Peyron M, Pierens G K, Lucas A J, Hall L D, Potter G F, Stewart R C, Phelps D W
Herchel Smith Laboratory for Medicinal Chemistry, University of Cambridge School of Clinical Medicine, UK.
Magn Reson Imaging. 1994;12(2):295-8. doi: 10.1016/0730-725x(94)91539-3.
The simple pulse-acquire experiment has been used to evaluate the level of accuracy and precision achievable in NMR fluid saturation measurements for a range of rock core samples saturated with either brine or hydrocarbons. For a set of more than 70 cores measured at 0.66 T the mean error in the NMR measurement is only 0.35% porosity when the sample linewidths are less than 50 ppm. However, for a significant portion of cores, those with very broad NMR linewidths (> 50 ppm), difficulties associated with nonuniform excitation are encountered. The magnetic susceptibility difference between pore fluid and rock matrix translates into relatively broad NMR linewidths, and this feature of petrophysical samples is the major difficulty in performing quantitative NMR experiments. Numerical simulations are used to complement the experimental results in order to develop strategies for obtaining accurate NMR results with these difficult samples.
简单的脉冲采集实验已被用于评估一系列用盐水或碳氢化合物饱和的岩芯样品在核磁共振流体饱和度测量中所能达到的准确度和精密度水平。对于在0.66 T下测量的一组70多个岩芯，当样品线宽小于50 ppm时，核磁共振测量的平均误差仅为孔隙率的0.35%。然而，对于很大一部分岩芯，即那些具有非常宽的核磁共振线宽（> 50 ppm）的岩芯，会遇到与非均匀激发相关的困难。孔隙流体和岩石基质之间的磁化率差异导致相对较宽的核磁共振线宽，而岩石物理样品的这一特征是进行定量核磁共振实验的主要困难。数值模拟被用来补充实验结果，以便制定策略，从而从这些困难样品中获得准确的核磁共振结果。
