal collected by MRT6910 nuclear magnetic resonance logging tool is weak.Under the background of high noise,the signal-to-noise ratio of the echo signal is low and the signal intensity is weak.In this case,the inversion effect and the accuracy of log interpretation are reduced.This study investigates the influence of wavelet denoising method and decomposition layer on the denoising effect through simulation analysis,introduces the evaluation index of denoising effect,proposes a automatic wavelet threshold de-noising method suitable for NMR echo signal.The simulation results show that the signal-to-noise ratio is enhanced after wavelet denoising,and the accuracy of T2 spectral inversion is greatly improved.