METHOD OF OIL RECOVERY FROM FORMATION Russian patent published in 2000 - IPC

FIELD: oil producing industry, particularly, methods of oil recovery from formations with use of displacing agents in form of alkali solutions. SUBSTANCE: method includes oil displacement from formation to producing well by cyclic injection of still waste and sewage water. Still water is injected with pH 5.5-7.0 in amount of 0.04-0.09 of pore volume washed with water, and sewage water with density of, at least, 1100 kg/cu.m in amount of 0.017-0.03 of pre volume washed with water, and still water-sewage water ratio in each cycle amounts to 2:1 to 5:1. EFFECT: higher displacement efficiency, reduced water cutting of well production and increased coverage of formation with flooding. 2 dwg, 3 tbl, 2 ex