The objective of this research is to study experimentally the effect of number of stages on the overall performance of a multistage ESP. Therefore, a series of experiments injecting gas at certain stage and monitoring the pressure increment on stages downstream from the injection point are conducted at different inlet pressure, and rotational speed. The experimental result reveals that two-phase performance of a single stage does not directly represent the two-phase ESP overall performance.

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... ver, a strong relationship between two-phase stage performance, number of stages and the pump overall performance exists. Results also show that increasing the number of stages extends the operating region in which every stage equally contributes on the overall pump performance. This region is bracketed by a critical gas quality that also varies with the increase of the number of stages. Thus, the prediction of the number of stage varies depending on the gas quality. At low gas quality the serial pump rule is suitable for practical application purpose. But, this rule may underestimate the number of stages at higher gas quality in which the serial pump rule is no longer applicable.