Terpolymer composition for aqueous drilling fluids

Abstract

A method of improving high temperature fluid loss and rheology stabilization of high calcium brine clay-containing oil well drilling fluids which comprises adding thereto a stabilizing amount of a water-soluble terpolymer composition comprising: ______________________________________ Ingredients % by weight ______________________________________ NaAMPS 72-3.8 N,N-dimethylacrylamide 13.5-0.7 Acrylonitrile 9.5-0.5 ______________________________________ said composition containing lignin, modified lignin, brown coal or modified brown coal in an amount ranging between 5-95% with the lignin, modified lignin, brown coal or modified brown coal having been present during the polymerization of the water-soluble polymer.

Having thus described our invention, it is claimed as follows: .[.1. A method of improving high temperature fluid loss and rheology stabilization of high calcium brine clay-containing aqueous oil well drilling fluids which comprises adding thereto a stabilizing amount of a water-soluble terpolymer composition comprising: a polymer prepared by polymerizing the following monomer ingredients:.]. 
     
        20-35% by weight..]. .Iadd.4.  A composition comprising: terpolymer segments comprising units derived from acrylonitrile, N,N-dimethylacrylamide, and 2-acrylamido-2-methylpropane sulfonic acid, sodium salt wherein said acrylonitrile is present in an amount up to about 9.5%, said N,N-dimethyacrylamide is present in an amount up to about 18.4% and said 2-acrylamido-2-methylpropane sulfonic acid, sodium salt is present in an amount of about 3.8% to about 72%;   from about 5% to about 95% by weight of a lignin, modified lignin, brown coal or modified brown coal selected from the group consisting of lignites, sulfonated lignites, lignins, leonardites, lignosulfonates, humic acids, sulfonated humic acids, and the salts of each;   said terpolymer segments being formed in the presence of said material.   
     
     
        .Iaddend. .Iadd.5.  A composition comprising: terpolymer segments comprising units derived from acrylonitrile, N,N-dimethylacrylamide, and 2-acrylamido-2-methylpropane sulfonic acid, sodium salt wherein said acrylonitrile is present in an amount up to about 9.5%, said N,N-dimethylacrylamide is present in an amount up to about 18.4%, and said 2-acrylamido-2-methylpropane sulfonic acid, sodium salt is present in an amount of about 3.8% to about 72%;   from about 20% to about 35% by weight of a lignin, modified lignin, brown coal or modified brown coal selected from the group consisting of lignites, sulfonated lignites, lignins, leonardites, lignosulfonates, humic acids, sulfonated humic acids, and the salts of each;   said terpolymer segments being formed in the presence of said material.   
     
     
        .Iaddend. .Iadd.6.  A composition comprising: terpolymer segments comprising units derived from acrylonitrile, N,N-dimethylacrylamide, and 2-acrylamido-2-methylpropane sulfonic acid, sodium salt, wherein said acrylonitrile is present in an amount of at least about 0.5% to about 9.5%, said N,N-dimethylacrylamide is present in an amount of at least about 0.7% to about 13.5% and said 2-acrylamido-2-methylpropane sulfonic acid, sodium salt is present in an amount of at least about 3.8% to about 72%;   from about 5% to about 95% by weight of a lignin, modified lignin, brown coal or modified brown coal selected from the group consisting of lignites, sulfonated lignites, lignins, leonardites, lignosulfonates, humic acids, sulfonated humic acids, and the salts of each;   said terpolymer segments being formed in the presence of said material. .Iaddend. .Iadd.7. A composition comprising:   terpolymer segments comprising units derived from acrylonitrile, N,N-dimethylacrylamide, and 2-acrylamido-2-methylpropane sulfonic acid, sodium salt, wherein said acrylonitrile is present in an amount of at least about 0.5% to about 9.5%, said N,N-dimethylacrylamide is present in an amount of at least about 0.7% to about 13.5% and said 2-acrylamido-2-methylpropane sulfonic acid, sodium salt is present in an amount of at least about 3.8% to about 72%;   from about 20% to about 35% by weight of a lignin, modified lignin, brown coal or modified brown coal selected from the group consisting of lignites sulfonated lignites, lignins, leonardites, lignosulfonates, humic acids, sulfonated humic acids, and the salts of each;   said terpolymer segments being formed in the presence of said material. .Iaddend.