| abstract |
The present invention provides a composition useful as a sulfide scale inhibitor for application in oilfield operations, comprisingn 1) at least one copolymer that comprises as monomers a) 0.1 to 10 mol-%, of structural units derived from vinylphosphonic acid and/or of a salt thereof, b) 40 to 80 mol-% of structural units derived from compounds of the formula (1) nn n n n n n n n n n n n c) 1 to 50 mol-% of structural units derived from compounds of the formula (2) n n n n n n n n n n n n n n n n in which n X is OH or NR3R4, and R3 and R4, independently of one another, are H or C 1 -C 4 -alkyl, n 2) at least one of tris (hydroxymethyl) phosphine or a tetrakis(hydroxymethyl)phosphonium salt, n 3) at least one surfactant, n 4) at least one amine or ammonium salt. |