ELECTRIC MOTOR SELECTION FOR A PCP PUMPS 1

[neca]

Hi,
I would like to get some information about how to select the right electric motor for an oil pcp pump application.

My client has a 50 HP motor and they need to change this, but they think that this motor is to high for their application.

Best regard,
Neca.

 

[CBlundell]

Depends on pump, depth and speed. Generally the suppliers - Weatherford, Wilson etc all have predictive programs which tell you how much. Rough number would be to assume overall system efficiency of 50% (be sure to add line pressure to pumping head)

 

[jorgerobles]

For this system you will have also to design a rod string, which has a maximum allowed Torque. A practice I recomend is to size the motor to handle the maximum operational torque (hydraulic and frictional torque at the pump + rod friction) but below the maximum value allowed by the rods.

In cases with high sand cut or high viscosity (heavy oil or emulsions) the starting torque could be way above the value obtained from a computer simulation. This should be taken into account for the rod string size/material and Motor power.

The main problems of having an oversized motor are the risk of breaking the rods and the difficulties to diagnose or protect the system based on current (amps) meassurement, since its sensitivity to operational conditions will be mask by the low efficiency you will find at low % of load.

good luck,
Jorge