METHOD OF MEASURING FLOW PROPERTIES OF A MULTIPHASE FLUID

• US 20110138928A1
• Filed: 12/11/2009
• Published: 06/16/2011
• Est. Priority Date: 12/11/2009
• Status: Active Grant

• Current Assignee: Schlumberger Technology Corporation (SLB)
• Original Assignee: Schlumberger Technology Corporation (SLB)
• Inventors: Xie, Cheng-gang, Huang, Songming
• Granted Patent: US 8,322,228 B2
• Time in Patent Office: Days
• US Class Current: 73/861.04
• CPC Class Codes: G01F 1/36 the pressure or differential pressure being created by the use of flow constriction
• CPC Class Codes: G01F 1/44 Venturi tubes
• CPC Class Codes: G01F 1/663 by measuring Doppler frequency shift
• CPC Class Codes: G01F 1/74 Devices for measuring flow of a fluid or flow of a fluent solid material in suspension in another fluid

Abstract

A method and system for measuring a property of a multiphase fluid comprising a mixture of at least an oil phase and a water phase travelling through a conduit, the method comprising measuring the thickness of the liquid mixture, measuring the permittivity of a portion of the multiphase fluid, combining the thickness measurement with the permittivity measurement to obtain a derived value for the permittivity of the liquid mixture, and using at least the derived permittivity of the liquid mixture and a relationship between a single phase liquid property and a corresponding two-phase property of the liquid mixture, to obtain a calculated water-to-liquid ratio of the liquid mixture.

Claims

1. A method of measuring a property of a multiphase fluid, the multiphase fluid including a gas phase and a liquid phase and the liquid phase comprising at least one of oil and water, travelling through a conduit, wherein the liquid phase travels substantially along an inside-wall of the conduit, the method comprising:

measuring a thickness of the liquid mixture;

measuring at least one of a permittivity and a conductivity of a portion of the multiphase fluid;

combining the thickness measurement with the at least one of the permittivity and the conductivity measurement to obtain a derived value for at least one of the permittivity and the conductivity of the liquid mixture; and

using at least one of the derived permittivity and the derived conductivity and a relationship between a single phase liquid property and a corresponding two-phase property of the liquid mixture to obtain a calculated water-to-liquid ratio of the liquid mixture.

2. A method according to claim 1, further comprising flowing the multiphase fluid through a venturi, wherein the venturi comprises a constriction region.

3. A method according to claim 2, further comprising inducing the multiphase fluid to exhibit swirling flow in the constriction region.

4. A method according to claim 1, wherein the thickness of the liquid mixture is measured using an ultrasonic sensor.

5. A method according to claim 1, further comprising measuring a speed of sound in the multiphase fluid.

6. A method according to claim 5, wherein the speed of sound is measured in-line or in a bypass flowline.

7. A method according to claim 4, wherein a speed of sound is estimated from a mixing rule utilising single phase speeds of sound in oil and in water.

8. A method according to claim 7, wherein a calculated water-in-liquid ratio is compared to a notional water-in-liquid ratio and the notional water-in-liquid ratio is changed accordingly, and wherein the calculating the water-in-liquid ratio, comparing the calculation to a notional water-in-liquid ratio and changing the notional water-in-liquid ratio accordingly is carried out iteratively until the notional water-in-liquid ratio is approximately equal to the calculated water-in-liquid ratio.

9. A method according to claim 1, wherein the at least one of the permittivity and the conductivity is measured by at least one of a transmission and a reflection electromagnetic method.

10. A method according to claim 1, wherein water conductivity is employed in the calculation of the water-in-liquid ratio of water continuous liquid.

11. A method according to claim 10, wherein water conductivity is estimated from at least one of the measurement of the permittivity and the measurement of the conductivity of the multiphase mixture.

12. A method according to claim 1, wherein the single phase liquid property is at least one of permittivity and conductivity.

13. A method according to claim 1, further comprising the step of determining a flow rate of the liquid mixture.

14. A method according to claim 13, wherein the flow rate is determined obtainable from an axial velocity and the thickness of the liquid mixture.

15. A method according to claim 13, wherein the axial velocity and the thickness of the liquid mixture are measured using an ultrasonic sensor.

16. A method according to claim 13, wherein the liquid flow rate is combined with the water-in-liquid ratio to give the flow rates of the individual oil and water phases.

17. A method according to claim 1, further comprising the step of measuring a total flow rate of the multiphase fluid.

18. A method according to claim 17, wherein the total flow rate is determined from a venturi differential pressure measurement and a multiphase fluid density obtained from the water-in-liquid ratio and the thickness of the liquid mixture.

19. A method according to claim 17, wherein a liquid flow rate is combined with the total flow rate to give a flow rate of the gas phase.

20. A multiphase flowmeter for measuring properties of a fluid comprising a mixture of at least an oil phase and a water phase travelling through a conduit, wherein the oil and water phases are travelling substantially along an inside wall of the conduit as a liquid mixture, wherein the flowmeter comprises:

a sensor for measuring a thickness of the liquid mixture;

a sensor for measuring at least one of a permittivity and a conductivity of a portion of the multiphase fluid;

and a processing means configured to combining the thickness measurement with the at least one of the permittivity and the conductivity measurement to obtain a derived value for at least one of the permittivity and the conductivity of the liquid mixture and to process a calculated water-to-liquid ratio of the liquid mixture using at least one of the derived permittivity and the derived conductivity and a relationship between a single phase liquid property and a corresponding two-phase property of the liquid mixture.

21. A flowmeter according to claim 20, further comprising a venturi, wherein the venturi comprises a constriction region providing a reduced conduit cross-section.

22. A flowmeter according to claim 21, further comprising a swirl generator configured to induce a swirling flow of the fluid through the venturi.

23. A flowmeter according to claim 20, wherein the sensor for measuring the thickness of the liquid mixture comprises an ultrasonic sensor.

24. A flowmeter according to claim 20, further comprising an insertion ultrasound sensor for measuring a speed of sound in the liquid mixture.

25. A flowmeter according to claim 24, wherein the insertion ultrasound sensor is located on the conduit-wall at an inlet before a constriction in the conduit.

26. A flowmeter according to claim 20, wherein the sensor for measuring the one of the permittivity and the conductivity comprises a transmission electromagnetic sensor.

27. A flowmeter according to claim 20, wherein the sensor for measuring the one of the permittivity and the conductivity comprises a reflection electromagnetic sensor.

28. A flowmeter according to claim 20, wherein the flowmeter comprises both a transmission and a reflection electromagnetic sensor.

29. A flowmeter according to claim 20, wherein the sensor for measuring the liquid thickness and the sensor for measuring the one of the permittivity and the conductivity are at located at the same axial location on the conduit.

30. A flowmeter according to claim 20, further comprising a sensor for measuring the speed-of-sound in the liquid phase, wherein the speed-of-sound sensor is located with the sensor for measuring the one of the permittivity and the conductivity at a bypass line.

31. A flowmeter according to claim 21, wherein the flowmeter comprises a clamp-on flowmeter that is configured to be fitted to a pipe.