WO2008046805A1 - Method for measuring the flowrates of the different phases of a multiphase flow, and device for implementing the method - Google Patents
Method for measuring the flowrates of the different phases of a multiphase flow, and device for implementing the method Download PDFInfo
- Publication number
- WO2008046805A1 WO2008046805A1 PCT/EP2007/060946 EP2007060946W WO2008046805A1 WO 2008046805 A1 WO2008046805 A1 WO 2008046805A1 EP 2007060946 W EP2007060946 W EP 2007060946W WO 2008046805 A1 WO2008046805 A1 WO 2008046805A1
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- WIPO (PCT)
- Prior art keywords
- constriction
- cross
- flow
- venturi
- correlation
- Prior art date
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/74—Devices for measuring flow of a fluid or flow of a fluent solid material in suspension in another fluid
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/05—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects
- G01F1/34—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects by measuring pressure or differential pressure
- G01F1/36—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects by measuring pressure or differential pressure the pressure or differential pressure being created by the use of flow constriction
- G01F1/40—Details of construction of the flow constriction devices
- G01F1/44—Venturi tubes
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/704—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow using marked regions or existing inhomogeneities within the fluid stream, e.g. statistically occurring variations in a fluid parameter
- G01F1/708—Measuring the time taken to traverse a fixed distance
- G01F1/712—Measuring the time taken to traverse a fixed distance using auto-correlation or cross-correlation detection means
Definitions
- the present invention relates to a method for measuring the flowrates of the different phases of a multiphase flow, and a device for implementing the method.
- Methods for measuring the flowrates of the different phases of a multiphase flow are known, for example for the crude petroleum leaving a petroleum well and consisting of a mixture of oil, water and gas.
- the problem which normally arises in these cases is linked to the fact that the flowrates of the different phases of a multiphase flow passing through a conduit are measured indirectly via measurements of the pressure difference between two measurement points spaced along the conduit, known as cross-correlation measurements, enabling the flow velocity to be determined, together with impedance measurements (capacitance and/or conductance).
- the problem is solved according to the invention by a method for measuring the flowrates of the different phases of a multiphase flow as described in claim 1 .
- cross-correlation measurements and impedance measurements are made within a said second constriction in the form of a passage bounded by two flat parallel surfaces.
- a device for implementing the method of the invention is described in claim 3.
- Figure 1 shows schematically a traditional method for determining the flowrate of the individual components of a multiphase flow
- Figure 2 shows schematically the method of the invention
- Figure 3 is a longitudinal section through a device for implementing the method of the invention
- Figure 4 is a cross-section therethrough on the line IV-IV of Figure 3.
- Figure 1 shows a traditional method for determining the flowrate of the individual phases of a fluid, for example crude petroleum, containing gas, water and oil, from which it can be seen that input data, in the form of the pressure difference dP between two measurement points at a venturi, the value of the velocity V of the multiphase flow measured by traditional cross- correlation measurements, and the value of the fluid impedance Z, are fed into the mathematical model representative of the measurement instrument.
- a fluid for example crude petroleum, containing gas, water and oil
- the mathematical model By processing the input data the mathematical model provides as output the flowrates Q 9 of the gas, Q 3 of the water, and Q 0 of the oil .
- the velocity value V is an average value, which is that measured by the cross-correlation method, but not the actual velocity of the liquid and of the gas (the water velocity V 3 and the oil velocity V 0 are substantially close to each other).
- the invention uses the device shown by way of example in Figures 3 and 4. It comprises a measurement conduit 2 in which a first constriction is provided, in the form of a venturi comprising a first convergent section 4, preferably formed from two frusto- conical portions joined by a cylindrical portion, and a throat 6.
- a first constriction in the form of a venturi comprising a first convergent section 4, preferably formed from two frusto- conical portions joined by a cylindrical portion, and a throat 6.
- the venturi does not present a divergent portion downstream of the throat 6, although this could be present but would have to be very short in order to facilitate creation of a turbulence in the flow.
- a differential pressure meter 8 is associated, with one measurement point 10 within the convergent section of the venturi and the other measurement point 12 within the throat 6.
- a mixing chamber 16 is provided, of length preferably between 0.5 and 1 times the chamber diameter. This is followed by a second constriction, bounded by two lateral parallel walls 18 and hence having a cross-section different from the circular cross-section of the throat 6.
- Electrodes 20, 22 are applied to these walls 18 to measure the cross-correlation and impedance.
