experimental study of phase inversion phenomena in
TRANSCRIPT
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Experimental Study of Phase Inversion Phenomena in Electrical Submersible
Pumps under Oil/Water Flow Natan Augusto Vieira Bulgarelli School of Mechanical Engineering, University of Campinas, Rua Mendeleyev, 200, Cidade Universitaria, Campinas, São Paulo 13083-860, Brazil [email protected] Jorge Luiz Biazussi Center for Petroleum Studies, Rua Cora Coralina, 350, Cidade Universitaria, Campinas, São Paulo 13083-896, Brazil [email protected] William Monte Verde Center for Petroleum Studies, Rua Cora Coralina, 350, Cidade Universitaria, Campinas, São Paulo 13083-896, Brazil [email protected] Marcelo Souza de Castro School of Mechanical Engineering, University of Campinas, Rua Mendeleyev, 200, Cidade Universitaria, Campinas, São Paulo 13083-860, Brazil [email protected] Antonio Carlos Bannwart School of Mechanical Engineering, University of Campinas, Rua Mendeleyev, 200, Cidade Universitaria, Campinas, São Paulo 13083-860, Brazil [email protected] ABSTRACT
Despite the common presence of water in oil production, just recently, the scientific community has
devoted efforts to studying the influence of emulsion phenomena effects related to oil production using
pumps. In the context of this study of phase inversion phenomena, the influence of viscosities and
rotational speeds in Electrical Submersible Pumps (ESPs) are evaluated as part of this effort. This study is
aimed at investigating the influence of viscosity in phase inversion phenomena. An 8-stage ESP was tested
with three different rotational speeds and two different oil viscosities for the best efficiency point (BEP)
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flow rates. Initially, the total flow rate was obtained in relation to BEP using ESP performance curves for
pure oil at 52 cP and 298 cP and rotational speeds of 800 rpm, 1200 rpm and 2400 rpm. The total flow rate
was kept constant and the water cut was increased from zero to a hundred percent. The inversion phase
phenomenon was detected by the performance improvement when the water cut increased. The factors
analyzed were the head and efficiency of the ESP as a function of the water cut. The phase inversion
experimental data obtained in this study was compared with literature models for horizontal pipes. The
results of this comparison presented satisfactory agreement. The phase inversion phenomena occur in all
8-stage at same time. Hysteresis was observed in ESPs for oil viscosity of 52 cP and rotating speed of 800
rpm and 1200 rpm.
1. INTRODUCTION
An Electrical Submersible Pump (ESP) is a method of artificial lift that stands out
for great production and wide application in several scenarios. The oil exploration
industries use the ESP in conjunction with an electric motor, sensors and other
equipment allowing remote operation of the system. The ESP operates with mixtures
characterized by multiphase flows of gas-liquid (gas-oil), liquid-liquid (oil-water) and gas-
liquid-liquid (gas-oil-water) in oil extraction. Liquid-liquid mixtures are observed in many
industrial and natural processes; the mixtures can be composed of two immiscible
phases with flow patterns arranged in various geometric configurations. When well
mixed, they are known as emulsions and have greater viscosity than the pure oil. An
emulsion is composed of a dispersed phase and a continuous phase. Formation of
emulsion takes place in the oil-water flow. This emulsion can be oil-in-water, the oil is
the dispersed phase, or water-in-oil, the water is the dispersed phase. The properties of
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emulsions depend on which phase is dispersed. The boundary that separates the two
types of dispersion (oil-in-water and water-in-oil) is the phase inversion point. A physical
property affected by the continuous phase in emulsion is the viscosity. Factors like
viscosity of the oil and water, water content, temperature, droplet size distribution and
shear rate can influence the apparent viscosity of the emulsion [1]. The apparent
viscosity directly affects the lift performance of the ESP [2].
