Demulsifying super-heavy crude oil with bifunctionalized block copolymers

One of the main problems that petroleum industry must face is the growing difficulty to extract both water and salts present in heavy crude oils. High viscosity, and enormous contents of resins and asphaltenes contribute to stabilize the water droplets dispersed in crude oil, making petroleum demulsification harder and the development of new dehydrating agents necessary. A series of copolymers consisting on a central block polypropylene oxide (PPO), and two side block of ethylene oxide (EO) were synthesized. These copolymers were afterwards submitted to a functionalization process, in order to graft some secondary amines to EO segments, to increase their interactions with the aqueous phase dispersed in the petroleum. The average molecular weight of the functionalized copolymers was adjusted according to the weight-average molecular weight (M-w) of the sample of super-heavy crude oil. The water removals from the petroleum sample were evaluated by bottle testing, mainly varying the kind of functional group and copolymer content. It was observed that these novel demulsifying agents have a better performance than traditional compounds, such as non-functionalized block copolymers and commercial formulations commonly used to remove water from super-heavy crude oil. The existence of maximal water separation at a certain concentration of the functionalized copolymers was observed, and explained in terms of a saturation of the water/oil interphase with polymeric chains. (C) 2012 Elsevier Ltd. All rights reserved.