Jorge Robles Villa's Thesis
by
Jorge Robles Villa, MSE
University of Texas at Austin, 1996
Supervisor: Augusto L. Podio
One of the weakest points in the analysis of sucker rod and progressing cavity
pumps artificial lift systems is the prediction of the downhole gas separation
efficiency at the pump intake. This parameter affects dramatically the behavior
of the pump and, therefore, the final result of any study.
The objective of this research project is to characterize experimentally in the
Laboratory the behavior of the most common downhole gas separators (gas
anchors), in order to obtain models or correlations that allow predicting the
efficiency of these systems in real conditions.
In order to determine the effect of the separator efficiency on the pump's
volumetric efficiency, a computer program was developed to simulate the
hydrodynamics of the separator-pump system, for the cases of conventional sucker
rod pumping, constant velocity pumping and progressing cavity pumping.
Major modifications were performed to enhance the experimental facilities at
the artificial lift laboratory of the Petroleum and Geosystems Engineering
Department of the University of Texas at Austin, and a control and data acquisition
system was developed.
An experimental methodology and program were developed. The first stage of
this program was completed and the data analysis strategy for the experimental
characterization of downhole gas separators was established.
It was found that the separation efficiency was not a suitable parameter for the
characterization of the downhole gas separators. The gas flow rate handled by the
pump and the liquid fraction at the separator outlet were found to be more
representative parameters of the downhole separator performance. Correlations
were found to predict the gas flow rate handled by the pump for the decentralized
and Gilbert-cup separators tested and the low viscosity oil used in the first stage of
the experimental program. Equations for computing the liquid fraction at the
separator outlet and the volumetric efficiency of the pump are presented.
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