Shale hydration inhibition agent and method of use

Abstract From the Canadian patent

A water-base wellbore fluid for use in subterranean wells that penetrate through a subterranean formation containing a shale which swells in the presence of water. The well bore fluid includes an aqueous based continuous , phase, and a shale hydration inhibition agent. One illustrative shale hydration inhibition agent is preferably the reaction product of a hydrogenation reaction of the product of the reaction of an aromatic amine with an aldehyde, preferably formaldehyde. Alternatively the shale hydration inhibition agent may be the reaction product of a hydrogenation reaction of the product of the reaction of aniline and formaldehyde. In one illustrative embodiment, the shale …