Several phenomena related to the multiphase flow inside pumps such as
foaming, cavitation and emulsion still have unknown effects on ESP performance. For
high flow rates of liquid and high oil fractions, the pump has similar performance to that
observed in oil single-phase flows. Therefore, the performance suffers degradation
when the pump operates with high viscosity liquids or with emulsions. The presence of
water generates emulsions within the ESP impeller that strongly affect the lift capacity.
The formation of stable emulsions in the oil lift process affects the performance of oil
separators on platforms, which considerably increases the time and energy required to
separate the phases.
The study of oil-water emulsion in ESPs is recent, so there are no references in
the literature about subject. The liquid-liquid (oil-water) flow in pipes, which usually
occurs in the petroleum industry, has been investigated by several research studies [3-
5]. Reference [3] studied oil/water flows in horizontal pipes via various experiments
using a wide range of oil viscosity. They proposed a correlation in predicting the phase
inversion point. They also observed that the main factor that influences the inversion
point is oil viscosity, and the water fraction input required to invert the dispersed phase
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increases with decreasing oil viscosity. A sudden drop in pressure loss due to friction
when the continuous phase changed from oil to water was also observed [3]. The
correlation in predicting the phase inversion point of an oil-water system was applied in
various experimental data in the literature and provided satisfactory results.
Reference [4] analyzed the phase inversion phenomenon in oil-water flow and its
effects on pressure loss in pipelines composed of two materials (steel and acrylic) and
two pipe diameters (60 and 32mm i.d.). They observed that the mixture velocity and
initial conditions (water in-oil or oil-in-water emulsion) modify the phase inversion point
(hysteresis effect). The effect on pressure loss was the same as observed by [3].
The other methodology to predict phase inversion in pipelines was proposed by
[5]. This method consists of comparing the apparent viscosity when oil or water are the
continuous phase. The phase inversion point is determined when these apparent
viscosities are equal. Various correlations presented in literature to predict the mixture
viscosity were used. Among the analyzed correlations, [6-9] predicted inversion within
the experimental phase inversion range. This methodology was also compared with
critical phase fraction models from literature. A satisfactory result was obtained
between [5, 10] as well as for experimental data for a range of oil viscosities.
Recent studies on ESPs were done by [2, 11] for single-phase flows and [12] for
gas-water two-phase flows.
In this research, the effects of phase inversion within an 8-stage ESP was
investigated, mainly, at efficiency and lift capacity (head) as a function of the water cut
(water fraction at emulsion). The phase inversion point was compared with the
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correlation developed by [3]. The experimental data was collected in a flow loop facility
specially designed for ESP performance testing with oil-water emulsion flow (Figure 1).
2. MATERIALS AND METHOD
The experimental study was conducted at LabPetro - Experimental Laboratory
for Petroleum "Dr. Kelsen Valente" at the University of Campinas – Brazil, in a flow loop
facility specially designed for ESP performance testing with oil-water emulsion flows. To
carry out the tests mineral oil was used at two viscosities, 298±1 cP and 52±1 cP.
Initially, the efficiency and head curve of the ESP was obtained for pure oil at two
temperatures and at three ESP rotating speeds (800 rpm, 1200 rpm and 2400 rpm). The
rotational Reynolds range tested was from 3 × 103 to 3 × 106. The first curve is
determined by ESP efficiency as a function of the flow rate dimensionless. The other
curve is composed of the dimensionless head in function of the dimensionless flow rate.
With two curves it is possible to analyze the ESP performance. These curves are
determinants which maintain the temperature and ESP rotating speed and vary the total
flow rate.
The ESP efficiency curve is used to obtain the best ESP operation point, relating
to the lifting capacity and the total flow rate which provides the best performance. This
point is designated Best Efficiency Point (BEP). The viscosity and rotating speed variation
directly affect the ESP efficiency curve. Thus, the BEP varied with the rotation and
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temperature, and consequently, the total flow rate changes for each operating
condition.
The standard test procedure started with oil as continuous phase and finished
with water as continuous phase. Both fluids were joined in the “T” intersection where
the water was injected into the bottom of the pipe and flow to ESP inlet, as presented in
Figure 1 (black box).