- the distance between the electrodes 20, 22 is less than the internal diameter of the throat 6.
- the device of the invention operates in the following manner.
- the multiphase flow of crude petroleum which enters the conduit 2 passes through the convergent section 4 of the venturi and increases its velocity, with consequent reduction in its pressure.
- the differential pressure dP is measured between its measurement points 10 and 12.
- the multiphase flow leaving the venturi throat 6 enters the chamber 16, within which the sudden cross-section variation subjects the flow to high turbulence and hence to intense homogenisation.
- the flow homogenized in this manner passes through the second constriction, within which it is subjected to cross-correlation measurements and measurements of its impedance Z.
- the method and device of the invention are particularly advantageous, and in particular:
- the multiphase flow is premixed, so further improving measurement accuracy.
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- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- General Physics & Mathematics (AREA)
- Measuring Volume Flow (AREA)
- Investigating Or Analysing Biological Materials (AREA)
- Paper (AREA)
Abstract
A method for measuring the flowrates of the different phases of a multiphase flow, by which the flow passing through a conduit (2) is subjected to at least one differential pressure measurement, to cross-correlation measurements to determine the flow velocity, and to impedance measurements, characterised by making the differential pressure measurement within a first constriction in the form of a venturi with a reduced recovery section, then immediately downstream thereof subjecting the flow to mixing, and then subjecting it, before slip reforms, to cross-correlation and impedance measurements within a second constriction having a non-circular passage cross-section.
Description
METHOD FOR MEASURING THE FLOWRATES OF THE DIFFERENT PHASES OF A MULTIPHASE FLOW, AND DEVICE FOR IMPLEMENTING THE METHOD
The present invention relates to a method for measuring the flowrates of the different phases of a multiphase flow, and a device for implementing the method.
Methods for measuring the flowrates of the different phases of a multiphase flow are known, for example for the crude petroleum leaving a petroleum well and consisting of a mixture of oil, water and gas. The problem which normally arises in these cases is linked to the fact that the flowrates of the different phases of a multiphase flow passing through a conduit are measured indirectly via measurements of the pressure difference between two measurement points spaced along the conduit, known as cross-correlation measurements, enabling the flow velocity to be determined, together with impedance measurements (capacitance and/or conductance).
However the presence of gas bubbles in the flow, and in particular of relatively large gas bubbles, gives rise to the undesirable slip phenomenon, linked to the fact that whereas small gas bubbles have a velocity close to that of the liquid, the larger bubbles have a greater velocity. It follows that the average velocity of the gas is greater than the average velocity of the liquid, and as a single velocity value is used to determine the flowrates of the different phases of the multiphase flow the measurement is inevitably imprecise. Various solutions have been proposed to reduce this drawback, partly based on the principle of not mixing the multiphase flow before the measurements, and partly based on the principle of mixing said flow.
A multi-velocity measurement method can be used to measure the liquid and gas velocities. However it has proved disadvantageous because of the very large velocity distribution (from 5 to 10m /sec) and the difficulty of determining which average velocity to use. A mixed flow should theoretically enable the slip phenomenon to be eliminated and to hence have a single velocity to be measured. However it has been found that the fluid slip reforms very rapidly after mixing and for this reason not only must the measurements be made close to the mixing region, but the slip must also be prevented from reforming before the measurements are made.
The problem is solved according to the invention by a method for measuring the flowrates of the different phases of a multiphase flow as described in claim 1 .
Advantageously the cross-correlation measurements and impedance measurements are made within a said second constriction in the form of a passage bounded by two flat parallel surfaces.
A device for implementing the method of the invention is described in claim 3.
A preferred embodiment of the present invention is further clarified by way of non-limiting example with reference to the accompanying drawings, in which: Figure 1 shows schematically a traditional method for determining the flowrate of the individual components of a multiphase flow, Figure 2 shows schematically the method of the invention, Figure 3 is a longitudinal section through a device for implementing the method of the invention, and
Figure 4 is a cross-section therethrough on the line IV-IV of Figure 3.
Figure 1 shows a traditional method for determining the flowrate of the individual phases of a fluid, for example crude petroleum, containing gas, water and oil, from which it can be seen that input data, in the form of the pressure difference dP between two measurement points at a venturi, the value of the velocity V of the multiphase flow measured by traditional cross- correlation measurements, and the value of the fluid impedance Z, are fed into the mathematical model representative of the measurement instrument.
By processing the input data the mathematical model provides as output the flowrates Q9 of the gas, Q3 of the water, and Q0 of the oil .
