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Brazilian Archives of Biology and TechnologyVol.49, Special : pp. 65-71, January 2006
ISSN 1516-8913 Printed in Brazil BRAZILIAN ARCHIVES OF
BIOLOGY AND TECHNOLOGY
AN I N T E R N A T I O N A L J O U R N A L
Influence of the Temperature, Pressure and Viscosity on the
oil Measurement with Turbine Type Measurers
Magalí Araújo Damasceno1*, Janaina Karla de Medeiros Penha1, Nivaldo Ferreira da Silva
Junior1, Raimundo Nonato B. Felipe1, Renata Carla Tavares dos Santos Felipe1 and Gilson
Gomes de Medeiros1,2
1Centro Federal de Educação Tecnológica do Rio Grande do Norte - CEFET-RN; Av. Sen. Salgado Filho, 1559;
Tirol; Natal - RN - Brasil. 2Universidade Federal do Rio Grande do Norte - UFRN/DEQ;Campus Universitário;
Natal - RN - Brasil
ABSTRACT
The flow measurement of liquids and gases is a necessity in many industrial applications. There is a great amount of
measurers for such purpose, as, for example, the coriolis, positive displacement and type turbine measurers. A
measurer sufficiently used for the oil flow measurement is the turbine type, because it uses the proper extracted
energy of the measured flow for its functioning, moreover is also used as standard for the calibration of other
measurers. For this reason, it is important to study the parameters that influence the measurement process for
turbine measurers. In Brazil, to measure the volume of oil, regardless the type of measurer, it is necessary to
observe “Portaria Conjunta Nº. 1”, of June 19, 2000, that approved the Technical Regulation of Measurement of
Oil and Natural Gas, establishing the minimum conditions and requirements for the systems of oil and natural gas
measurement, in order to get a measurement standard. As such, the present work has the objective of determining
parameters that influence in the measurement of oil volumes using turbine measurers.
Key words: Oil, measurement, turbine
* Author for correspondence
INTRODUCTION
The oil is the main worldwide energy source and
the basic element for the modern industrial
society. From its extraction, the fluid is measured
to know the amount that each well and each field
produces.
The Brazilian norm “Portaria Conjunta Nº 1”
(ANP/INMETRO, 2000) approved the use of
several fluid measurers, such as the measurers type
positive displacement, coriolis and measurers type
turbines. Other types of measurers can be used,
since its use is duly authorized by the National
Agency of Oil - ANP.
Each one of these tools has its proper principle of
functioning and fields of application, determined
by the work conditions , which include: type of
fluid, temperature and other important factors.
Therefore, to get a true value of a measurement of
oil, it is necessary to know the involved
parameters in the process. The result of a
measurement can be evaluated by statistics
methods or through variation of the factors of
which this result depends on, with the objective to
guarantee the certainty in the measurement of the
produced and transferred volumes.
The turbine types of the industrial series are used
as the instrument of measurement for oil and its
Damasceno, M. A. et al.
Brazilian Archives of Biology and Technology
66
derivatives and gases. There are several types of
turbines, depending on the positioning of axle of
the rotor in relation to the flow, as well as the
methods of measuring their rotations.
Some turbine types are purely mechanical and
others are equipped with sophisticated electronic
secondary elements. The measurer turbine is also
used as standard for the calibration of other
measurers.
In this type of measurer, the exit of pulses is
convenient for the direct totaling of the flow. The
linear relation between the frequency and the flow
results in great range of measuring (Ribeiro,
1997).
The conventional measurer is a type of turbine that
is sufficiently used because the rotor is made with
longitudinal axle to the flow, integral bifool and
has approximately equal diameter to the one of the
tubing, as seen in the figure 1. It shows a great
performance and the highest precision, linearity
and repeatability, and is very much used for the
calibration of other measurers (Ribeiro, 1997).
The measurer consists basically of a rotor with
vanes that are put inside the perpendicular tubing
the flow. The fluid to be measured stimulates the
rotor and it makes it turn in a definite angular
speed. The rotational speed of the vanes is directly
proportional to the flow and can be detected by a
mechanical or electric sensor, which can get the
value of the flow from the passage of the blades of
the rotor of the turbine.