The ESP experimental setup has two main lines, one for water and the other for
oil. Both lines have an oil/water separator tank, a booster pump to move the fluid from
the tank to the ESP inlet, coriolis flow meters (manufactured by Micromotion with
accuracy of 0.02%), choke valves and differential pressure transducers (Rosemount
2088, manufactured by Emerson and with accuracy of 0.08% F.S.). Only the oil line has a
heat exchanger and a water cut meter (Nemko 05 ATEX 112, manufactured by ROXAR
and with accuracy of 1% F.S.). The fluids are mixed at the intersection between the oil
and water line prior to the ESP inlet. This mixture goes through the 8-stage ESP (Baker
Hughes P100LS with characteristic diameter of 0.108 m), and then enters the return line
that connects it with the oil/water separator tank. The inlet temperature (Ti) was
measured and controlled by a resistance temperature detector, type PT100
manufactured by Ecil and with 1/10 DIN accuracy.
The oil injection was carried out by a progressive cavity pump and the water by a
centrifugal pump. Before mixing the oil and water, the water fraction contained in oil
flow is verified using the water cut meter present in oil line. After that, water is added
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until it reaches the desired water cut. For each acquisition data point it is necessary to
await the stabilization of the ESP pressure gradient and the inlet temperature.
To analyze and compare different rotating speeds and total flow rates in
centrifugal pumps, dimensionless analyses of flow machines should be used. Using the
Buckingham’s Pi Theorem one might obtain Equation 1 which corresponds to
dimensionless head and Equation 2, to dimensionless flow rate. Thus, one can normalize
this factor to other scales for all rotating speeds and total flow rates.
2 2m
e
P
D
(1)
3
q
D
(2)
The static pressure difference is used to calculate the dimensionless head, once
the elevation and the dynamic pressure between the pump inlet and outlet are
negligible.
The emulsion density is obtained using Equation (3) based on homogenous
model [13].
1e w w w of f (3)
The ESP efficiency is calculated by the ratio between the hydraulic power and
shaft power (Equation 4).
e
s
q P
W
(4)
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Equation 4 presents the correlation presented by [3] which was used to compare
the phase inversion experimental data and it is analyzed if can be used for oil/water
flow through ESPs.
, 0.500 0.1108log ow INV
w
f
(5)
3. RESULTS
Experiments with oil temperature variation were performed to investigate oil viscosity
influence. The first step was to find the function of oil viscosity with temperature to find
out what temperature is necessary to achieve some level of viscosity. The oil viscosity
curve function with the temperature is presented in Fig. 2.
2.1. ESP Single-phase curves with pure oil
Previously, the ESP’s efficiency and head curves for pure oil were experimentally
obtained. Fig. 3, 4 and 5 represent the ESP head curves for three rotating speeds, 800
rpm, 1200 rpm and 2400 rpm, respectively, in two oil viscosities (52 cP and 298 cP).
With the decrease in viscosity, the ESP lift capacity is improved, as observed in Fig. 3, 4
and 5.
The ESP efficiency curves are shown in Fig. 6, 7 and 8, the head curves for the same
parameters.
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With the ESP efficiency curves, it is possible to determine the BEP for each rotating
speed and temperature. With the function of the efficiency curves as a function of the
dimensionless flow rate, the BEP might be obtained by matching the zero-derivative
point of these functions in relation to dimensionless flow rate. Thus, the peak point of
the ESP efficiency curve can be determined.
The operating conditions obtained are presented in Table 1.
2.2. Effect of phase inversion in ESP head
Two-phase liquid-liquid experiments were performed, as presented in Table 1. In Fig. 9,
10 and 11, the dimensionless head is presented as a function of the water cut for 800,
1200 and 2400 rpm. The rotational speed, the total flow rate, and the temperature were
kept constant during the experiments. Then, the head behavior of the ESP with two
different viscosities is compared for the same rotational speeds.
