One of the effective solutions for increasing oil and gas reservoirs is the method of simultaneous water alternating gas (SWAG) on a reservoir by pump-ejector systems. In this system are using the multistage centrifugal pump for injection water-gas mixtures, which prepared by ejector. Previous studies have shown that the strong influence of free gas on the characteristics of pressure and pressure in the aquatic environment cannot using to determine the characteristics and the rational using of these devices in the well at higher pressures. In field conditions, at the Samodurovskoye field, when gas flows, at the heights of the Samoerovskoye, Efremo-Zykovskoye and Spasskoye fields, under pressure until 0.2 to 0.4 MPa. The water-gas mixture at the inlet of the booster pump, as well as at the gas pipeline at the inlet to pump ejector installation by a low-pressure compressor system also supplies associated petroleum gas from the neighboring Ponomarevskoye field. Thus, it is necessary to conduct a study of the characteristics of a multistage centrifugal pump at elevated pressures during operation of the jet apparatus. Research conducted on a mock-up of a pump-ejector system. As a result, of experimental studies, it found that with decreased inlet pressure, and the influence of gas on the characteristics of the booster pump in water-gas mixtures. This leads to a significant reduction in the harmful effects of gas on the working pump of the pump. The difficulty of the combining gas bubbles into cavities with increasing pressure in the flow of a finely dispersed mixture can be describe by the increase in this stable mixture. The modernization of laboratory bench, it was possible to provide a gas supply at an overpressure of O. 2 to 0.37 MPa, similar to field conditions.