The procedure proposed by Packer and Rees (J. Colloid Interface Sci. 40 (1972) 206) to interpret pulsed field gradient spin-echo (PGSE) experiments on emulsions is commonly used to resolve for the distribution of droplet sizes via nuclear magnetic resonance (NMR). Nevertheless, such procedure is based on several assumptions that may restrict its applicability in many practical cases. Among such constrains, (a) the amplitude of the spin-echo (signal) must be influenced solely by the drop phase, and not by the continuous phase; and (b) the shape of the drop size distribution must be assumed a priori. This article discusses new theory to interpret results from PGSE experiments and a novel procedure that couples diffusion measurements (PGSE) with transverse relaxation rate experiments (the so-called CPMG sequence) to overcome the above limitations. Results from experiments on emulsions of water dispersed in several crude oils are reported to demonstrate that the combined CPMG-PGSE method renders drop size distributions with arbitrary shape, the water/oil ratio of the emulsion and the rate of decay of magnetization at the interfaces, i.e. the surface relaxivity. It is also shown that the procedure allows screening if the dispersion is oil-in-water (o/w) or water-in-oil (w/o) in a straightforward manner and that it is suitable to evaluate stability of emulsions.

中文翻译：

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通过NMR扩散和横向弛豫实验增强了油田乳液的表征。

Packer和Rees（J.Colloid Interface Sci.40（1972）206）提出的用于解释乳剂的脉冲场梯度自旋回波（PGSE）实验的程序通常用于通过核磁共振解析液滴尺寸的分布（ NMR）。但是，这种程序是基于一些假设的，这些假设可能会限制其在许多实际情况下的适用性。在这些约束中，（a）自旋回波（信号）的幅度必须仅受下降阶段的影响，而不受连续阶段的影响；（b）液滴大小分布的形状必须先验地假定。本文讨论了解释PGSE实验结果的新理论，以及一种将扩散测量（PGSE）与横向弛豫速率实验（所谓的CPMG序列）结合起来的新方法，以克服上述限制。据报道，将水分散在几种原油中的乳化液的实验结果表明，组合的CPMG-PGSE方法可提供任意形状的液滴尺寸分布，乳化液的水/油比以及界面处的磁化强度衰减率，即表面松弛度。还显示出该程序允许以简单的方式筛选分散体是水包油（o / w）还是油包水（w / o），并且它适合于评估乳液的稳定性。