Paper: Correlation Of Performance Data For Electric Submersible Pumps With Gas-Liquid Flow

This paper describes a program to define the effects of free gas on the performance of electric submersible centrifugal pumps. The effects of the free gas show up as a deterioration of the head-capacity curve, such as areas of unstable head production, and effects similar to cavitation at higher flow rates. Depending on the amount of free gas through the pump, these effects may vary from slight interference to gas locking. Gas interference is indicated on the surface amp chart by rapid variation of the motor loading. Gas Locking occurs when the pump ingests too much gas and actually stops pumping because its head (or pressure) production is drastically decreased. This causes the motor to unload and to shut down because of low ampere surface control protection. When designing an electric submersible pump for a gassy application, it is desirable to know the amount of free gas the pump can tolerate and to compare this to downhole gas conditions. Thus, the objectives of this project were (1) to generate experimental data relating pump performance (i.e., head-capacity) to gas-Liquid ratio at the pump suction and to the pump suction pressure, (2) to correlate these data, and (3) to develop a model which would predict head-capacity performance of a submersible pump as a function of gas-liquid ratio, suction pressure, pump type, and any other pertinent parameter.