TECHNIQUE TO DEVELOP OIL DEPOSIT Russian patent published in 2003 - IPC

FIELD: oil production. SUBSTANCE: oil is withdrawn through production wells to reduce formation pressure to value beneath saturation pressure and water is pumped through injection wells from start of development till water content in production well reaches 70% and more. After this water fringe containing foam-forming oil-soluble reagent with concentration of 0.01-5.0% by mass of volume of 2-10% of oil remaining in pool is pumped through injection wells. This reagent dissolves better in oil than in water. Then volume of pumped water is diminished or water pumping is stopped till formation pressure becomes lower than saturation pressure under which 10-20% of porous volume of pool are filled with gas liberated from oil. After this water pumping is continued with keeping present formation pressure. EFFECT: raised oil output of deposit. 1 cl