Scale and corrosion inhibitors for high temperature and pressure conditions

A method for inhibiting corrosion of metal in contact with an aqueous system and/or inhibiting scale formation in the aqueous system, said method comprising adding to the aqueous system an effective amount of a polymer composition comprising polymerized units derived from:

• a) 1% to 100%, by weight, of a phosphorus-containing amide monomer having the general formula;
• wherein X1, X2 are each, individually, hydrogen, linear or branched C1-C4 alkyl groups, aryl groups, nitrogen-containing groups, or metal ions;
• X1 and X2 together may be a multivalent metal atom, or X1 and X2 may be linked together to form a cyclic structure;
• R1, R2, R3, R4 are each, individually, hydrogen, linear or branched C1-C4 alkyl groups, aryl groups, and combinations thereof;
• and R5 is absent, or R5 is linear or branched C1-C20 alkyl groups, aryl groups, ethylene oxide residue, propylene oxide reside, or combinations thereof;
• or R5 is —R6—O—, where R6 is either absent or, when it is present, it is linear or branched C1-C20 alkyl groups, aryl groups, ethylene oxide residue, propylene oxide reside, or combinations thereof;
• wherein the weight percent is based on the total weight of said polymer composition and the weight percents of all components totals 100%, and wherein said polymer composition has a weight average molecular weight of between 1,000 and 200,000 grams/mole, and wherein the aqueous system has a temperature up to 250° C., a pressure up to 68.9 MPa, or both.