Characterization of water-in-crude-oil emulsions in a complex shear field

• Innovative nuclear magnetic resonance experiments quantify drop size distributions.
• Illustration of the effects of several key parameters on emulsion formation.
• Characterization of concentrated crude oil emulsions.

Understanding the formation and stability characteristics of concentrated emulsions generated in complex flow fields is of importance to the energy industry. Knowledge about the transient stability of water-in-crude-oil emulsions aids in formulating flow assurance strategies to problems such as water separation and gas hydrate formation. During the production of crude oil, the produced fluids can experience a wide range of flow conditions, such as flow through pumps, reductions and expansions, and perforations which affect both the formation and stability of the emulsions. This work focuses on complex water-in-crude-oil emulsion formation and stability. The emulsions are formed with a rotating turbine using synthetic seawater as the dispersed phase and two crude oils as the continuous phase. This work employs the Carr–Purcell–Meiboom–Gill (CPMG) nuclear magnetic resonance (NMR) technique to measure the transient drop size distributions. The effects of parameters such as the mixing Reynolds number, energy input, and mixing time on emulsion formation and stability were quantified. The effect of mild shear after emulsification was also evaluated.