利用SE求取SNMR横向弛豫时间方法研究
SE Obtained Utilizing SNMR Transverse Relaxation Time Methods
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摘要: 自旋回波作为测量<i<T</i<<sub<2</sub<时间的重要脉冲序列,由该脉冲系列交变磁场激发而获得的核磁共振信号不受磁场不均匀性的影响,这对于以地磁场作为稳定磁场的SNMR方法来说,可以减小地磁场不均匀对NMR信号的影响,得到真实、可信的<i<T</i<<sub<2</sub<值,提高信噪比。将自旋回波信号应用到地面核磁共振找水方法中求取<i<T</i<<sub<2</sub<分布,在国内尚属首例,本文借鉴核磁共振测井中的多指数反演方法,采用奇异值分解算法编程,反演得到<i<T</i<<sub<2</sub<分布,并与SNMR反演软件的结果<i<T</i<<sub<2</sub<<sup<*</sup<对比。结果证明,用SE信号提取<i<T</i<<sub<2</sub<时间,可以减少地磁场不均匀对NMR信号的影响,更真实地反映<i<T</i<<sub<2</sub<分布,提高信噪比。Abstract: Spin-echo is an important impulse series of <i<T</i<<sub<2</sub< time measuring which does not affect by magnetic field inhomogeneity when alternating magnetic field boosts signals. The earth magnetic field is relatively stable and this could reduce the influence to NMR signal from earth magnetic field, so we could obtain a real <i<T</i<<sub<2</sub< value and improve the SNR. This is the first time apply spin-echo signal method to the surface nuclear magnetic resonance to calculating <i<T</i<<sub<2</sub< distribution, The article referenced NMR logging multi Index Inversion, utilized singular value decomposition algorithm programming, obtained <i<T</i<<sub<2</sub< distribution and contrast with the results of SNMR inversion software of <i<T</i<<sub<2</sub<<sup<*</sup<. The research shows that use SE signal to extract <i<T</i<<sub<2</sub< time could reduce the influence of earth magnetic field inhomogeneity to NMR signal, reflect the <i<T</i<<sub<2</sub< distribution more realistically and improve SNR.
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