The stability and flow properties of w/o emulsions are investigated using two Brazilian crude oils: a heavy crude oil and a waxy crude oil. Stable emulsions are shown to form with the heavy crude oil at water cuts up to 50 vol %, while the waxy oil forms stable emulsions with water cuts as high as 70 vol %. Rheological flow curves show shear thinning behavior for the crude oils as well as emulsions at low-temperature conditions. The presence of emulsified water is shown to significantly increase the yield strength of waxy crude oil gels formed by quiescent cooling. The waxy gels exhibit third-order degradation kinetics with respect to absolute imposed strain. Nuclear magnetic resonance (NMR) analysis confirms tight emulsions with average droplet sizes of 1.7 µm at 30 vol % water cut. Electro-coalescence measurements indicate decreasing critical electric field values with increasing temperature, resulting from a lower viscosity of the continuous phase as well as dissolution of paraffin wax. From a fluid processing perspective, high emulsion stability and shear thinning behavior are promising characteristics for using emulsion transport of hydrate particles at low-temperature and elevated pressure conditions. To prevent hydrate plugging, low water cuts should be maintained and emulsification should be completed before the fluid enters the hydrate formation envelope. Mixing of dissimilar formation fluids should be avoided subsequent to hydrate formation. In addition, pipeline startup risks associated with paraffin wax gelling should be considered during the design phase of the production system.

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A matrix of 30 crude oils have been analyzed to investigate if there is any correlation between the physiochemical properties of the crude oils and the quality of the produced water. As an approach to study produced water quality, oil. and brine water (3.5 wt%) have been mixed together, and transmission profiles from the separation process have been investigated by means of Turbiscan LAb. The Turbiscan LAb enables the study of stability of colloidal dispersions without any dilution or modification of the sample. The oil-in-water emulsions (30:70) were made by mixing oil and water at low speed to be sure that they separate within a short period of time. Drop size distributions were investigated for all crude oil emulsions by using a Coulter Counter (COULTER Multisizer II). The correlations between transmission profiles and crude oil characteristics were made by using principal component analysis (PCA), a method that helps visualize the most important information contained in a data set and find combinations of variables that describe major trends. A Vortoil K-liner hydrocyclone connected to a mixing rig has been used to separate oil and water in larger scale experiments. The objective with these experiments was to compare the results with separation experiments done at bench scale. Six crude oils have been investigated at the separation rig, and both droplet size distribution and dispersed oil concentration have been performed. The main conclusions from this work are that Turbiscan LAb is a suitable technique to study the separation of oil-in-water with good reproducibility. The results from the multivariate data analysis show that the crude oils group according to if they are light or heavy and according to if they get high or low transmission. From the larger scale experiments it has been shown that the droplet sizes, oil/water density differential, and viscosity have a significant impact on separation efficiency.