Economic Considerations for Sizing Tubing and Power Cable for Electric Submersible Pumps

Abstract

Power consumption of an electric submersible pump (ESP) installation may be categorized into three components: the energy required to perform useful work, which is equivalent to the net hydraulic load divided by the product of pump and motor efficiencies; the energy absorbed by tubing friction, which is equal to the dissipated hydraulic energy divided by the efficiency product; and power-cable electrical losses. An improved design technique is presented that brings the first two categories into economic perspective. The interrelated effects of tubing friction, power-cable resistance, and motor voltage on ESP power consumption are demonstrated, as is the degree of desirability for using a motor of the highest available voltage. An equation, useful in making economic evaluations of alternatives, is developed for calculating power consumption for combinations of tubing size, power-cable size, and motor voltage. Variations of power consumption are illustrated graphically for various combinations of these three parameters. Also illustrated is the effect of the nature of a specific net hydraulic load-Le., the product of rate, net lift, and specific gravity. Practical examples using the design techniques developed here are presented and comparisons made to designs based on common practice.

Software Complex for Sensorless Control of an Electrical Submersible Pump

“…Expression (12) describes load torque of a pump in a range of operating angular velocity values, except for the "shut-down" mode of an installation. Divergence of estimated load torque values depends on the accuracy of BHP polynomial which gathered either from catalog characteristics or by means of interpolation on the test data set.…”

“…Nowadays, telemetry systems are used to monitor the ESP technological parameters, which consist of both the surface part and the underground part. The underground part of telemetry systems is located in an aggressive environment, where at any time an unpredictable event can damage the measuring instruments [11][12][13]. Accordingly, such conditions affect the instruments' service life.…”

Analysis and Optimization

“…Because of the maximum 1% to 3% differences [20], the use of the ESP motor's power factor is justified. The ESP motor and the downhole electric cable are connected in series, and their combined power factor is found from the individual power factors of the motor and the cable.…”

“…It follows from the previous discussion that maximum power efficiency of the ESP system can basically be ensured by attaining the maximum pump and motor efficiencies while minimizing the power loss in the electric cable [21]. In such cases optimum conditions are reached when the ESP system's power efficiency is at the maximum.…”