US Patent 11851604 Cationic nitrogen-containing heterocycles and their application in wellbore stability

A method of inhibiting shale formation during water-based drilling of subterranean formations include s introducing a shale inhibitor to the subterranean formation during the water-based drilling, the shale inhibitor comprising a cationic polymer comprising repeating units of [A-B]. A is a substituted benzene or a substituted triazine of formula (2). B is a N-containing heterocycle. The cationic polymer and a method of making the cationic polymer are also described.