DOWNHOLE MEASUREMENT OF SUBSTANCES IN EARTH FORMATIONS

• US 20080111064A1
• Filed: 11/10/2006
• Published: 05/15/2008
• Est. Priority Date: 11/10/2006
• Status: Abandoned Application

• Current Assignee: Schlumberger Technology Corporation (SLB)
• Original Assignee: Schlumberger Technology Corporation (SLB)
• Inventors: Tarvin, Jeffrey A., Stephenson, Kenneth E., Andrews, Albert Ballard
• Application Number:
  US11/558,648
• Publication Number:
  US 20080111064A1
• Time in Patent Office: Days
• US Class Current: 250/269.1
• CPC Class Codes: E21B 49/081 with down-hole means for trapping a fluid sample E21B49/10 takes precedence
• CPC Class Codes: E21B 49/088 combined with sampling
• CPC Class Codes: G01N 21/65 Raman scattering
• CPC Class Codes: G01N 21/85 Investigating moving fluids or granular solids
• CPC Class Codes: G01N 2201/129 Using chemometrical methods
• CPC Class Codes: G01V 8/02 Prospecting

Abstract

A method for determining a property of earth formations surrounding a borehole, including the following steps: isolating a region of the borehole, and obtaining a sample of borehole fluid from the isolated region; and implementing measurements, dowhole, of the Raman scattering of electromagnetic energy directed at the fluid sample; the property of the earth formations being determinable from the measurements. In a disclosed embodiment, the steps of isolating a region of the borehole and obtaining a sample of borehole fluid from the isolated region include: providing a logging device in the borehole in sealing engagement with the isolated region, causing formation fluid from the isolated region to flow in a flow line of the logging device, and providing a measurement cell in the logging device which receives the sample of formation fluid via the flow line.

Claims

1. A method for determining a property of earth formations surrounding a borehole, comprising the steps of:

isolating a region of the borehole, and obtaining a sample of borehole fluid from the isolated region; and

implementing measurements, of the Raman scattering of electromagnetic energy directed at the fluid sample;

said property of the earth formations being determinable from said measurements.

2. The method as defined by claim 1, wherein said steps of isolating a region of the borehole and obtaining a sample of borehole fluid from the isolated region comprise:

providing a logging device in the borehole in sealing engagement with the isolated region, causing formation fluid from the isolated region to flow in a flow line of said logging device, and providing a measurement cell in said logging device which receives said sample of formation fluid via said flow line.

3. The method as defined by claim 1, wherein said step of implementing measurements, downhole, of electromagnetic energy directed at the fluid sample, comprises:

directing a light beam at said sample and detecting Raman scattering of said light from the sample to obtain said measurements.

4. The method as defined by claim 2, wherein said step of implementing measurements, downhole, of electromagnetic energy directed at the fluid sample, comprises:

directing a light beam at said sample and detecting Raman scattering of said light from the sample to obtain said measurements.

5. The method as defined by claim 2, wherein said property comprises the presence of a substance selected from the group consisting of hydrocarbon species, carbon dioxide, and hydrogen sulfide.

6. The method as defined by claim 2, wherein said property comprises the concentration of a substance selected from the group consisting of hydrocarbon species, carbon dioxide, and hydrogen sulfide.

7. The method as defined by claim 4, wherein said steps of directing a light beam at said sample and detecting Raman scattering of the light from said sample includes discriminating against fluorescence in the detecting of Raman scattering.

8. The method as defined by claim 7, wherein said step of discriminating against fluorescence in the detecting of Raman scattering includes pulsing said light beam and gating said detector.

9. The method as defined by claim 4, wherein said step of directing a light beam at said sample and detecting Raman scattering of said light from the sample comprises providing a laser diode for producing a laser beam directed at said sample, and providing a detector array to detect Raman scattering of said light.

10. The method as defined by claim 9, further comprising providing a first fiber optical link coupled between said laser diode and said sample, and providing a second fiber optical link between said sample and said detector array.

11. The method as defined by claim 9, further comprising providing the step of thermoelectric cooling for said laser diode.

12. The method as defined by claim 9, wherein said step of providing a detector array to detect Raman scattering of said light further comprises providing a diffraction grating in the path of Raman scattered light detected by said detector array.

13. The method as defined by claim 2, wherein said measurements of Raman scattering are measurements of enhanced Raman scattering.

14. The method as defined by claim 1, wherein said method is implemented with a logging device suspended in the borehole on a wireline.

15. The method as defined by claim 1, wherein said method is implemented with a logging tool on a drill string.

16. The method as defined by claim 1, further comprising the step of determining said property of the earth formations from said measurements;

and wherein at least a part of said step of determining said property is performed.

17. The method as defined by claim 1, further comprising the step of determining said property of the earth formations from said measurements;

and wherein at least a part of said step of determining said property is performed uphole.

18. The method as defined by claim 3, further comprising performing said method at a number of different depth levels in the borehole and forming a log of said measurements.

19. Apparatus for determining a property of earth formations surrounding a borehole, comprising:

a logging device in the borehole adapted for sealing engagement with an isolated region of the borehole;

a flow line in said device for receiving formation fluid;

a measurement cell in said logging device which receives said sample of formation fluid via said flow line;

a laser source for directing a light beam at said measurement cell; and

a detector for obtaining measurements of Raman scattering of said light from the sample;

said property of the earth formations being determinable from said measurements.

20. Apparatus defined by claim 19, wherein said property comprises the presence of a substance selected from the group consisting of hydrocarbon species, carbon dioxide, and hydrogen sulfide.

21. Apparatus as defined by claim 19, wherein said property comprises the concentration of a substance selected from the group consisting of hydrocarbon species, carbon dioxide, and hydrogen sulfide.

22. Apparatus as defined by claim 19, wherein said laser source comprises a pulsed laser diode, and said detector comprises a gated detector for discriminating against fluorescence in the detecting of Raman scattering.

23. Apparatus as defined by claim 19, further comprising a first fiber optical link coupled between said laser source and a window of said measurement cell, and a second fiber optical link between said window and said detector.

24. Apparatus as defined by claim 22, further comprising providing a thermoelectric device in said logging device for cooling for said laser diode.

25. Apparatus as defined by claim 22, wherein said detector comprises a detector array and further comprising a diffraction grating in the path of Raman scattered light detected by said detector array.

26. Apparatus as defined by claim 22, wherein said detector comprises a bank of filters, each having an associated detector.