In these experiments, the water cut was increased from zero to one hundred percent.
For low water cut values, the oil is the continuous phase and lift capacity of the ESP is
low. A sharp increase on ESP head is observed by increasing the water cut. This happens
for all ESP rotational speeds and the hypotheses to explain this behavior is that the
water phase become the continuous phase.
For all experiments, the head was severely affected in the region of low water cut
values, due to the increase of effective viscosity of emulsion when the oil was the
continuous phase. Two distinct levels of head were observed before and after the
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inversion phenomenon, which were delimited by the phase inversion point of the
emulsion within the ESP.
As can be seen, when the oil viscosity decreases, the critical water cut for inversion
increases. The same behavior is observed in oil/water flow in pipes, when the oil has no
surfactants. Note that before phase inversion, the ESP head increases as the oil viscosity
decreases. This effect is caused by the high effective viscosity of the oil (continuous
phase). Because of that, the ESP lift capacity is heavily affected by the viscous flow
(Reynolds number decreases). After phase inversion, the effective viscosity decreases
abruptly (Reynolds number become bigger), and the dimensionless head becomes a
function of the dimensionless flow rate only (Ψ=f(Φ)).
Comparing the BEP flow rate for each oil viscosity, for all ESP rotational speeds tested
the total flow rates were higher for 52 cP than 298 cP. The dimensionless head was
higher for 298 cP than 52 cP, as expected by similarity rules. But, for oil as continuous
phase there was an opposite behavior, which the smaller oil viscosity (high rotational
Reynolds) presented higher head capacity than more viscous oil.
2.3. Effect of phase inversion in each ESP stage
The phase inversion phenomenon can be observed for each ESP stage and have the
same behavior that was shown by Fig. 9, 10 and 11. Fig. 12 presents the dimensionless
head for each ESP stage as a function of the water cut for 2400 rpm at oil viscosity of
298 cP.
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It is shown that the phase inversion occurs at the same water cut for all ESP stages, and
at the same time. In addition, the first stage presented the better performance before
phase inversion when compared with the others stages of ESP. The hypothesis that
could explain this difference is that first stage has segregate flow in the inlet, and the
others are under emulsion/dispersion flow. Specific tests to confirm the assumptions
are necessary and will help for a better understand of this phenomenon.
2.4. Comparison between ESP experimental data with the correlation proposed by [3]
Fig. 13 and 14 shows the dimensionless head comparison of the different rotational
speeds for the same oil viscosity using the oil A. The black line represents the phase
inversion point calculated by the model of [3].
For the 298cP oil (Fig. 13), the model presented a small deviation from the experimental
data. This difference might have occurred because of correlation was fitted with only
two high viscosities – 237 cP and 2116 cP oils. For the 52cP oil viscosity (Fig. 14), the
model compares satisfactorily with the ESP experimental data. An important finding is
that the ESP rotational speed does not affect the phase inversion point.
Other factors that influence the observed deviation are the average drop size, drop size
distribution and turbulent flow within ESP. Detailed studies are needed for each factor.
2.5. Effect of phase inversion in ESP efficiency
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Another important ESP parameter affected by water cut is ESP efficiency, mostly caused
by the increasing of viscous degradation (Fig. 6, 7 and 8) due to emulsion formation. Fig.
15, 16 and 17 shows the efficiency behavior as a function of the water cut for each
rotational speed for the two oil viscosities (52 and 298 cP).
For the lowest water cut values, the efficiency is similar to that of the ESP operating with
single-phase oil flows. Along with the phase inversion, ESP efficiency increases abruptly
and, after completed the process, the efficiency continues to rise as the water cut
increases until it reaches that of the ESP operating with single-phase water flow.
The same influence of the phase inversion phenomenon is observed in head capacity
and ESP efficiency due to the change of the emulsion viscosity, this can be observed in
the viscous degradation curves. There is a great improvement in both factors when the
ESP operates with emulsions in which the continuous phase is water.
