Polymers for use as filtration control aids in drilling muds
AssigneeCalgon Corporation
InventorsShih-Ruey T. Chen, Christine A. Costello, Gary F. Matz
Life of this patent
Estimating the term…
Abstract
The instant invention is directed to a polymer, having an intrinsic viscosity of 1.0 to 7.0, preferably 1.5 to 5.0, dl/g in 1.0 M NaCl, prepared from: (A) 2.5 to 45%, by weight, of at least one unsaturated carboxylic acid, or its salt; (B) 5.0 to 85%, by weight, of at least one unsaturated sulfonic acid, or its salt; (C) 2.5 to 15%, by weight, of at least one unsaturated cationic-containing monomer; and (D) 0 to 90%, by weight, of at least one unsaturated non-ionic monomer. The instant invention is also directed to the polymer in combination with an aqueous clay dispersion and the use of the admixture as a filtration aid in drilling muds.
Claims3
An aqueous drilling fluid comprising:
- (i) an aqueous clay dispersion;
- and
- (ii) a polymer, having an intrinsic viscosity of 1.0 to 7.0 dl/g in 1.0 M NaCl, prepared from:
- (A) 25 to 35%, by weight, of at least one unsaturated carboxylic acid selected from the group consisting of acrylic acid, methacrylic acid and their salts;
- (B) 25 to 40%, by weight, of at least one unsaturated sulfonic acid selected from the group consisting of 2-acrylamido-2-methylpropyl sulfonic acid, 2-methacrylamido-2-methylpropyl sulfonic acid, and their salts;
- (C) 5 to 10%, by weight, of at least one unsaturated cationic containing monomer selected from the group consisting of dimethyldiallyl ammonium chloride, dimethyldiallyl ammonium chloride and methacryloyloxyethyl trimethyl ammonium chloride;
- and
- (D) 15 to 45%, by weight, of at least one unsaturated non-ionic monomer selected from the group consisting of acrylamide and methacrylamide.
A method for drilling a well in a subterranean formation, comprising circulating into the well, during drilling, an aqueous drilling fluid, the improvement wherein said aqueous drilling fluid comprises:
- (i) an aqueous clay dispersion;
- and
- (ii) a polymer, having an intrinsic viscosity of 1.0 to 7.0 dl/g in 1.0 M NaCl, prepared from:
- (A) 25 to 35%, by weight, of at least one unsaturated carboxylic acid selected from the group consisting of acrylic acid, methacrylic acid and their salts;
- (B) 25 to 40%, by weight, of at least one unsaturated sulfonic acid selected from the group consisting of 2-acrylamido-2-methylpropyl sulfonic acid, 2-methacrylamido-2-methylpropyl sulfonic acid, and their salts;
- (C) 5 to 10%, by weight, of at least one unsaturated cationic containing monomer selected from the group consisting of dimethyldiallyl ammonium chloride, dimethyldiallyl ammonium chloride and methacryloyloxyethyl trimethyl ammonium chloride;
- and
- (D) 15 to 45%, by weight, of at least one unsaturated non-ionic monomer selected from the group consisting of acrylamide and methacrylamide.
Dependencies are inferred from the claim text.