COMBINED NMR PGSE ― CPMG TECHNIQUE TO CHARACTERIZE WATER-IN-OIL EMULSIONS

摘要

This paper reports results from the implementation of a combined pulse magnetic field gradient spin echo (PGSE) / Carr-Purcell-Meiboom-Gill (CPMG) experimental technique to characterize emulsions of water dispersed in refined and crude oils. The basis of me method can be summarized as follows: The drop size distribution of the tested emulsions can be resolved from both PGSE and CPMG measurements, but the latter is usually faster and thus more suitable to follow the transient behavior. In addition, the CPMG test provides a direct and accurate measurement of the relative amounts of water and oil present in the emulsion. However, the interpretation of the CPMG data requires knowing the average magnetization relaxivity at the water-oil interfaces. The PGSE measurement is independent of this property. Therefore, the combination of the two methods allows simultaneous determination of the drop size distribution, the surface relaxivity and the water-oil ratio.