The same influence of the phase inversion phenomenon is observed in head capacity
and efficiency due to viscosity emulsion variation. There is a great improvement in both
factors when the ESP operates with emulsions in which the continuous phase is water.
It is possible to observe that even after the phase inversion point, the ESP efficiency
operating oil-in-water emulsion is lower than water, especially for low ESP rotational
speeds and high oil viscosities. This could be explained due to turbulent energy
dissipation (shear rate) to break the continuous oil phase in oil droplets, increasing the
power shaft in low ESP rotational speeds. In high rotational speeds, the shear rate and,
consequently, the turbulent energy are high enough to break the oil droplets without to
prejudice the ESP performance.
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2.6. Hysteresis in Phase Inversion Point
The analysis of hysteresis presence in the experiments was done starting the tests with
100% of water cut going to zero. Hysteresis is observed only for 800 rpm and 1200 rpm
at 52 cP. Thus, with low viscosity and low degree of agitation, the liquid-liquid mixture is
easier separated, changing the phase inversion point. This hysteresis also is influenced
by surface wettability and the initial arrangement of the phases. This phenomenon is
presented in Fig. 18 and 19.
For the rotation speeds of 800 rpm, 1200 rpm and 2400 rpm at 298cP and 2400 rpm at
52 cP hysteresis did not occur. In other words, high viscosity or high rotational speed
make the phases separation difficult leading to no hysteresis. More detailed studies are
necessary to exactly understands the factors that influence hysteresis in ESP.
3. CONCLUSION In this study an experimental analysis of the phase inversion phenomenon in electrical
submersible pumps under oil-water two-phase flows was performed. The influence of
oil viscosity in the phase inversion phenomenon was investigated. An 8-stage ESP was
tested with three different rotational speeds (800 rpm, 1200 rpm e 2400 rpm) and two
different oil viscosities (approximately 52 cP and 298 cP) for BEP flow rates. The oil
viscosity was controlled by changing its temperature.
The lift capacity and efficiency of centrifugal pumps are affected by viscosity [2]. This
fact can be observed in Fig. 3, 4, 5, 6, 7 and 8.
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In emulsions, the continuous phase directly influences the effective viscosity.
In this study, the experiments started with water cut equal to zero (oil single-phase
flow) and end with 100% water cut (water single-phase flow). For low water cuts, the
continuous phase is the oil and the head capacity and efficiency of the ESP is severely
affected, with high degradation. As water is added to the mixture the water cut
increases and the inversion phase takes place, so, the water becomes the continuous
phase and the head capacity and efficiency of the ESP is improved as shown in Fig. 9, 10,
11, 15, 16 and 17.
There are many studies of phase inversion phenomena in horizontal pipelines.
Reference [3] proposed a correlation based on oil and water viscosity to predict the
phase inversion point for horizontal pipes. The experimental data obtained in this study
was compared to the correlation presented by [3], and for low viscosity (52 cP) the
correlation showed small deviations from the ESP experimental data. For high viscosity
(298 cP), the correlation presented satisfactory results.
The hysteresis was observed in the ESP for 52 cP oil viscosity and rotating speeds of 800
rpm and 1200 rpm (Fig. 18 and 19), varying the phase inversion phase depending on the
initial condition (oil-to-water or water-to-oil). Thus, for low viscosity and low rotational
speed the phase separation process happens more easily. Other factors that may
influence this phenomenon are surface wettability and initial arrangement of the
phases. More detailed studies are needed to more exactly understand these and other
factors that affect the hysteresis in ESPs.
ACKNOWLEDGMENT
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The authors also thank Artificial Lift & Flow Assurance Research Group (ALFA), Center
for Petroleum Studies (CEPETRO), and School of Mechanical Engineering (FEM) all at the
University of Campinas (UNICAMP) in Brazil. The acknowledgements are extended to
FAPESP - Process 2017/15736-3 and CAPES - Finance Code 001.