Figure 1 - Constituent parts of the conventional measurer
turbine type. From Ribeiro (1997).
The exit signal is practically linear, therefore each
pulse corresponds to one certain volume. The
number of pulses for unit of flow is called factor K
of the turbine. This factor varies according to the
flow intensity, the pressure and the operating
temperature.
This work aims to analyze the parameters that
come to influence in the measurement of oil.
Three basic parameters of the measurers type
turbine were evaluated: firstly, the influence of the
temperature, which provides an error in case the
density is not corrected in the measurement
process and in case of bad distribution of the
temperature in the fluid; the second factor is the
influence of the viscosity, whose increase
provokes a reduction of factor K of the measurer;
and, finally, the influence of the pressure.
METHODOLOGY
The methodology used in this work consisted in
the accomplishment of a bibliographical research
on the oil measurer turbine, the norms that
establish the measurement and correction, as well
as a simulation of data, in order to evaluate the
parameters that influence in the process of
measurement of oil.
The study was developed on the basis of the
standards established by the norms “Portaria
Conjunta Nº 1” (ANP/INMETRO, 2000), ISO
4267 (1988) and the “Resolução nº 06/70” (CNP,
1970), which aims to establish the reliability of
the procedures of flow measurement of the Oil by
turbine type measurers..
Influence of the temperature on the
correction of the measured volume of oil
The temperature of the measured liquid affects the
performance of the turbine, due to a mechanical
effect caused by the expansion or thermal
contraction of the box and the turbine, when the
operating temperature is different from the
temperature of calibration. The variation of the
temperature affects the physical properties of the
measured fluid, such as its vapor pressure, density
and viscosity.
The right measurement of the temperature is one
of the most important factors in the operations, in
view of that small variations can present great
errors because of bad distribution of the
temperature of the fluid, intervening the
Influence of the Temperature, Pressure and Viscosity on the oil Measurement
Brazilian Archives of Biology and Technology
67
conversion of the volumes of the products for the
temperature standard of 20 ºC, adopted as
temperature of reference for the measurement of
derivatives of the oil, in accordance with “Portaria
nº 27” (MIC, 1959).
Therefore, it is also necessary to measure the
temperature of the product and to correct the
volume at room temperature for the standard
temperature, as mentioned in the previous
paragraph. This correction uses a factor which is
obtained from the collecting of a representative
sample of the product, in view of the correction of
the thermal expansion among the temperature
reference and the temperature of measurement,
through the correction of the density of the oil
measured in the conditions of work to 20 ºC,
according the norm of the National Council of
Petroleum, “Resolução nº 06/70” (CNP, 1970).
The absence of correction of the density generates
an error in function of the temperature of the oil.
Therefore, the need for this correction for the
attainment of more accurate measured volumes is
evident.
For the simulation, a sample of oil with estimated
density of 0.7852 g/m3 (representative average
value) in the work condition was used, for the
volumes established in table 1. On the other hand,
for the determination of the influence of the
temperature in the correction of the measured
volume of oil, the temperatures of work were
considered in accordance with table 2.
Table 1 - Dimensions of the analyzed measurers.
Measurer specifications
Identification of the
measurer Nominal diameter of the tubing
(mm)
Maximum flow
(m3/h)
M1 25 2
M2 250 1200
M3 500 6000
Tabela 2 - Operation temperatures.
Temperatures (ºC)
Temperature 1 26
Temperature 2 28
Temperature 3 30
Temperature 4 32
Temperature 5 34
Temperature 6 36
Influence of viscosity on the correction of
the measured volume of oil
The value of a measurement made for a measurer
turbine is affected by changes in the viscosity of
the fluid to be measured. The viscosity of the
liquid is dependent on the temperature. Therefore,
with the increase of the temperature a reduction of
viscosity occurs and, consequently, the
performance of the turbine is modified.
The measurement of kinematics viscosity is
desirable when the operation occurs at a great
range of temperature or at very low flows, and
mainly when a great precision is desired.
The linear range of the measurer is one of the
more affected parameters by the variation of
viscosity, specially if the turbine presents parallel
blades. This variation depends on the type of the
rotor. For a kinematics viscosity above of 100 cSt,
the turbine does not present the linear region
(Ribeiro, 1997).
