Phase fraction measurement using continuously adjusted light source

Patent metadata

Field	Value
Publication number	US-10054537-B2
Application number	US-201615194829-A
Country	US
Kind code	B2
Filing date	Jun 28, 2016
Priority date	Jun 28, 2016
Publication date	Aug 21, 2018
Grant date	Aug 21, 2018

Abstract

An apparatus includes a pipe through which a multiphase fluid flows, with a transparent window structure formed in the pipe. A collimated light source emits light through the transparent window structure into the pipe having a wavelength at which a component of a desired phase of the multiphase fluid is absorptive. A photodetector is positioned such that the emitted light passes through the multiphase fluid in the pipe to impinge upon the photodetector. The photodetector has an actual dynamic range for collimated light detection. Processing circuitry is configured to continuously adjust a power of the collimated light source dependent upon an output level of the photodetector so as to cause measurement of the emitted light over an effective dynamic range greater than the actual dynamic range, and determine a property of the multiphase fluid as a function of the power of the collimated light source.

First claim

The invention claimed is:

1. An apparatus comprising:
a pipe through which a multiphase fluid flows;
a transparent window structure formed in the pipe;
a collimated light source configured to emit light through the transparent window structure and into the pipe, the emitted light having a wavelength at which a component of a desired phase of the multiphase fluid is absorptive;
a photodetector positioned such that the emitted light passes through the multiphase fluid in the pipe and out through the transparent window structure to impinge upon the photodetector, wherein the photodetector has an actual dynamic range for collimated light detection;
processing circuitry coupled to the collimated light source and photodetector, the processing circuitry configured to:
continuously adjust a power of the collimated light source dependent upon an output level of the photodetector so as to cause measurement of the emitted light by the photodetector over an effective dynamic range greater than the actual dynamic range;
determine at least one property of the multiphase fluid as a function of the power of the collimated light source.

2. The apparatus of claim 1 , wherein the processing circuitry continuously adjusts the power of the collimated light source dependent upon the output of the photodetector by continuously adjusting the power of the collimated light source such that the output level of the photodetector remains constant.

3. The apparatus of claim 1 , wherein the emitted light passes through substantially an entire cross sectional area of the multiphase fluid in the structure.

4. The apparatus of claim 1 , further comprising at least one lens associated with the collimated light source for shaping the emitted light into a ribbon shape.

5. The apparatus of claim 1 , wherein the collimated light source comprises a first collimated light source having a first wavelength at which a component of a first phase of the multiphase fluid is absorptive; and further comprising a second collimated light source having a second wavelength at which a component of a second phase of the multiphase fluid is absorptive, and a third collimated light source having a third wavelength at which components of the first and second phases of the multiphase fluid are not absorptive.

6. The apparatus of claim 5 , wherein the first phase of the multiphase fluid comprises oil; wherein the second phase of the multiphase fluid comprises water; wherein a third phase of the multiphase fluid comprises gas; and wherein the at least one property of the multiphase fluid comprises phase fractions of gas, oil, and water.

7. The apparatus of claim 6 , wherein the first wavelength is substantially at a hydrocarbon peak absorption band; wherein the second wavelength is at a water absorption band where water is more absorptive of light than oil; and wherein the third wavelength is at a band where neither water nor oil is substantially absorptive.

8. The apparatus of claim 5 , wherein a fourth phase of the multiphase fluid comprises a solid phase; further comprising a fourth collimated light source having a fourth wavelength at which components of the solid phases of the multiphase fluid is absorptive.

9. The apparatus of claim 5 , wherein the processing circuitry is configured to pulse the first, second, and third collimated light sources in a pattern such that but one of the first, second, and third collimated light sources is emitting light at a time.

10. The apparatus of claim 5 , wherein the processing circuitry is configured to pulse the first, second, and third collimated light sources simultaneously and at different pulsing frequencies from one another, and is configured to perform phase-sensitive detection simultaneously for the first, second, and third collimated light sources.

11. The apparatus of claim 10 , wherein the processing circuitry is configured to discriminate between components of the emitted light impinging upon the photodetector that were emitted by the first collimated light source, components of the emitted light impinging upon the photodetector that were emitted by the second collimated light source, and components of the emitted light impinging upon the photodetector that were emitted by the third collimated light source, using phase sensitive detection.

12. The apparatus of claim 5 , wherein:
the first collimated light source comprises a first laser light source configured to emit laser light along a path that does not include the transparent window structure, and a first mirror configured to reflect the laser light from the first laser light source along a path that includes the transparent window structure;
the second collimated light source comprises a second laser light source configured to emit laser light along a path that does not include the transparent window structure, and a second mirror configured to reflect the laser light from the second laser light source along a path that includes the transparent window structure; and
the third collimated light source comprises a third laser light source configured to emit laser light along a path that does not include the transparent window structure, and a third mirror configured to reflect the laser light from the third laser light source along a path that includes the transparent window structure;
and further comprising:
at least one lens to focus the reflected laser light from the first, second, and third laser light sources.

13. The apparatus of claim 1 , wherein the processing circuitry is configured to differentiate between sand, and bubbles or droplets.

14. The apparatus of claim 1 , further comprising an additional photodetector positioned such that emitted light that scatters off the multiphase fluid and out through the transparent window structure impinges upon the additional photodetector; wherein the processing circuit is configured to measure the scattered emitted light; and wherein the processing circuitry also determines the at least one property of the multiphase fluid as a function of the measured scattered emitted light.

15. The apparatus of claim 14 , wherein the at least one property of the multiphase fluid comprises a phase fraction of solids in the multiphase fluid.

16. A method of determining at least one property of a multiphase fluid comprising:
emitting, into the multiphase fluid, collimated light from a collimated light source, the emitted collimated light having a wavelength at which a component of a desired phase of the multiphase fluid is absorptive;
detecting light passing through the multiphase fluid impinging upon a photodetector, the photodetector having an actual dynamic range for collimated light detection;
continuously adjusting a power of the collimated light source dependent upon an output level of the photodetector so as to cause measurement of the emitted collimated light by the photodetector over an effective dynamic range greater than the actual dynamic range; and
determining at least one property of the multiphase fluid as a function of the power of the collimated light source.

17. The method of claim 16 , wherein continuously adjusting the power of the collimated light source comprises continuously adjusting the power of the collimated light source such that the output level of the photodetector remains constant.

18. The method of claim 16 , wherein adjustment of the power of the collimated light source over time yields a pattern of output power values; and wherein determining the at least one property of the multiphase fluid as a function of the power of the collimated light

Assignees

• Schlumberger Technology Corp

Inventors

• Arifin Arifin
• Xie Cheng-Gang

Classifications

• G01N2201/06113

  Coherent sources; lasers · CPC title

• G01N21/31 Primary

  Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry {(G01N21/72 takes precedence)} · CPC title

• G01P5/26 Primary

  by measuring the direct influence of the streaming fluid on the properties of a detecting optical wave · CPC title

• G01N2201/12

  Circuits of general importance; Signal processing · CPC title

• G01N2201/0633

  Directed, collimated illumination · CPC title