提升小波滤波在随钻核磁共振测井中的应用

针对随钻核磁共振测井受到遥传带宽的限制，必须在井下完成关键的谱反演，并以此获得数据量较少的孔隙度、渗透率和流体类型等信息的问题，根据核磁共振回波串信号与原始回波信号不同的频谱特征，提出利用9/7提升小波算法对回波串信号滤波和反演，在此基础上获得了孔隙度信息。研究结果表明，该算法可以有效地提取原始回波串数据中的回波信号，抑制了噪声，将信噪比提高了65％左右，反演结果和孔隙度信息能较好地反映地层属性。

Application of Lifting Wavelet Filtering in NMR-LWD

Limited by telemetry bandwidth in NMR logging -while-drilling, the key T2 spectrum inversion needs to be com-pleted in the underground.And the small amount of data, such as porosity, permeability, fluid type and other information is re-quired.Based on the difference between original echo signal spectral characteristics and NMR echo train signal spectral charaiteris -tics, the 9/7 lifting wavelet algorithm was presented .Echo train signal was filtered , and then the inversion was carried out to obtain porosity.The results show that the algorithm effectively extract the echo signal from the original echo string data and suppressing the noise.The signal-to-noise ratio increased by at least 65%.The inversion results and porosity logging can better reflect the actual situation.