METHOD OF DEVELOPMENT OF OIL DEPOSIT AT LATE STAGE Russian patent published in 2003 - IPC

FIELD: oil and gas producing industry, particularly, methods of oil recovery from nonuniform water- encroached formations at late stage of oil deposit development. SUBSTANCE: method includes injection into formation through injection well of aqueous solutions of reagents forming insoluble precipitate. One reagent is used in form of metal chloride. Ratio of injected reagents is taken in compliance with stoichiometric coefficients ensuring maximum yield of precipitate. Oil production is carried out through producing well. Injection of reagent aqueous solutions is effected successively or concurrently. Metal chloride is used in form of one component of the following group; calcium chloride, magnesium chloride, aluminum chloride, iron chloride. The other reagent is used in form of salt of polybasic acid or alkali. In addition, introduced together with solution of salts is water repellant. Concentration of reagents in solutions is selected proceeding from geological and physical characteristics of formation. To obtain precipitate in form of metal hydroxide, the other reagent is used in form of sodium or potassium hydroxide. Water repellant is used in form of water-soluble organosilicon compounds or anionic surfactants with concentration of 0.5-5%. EFFECT: provided water shutoff barriers with improved process parameters and increased duration of effect for formation zones with any permeability, extended assortment of chemical reagents applicable in method realization. 3 cl, 2 tbl