OIL DEPOSIT DEVELOPMENT METHOD Russian patent published in 2007 - IPC E21B43/20 

FIELD: oil production, particularly enhanced recovery methods for obtaining hydrocarbons, for instance by oil displacement with water.

SUBSTANCE: method involves dividing producing wells into two groups in the beginning of each water-gas treatment cycle, wherein the first group includes wells with current gas factor greater than average current gas factor of all wells and the second group includes remainder producing wells characterized by current gas factor smaller than average current gas factor of all wells; performing injection of water-gas mixture in three stages. The first stage involves injecting water-gas mixture in injection wells before gas factor increase in associated producing wells; performing shutdown of injection wells; carrying out hydrodynamic injection well survey by taking pressure drop curves up to bottom-hole pressure stabilization at reservoir pressure level and executing the second injection stage. At the second injection stage water-gas mixture plugs are cyclically serially injected in reservoirs, wherein each cycle begins from injection of the first water-gas mixture plug including only water and gas in amount of 5-10% of water-gas mixture volume injected in reservoirs at the first stage. After that injection wells are shutdown and hydrodynamic injection well survey is carried out by taking pressure drop curves up to bottom-hole pressure stabilization at reservoir pressure level. Then the second water-gas mixture plug is injected in injection wells, wherein the second water-gas mixture plug includes water, surfactant and gas. The second water-gas mixture plug is fed in amount of 5-10% of that injected in reservoirs at the first injection stage. Then above water-gas mixture plug injection cycles are repeated to reach predetermined summary water-gas mixture plug volume equal to 50-60% of initial in-place volume of oil deposit. At the third stage water is injected in injection wells. Producing wells are shutdown in each cycle of the second stage for the period until beginning of next water-gas mixture injection cycle.

EFFECT: increased oil recovery due to enhanced sweeping and displacement efficiency.

3 cl, 1 ex, 2 tbl