Patent ID: 6590050
Filing Date: 2003-07-08
Classification: C04B,C08F,C09K

Abstract:
A method of controlling fluid loss properties of water based oil and gas well fluid systems used in drilling, cementing and completion operations comprising adding to the aqueous system an effective amount for the purpose of a copolymer composition comprising(A) a monomeric repeat unit having the structure: &Parenopenst;E&Parenclosest;wherein E comprises the repeat unit obtained after polymerization of acrylamide or a substituted acrylamide;(B) a repeat unit obtained after the polymerization of a sulfonate containing compound having the structure: wherein R1 is hydrogen or a lower alkyl (C1-C5), R3 and R2 are identical or different and are selected from the group consisting of hydrogen and (C1-C5) alkyl groups and M+ is a water-soluble cation or hydrogen;(C) a repeat unit obtained from the polymerization of a substituted allyl alkylene ether compound having the structure: wherein R1 is hydrogen or a lower alkyl (C1-C5), R4 is a hydroxyl substituted alkylene group having from 1 to 6 carbon atoms, or a non-substituted alkyl or alkylene group having from 1 to 6 carbon atoms, X is an anionic radical, and Z is one or more hydrogen or water-soluble cation which together counterbalance the charge of X; and(D) a monomer selected from the group consisting of acrylic acid, methacrylic acid, maleic acid or anhydride, itaconic acid, crotonic acid, fumaric acid, and citraconic acid, wherein the individual mole percentage of repeat units (A), (B), (C), and (D) is from about 5% to about 95% with the proviso that the sum of the mole percentages is 100%.