a clay stabilizer which is capable of inhibiting swelling in a wide variety of clay types and is also capable of restoring permeability in formations which have previously been damaged by clay swelling . amine salts of differing molecular weights configurations and ionic strength are combined to provide transport into micropores , mesopores and macropores in the formation and to effect cationic change therein . a poly quaternary amine having a high to very high charge density is added along with lower molecular weight amine salts to substantially permanently exchange cations with the clay in the formation .