Branched Polyoxyalkylene Copolyesters
Branched polyesters contain oxalkylated primary fatty amines or oxalkylated polyamines together with at least trivalent oxalkylated alkanol that is responsible for branching. The condensation is achieved with a dicarboxylic acid or a dicarboxylic acid anhydride. In this way, branched polyoxyalkylene mixed polyesters are formed. Suitable solvents are water or organic solvents, such as methanol, isopropanol, butanol, or aromstic hydrocarbons ( e.g., toluene, xylene).
The branched polyoxyalkylene mixed polyesters possess a high demulsifier effect. In the usual range of oil-processing temperatures, a complete water removal and a reduction of the salt content is achieved after a short time. In the heavy oil reservoirs with highly porous sands, cyclic steamflooding may cause the formation of stable emulsions. These emulsions can block the production paths in the wellbore. In steam cycle treatments, a blend of oxyalkylated alkanolamines and sulfonates showed a dramatic improvement over non-chemically enhanced steam cycles.