For the same pressure, the flow diminishes when
the fluid viscosity increases. For a given flow, an
increase of viscosity can present a reduction in the
factor K of the measurer.
Influence of the pressure on the correction
of the measured volume of oil
When the compressibility has a considerable
value, it is important to measure the pressure to
allow the correction of the measured flow.
The variation of the pressure causes changes in the
physical dimensions of the measurer due to
pressure made by the liquid, leading to an
Damasceno, M. A. et al.
Brazilian Archives of Biology and Technology
68
expansion or contraction of the box measurer, as
established by the norm ISO 2715 (1980).
According to Ribeiro (1997), if the pressure of the
liquid approaches to its vapor pressure, the local
vaporization can happen soon behind the vanes of
the rotor. This provokes an artificial increase in the
speed of the fluid, which can drastically affect the
factor K.
The variation of the pressure in meter is
proportional to the square of the flow. To have a
constant entrance, a maximum flow is necessary,
in which the measuring turbine can be operated
with an acceptable margin of error. This happens
due to the effect caused by the cavitation in the
measurer, that is the boiling of the liquid
originated for the reduction in the pressure, instead
of the temperature rise.
It is important to remember that, for any
installation, the downstream turbine flow needs to
be kept to a minimum pressure to prevent a
variation in the calibration factor due the
cavitation. The minimum pressure after the turbine
is function of the vapor pressure of the liquid and
the presence of dissolved gases.
M1
0.000
0.010
0.020
0.030
0.040
26 28 30 32 34 36
Temperature (ºC)
• V (m 3 )
Figure 2 - Variation of the measured volume by the M1 measurer due to the correction of the
density for the reference temperature, after one hour operation.
M2
4.00
6.00
8.00
10.00
12.00
14.00
16.00
18.00
26 28 30 32 34 36
Temperature (ºC)
• V (m3)
Figure 3 - Variation of the measured volume by the M2 measurer due to the correction of the
density for the reference temperature, after one hour operation.
Influence of the Temperature, Pressure and Viscosity on the oil Measurement
Brazilian Archives of Biology and Technology
69
M3
20.00
40.00
60.00
80.00
100.00
26 28 30 32 34 36
Temperature (ºC)
• V (m 3)
Figure 4 - Variation of the measured volume by the M3 measurer due to the correction of the
density for the reference temperature, after one hour operation.
Figure 5 - Influence of viscosity on the meter factor of the turbine (Faure Herman, 2004).
RESULTS AND DISCUSSION
Influence of the temperature
The obtained results from the simulation of the
measured volumes of oil, according to the norm
“Portaria Conjunta Nº 01” (ANP/INMETRO,
2000), must be corrected to the reference
temperature (20 ºC).
Taking an oil sample with density of 0.7852 g/m3
(representative average value), it is observed that
the variation of volume, due to the correction in
function of the operation temperature, is linear, as
shown in Figures 2, 3 and 4, when the
measurement system is evaluated in the range
from 26 ºC to 36 ºC.
It can be stated that, if the density is not corrected
from the actual oil temperature to the reference
temperature, an error is generated, thus influencing
in the measurement of the oil volume. So, it can be
concluded that this correction is necessary to
obtain more accurate measured volumes.
Damasceno, M. A. et al.
Brazilian Archives of Biology and Technology
70
Influence of the oil viscosity
Figure 5 shows the variation of the meter factor
(correction factor of the measurer) in function of
the flow, for different oil viscosities, when a 8”
diameter measurer is used (Faure Herman, 2004).
It can observed that, for a viscosity of 108 cSt
(blue curve), an substancial reduction in the meter
factor occurs reaching the flow of 2500 Bbl/h, and
that above this value the factor remains steady.
For an intermediate viscosity, as 49.2 cSt (green
curve), we can say that its result is not different
from the blue curve. The meter factor, even lower
than 108 cSt, also decreases up to 2000 Bbl/h,
remaining steady to higher flow values. For a
viscosity of 0.62 cSt (gray curve), the meter factor
practically remains steady.