However, as stated, because of the slip phenomenon, the velocity value V is an average value, which is that measured by the cross-correlation method, but not the actual velocity of the liquid and of the gas (the water velocity V3 and the oil velocity V0 are substantially close to each other). The method according to the invention, shown schematically in Figure
2, consists of intimately mixing the flow being measured such as to homogenize its phases, then subjecting it to cross-correlation and impedance measurements immediately afterwards, i.e. before the slip phenomenon arises. In this manner a substantial identity exists between the flow velocity value and the velocity values of the individual liquid phase Vi and gaseous phase V9, this enabling a single mixture velocity value V to be used to obtain more precise flowrate values Q9, Qa and Q0 for the different flow phases.
In practice, to implement the method the invention uses the device shown by way of example in Figures 3 and 4. It comprises a measurement conduit 2 in which a first constriction is provided, in the form of a venturi comprising a first convergent section 4, preferably formed from two frusto-
conical portions joined by a cylindrical portion, and a throat 6. In this example the venturi does not present a divergent portion downstream of the throat 6, although this could be present but would have to be very short in order to facilitate creation of a turbulence in the flow. With this venturi a differential pressure meter 8 is associated, with one measurement point 10 within the convergent section of the venturi and the other measurement point 12 within the throat 6.
Immediately downstream of the throat 6, with reference to the direction of advancement of the flow within the conduit 2, indicated by the arrow 14, a mixing chamber 16 is provided, of length preferably between 0.5 and 1 times the chamber diameter. This is followed by a second constriction, bounded by two lateral parallel walls 18 and hence having a cross-section different from the circular cross-section of the throat 6.
Traditional electrodes 20, 22 are applied to these walls 18 to measure the cross-correlation and impedance.
Preferably the distance between the electrodes 20, 22 is less than the internal diameter of the throat 6.
The device of the invention operates in the following manner.
The multiphase flow of crude petroleum which enters the conduit 2 passes through the convergent section 4 of the venturi and increases its velocity, with consequent reduction in its pressure. The differential pressure dP is measured between its measurement points 10 and 12.
The multiphase flow leaving the venturi throat 6 enters the chamber 16, within which the sudden cross-section variation subjects the flow to high turbulence and hence to intense homogenisation.
The flow homogenized in this manner passes through the second constriction, within which it is subjected to cross-correlation measurements and measurements of its impedance Z.
During this stage the variation in the fluid passage cross-section from circular at the throat 6 to non-circular at the second constriction enables the mixing effect to persist and to hence delay slip formation.
Essentially, by virtue of the mixing to which the multiphase flow is subjected between the differential pressure measurement and the cross- correlation and impedance measurements, the method and device of the invention are particularly advantageous, and in particular:
- they make the measurement substantially insensitive to the slip phenomenon, so that the measurement is extremely precise,
- absence of the venturi recovery section, i.e. its divergent portion, improves mixing, so further improving the measurement accuracy, - by virtue of the flat walls of the second constriction the distance between the electrodes 20, 22 can be reduced, with a consequent reduction in its length, leading to a reduced overall length of the device and a further improvement in measurement accuracy,
- if the convergent part 4 of the venturi is made as a double convergent section, i.e. with two frusto-conical portions joined by a cylindrical portion, as shown in Figure 3, the multiphase flow is premixed, so further improving measurement accuracy.
Claims
1 . A method for measuring the flowrates of the different phases of a multiphase flow, by which the flow passing through a conduit (2) is subjected to at least one differential pressure measurement, to cross-correlation measurements to determine the flow velocity, and to impedance measurements, characterised by making the differential pressure measurement within a first constriction in the form of a venturi with a reduced recovery section, then immediately downstream thereof subjecting the flow to mixing, and then subjecting it, before slip reforms, to cross-correlation and impedance measurements within a second constriction having a non-circular passage cross-section.
2. A method as claimed in claim 1 , characterised by making the cross- correlation and impedance measurements within a said second constriction in the form of a passage bounded by two flat parallel surfaces.
3. A device for implementing the method claimed in claim 1 , characterised by comprising a conduit (2) traversed by the multiphase flow and provided with a first constriction consisting of a venturi with a reduced recovery section, and a following second constriction having a non-circular passage cross- section, in which electrodes (20, 22) are provided for making the cross- correlation and impedance measurements.
4. A device as claimed in claim 3, characterised in that the recovery section of the venturi forming the first constriction has a divergence angle substantially close to 90°.
