Dissipative Particle Dynamics (DPD) Study of Crude Oil-Water Emulsions in the Presence of a Functionalized Co-polymer

摘要

This work presents a theoretical study of the effects of different molecular weights of a triblock co-polymer ethylene oxide./propyiene oxide/ethylene oxide, bifunctionalized with ethalamine. on the coalescence of water drops imbibed in a crude oil environment. The polymer/crude oil/water (PCW) time evolution of the emulsion was simulated using the framework of the dissipative particle dynamics (DPD) technique. The bead-bead interactions of the molecular components were calculated using the correlation between the solubility parameter,χ_(ij), of the Flory-Huggins theory and the conservative force parameter, a,,. The solubility parameter was obtained from atomic molecular models of prototype molecules of saturates, aromatics, resins, asphaStenes, and the triblock co-polymer, through the blend methodology. The dynamic evolution of coarse-grain mesomolecules was carried out in cells of 20 x 20 x 20 DPD unit length with periodic boundary conditions. The composition of the emulsion was chosen to be similar to a Mexican heavy crude oil: asphaltenes, 11.9%; resins, 11.8%; aromatics, 42.7%; saturates. 29.6%; polymer, 4%; and two water drops of 3 DPD length units in radius. Finally, a drastic change in the coalescence of water molecules is observed for a short co-polymer length with respect to long co-polymer lengths.