Abstract: There is provided an additive for and a method of using the additive to treat a clay-containing earthen formation, such as a subterranean formation, to substantially reduce formation damage caused by contact of the formation with an aqueous liquid foreign to the formation. The additive, which is employed in a water solution, is comprised of a chloride-free, quaternary ammonium compound which can be used without adverse affect upon animal, soil and water resources due to the chloride-free and substantial organic nature thereof. It thus biodegrades to environmentally acceptable end products.

Abstract: A composition for and method of treating a subterranean hydrocarbon producing formation is provided. The treatment, when conducted in the presence of ferric ions, prevents the development of insoluble ferric iron-containing compounds and also prevents the development of sludge in heavy crude.