In recent years there is a tendency of standing increase of ESP share in performance stock of oil recover companies. At the same time there is an increase of oil production from drowned wells observed in consequence of universal application of water flooding and depletion of most of the large deposits. The average water cut of recovered products at pump operation is at present from 80 to 85 per cent. As is known, one of the complicating factors of steady operation of ESP is free gas inflow into the pump. For the protection of ESP against free gas harmful effect on the oil-fields, gas separators are widely used because they allow to separate some of the gas into the annular space. When water cut increases, the quantity of free gas in the flow stream drops, and it becomes possible to apply a disperser, which is required for the generation of fine liquid-gas mixture which, on reaching the inlet of ESP, decreases free gas effect on the pump operation. The application of dispersers is also well grounded for zero water-cut oil fields with moderate-size gas oil ratio.

Frequently, in order to protect ESP from an adverse gas effect, gas separators are used, which drop part of precipitated gas into the annular space. A considerable part of associated gas in the annular space under certain conditions can lead to the formation of hydrate and paraffin-hydrate blocks which stop up the annular space and create conditions for both the separator and the ESP work breakdown, down to the pump starvation. It is noteworthy that the gas dropped in the annular space doesn't do raising fluid operation. This work is done by the pump, which leads to power consumption and production cost increase, as well as error-free running time decrease.

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