Pumping unit efficiency is highly disturbed by the presence of gas influx reducing the productivity and inducing unpredictable system response due to the change of its intrinsic properties such as the natural frequency. A poor estimation of those properties may affect the on-field crew and system safety as well as the production rate. The purpose of this paper is to construct a hydromechanical model describing the coupled multiphase flow-pumping unit system dynamics and to develop a procedure to control the pumping speed for safety assurance and oil production maximization. A coupled mechanical-multiphase flow model capturing the interplay between the gas void fraction (GVF) and the driving harmonic force of the pumping unit is developed. Specifically, the predicted downhole pressure is used to determine the sucker rod effective load. Consequently, a reduced-order model, capturing the dynamics of the sucker rod, is used to estimate the saddle bearings axial displacements which are function of polished rod loading. An error-driven adaptation using the difference between presumed bearing displacement with known GVF and the predicted bearing displacement from the proposed multiphysics model is employed to estimate the unknown downhole GVF. The obtained results prove that the adaptation allows an accurate evaluation of the pumped fluid's GVF, thereby circumventing the need for a costly and inaccurate measurement of the two-phase flow gas fraction. Based on this estimation, a control strategy is then proposed to regulate the pump speed while avoiding the resonance frequency of the sucker-rod system.

References

References
1.
Takacs
,
G.
,
2003
,
Sucker-Rod Pumping Manual
,
PennWell
, Tulsa, OK.
2.
Petalas
,
N.
, and
Ghajar
,
K. A.
,
2000
, “
A Mechanistic Model for Multiphase Flow in Pipelines
,”
J. Can. Pet. Technol.
,
39
(
6
), pp. 43–55.
3.
Woldesemayat
,
M. A.
, and
Ghajar
,
A. J.
,
2007
, “
Comparison of Void Fraction Correlations for Different Flow Patterns in Horizontal and Upward Inclined Pipes
,”
Int. J. Multiphase Flow
,
33
(4), pp.
347
370
.
4.
Zhao
,
Y.
,
Bi
,
Q.
, and
Hu
,
R.
,
2013
, “
Recognition and Measurement in the Flow Pattern and Void Fraction of Gas–Liquid Two-Phase Flow in Vertical Upward Pipes Using the Gamma Densitometer
,”
Appl. Therm. Eng.
,
60
(1–2), pp.
398
410
.
5.
Bhagwat
,
S.
, and
Ghajar
,
A. J.
,
2014
, “
A Flow Pattern Independent Drift Flux Model Based Void Fraction Correlation for a Wide Range of Gas–Liquid Two Phase Flow
,”
Int. J. Multiphase Flow
,
59
, pp.
186
205
.
6.
Hasan
,
A. R.
, and
Kabir
,
C. S.
,
1988
, “
A Study of Multiphase Flow Behaviour in Vertical Wells
,”
SPE Prod. Eng.
,
3
(2), pp.
263
274
.
7.
Lekia
,
S. D.
, and
Evans
,
R.
,
1995
, “
A Coupled Rod and Fluid Dynamic Model for Predicting the Behavior of Sucker-Rod Pumping Systems-Part 1: Model Theory and Solution Methodology
,”
SPE Prod. Facil.
,
10
(1), pp.
26
33
.
8.
Kermit
,
E. B.
,
1982
, “
Overview of Artificial Lift Systems
,”
J. Pet. Technol.
,
34
(
10
), pp.
2384
2396
.
9.
Doty
,
D. R.
, and
Schmidt
,
Z.
,
1983
, “
An Improved Model for Sucker Rod Pumping
,”
Soc. Pet. Eng. J.
,
23
(1), pp.
33
41
.
10.
Kang
,
X. Q.
,
Ren
,
T.
, and
Qu
,
W. T.
,
2013
, “
Dynamic Adjusting Mechanism of Counterbalance in Beam-Pumping Unit and Its Kinetic Analysis
,”
Appl. Mech. Mater.
,
455
, pp.
274
278
.
11.
Taitel
,
Y.
,
Barnea
,
D.
, and
Dukler
,
A. E.
,
1980
, “
Modelling Flow Pattern Transitions for Steady Upward Gas-Liquid Flow in Vertical Tubes
,”
AIChE J.
,
26
(3), pp.
345
354
.
12.
Danielson
,
T. J.
,
2012
, “
Transient Multiphase Flow: Past, Present and Future With Flow Assurance Perspective
,”
Energy Fuels
,
26
(
7
), pp.
4137
4144
.
13.
Omrani
,
A. E.
,
Franchek
,
M. A.
,
Grigoriadis
,
K.
, and
Tafreshi
,
R.
, “
Liquid Holdup Discretized Solution's Existence and Uniqueness Using a Simplified Averaged 1D Upward Tow-Phase Flow Transient Model
,”
ASME J. Dyn. Syst., Meas., Control
,
139
.
14.
Gibbs
,
S. G.
,
1963
, “
Predicting the Behavior of Sucker-Rod Pumping Systems
,”
J. Pet. Technol.
,
15
(7), pp.
769
778
.
15.
McCarthy
,
J. M.
, and
Soh
,
G. S.
,
2011
,
Geometric Design of Linkages
,
Springer
, New York.
16.
Levin
,
I. N.
,
1978
,
Physical Chemistry
,
6th ed.
,
McGraw-Hill
, New York, pp.
10
11
.
17.
Taitel
,
Y.
,
Shoham
,
O.
, and
Brill
,
J. P.
,
1989
, “
Simplified Transient Solution and Simulation of Two-Phase Flow in Pipelines
,”
Chem. Eng. Sci.
,
44
(
6
), pp.
1353
1359
.
18.
Guffey
,
C. G.
,
Rogers
,
J. D.
, and
Hester
,
L. R.
, II
,
1991
, “
Field Testing of Variable-Speed Beam-Pump Computer Control
,”
SPE Prod. Eng.
,
6
(2), pp.
155
160
.
You do not currently have access to this content.