Drilling fluid additive and method for inhibiting hydration

A method of reducing the swelling of clay in a well comprising circulating in the well a water-base drilling fluid comprising:

• (a) a weight material selected from the group consisting of barite, hematite, iron oxide, calcium carbonate, magnesium carbonate, and combinations thereof;
• an anionic polymer;
• and
• (b) a functionally effective concentration of the additive formed from the reaction product of a tertiary amine of the following general formula:
• ##STR21## wherein, R.sub.1 and R.sub.2 are methyl or hydroxyalkyl groups with one to three carbon atoms or combinations thereof, R.sub.3 is a hydroxyalkyl group with one to three carbon atoms, with an alkyl halide of the following general formula:
• R-X
• wherein, R is an alkyl radical having up to four carbon atoms, and X is a halogen selected from the group consisting of chlorine, bromine, iodine, or combinations thereof;
• said reaction product being further characterized by (1) low toxicity as demonstrated by said reaction product having an LC.sub.50 value of greater than 30,000 in the Mysid shrimp test as described in Duke, T. W., Parrish, P. R.;
• "Acute Toxicity of Eight Laboratory Prepared Generic Drilling Fluids to Mysids (Mysidopsis)" 1984 EPA-600/3-84-067, and (2) compatibility with anionic drilling fluid components, said compatibility being demonstrated by failure of said reaction product to yield a precipitant in the presence of anionic polymers, said reaction product being present in sufficient concentrations to reduce the swelling of said clay.

A water-base drilling fluid for use in drilling wells through a formation containing a clay which swells in the presence of water, said drilling fluid comprising an anionic polymer;

• the reaction product of a trihydroxyalkyl amine of the following general formula:
• ##STR23## wherein n=1-3, with a water soluble quaternary amine of the following general formula:
• Q-X
• wherein Q is a water soluble quaternary amine and X is a halogen selected from the group consisting of chlorine, bromine, iodine, or combinations thereof;
• said reaction product being further characterized by (1) low toxicity as demonstrated by said reaction product having an L.sub.50 value of greater than 30,000 in the Mysid shrimp test as described in Duke, T. W., Parrish, P. R.;
• "Acute Toxicity of Eight Laboratory Prepared Generic Drilling Fluids to Mysids (Mysidopsis)" 1984 EPA-600/3-84-067, and (2) compatibility with anionic drilling fluid components, said compatibility being demonstrated by failure of said reaction product to yield a precipitant in the presence of anionic polymers, said reaction products present in the drilling fluid in sufficient concentration to reduce the swelling of said clay and a weight material selected from the group consisting of barite, hematite, iron oxide, calcium carbonate, magnesium carbonate, and combinations thereof.

A water-base drilling fluid for use in drilling wells through a formation containing a clay which swells in the presence of water, said drilling fluid comprising an anionic polymer;

• the water soluble polyquaternary amine formed from the condensation reaction product of a trihydroxyalkylamine of the following general formula:
• ##STR25## wherein n=1-3, with an alkyl halide of the following general formula:
• R-X
• wherein R is an alkyl radical having up to four carbon atoms and X is selected from the group consisting of chlorine, bromine, iodine, or combinations thereof, said polyquaternary amine being further characterized by (1) low toxicity as demonstrated by said reaction product having an LC.sub.50 value of greater than 30,000 in the Mysid shrimp test as described in Duke, T. W., Parrish, P. R.;
• "Acute Toxicity of Eight Laboratory Prepared Generic Drilling Fluids to Mysids (Mysidopsis)" 1984 EPA-600/3-84-067 and (2) compatibility with anionic drilling fluid components, said compatibility being demonstrated by failure of said reaction product to yield a precipitant in the presence of anionic polymers, said polyquaternary amine present in the drilling fluid in sufficient concentrations to reduce the swelling of said clay and a weight material selected from the group consisting of barite, hematite, iron oxide, calcium carbonate, magnesium carbonate, and combinations thereof.