Single magnet fluid densitometer

Patent metadata

Field	Value
Publication number	US-9645114-B2
Application number	US-201214391612-A
Country	US
Kind code	B2
Filing date	May 3, 2012
Priority date	May 3, 2012
Publication date	May 9, 2017
Grant date	May 9, 2017

Abstract

An instrument for determining fluid properties is provided. The instrument ( 300 ) includes a tube ( 304 ) receiving the fluid, a single magnet ( 302 ) attached to the tube, and a single coil ( 306 ) wound around the single magnet. The single coil is coupled to a pulse current source ( 312 ) and receives a pulse current that creates a magnetic field in the single coil, the created magnetic field interacting with the single magnet to drive the tube to vibrate. The instrument further includes a detector ( 306 ) coupled to the tube, wherein the detector is coupled to measurement circuitry ( 310 ) and detects properties of the tube as it vibrates, and the measurement circuitry determines the fluid properties based on the detected properties. The instrument also includes a housing ( 314 ) enclosing the tube, the single magnet, and the single coil wound around the single magnet.

First claim

The invention claimed is:

1. An instrument for measuring fluid properties, comprising:
a tube, the tube receiving a sample of the fluid;
a testing module including measurement circuitry and a current source;
an excitation source coupled to the testing module, the excitation source comprising at least one coil wound around a single magnet, the excitation source being configured to excite the tube into a vibrating state;
a strain gauge coupled to the tube and coupled to the measurement circuitry; and
a strain gauge current source coupled to the strain gauge and providing a strain gauge current, wherein:
a resistance of the strain gauge changes in response to mechanical stress generated along the tube as it vibrates;
a voltage induced by the strain gauge current varies as the resistance changes; and
the measurement circuitry measures the varying voltage induced in the strain gauge by the strain gauge current over time to determine the resonance frequency of the tube.

2. The instrument of claim 1 , wherein the single magnet is attached to the tube and the at least one coil is coupled to the current source.

3. The instrument of claim 2 , wherein the current source provides a current to the at least one coil wound around the single magnet to produce a magnetic field that interacts with the single magnet to excite the tube into the vibrating state.

4. The instrument of claim 3 , wherein the single magnet vibrates in the at least one coil as the tube vibrates to generate a voltage in the at least one coil that varies over time, and the varying voltage is detected by the measurement circuitry.

5. The instrument of claim 4 , wherein the measurement circuitry performs a transform on the detected voltage to determine a resonance frequency of the tube and determines a density of the fluid from the determined resonance frequency.

6. The instrument of claim 3 , further comprising a detector coupled to the measurement circuitry, the detector having a Q-factor and measuring parameters related to the vibration of the tube, wherein:
the measured parameters are provided to the measurement circuitry to determine a resonance frequency of the tube; and
a temporal decay rate of the measured parameters is determined by the measurement circuitry to measure the Q-factor of the detector, wherein a viscosity of the fluid can be determined from the measured Q-factor.

7. The instrument of claim 2 , wherein the excitation source further comprises:
an electric hammer coupled to the test circuitry and the tube, the electric hammer receiving a current pulse from the test circuitry and striking the tube to excite the tube into the vibrating state; and
the single magnet vibrates in the at least one coil as the tube vibrates to generate a voltage in the at least one coil that varies over time, and the varying voltage is detected by the measurement circuitry.

8. The instrument of claim 7 , wherein the measurement circuitry performs a transform on the detected voltage to determine a resonance frequency of the tube and determines a density of the fluid from the determined resonance frequency.

9. The instrument of claim 7 , wherein the single magnet and at least one coil are spaced away from the tube by a predetermined distance.

10. The instrument of claim 7 , further comprising:
at least one tab attached to a side of the tube, wherein the electric hammer strikes the tab to provide a torsional force on the tube and produce a torsional vibration of the tube.

11. The instrument of claim 1 , wherein the strain gauge comprises at least one of a metallic wire lined along a length of the tube, a semiconductor material deposited on the tube.

12. The instrument of claim 1 , wherein:
the strain gauge is wrapped around the tube to measure a hoop stress of the tube; and
the measurement circuitry determines a pressure of the fluid in the tube from the measured hoop stress.

13. The instrument of claim 1 , further comprising:
at least one tab attached to a side of the tube; and
the single magnet is attached to the at least one tab, wherein:
the single magnet interacts with the tab to provide a torsional force on the tube and produce a torsional vibration of the tube.

14. An instrument for determining fluid properties, comprising:
a tube receiving the fluid;
a single magnet;
at least one coil wound around the single magnet, wherein the at least one coil is coupled to a pulse current source and receives a pulse current that creates a magnetic field in the at least one coil, the created magnetic field interacting with the single magnet to excite the tube into a vibrating state; and
a detector coupled to the tube, wherein:
the detector is coupled to measurement circuitry and detects properties of the tube as it vibrates, and the measurement circuitry determines the fluid properties based on the detected properties;
the detector comprises a strain gauge coupled to the tube and coupled to the measurement circuitry, the detector further comprising a strain gauge current source coupled to the strain gauge and providing a strain gauge current,
a resistance of the strain gauge changes in response to mechanical stress generated along the tube as it vibrates;
a voltage induced by the strain gauge current varies as the resistance changes; and
the measurement circuitry measures the varying voltage induced in the strain gauge by the strain gauge current over time to determine the resonance frequency of the tube.

15. The instrument of claim 14 , wherein:
the detector comprises the at least one coil wound around the single magnet;
the single magnet vibrates in the at least one coil as the tube vibrates to generate a voltage in the at least one coil that varies over time, and the varying voltage is detected by the measurement circuitry;
the measurement circuitry performs a transform on the detected voltages to determine a resonance frequency of the tube; and
the measurement circuitry determines a density of the fluid from the determined resonance frequency.

16. The instrument of claim 14 , wherein the strain gauge comprises at least one of a metallic wire lined along a length of the tube, or a semiconductor material deposited on the tube.

17. The instrument of claim 14 , wherein:
the strain gauge is wrapped around the tube to measure a hoop stress of the tube; and
the measurement circuitry determines a pressure of the fluid in the tube from the measured hoop stress.

18. An instrument for measuring fluid properties, comprising:
a tube, the tube receiving a sample of the fluid;
a testing module including measurement circuitry and a current source;
an excitation source coupled to the testing module, the excitation source comprising at least one coil wound around a single magnet, the excitation source being configured to excite the tube into a vibrating state;
an optical fiber coupled to the tube and to the measurement circuitry, the optical fiber comprising a cladding surrounding a core, and a Bragg grating formed in the core; and
a light source coupled to the optical fiber and providing light through the optical fiber, wherein:
properties of the light through the optical fiber change in response to a mechanical stress caused by the vibration of the tube; and
the measurement circuitry detects the changing light properties and determines a resonant frequency and a fluid density.

19. An instrument for measuring fluid properties, comprising:
a tube, the tube receiving a sample of the fluid;
a testing module including measurement circuitry and a curre

Assignees

• Gao Li
• Pelletier Michael T
• Proett Mark A
• Halliburton Energy Services Inc

Inventors

• Gao Li
• Pelletier Michael T
• Proett Mark A

Classifications

• G01N2009/006

  vibrating tube, tuning fork · CPC title

• G01N33/2823

  Raw oil, drilling fluid or polyphasic mixtures · CPC title

• G01N11/16

  by measuring damping effect upon oscillatory body · CPC title

• G01N9/002

  using variation of the resonant frequency of an element vibrating in contact with the material submitted to analysis (G01N9/34 takes precedence) · CPC title

• E21B49/00

  Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to earth drilling or wells · CPC title