Abstract: A process for recovering petroleum from subterranean reservoirs where high salt content water is used in a secondary recovery process consisting of forming as the displacement fluid a dilute alkaline silicate solution utilizing the high salt content water and filtering the alkaline flooding solution to remove scale-forming alkali insoluble salts which include a substantial proportion of calcium and magnesium salts. The filtered solution is injected into the reservoir and this is followed by an injection of a slug of substantially neutral water. A dilute acid solution is utilized to contact and dissolve the alkaline insoluble salts which have been filtered from the alkaline solution and the thus formed solution which includes a substantial portion of soluble calcium and magnesium salts is injected into the reservoir for subsequent contact with the alkaline silicate solution.