J.N. McCoy, Echometer Company; Forrest Collier, Mobil E&P; A.L. Podio, University of Texas at Austin
A systematic study was undertaken in order to establish a procedure by which the effect of operating conditions on the efficiency of beam pumping systems can be determined with a minimum of expense. The study concentrated on the effect of easily controllable parameters such as direction of rotation, counterbalance effect, motor selection, torque mode for variable torque motors, tubing back pressure, stuffing box friction and motor slip on the energy usage. The paper describes the instrumentation, data acquisition and processing system which allows accurate measurement of instantaneous motor power during a pump stroke. This measurement was correlated with dynamometer measurements in order to determine the surface system efficiency. Calculation of the downhole pump dynamometer allows determination of the effect of operating conditions on the volumetric efficiency of the pump. From these measurements, an overall efficiency can be established as a means of comparison; that is , the overall work output at the pump versus the work input at the motor.