FUNDING
The authors would like to thank Equinor Brazil, ANP (“Compromisso de Investimentos
com Pesquisa e Desenvolvimento”), and PRH/ANP for providing financial support for this
study.
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NOMENCLATURE
ESP electrical submersible pump
BEP best efficiency point
q flow rate at BEP, m³/s
m mean dimensionless head
dimensionless head per ESP stage
P differential pressure between ESP inlet and outlet, Pa
ESP rotating speed, rad/s
D ESP diameter, m
flow rate dimensionless
ESP efficiency
e emulsion density, kg/m³
o oil density, kg/m³
w water density, kg/m³
sW
staff potential, J/s
wf water cut
,w INVf phase inversion point
o oil viscosity, cP
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w water viscosity, cP
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REFERENCES (Samples of the most commonly referenced materials are provided. If in doubt, please refer to the latest editor of the Chicago Manual of Style. DOIs should be provided whenever possible for the greatest accuracy. [1] Kokal, S., 2005. “Crude-oil emulsions, a state-of-the-art review”. SPE 77497-PA. Production and Facilities. [2] Zhu, J., Banjar, H., Xia, Z. and Zhang, H.Q., “CFD simulation and experimental study of oil viscosity effect on multi-stage electrical submersible pump (ESP) performance”. Journal of Petroleum Science and Engineering, [s.l.], v. 146, p.735-745, out. 2016. [3] Arirachakaran, S., Oglesby, K. D., Malinawsky, M. S., Shoham, O. and Brill, J. P., 1989. “An analysis of oil/water flow phenomena in horizontal pipes”. SPE paper 18836. SPE Prof. Prod. Operating Symp., Oklahoma. [4] Ioannou, K., Hu, B., Matar, O. K., Hewitt, G. F. and Angeli, P. 2004, “Phase inversion in dispersed liquid-liquid pipe flows”, In Proceedings of the 5th International Conference on Multiphase Flow, Yokohama, Japan. [5] Ngan, K. H., Ioannou, K., Rhyne, L. D., Wang, W. and Angeli, P. “A methodology for predicting phase inversion during liquid–liquid dispersed pipeline flow”. Chemical Engineering Research and Design, [s.l.], v. 87, n. 3, p.318-324, mar. 2009. [6] Brinkman, H. C., 1952, “The viscosity of concentrated suspensions and solutions”. J Chem Phys, 20(4): 571. [7] Roscoe, R., 1952, “The viscosity suspensions of rigid spheres”. Br J Appl Phys, 3: 267-269. [8] Furuse, H., 1972, “Viscosity of concentrated solution”. Jpn J Appl Phys, 11(10): 1537-1541. [9] Pal, R., 2001, “Single-parameter and two-parameter rheological equations of state for nondilute emulsions”. Ind Eng Chem Res, 40: 5666-5674 [10] Yeh, G. C., Haynei, F. H., Jr. ande Moses, R. A., 1964, “Phase volume relationship at the point of phase inversion in liquid dispersions”. AIChE J, 10(2): 260-265 [11] Vieira, T. S., Siqueira, J. R., Bueno, A. D., Morales, R. E. M. and Estevam, V., “Analytical study of pressure losses and fluid viscosity effects on pump performance during monophase flow inside an ESP stage”. Journal of Petroleum Science and Engineering, [s.l.], v. 127, p.245-258, mar. 2015.
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[12] Pineda, H., Biazussi, J., López, F., Oliveira, B., Carvalho, R. D. M., Bannwart, A. C. and Ratkovich, N., “Phase distribution analysis in an Electrical Submersible Pump (ESP) inlet handling water–air two-phase flow using Computational Fluid Dynamics (CFD)”. Journal of Petroleum Science and Engineering, [s.l.], v. 139, p.49-61, mar. 2016.. [13] Guet, S., Rodriguez O. M. H., Oliemans R. V. A. and Brauner N. “An inverse dispersed multiphase flow model for liquid production rate determination”. International Journal of Multiphase Flow, [s.l.], v. 32, n. 5, p.553-567, maio 2006.
