Addition of Non-endogenous Paraffins in Brazilian Crude Oils and Their Effects on Emulsion Stability and Interfacial Properties

The formation of emulsions is recognized to be a challenging problem during crude oil production and processing. Emulsion stability and interfacial properties were investigated in this work for paraffinic modified Brazilian crude oils. Crude oil modifications were made by the addition of two different non-endogenous paraffins, n-hexadecane and a commercial paraffinic pool (melting point range of 53–57 °C), to a heavy crude oil, here, named P1, based on asphaltene destabilization results previously published ( Romero Yanes, J. F. ; Feitosa, F. X. ; do Carmo, F. R. ; de Sant’Ana, H. B. Paraffin Effects on the Stability and Precipitation of Crude Oil Asphaltenes: Experimental Onset Determination and Phase Behavior Approach. Fluid Phase Equilib. 2018, 474, 116−125, 10.1016/j.fluid.2018.07.017). Paraffinic modified oils were emulsified with synthetic brine (pH 7 and 60 g L–1 NaCl) to identify the phases of the emulsion formed when varying the water content from 10 to 90% (v/v) and temperature from 30 to 80 °C. From the phase diagrams of the emulsion, it was determined that all paraffinic modified oils allow for the inclusion of at least 10% (v/v) more water as the stable emulsified phase, also with a notable decrease in required energy to promote emulsification. It means that less stir velocity was needed in the emulsification process for paraffinic modified crude oils with a remarkable effect for the paraffinic pool modified sample. Interfacial tension measurements between brine and modified crude oils were evaluated, showing a reduction when compared to the unmodified oil in all of the temperatures tested. These results could be related to the asphaltene solubility variation in modified crude oils. Additionally, wax crystal formation, detected by the wax appearance temperature measurements and polarized light optical microscopy, also contributed to emulsion stability for the crude oil modified with the paraffinic pool.