Patent ID: 8461088

Claim:
A method for oil recovery comprising the step of injecting into marine oil wells an aqueous solution of an aminoacid phosphonic acid scale inhibitor in a level of from 0.1 to 100000 ppm, where the scale inhibitor is selected from the group consisting of: i. aminoacid alkylphosphonic acids having the formula A 1 -(B) x wherein A 1 has the formula HOOC-A-NH 2 wherein A is independently selected from C 2 -C 20 linear, branched, cyclic or aromatic hydrocarbon chains, optionally substituted by C 1 -C 12 linear, branched, cyclic or aromatic hydrocarbon groups, optionally substituted by OH, COOH and/or NH 2 moieties, and B is an alkylphosphonic acid moiety having from 1 to 6 carbon atoms in the alkyl group and x is an integer of from 1 to 10, and ii. aminoacid alkylphosphonic acids having the formula A 2 -B y wherein A 2 has the formula HOOC—C(NH 2 )(R)(R′) wherein R and R′ are independently selected from C 1 -C 20 linear, branched, cyclic or aromatic hydrocarbon chains, optionally substituted by C 1 -C 12 linear, branched, cyclic or aromatic NH 2 and/or COOH, and one of R or R′ can be hydrogen with the proviso of excluding: compounds wherein R and/or R′ are electron rich moieties containing, at least, one lone pair of electrons, which moiety is directly attached to an aromatic moiety by a covalent bond; or aromatics wherein at least one of the carbon atoms has been substituted by a heteroatom; and compounds, in the event R is —C(X)(R″)(R′″) and R′, R″ and R′″ are hydrogen wherein X is an electron withdrawing group selected from NO 2 , CN, COOH, SO 3 H, OH and halogen, and with the further proviso that when: A 2 is L-lysine, at least one L-lysine amino radical carries 2 (two) alkyl phosphonic acid moieties; and when A 2 is L-glutamic acid, the term glutamic acid phosphonate represents a combination of from 50-90% by weight pyrrolidone carboxylic acid N-methylene phosphonic acid and from 10-50% by weight of L-glutamic acid diphosphonic acid, expressed on the basis of the reaction products; and B is an alkylphosphonic acid moiety having from 1 to 6 carbon atoms in the alkyl group and y is an integer in the range of from 1 to 10.