ROD PUMP FLOW RATE DETERMINATION FROM MOTOR POWER

摘要

ROD PUMP FLOW RATE DETERMINATION FROM MOTOR POWER A pump controller coupling the electric motor of a cyclically operating well pump to a power line is arranged to measure instantaneous power consumption of the motor, to integrate the power consumption over pump cycles, and to assess the performance of the well and/or pump by using the total power consumption to estimate fluid flow. The controller determines a phase reference in the cycle of the pump by monitoring for a peak or zero crossing in the instantaneous power level, specifically the point at which the pump changes over from a power stroke to regenerative operation due to pump momentum. The integrated total power consumption is reduced by an offset factor representing frictional losses, and scaled to obtain an approximate fluid volume determination for the pump and well. The factors used for offset and scaling can be adjusted by calibration using at least intermittent measurements of actual fluid flow and fluid density. The offset factor representing friction can be monitored for deciding when maintenance is needed on the pump.