Method and apparatus for composition analysis in a production logging environment

• US 20070035737A1
• Filed: 08/15/2005
• Published: 02/15/2007
• Est. Priority Date: 08/15/2005
• Status: Active Grant

• Current Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Original Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Inventors: Jundt, Jacques, Raghuraman, Bhavani, Mullins, Oliver, Schroeder, Robert, Andrews, A.
• Granted Patent: US 7,279,678 B2
• Time in Patent Office: Days
• US Class Current: 356/436
• CPC Class Codes: G01N 21/3577 for analysing liquids, e.g. polluted water

Abstract

Methods and apparatus for analyzing a hydrocarbon mixture are disclosed, comprising at least one light-emitting diode (LED) and at least one photodetector positioned to detect energy transmitted by the LED through a sample of the hydrocarbon mixture. In at least one embodiment an optical filter is coupled to the output of the LED to mitigate the adverse effects of the LED'"'"'s sensitivity to temperature.

Claims

1. An apparatus for analyzing a hydrocarbon mixture, comprising:

at least one light-emitting diode (LED); and

at least one photodetector positioned to detect energy transmitted by said LED through a sample of said hydrocarbon mixture or back scattered from said hydrocarbon mixture.

2. The apparatus according to claim 1, further comprising at least one optical bandpass filter for filtering the energy transmitted by said LED.

3. The apparatus according to claim 2 wherein parameters of said optical bandpass filter are chosen to mitigate a temperature dependent wavelength shift of said LED.

4. The apparatus according to claim 2 wherein parameters of said optical bandpass filter are selected to allow passage of a pre-selected wavelength band.

5. The apparatus according to claim 4 wherein said pre-selected wavelength band corresponds to at least one spectral characteristic of hydrocarbon.

6. The apparatus according to claim 5 wherein the bandwidth of said optical bandpass filter is between 15-20 nm.

7. The apparatus according to claim 2 wherein parameters of said LED and said optical bandpass filter are selected to enable analysis of live hydrocarbon mixtures in a downhole environment.

8. The apparatus according to claim 1 wherein

said at least one LED comprises a plurality of LEDs arranged in a matrix;

and

said at least one photodetector comprises a plurality of photodetectors arranged in a matrix and respectively positioned to detect energy transmitted by said plurality of LEDs through said sample.

9. The apparatus according to claim 8 wherein said at least one optical bandpass filter comprises a plurality of optical bandpass filters for respectively filtering the energy transmitted by said plurality of LEDs.

10. The apparatus according to claim 9 wherein a response curve of each of said plurality of photodetectors is respectively matched to parameters of said plurality of optical bandpass filters.

11. The apparatus according to claim 8 further comprising a processor for controlling the operation of said plurality of LEDs, for digitally modulating said plurality of LEDs, and for analyzing said sample.

12. The apparatus according to claim 11 further comprising:

a transimpedance amplifier, an input of which is connected to an output of said plurality of photodetectors;

a lock-in amplifier, an input of which is connected to an output of said transimpedance amplifier; and

an analog-to-digital converter, an input of which is connected to an output of said lock-in amplifier and an output of which is connected to said processor.

13. The apparatus according to claim to claim 8, further comprising a cooling element in thermal communication with said plurality of LEDs.

15. The apparatus according to claim 8, further comprising focusing optics positioned between said plurality of optical bandpass filters and said sample for focusing the energy transmitted by said plurality of LEDs.

16. The apparatus according to claim 15 wherein said focusing optics focus the energy transmitted by said plurality of LEDs into a collimated beam.

14. The apparatus according to claim to 1, further comprising a downhole fluid sampling tool having the at least one LED and photodetector.

17. An apparatus comprising:

a subterranean sample analysis tool, comprising;

a plurality of light-emitting diodes (LEDs) arranged in a matrix; and

a plurality of photodetectors arranged in a matrix and respectively positioned to detect energy transmitted by said plurality of LEDs through a live hydrocarbon mixture.

18. The apparatus according to claim 17, further comprising a plurality of optical bandpass filters for respectively filtering the energy transmitted by said plurality of LEDs.

32. The apparatus according to claims 17, wherein one or more of the LEDs is used to detect sample fluorescence by front surface reflection from the optical window using at least one photodetector.

19. A method for analyzing a hydrocarbon mixture, comprising:

transmitting energy through a sample of said hydrocarbon mixture using at least one light-emitting diode (LED); and

detecting the energy transmitted through said sample using at least one photodetector.

20. The method according to claim 19, further comprising:

inserting a downhole sampling tool into a borehole;

drawing down the sample of said hydrocarbon mixture.

21. The method according to claim 19 further comprising filtering the energy transmitted by said LED using at least one optical bandpass filter.

22. The method according to claim 21, further comprising selecting parameters of said optical bandpass filter to mitigate a temperature dependent wavelength shift of said LED.

23. The method according to claim 20, wherein parameters of said optical bandpass filter are selected to allow passage of a pre-selected wavelength band corresponding to at least one spectral characteristic of hydrocarbon.

24. The method according to claim 20, further comprising selecting parameters of said LED and said optical bandpass filter to enable analysis of live hydrocarbon mixtures in a downhole environment.

25. The method according to claim 19 wherein

said at least one LED comprises a plurality of LEDs arranged in a matrix;

and

said at least one photodetector comprises a plurality of photodetectors arranged in a matrix and respectively positioned to detect energy transmitted by said plurality of LEDs through said sample.

26. The method according to claim 25, further comprising respectively filtering the energy transmitted by said plurality of LEDs using a plurality of optical bandpass filters.

27. The method according to claim 26, further comprising respectively matching a response curve of each of said plurality of photodetectors to parameters of said plurality of optical bandpass filters.

28. The method according to claim 25, further comprising:

controlling the operation of said plurality of LEDs using a processor;

digitally modulating said plurality of LEDs using said processor; and

analyzing spectral characteristics of said sample using said processor.

29. The method according to claim 25, further comprising focusing the energy transmitted by said plurality of LEDs into said sample using focusing optics.

30. A method, comprising:

characterizing a live downhole fluid sample using a downhole LED.

31. The method of claim 30 wherein the using a downhole LED comprises:

transmitting LED energy to the sample downhole;

detecting the LED energy transmitted from the sample downhole;

communicating detected LED energy measurements uphole to surface electronics.