Patent ID: 7572381

Claim:
A process to inhibit the formation of scale in a water system at both wellhead and seabed temperatures comprising a step of adding to the water system a scale inhibiting amount of a composition comprising: (a) a copolymer of an unsaturated phosphonic acid or a salt of such an acid with an unsaturated sulphonic acid or a salt of such an acid or an unsaturated carboxylic acid or a salt of such an acid; or (b) a terpolymer of an unsaturated phosphonic acid or a salt of such an acid with an unsaturated sulphonic acid or a salt of such an acid and an unsaturated carboxylic acid or a salt of such an acid, wherein the system water temperature at a wellhead is in the range of 80-200° C. and a seabed temperature is below 40° C., and wherein the formation of scale in the water system is inhibited at both the wellhead and seabed temperatures.