High performance demulsifiers for heavy crude oil based on alkyl acrylic-amino alkyl acrylic random bipolymers

Abstract

• Novel demulsifiers for heavy and extra-heavy crude oils based on acrylic monomers. • Chemical demulsifiers to treat and destabilize complex crude oil emulsions. • Superior dehydrating and clarifying capacity to that of polyethers formulations. • DPD simulation to stablish the dehydrating mechanism of new acrylic demulsifiers. In this work, a series of novel random alkyl acrylic-amino alkyl acrylic bipolymers was synthetized by semi-continuous emulsion polymerization technique. The obtained bipolymers were characterized mainly by Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), 1D and 2D nuclear magnetic resonance (NMR) and size exclusion chromatography (SEC). Afterwards, these bipolymers were evaluated as demulsifying agents in four heavy crude oils. The evaluations revealed that the efficiency of the synthesized acrylic bipolymers to break the emulsion, induce the drop coalescence and clarify the remaining aqueous phase depends strongly on their alkyl acrylic/amino alkyl acrylic ratio in the chain and average molecular mass. Likewise, it could be noted in three samples of heavy crude oils from Motul field that a greater content of the amino alkyl acrylate monomer in the bipolymer chain and a higher molecular mass allowed reaching higher emulsion removal efficiencies, with good water clarification. It was also shown that, in all the cases, a single acrylic bipolymer is able to remove the water dispersed in petroleum in a more efficient way than a commercial formulation of four triblock bipolymers based on ethylene and propylene oxide, when it possesses convenient structural features. In addition, for a better understanding of the improved dehydrating efficiency of the new acrylic demulsifiers reported in this study, a mechanism of bridge formation between water drops to provoke coalescence was established by dissipative particle dynamics (DPD) simulation. This theoretical technique was also applied to calculate the decrease of the interfacial tension as a function of the number of alkyl acrylic-amino alkyl acrylic chains at the water/crude oil interface.