The water-alternating-gas (WAG) injection is the effective method to increase the oil recovery of reservoirs. However, with the help of known technologies it is impossible to solve all the problems of widespread introduction of WAG injection and utilization of associated gas. WAG injection with the use of pump-ejecting systems has good prospects in their solution by simple means. At the Kotovskoye field, a joint injection of high-pressure gas from a gas cap and water using a cavitation-dispersing countercurrent device was used at the entrance of which a liquid-gas ejector was installed. At the Samodurovskoye field, the pump-ejecting system, containing a power pump, an ejector and a booster pump, worked steadily in various modes using low-pressure associated gas, there were no capacity breakdowns of the ejectors and pumps.
In many cases, for the effective implementation of WAG technology, it is necessary to provide simultaneously high values of the gas-water factor and the pressure of the injection of the water-gas mixture when using low-head associated petroleum gas. This can be done with the use of WAG injection unit intended for use in reservoir pressure maintenance systems for oil and gas producing enterprises. The installation will ensure full utilization of associated gas, increasing the recovery of oil from the reservoir and improving the environment. The proposed installation of the injection of water-gas mixture includes ejectors, electric centrifugal pumps and separators. Mixing and compression of the water-gas mixture occurs in ejectors placed consistently. The water is supplied into the nozzles of jet devices by means of electric centrifugal pumps located in pits. After each ejector (compression stage), the water-gas mixture enters a separator in which water and gas are separated. At the same time, the gas with increased pressure enters the ejector inlet of the next stage, and water with higher pressure is fed into the electric centrifugal pump and then into the ejector of the next stage. The suggested installation of the WAG injection allows obtainment the 20% volumetric gas content in the water under reservoir conditions and provides a discharge pressure of up to 35 MPa.
References
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