ESP (Electrical Submersible Pump) is one the most important artificial lift methods for oil in Brazil and worldwide. In this method, the centrifugal pump is driven by an electric motor directly coupled to the pump shaft. ESPs are commonly provided with a set of sensors that monitor the motor operation, temperature and head.

Measurement of liquid flow rate produced by each well is traditionally performed with specialized, costly instrumentation. As the motor sensor and the frequency inverter that drives the ESP provide useful information for pump monitoring and well management, the local flow rate through the ESP could also be determined from in-field calibration curves relating the flow rate with monitored data. Specifically, the head generated by the ESP and/or the electrical power consumed by the motor, which are usual performance curves describing the pump behavior, can be related to the flow rate of the fluid being produced. Appraisal of such flow rate measurement techniques should of course be based on the uncertainties propagated from each calibration curve. In this study, ESP performance curves of head and electrical power obtained at different operating conditions (including two-phase and viscous fluids) are used to determine the uncertainties in the liquid flow rate measurement from the curves. Results on the suitability of each method are discussed in the light of the API RP 11S2 standard, which establishes the best practices for ESP testing.

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