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Figure Captions List
Fig. 1 Experimental flow loop, the black box indicates the intersection where the
fluids are mixed before entering the ESP.
Fig. 2 Viscosity as a function of temperature.
Fig. 3 Comparison of dimensionless head as a function of dimensionless flow
rate between 52 cP, 298 cP and water for 800 rpm.
Fig. 4 Comparison of dimensionless head as a function of dimensionless flow
rate between 52 cP, 298 cP and water for 1200 rpm.
Fig. 5 Comparison of dimensionless head as a function of dimensionless flow
rate between 52 cP, 298 cP and water for 2400 rpm.
Fig. 6 Comparison of ESP efficiency as a function of dimensionless flow rate
between 52 cP, 298 cP and water for 800 rpm.
Fig. 7 Comparison of ESP efficiency as a function of dimensionless flow rate
between 52 cP, 298 cP and water for 1200 rpm.
Fig. 8 Comparison of ESP efficiency as a function of dimensionless flow rate
between 52 cP, 298 cP and water for 2400 rpm.
Fig. 9 Comparison of dimensionless head as a function of water cut between
298cP (BEP 7.65m³/h) and 52cP (BEP 10.78m³/h) for 800 rpm.
Fig. 10 Comparison of dimensionless head as a function of water cut between
298cP (BEP 12.25m³/h) and 52cP (BEP 25.94m³/h) for 1200 rpm.
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Fig. 11 Comparison of dimensionless head as a function of water cut between
298cP (BEP 26.94 m³/h) and 52cP (BEP 33.70 m³/h) for 2400 rpm.
Fig. 12 Comparison of dimensionless head as a function of water cut by ESP stage
at 298cP (BEP 26.94 m³/h) for 2400 rpm.
Fig. 13 Comparison of dimensionless head as a function of water cut between the
three rotating speeds (800 rpm, 1204 rpm and 2400 rpm) for the same
viscosity (298 cP) and model of [3].
Fig. 14 Comparison of dimensionless head as a function of water cut between the
three rotating speeds (800 rpm, 1200 rpm and 2400 rpm) for the same
viscosity (52 cP) and model of [3].
Fig. 15 Comparison of ESP efficiency as a function of water cut between two
viscosities (52 cP and 298 cP) for 800 rpm ESP rotating speed.
Fig. 16 Comparison of ESP efficiency as a function of water cut between two
viscosities (52 cP and 298 cP) for 1200 rpm ESP rotating speed.
Fig. 17 Comparison of ESP efficiency as a function of water cut between two
viscosities (52 cP and 298 cP) for 2400 rpm ESP rotating speed.
Fig. 18 Comparison of head as a function of water cut at 52 cP for 800 rpm ESP
rotating speed for two initial conditions (oil-to-water and water-to-oil).
Fig. 19 Comparison of head as a function of water cut at 52 cP for 1200 rpm ESP
rotating speed for two initial conditions (oil-to-water and water-to-oil).
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Table Caption List
Table 1 Matrix of experimental tests
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Table 1 - Matrix of experimental tests.
Oil viscosity [cP] Rotating speed [rpm] q [m³/h] [-]
298 ± 1
800 7.65 0.020
1200 12.25 0.022
2400 26.94 0.024
52 ± 1
800 10.78 0.028
1200 25.94 0.029
2400 33.70 0.030
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Figure 1. Experimental flow loop, the black box indicates the intersection where the
fluids are mixed before entering the ESP.
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Figure 2. Viscosity as a function of temperature.
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Figure 3. Comparison of dimensionless head as a function of dimensionless flow rate
between 52 cP, 298 cP and water for 800 rpm.
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Figure 4. Comparison of dimensionless head as a function of dimensionless flow rate
between 52 cP, 298 cP and water for 1200 rpm.
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Figure 5 Comparison of dimensionless head as a function of dimensionless flow rate
between 52 cP, 298 cP and water for 2400 rpm.
