Patent attributes
A method of using a water-base wellbore fluid 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 hydration inhibition agent is selected from the class of compounds known as polycycloaliphatic amines. Further the shale hydration inhibition agent may be present in the form of a free-base or in the form of an acid salt of the disclosed amine compounds. The shale hydration inhibition agent is present in sufficient concentration to substantially reduce the swelling of shale drilling cuttings upon contact with the fluid.
