METHOD TO DEVELOP OIL DEPOSIT WITH GAS CAP (VARIANTS) Russian patent published in 2007 - IPC E21B43/24 

FIELD: oil industry, particularly enhanced recovery methods for obtaining hydrocarbons.

SUBSTANCE: method in accordance with the first variant involves drilling injection and production wells in oil reservoir; injecting working agent, namely hot water, in gas-oil contact zone and in oil plug zone through injection wells. In the case of low sandy coefficient and increased average number of permeable reservoir intervals hot water has temperature higher than initial reservoir temperature and lower than boiling temperature under injection well head pressure. The wells are horizontal. Upper well parts expose gas cap, lower ones expose all oil-saturated interlayers to arrange injection wells over production ones with gas-tight bridge located between gas cap and oil plug. If said bridge is absent injection wells are located between production ones. Method in accordance with the second embodiment involves drilling injection and production wells in oil reservoir; injecting working agent, namely water-gas mixture, in gas-oil contact zone through injection wells. In the case of low sandy coefficient and low average number of permeable reservoir intervals water-gas mixture has temperature higher than initial reservoir temperature and lower than boiling temperature under injection well head pressure. Water-gas mixture is obtained by hot water dispersion with gas to create fine mixture having density lower than that of oil. The wells are horizontal. Upper well parts expose gas cap, lower ones expose all oil-saturated interlayers to arrange injection wells over production ones with gas-tight bridge located between gas cap and oil plug. If said bridge is absent injection wells are located between production ones.

EFFECT: increased efficiency of oil displacement due to decreased oil viscosity at initial development stage and due to maximized horizontal sweep.

2 cl, 3 ex