Summary
This paper presents a new incompressible single-phase model for ESP head
performance. Sachdeva (1988, 1994) and Cooper and Bosch (1966) developed models
for ESP channels and for inducers, respectively. The model presented in this
paper is based on 1D approximation along an ESP channel. The new derived
pressure ordinary differential equation (ODE) for frictionless incompressible
flow (Bird 1960) is consistent with the pump Euler equation. New models
for pump frictional and shock losses have been proposed. Finally, a comparison
between the predicted pump performance and the pump performances derived from
the affinity law for different rotational speeds is presented. The single-phase
model can predict ESP performance under different fluid viscosities and also is
the basis of a gas/liquid model for ESP head performance.
Introduction
ESPs are dynamic multistage devices that use kinetic energy to increase
liquid pressure. The relationship between the head developed by the pump and
the flow rate through the pump for a certain rotational speed is usually known
as the pumphead performance curve. This curve is experimentally determined by
the pump manufacturer using water as the working fluid. As a consequence,
published pumphead performance curves can be used for any other low-viscosity,
single-phase liquid, independent of its density. Pump performance, however, is
significantly affected by the presence of free gas or high-viscosity
fluids.
The U. of Tulsa Artificial Lift Projects (TUALP) is currently conducting
experimental as well as theoretical research to improve the understanding of
pump performance when handling viscous fluids and two-phase flow mixtures at
different pump rotational speeds. A better understanding of the pump
performance under those conditions will certainly contribute to a reduction in
the uncertainty of engineering tools for the selection, design, and operation
of ESPs in more challenging applications.
This paper presents the new single-phase model developed for the prediction
of an ESP's performance. The model consists of the mass and momentum equations,
based on the streamline approach or 1D assumption. In the momentum equations,
the calculation of the friction factor proposed by Sachdeva is improved by
incorporating the channel curvature, channel rotation, and channel
cross-sectional effects. A new shock loss model, including rotational speeds,
has been proposed. The new single-phase model is capable of predicting the pump
performance for different pump rotational speeds and for different fluid
viscosities.
© 2006. Society of Petroleum Engineers
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History
- Original manuscript received:
12 May 2003
- Revised manuscript received:
17 October 2005
- Manuscript approved:
27 October 2005
- Version of record:
20 March 2006
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