[OPTICAL FLUID ANALYSIS SIGNAL REFINEMENT]

• US 20040233446A1
• Filed: 05/22/2003
• Published: 11/25/2004
• Est. Priority Date: 05/22/2003
• Status: Active Grant

• Current Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Original Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Inventors: HEGEMAN, PETER S., MULLINS, OLIVER C., DONG, CHENGLI, CARNEGIE, ANDREW J., KURKJIAN, ANDREW L., HSU, KAI
• Granted Patent: US 6,992,768 B2
• Time in Patent Office: Days
• US Class Current: 356/409
• CPC Class Codes: E21B 49/10 using side-wall fluid samplers or testers
• CPC Class Codes: G01N 2021/3129 Determining multicomponents by multiwavelength light
• CPC Class Codes: G01N 21/31 Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry G01N21/72 takes precedence

Abstract

A method for refining fluid sample data includes obtaining optical density data for a fluid sample in at least two color channels and at least one fluid component channel and determining a color-absorption function from the optical density data for the fluid sample in the at least two color channels. The method also includes calculating a portion of the optical density caused by color absorptions in each of the at least one fluid component channels, and de-coloring the optical density data in each of the at least one fluid component channels by removing the portion of the optical density data caused by color absorption.

Claims

1. A method for refining fluid sample data, comprising:

obtaining optical density data for a fluid sample in at least one color channel and at least one fluid component channel;

determining a color-absorption function from the optical density data for the fluid sample in the at least one color channel;

calculating a portion of an optical density in the at least one fluid component channel caused by color absorptions; and

de-coloring the optical density data for the at least one fluid component channel by removing the portion of the optical density in the at least one fluid component channel caused by color absorption.

2. The method of claim 1, wherein the at least one color channel comprises at least two color channels and the color-absorption function comprises two unknowns.

3. The method of claim 1, wherein the determining the color-absorption function, the calculating the portion of the optical density caused by color absorptions, and the de-coloring are performed on optical density data collected at a plurality of times.

4. The method of claim 1, wherein the color-absorption function is dependent on a wavelength of an incident light.

5. The method of claim 1, wherein the at least one fluid component channel comprises one selected from the group consisting of a methane channel, an oil channel, and both the methane channel and the oil channel.

6. The method of claim 1, further comprising calculating a gas oil ratio of the fluid sample.

7. The method of claim 1, further comprising calculating a percent contamination of the fluid sample.

8. The method of claim 1, further comprising:

obtaining optical density data for the fluid sample in a base channel;

calculating a portion of an optical density in the base channel caused by color absorptions from the color-absorption function;

de-coloring the optical density data in the base channel by removing the portion of the optical density in the base channel caused by color absorption; and

de-scattering the optical density data for the at least one fluid component channel by removing the optical density of the base channel from the optical density of the at least one fluid component channel.

9. A method for refining fluid sample data, comprising:

obtaining optical density data for a fluid sample in a water channel and in at least one fluid component channel;

calculating a portion of an optical density in the at least one fluid component channel caused by water absorptions based on an optical density in the water channel and a water-absorption ratio for the at least one fluid component channel; and

de-watering the optical density data in the at least one fluid component channel by removing the portion of the optical density in the at least one fluid component channel caused by water absorptions.

10. The method of claim 9, wherein the calculating the portion of the optical density data caused by water absorptions and the de-watering are performed on optical density data collected at a plurality of times.

11. The method of claim 9, wherein the water-absorption ratio is determined by experimentation.

12. The method of claim 9, wherein the at least one fluid component channel comprises one selected from the group consisting of a methane channel, an oil channel, and both the methane channel and the oil channel.

13. The method of claim 9, further comprising:

obtaining optical density data for the fluid sample in a base channel; and

calculating a portion of an optical density in the base channel caused by water absorptions based on the optical density in the water channel and a water-absorption ratio for the base channel;

de-watering the optical density data in the base channel by removing the portion of the optical density caused by water absorptions in the base channel; and

de-scattering the optical density data for the at least one fluid component channel by removing the optical density of the base channel from the optical density of the at least one fluid component channel.

14. The method of claim 9, further comprising calculating a gasoil ratio of the fluid sample.

15. The method of claim 9, further comprising calculating a percent contamination of the fluid sample.

16. A method for refining fluid sample data, comprising:

obtaining optical density data for a fluid sample in at least one color channel, a water channel, and at least one fluid component channel;

determining a color-absorption function from the optical density data of the fluid sample in the at least one color channel;

calculating a portion of an optical density in the at least one fluid component channel caused by color absorptions;

calculating a portion of the optical density in the at least one fluid component channel caused by water absorptions based on an optical density in the water channel and a water-absorption ratio for the at least one fluid component channel; and

adjusting the optical density data in the at least one fluid component channel by removing the portion of the optical density in the at least one fluid component channel caused by color absorptions, and by removing the portion of the optical density in the at least one fluid component channel caused by water absorptions.

17. The method of claim 16, wherein the at least one color channel comprises two color channels and the color-absorption function comprises two unknowns.

18. The method of claim 16, wherein the determining the color-absorption function, the calculating a portion of the optical density in the at least one fluid component channel caused by color absorptions, the calculating a portion of the optical density in the at least one fluid component channel caused by water absorptions, and the adjusting the optical density data are performed on optical density data collected at a plurality of times.

19. The method of claim 16, further comprising:

obtaining optical density data for a fluid sample in a base channel;

calculating a portion of an optical density in the base channel caused by color absorptions from the color-absorption function;

calculating a portion of the optical density in the base channel caused by water absorptions based on the optical density in the water channel and a water-absorption ratio for the base channel;

adjusting the optical density data in the base channel by removing the portion of the optical density in the base channel caused by color absorptions, and by removing the portion of the optical density in the base channel caused by water absorptions; and

de-scattering the optical density data for the at least one fluid component channel by removing the optical density in the base channel from the optical density in the at least one fluid component channel.

20. A method for refining fluid sample data, comprising:

obtaining optical density data for a fluid sample in a plurality of optical channels;

developing a system of equations that model an optical density in each of the plurality of optical channels as a sum of at least two of the group consisting of color absorptions, molecular vibration absorptions, water absorptions, and scattering; and

solving the system of equations to determine the molecular vibration absorptions in at least a methane channel and an oil channel.

21. The method of claim 20, wherein the developing the system of equations and the solving the system of equations are performed on optical density data collected at a plurality of times.

22. The method of claim 20, wherein the at least two of the group consisting of color absorptions, molecular vibration absorptions, water absorptions, and scattering comprises a wavelength function of color absorptions.

23. The method of claim 20, wherein the at least two of the group consisting of color absorptions, molecular vibration absorptions, water absorptions, and scattering comprises a wavelength function of water absorptions.

24. The method of claim 20, wherein the at least two of the group consisting of color absorptions, molecular vibration absorptions, water absorptions, and scattering comprises a wavelength function of scattering.

25. An electronics system, comprising:

an input device adapted to receive optical density data for a fluid sample at a plurality of times;

a memory operatively coupled with the input device to store the received data; and

a processor operatively coupled to the memory and adapted to use the optical density data to develop a system of equations that model an optical density in each of the plurality of optical channels as a sum of at least two of the group consisting of color absorptions, molecular vibration absorptions, water absorptions, and scattering, and adapted to solve the system of equations to determine the molecular vibration absorptions in a methane channel and an oil channel.

26. The electronics system of claim 25, wherein the electronics system is operatively connected to a downhole fluid sampling tool.

27. The electronics system of claim 25, wherein the electronics system is adapted to be integral with a downhole fluid sampling tool.