Shale hydration inhibition agent and method of use

A drilling fluid for use in drilling a subterranean well through one or more subterranean formations containing a shale which swells in the presence of water, the fluid comprising:

• an aqueous based continuous phase;
• a viscosifying agent and
• a shale hydration inhibition agent, wherein the shale hydration inhibition agent is selected from:
• as well as mixtures of these, wherein R is an alkyl chain comprising 1 to 15 carbon atoms, and X is an anion;
• and
• wherein the shale hydration inhibition agent is present in sufficient concentration to reduce the swelling of shale.

A fracturing fluid for use in a subterranean well through one or more subterranean formations containing a shale which swells in the presence of water, the fluid comprising:

• an aqueous based continuous phase;
• a viscosifying agent and
• a shale hydration inhibition agent, wherein the shale hydration inhibition agent is selected from:
• as well as mixtures of these, wherein R is an alkyl chain comprising 1 to 15 carbon atoms, and X is an anion;
• ;
• and
• wherein the shale hydration inhibition agent is present in sufficient concentration to reduce the swelling of shale.

A method of decreasing the toxicity of a water-based wellbore fluid comprising circulating in the well a water-base drilling fluid comprising:

• an aqueous based continuous phase and
• a shale hydration inhibition agent, wherein the shale hydration inhibition agent is selected from:
• as well as mixtures of these, wherein R is an alkyl chain comprising 1 to 15 carbon atoms, and X is an anion;
• ;
• and
• wherein the shale hydration inhibition agent is present in sufficient concentration to reduce the toxicity of the wellbore fluid.

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

• an aqueous based continuous phase and
• a shale hydration inhibition agent wherein the shale hydration inhibition agent is selected from:
• as well as mixtures of these, wherein R is an alkyl chain comprising 1 to 15 carbon atoms, and X is an anion;
• wherein the shale hydration inhibition agent is present in sufficient concentration to reduce the swelling of shale.