Figure 6 shows the influence of viscosity in the
pressure drop (loss of load) of the turbine
measurer type. It can be observed that this drop
varies not linearly with viscosity. For the range of
viscosity from 0 to 100 cSt, the drop varied from
0.2 to 0.5 bar.
0
0.1
0.2
0.3
0.4
0.5
0.6
0 10 20 30 40 50 60 70 80 90 100
Viscosity (cSt)
Loss of Load (bar)
Figure 6 - Pressure drop as function of viscosity. Adapted from Faure Herman (2004).
CONCLUSION
O estudo dos parâmetros, variabilidades e a forma
de apresentação dos resultados, proporcionaram
uma visão geral do desempenho do medidor
turbina, assim como a simulação de dados
contribuiu para a quantificação destes resultados
observados. Caracterizando-se as variabilidades
quanto ao desempenho do medidor, bem como
suas faixas de influências, é possível concretizar as
aplicações de medidores turbinas na indústria de
petróleo. A forma de apresentação dos resultados
irá permitir a comparação de desempenho de
medidores turbinas com outros medidores de
vazão.
The study of the influence of the analyzed
parameters provided a general view about the
performance of the turbine measurer type. The
data simulation contributed for the quantification
of the results. The characterization of the
performance of the measurers in the face of the
variations in those parameters, as well as its ranges
of influence, made the applications of measurer
turbines in the oil industry possible.The
presentation of the results will allow the
comparison between the performance of turbine
and other flow measurers.
ACKNOWLEDGEMENTS
This work was undertaken as part of the research
project "Uncertainty of Measurement of Oil and
Natural Gas", included in the Rede de
Instrumentação e Controle (Rede 10/05). The
authors are grateful to the Finep, CNPq e
CENPES-Petrobras, for the financial support,
which was essential for its accomplishment.
Influence of the Temperature, Pressure and Viscosity on the oil Measurement
Brazilian Archives of Biology and Technology
71
RESUMO
A medição de fluxo em líquidos e gases é uma
necessidade em muitas aplicações industriais.
Existe uma grande quantidade de medidores para
tal finalidade, como, por exemplo, os medidores
de velocidade tipo turbina, deslocamento positivo
e coriolis. Um medidor bastante utilizado para a
medição de vazão de petróleo é o tipo turbina,
porque utiliza a própria energia extraída da vazão
medida para seu funcionamento. Além disso, é
também usado como padrão para a calibração de
outros medidores. Daí a importância de se estudar
os parâmetros que influenciam o processo de
medição por medidores tipo turbina. Para se medir
o volume de petróleo, independentemente do tipo
de medidor, é necessário observar o que determina
a Portaria Conjunta Nº. 1, de 19 de junho de 2000,
que aprovou o Regulamento Técnico de Medição
de Petróleo e Gás Natural, estabelecendo as
condições e requisitos mínimos para os sistemas
de medição de petróleo e gás natural, a fim de se
obter um padrão de medição. Com isso, este
trabalho visa determinar os parâmetros que
influenciam na medição de volumes de petróleo
utilizando medidores do tipo turbina.
REFERENCES
ANP/INMETRO (2000), Portaria Conjunta n. 01.
Regulamento técnico da medição de petróleo e gás
natural.
CNP (1970), Resolução n. 06/70. Tabelas de correção
de volume do petróleo e derivados.
Delmée. G. J. (1982), Manual de medição de vazão.
São Paulo: Edgard Blücher.
Faure Herman (2004), HELIFLUTM TZN, the dedicated
turbine flowmeter for custody transfer measurement.
Disp. in: http://www.faureherman.com/download/
tzn.pdf.
ISO 2715 (1980), Liquid Hydrocarbons - Volumetric
Measurement by Turbine Meter Systems.
ISO 4267 (1988), Petroleum and liquid petroleum
products - Calculation of oil quantities - Part 2:
Dynamic measurement.
Ministério da Indústria e Comércio (1959), Portaria
n. 27/59.
Ribeiro, M. A. (1997), Medição de vazão -
fundamentos e aplicações. Salvador: Tek
Treinamento & Consultoria.
Received: July 29, 2005;
Revised: September 05, 2005;
Accepted: November 22, 2005.
FOLHA
EM
BRANCO