METHOD FOR INCREASE OF OIL RECOVERY FROM FORMATIONS Russian patent published in 1996 - IPC

FIELD: oil producing industry; applicable in increasing of oil recovery of water-encroached terrigenic and carbonate reservoirs and regulation of their permeability at the middle and late stages of oil deposit development. SUBSTANCE: method for increase of oil recovery from formations is effected by injection of spent alkali or its mixture with fresh water and subsequent forcing by fresh water into formation. For deposits with mineralized water, prefringe of fresh water is used. Used spent alkalis are of medium and large quantities of secondary material resources of petrochemical production. They should contain 6-26 mas.% of alkali components (sodium hydroxide and/or sodium carbonate) and pH > 10. EFFECT: higher efficiency of application of alkali water encroachment. 2 cl, 5 tbl