Patent ID: 7795183

Claim:
A method of asphaltene control in a hydrocarbon fluid, the method employing a composition comprising: a hydrocarbon fluid, optionally an oil of lubricating viscosity and a dispersant of formulae (I) or (II), including salts thereof (T-(O-A-CO) n (O—B—CO) m — p Z (I) or (T′-(O-A′-CO) n′ — p′ Z′ (II) wherein T or T′ is hydrogen or a polymerising terminating group; A is C 16-20 alkylene or alkenylene group; B is C 10-20 alkylene or alkenylene group; Z and Z′ are the residue of a polyamine or polyimine, wherein the polyamine or polyimine has a weight-average molecular weight from 1,000 to 200,000; n is 2 to 50; m is 0 to 25; p and p′ are 2 or more; A′ is C 8-20 alkylene or alkenylene group; n′ is 2 to 10; and the weight ratio of T-(O-A-CO) n (O—B—CO) m to Z or T′-(O-A′-CO) n′ to Z′ is at least 5:1, wherein the hydrocarbon fluid is an oil field product, a refinery or petrochemical process stream, a heavy distillate or residual fuel, and wherein the hydrocarbon fluid has an asphaltene content of at least 0.01 wt %.