METHOD OF OIL DEPOSIT DEVELOPMENT BY WATER AND GAS INJECTION Russian patent published in 2014 - IPC E21B43/20 

FIELD: oil and gas industry.

SUBSTANCE: method includes drilling of producers and injectors or selection of ready producers and injectors within the oil deposit site, injection of water and associated gas to injectors and withdrawal of the product through producers. In compliance with this invention, vertical wells drilling data are used for calculation of optimum injection parameters for water and gas using the hydrodynamic model. Injection is made by cycles consisting of three stages. At the first stage the producers are shut in, gas in injected in volume selected during their operation. At the second stage, with shut in producers, water injection is made till injection pressure increases 2 times in comparison with the initial value. At that the initial injection pressure is maintained within the range of P_i=(0.45…0.55)·P_r, where P_r is vertical rock pressure. Thereafter the third stage is started. Injection is stopped and producers are launched. Associated gas is collected to tanks for its further use at the first stage. When the reservoir pressure decreases per more than 20% from the initial value the cycle is repeated. At that at the first stage injection rate of the gas q_q to each injector is determined by the analytic expression. In deposits with oil viscosity more than 50 mPa·s at the second stage water is injected with down temperature of 90°C at least. Gas and water are injected respectively at the first and second stages as for injectors.

EFFECT: higher reservoir recovery, lower oil viscosity and higher displacement efficiency.

3 cl, 3 ex