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Figure 6. Comparison of ESP efficiency as a function of dimensionless flow rate between
52 cP, 298 cP and water for 800 rpm.
Journal of Offshore Mechanics and Arctic Engineering
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OMAE-17-1150 Bulgarelli, N. A. V.
Figure 7. Comparison of ESP efficiency as a function of dimensionless flow rate between
52 cP, 298 cP and water for 1200 rpm.
Journal of Offshore Mechanics and Arctic Engineering
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OMAE-17-1150 Bulgarelli, N. A. V.
Figure 8. Comparison of ESP efficiency as a function of dimensionless flow rate between
52 cP, 298 cP and water for 2400 rpm.
Journal of Offshore Mechanics and Arctic Engineering
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OMAE-17-1150 Bulgarelli, N. A. V.
Figure 9. Comparison of dimensionless head as a function of water cut between 298cP
(BEP 7.65m³/h) and 52cP (BEP 10.78m³/h) for 800 rpm.
Journal of Offshore Mechanics and Arctic Engineering
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OMAE-17-1150 Bulgarelli, N. A. V.
Figure 10. Comparison of dimensionless head as a function of water cut between 298cP
(BEP 12.25m³/h) and 52cP (BEP 25.94m³/h) for 1200 rpm.
Journal of Offshore Mechanics and Arctic Engineering
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OMAE-17-1150 Bulgarelli, N. A. V.
Figure 11. Comparison of dimensionless head as a function of water cut between 298cP
(BEP 26.94 m³/h) and 52cP (BEP 33.70 m³/h) for 2400 rpm.
Journal of Offshore Mechanics and Arctic Engineering
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OMAE-17-1150 Bulgarelli, N. A. V.
Figure 12. Comparison of dimensionless head as a function of water cut by ESP stage at
298cP (BEP 26.94 m³/h) for 2400 rpm.
Journal of Offshore Mechanics and Arctic Engineering
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OMAE-17-1150 Bulgarelli, N. A. V.
Figure 13. Comparison of dimensionless head as a function of water cut between the three rotating speeds (800 rpm, 1204 rpm and 2400 rpm) for the same viscosity (298 cP) and model of Arirachakaran et al. (1989).
Journal of Offshore Mechanics and Arctic Engineering
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OMAE-17-1150 Bulgarelli, N. A. V.
Figure 14. Comparison of dimensionless head as a function of water cut between the
three rotating speeds (800 rpm, 1200 rpm and 2400 rpm) for the same viscosity (52 cP) and model of Arirachakaran et al. (1989).
Journal of Offshore Mechanics and Arctic Engineering
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OMAE-17-1150 Bulgarelli, N. A. V.
Figure 15. Comparison of ESP efficiency as a function of water cut between two
viscosities (52 cP and 298 cP) for 800 rpm ESP rotating speed.
Journal of Offshore Mechanics and Arctic Engineering
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OMAE-17-1150 Bulgarelli, N. A. V.
Figure 16. Comparison of ESP efficiency as a function of water cut between two
viscosities (52 cP and 298 cP) for 1200 rpm ESP rotating speed.
Journal of Offshore Mechanics and Arctic Engineering
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OMAE-17-1150 Bulgarelli, N. A. V.
Figure 17. Comparison of ESP efficiency as a function of water cut between two
viscosities (52 cP and 298 cP) for 2400 rpm ESP rotating speed.
Journal of Offshore Mechanics and Arctic Engineering
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OMAE-17-1150 Bulgarelli, N. A. V.
Figure 18. Comparison of head as a function of water cut at 52 cP for 800 rpm ESP
rotating speed for two initial conditions (oil-to-water and water-to-oil).
Journal of Offshore Mechanics and Arctic Engineering
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OMAE-17-1150 Bulgarelli, N. A. V.
Figure 19. Comparison of head as a function of water cut at 52 cP for 1200 rpm ESP
rotating speed for two initial conditions (oil-to-water and water-to-oil).