5. A device as claimed in claim 3, characterised in that the second constriction is formed from two flat parallel walls (18).
6. A device as claimed in claim 3, characterised in that the mixing chamber (16) has a length between 0.5 and 1 times the chamber diameter.
7. A device as claimed in claim 5, characterised in that the distance between the walls (18) of the second constriction is less than the diameter of the throat (6) of said venturi.
8. A device as claimed in claim 3, characterised in that the convergent part (4) of the first constriction is a venturi made as a double convergent section, with two frusto-conical portions joined by a cylindrical portion.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| ITVE2006A000066 | 2006-10-20 | ||
| IT000066A ITVE20060066A1 (en) | 2006-10-20 | 2006-10-20 | MEASUREMENT METHOD OF THE FLOWS OF THE DIFFERENT PHASES OF A MULTIFASE FLOW AND DEVICE FOR IMPLEMENTING THE METHOD. |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO2008046805A1 true WO2008046805A1 (en) | 2008-04-24 |
Family
ID=39166834
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/EP2007/060946 WO2008046805A1 (en) | 2006-10-20 | 2007-10-15 | Method for measuring the flowrates of the different phases of a multiphase flow, and device for implementing the method |
Country Status (2)
| Country | Link |
|---|---|
| IT (1) | ITVE20060066A1 (en) |
| WO (1) | WO2008046805A1 (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2423647A1 (en) * | 2010-08-24 | 2012-02-29 | General Electric Company | Apparatus for use in determining a plurality of characteristics of a multiphase flow within a pipe |
| WO2013084183A3 (en) * | 2011-12-06 | 2013-08-08 | Schlumberger Technology B.V. | Multiphase flowmeter |
| CN108421756A (en) * | 2018-04-24 | 2018-08-21 | 浙江理工大学 | A kind of cavitation jet cleaning cavitation device |
| US10132847B2 (en) | 2011-12-06 | 2018-11-20 | Schlumberger Technology Corporation | Tomography of multiphase mixtures |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5287752A (en) * | 1991-04-26 | 1994-02-22 | Shell Oil Company | Measurment of gas and liquid flowrates and watercut of multiphase mixtures of oil, water and gas |
| WO2002008702A1 (en) * | 2000-07-21 | 2002-01-31 | Lattice Intellectual Property Ltd | A meter for the measurement of multiphase fluids and wet gas |
| WO2002044664A1 (en) * | 2000-11-29 | 2002-06-06 | Expro North Sea Limited | Multiphase flow meter using multiple pressure differentials |
-
2006
- 2006-10-20 IT IT000066A patent/ITVE20060066A1/en unknown
-
2007
- 2007-10-15 WO PCT/EP2007/060946 patent/WO2008046805A1/en active Application Filing
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5287752A (en) * | 1991-04-26 | 1994-02-22 | Shell Oil Company | Measurment of gas and liquid flowrates and watercut of multiphase mixtures of oil, water and gas |
| WO2002008702A1 (en) * | 2000-07-21 | 2002-01-31 | Lattice Intellectual Property Ltd | A meter for the measurement of multiphase fluids and wet gas |
| WO2002044664A1 (en) * | 2000-11-29 | 2002-06-06 | Expro North Sea Limited | Multiphase flow meter using multiple pressure differentials |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2423647A1 (en) * | 2010-08-24 | 2012-02-29 | General Electric Company | Apparatus for use in determining a plurality of characteristics of a multiphase flow within a pipe |
| CN102419193A (en) * | 2010-08-24 | 2012-04-18 | 通用电气公司 | Apparatus for use in determining a plurality of characteristics of a multiphase flow within a pipe |
| CN102419193B (en) * | 2010-08-24 | 2015-11-25 | 通用电气公司 | For determining the device of the multifrequency nature of the polyphasic flow in pipe |
| WO2013084183A3 (en) * | 2011-12-06 | 2013-08-08 | Schlumberger Technology B.V. | Multiphase flowmeter |
| US9927270B2 (en) | 2011-12-06 | 2018-03-27 | Schlumberger Technology Corporation | Multiphase flowmeter |
| US10132847B2 (en) | 2011-12-06 | 2018-11-20 | Schlumberger Technology Corporation | Tomography of multiphase mixtures |
| CN108421756A (en) * | 2018-04-24 | 2018-08-21 | 浙江理工大学 | A kind of cavitation jet cleaning cavitation device |
Also Published As
| Publication number | Publication date |
|---|---|
| ITVE20060066A1 (en) | 2008-04-21 |
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