Emulsion Stability Studied by Nuclear Magnetic Resonance (NMR)

Abstract

A method using low-field nuclear magnetic resonance (NMR) for measurement of water-in-crude oil emulsion stability has been optimized and compared to light transmission measurements. Two NMR sequences have been used; one of them applies a diffusion T 2 -weighted profile measurement sequence, which can return a water profile of an emulsion within 30 s. The stability of the emulsions was compared by studying emulsions in parallel in Turbiscan and NMR. Three different crude oils were used in the experiment. The emulsions prepared had water cut at 50%. The correlation between NMR and Turbiscan regarding the free water formation was good for the emulsions. The potential limitations and advantages of the technique are discussed.

Separation profile of model water-in-oil emulsions followed by nuclear magnetic resonance (NMR) measurements: Application range and comparison with a multiple-light scattering based apparatus

“…Indeed as seen in Fig. 9, even though a region of free water has formed, the brine profile indicates less than 100% of water in this region as also noticed by Opedal et al [27]. Visually we see that it remains some spot of emulsions stuck on the tube wall.…”

“…If we compare the results obtained with the two techniques, it appears that the initial coalescence velocity seems to be the same but after 30 min, free water layer slows down its increases in Turbiscan case and reaches a plateau at 15% significantly lower than for the NMR case. Comparison between NMR and Turbiscan were performed by Opedal et al [27] on petroleum crude oil systems and similar results were obtained i.e. the plateau water cut determined by NMR is higher than the one determined by the Turbiscan.…”

“…The application of these new NMR sequences to study real crude oil systems is the object of another article [27].…”

Model molecules mimicking asphaltenes

“…The stability of resulting emulsions is assessed by measuring the free water appearance kinetics (bottle test). Low Field Nuclear Magnetic Resonance (LF-NMR) can also be studied [138][139][140] .…”

Population Balance Model for Batch Gravity Separation of Crude Oil and Water Emulsions. Part I: Model Formulation

“…[34][35][36] The model predicts the evolution of the volume fraction of the dispersed phase at any axial position and time in the separator, which can also be directly measured experimentally by NMR. [35,36] Furthermore, the model predicts the location of the resolved dispersed phase interface as a function of time. For any axial position and time in the settler, the model predicts the evolution of the average number density of droplets, the average volume=radius of droplets, the standard deviation of the droplet volume=radius, and the rate of growth of the droplets.…”