A method of treating a formation with a well treatment fluid comprising a clay stabilizer comprising a polyamine ether before or during a well treatment such as cleanup, gravel packing, fracturing, or the like. The stabilizer can continue to inhibit fines migration in the treatment zone even after an aqueous fluid without the stabilizer, e.g. a production fluid or injection fluid, displaces the original treatment fluid. When the stabilizer is used in a viscoelastic system (VES) with an acid blend component, the viscosity of the VES is essentially unchanged relative to the VES alone without the stabilizer.