Shale inhibitor additives, wellbore fluids comprising said additives, and methods of using said fluids

A wellbore fluid, comprising:

• an aqueous base fluid;
• a shale inhibition additive comprising at least one hydrophobic amine that is a neutralized byproduct of a Nylon-6,6 manufacturing process, wherein the at least one hydrophobic amine is present at a concentration of at least about 40% of a total active amine concentration of the shale inhibition additive;
• and
• at least one polymeric viscosifier;
• wherein the at least one hydrophobic amine comprises a triamine-based shale inhibition agent and a diamine-based shale inhibition agent, and a ratio of the triamine-based shale inhibition agent to the diamine-based shale inhibition agent is from about 3:1 to about 10:1, and
• wherein the wellbore fluid facilitates at least one of an increase in bulk hardness, an increase in shale inhibition, an increase in inhibition agent adsorption, a decrease in clay dispersion, or a decrease in cation exchange activity when the wellbore fluid is introduced into a subterranean formation.