The amount of unconventional oil resources in the world is increasing more and more up today, therefore the search for effective methods of layer stimulation is required. One of the methods of Enhanced Oil Recovery (EOR) is water-gas injection with a new approach - simultaneous injection of water and gas (SWAG - Simultaneous Water Alternating Gas) as a mixture with a bubble structure by means of multistage pump-ejecting systems. They allow to prepare a stable water-gas mixture on the surface and to inject it into the reservoir, using simple, reliable, and commonly used equipment.

The main effects of SWAG are enhanced oil recovery and utilization of low-pressure associated gas. Distinctive features of the pump-ejecting technology are a minimum of capital investment and the use of existing oil-field infrastructure.

For the conditions of Russkoye and Samodurovskoye oil fields laboratory filtration tests on sand-packed models were conducted, and also calculations of different process flowsheets based on the results of ejectors and ESP bench tests were carried out. Experiments have shown that SWAG significantly increases the oil-displacement efficiency, while the maximum effect is observed in the gas content 25% with the addition of surfactants in a water-gas mixture. Selected technical layouts of pump-ejecting systems allow injecting the water-gas mixture under a pressure up to 16 MPa at the lowest inlet pressures. Due to developed technical solutions the used equipment can operate in wide ranges of adjustment without significant reduction in the energy efficiency.

Thus, the generalized results have showed high efficiency and availability of this technology at a number of Russian oil fields.

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