Magneto-Optical Method and Apparatus for Determining Properties of Reservoir Fluids

• US 20080111551A1
• Filed: 11/10/2006
• Published: 05/15/2008
• Est. Priority Date: 11/10/2006
• Status: Active Grant

• Current Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Original Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Inventors: Freedman, Robert
• Granted Patent: US 7,482,811 B2
• Time in Patent Office: Days
• US Class Current: 324/324
• CPC Class Codes: G01V 8/02 Prospecting

Abstract

A method for determining a property of earth formations surrounding a borehole includes the following steps: deriving a fluid sample downhole in the borehole, subjecting the sample while downhole to a magnetic field; measuring a magneto-optical shift of a beam of electromagnetic radiation passed through the sample, and determining the property from the measured magneto-optical shift.

Claims

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

deriving a fluid sample downhole in the borehole;

subjecting the sample while downhole to a magnetic field;

measuring a magneto-optical shift of a beam of electromagnetic radiation passed through said sample; and

determining said property from said measured magneto-optical shift.

2. The method as defined by claim 1, wherein said property is the dielectric permittivity of the fluid.

3. The method as defined by claim 1, wherein said property is the Verdet constant of the fluid.

4. The method as defined by claim 1, wherein said property is a molecular property of the fluid.

5. The method as defined by claim 1, wherein said steps of subjecting the sample to a magnetic field and determining the magneto-optical shift of a beam of electromagnetic radiation passed through the sample include subjecting the sample to a static magnetic field;

passing polarized light through said sample; and

determining the polarization shift of the light that has passed through the sample.

9. The method as defined by claim 1, wherein said step of deriving a sample of fluid comprises:

providing a logging device in the borehole;

causing the fluid to pass into a flow line of the logging device; and

providing a cell in the flow line that receives the fluid, said cell having a substantially transparent region through which said electromagnetic radiation is passed.

10. The method as defined by claim 9, wherein said cell is transmissive of said electromagnetic radiation.

11. The method as defined by claim 9, wherein said cell is reflective of said electromagnetic radiation.

14. The method as defined by claim 1, wherein said sample comprises fluid obtained from one or more of the formations.

15. The method as defined by claim 1, wherein said sample comprises fluid obtained from drilling fluid in the borehole.

16. The method as defined by claim 1, wherein said method is performed by a device suspended in said borehole on a wireline.

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

18. The method as defined by claim 1, wherein at least a part of said step of determining said property from said measured magneto-optical shift is performed downhole.

19. The method as defined by claim 1, wherein at least a part of said step of determining said property from said measured magneto-optical shift is performed uphole.

20. The method as defined by claim 1, wherein said steps of subjecting the sample to a magnetic field and measuring a magneto-optical shift of a beam of electromagnetic passed through the sample is performed while said sample is substantially stationary.

21. The method as defined by claim 1, wherein said steps of subjecting the sample to a magnetic field and measuring a magneto-optical shift of a beam of electromagnetic radiation passed through the sample is performed while said sample is in motion.

22. The method as defined by claim 1, wherein said steps of subjecting the sample to a magnetic field and measuring a magneto-optical shift of a beam at electromagnetic radiation passed through the sample is performed while said sample is flowing in a flow line.

23. The method as defined by claim 2, further comprising determining asphaltene concentration from said dielectric permittivity of the fluid.

24. The method as defined by claim 2, further comprising determining water cut in the fluid from said dielectric permittivity of the fluid.

25. The method as defined by claim 2, further comprising determining the extent of contamination of the fluid by drilling fluid from said dielectric permittivity of the fluid.

26. The method as defined by claim 2, further comprising determining the fluid types and fractional volumes of the fluid from said dielectric permittivity of the fluid.

6-8. -8. (canceled)

12-13. -13. (canceled)

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

a device deployed in the borehole for obtaining a sample of fluid;

a magnet in said device for subjecting said sample to a magnetic field;

a source of polarized electromagnetic radiation in said device for passing a beam of polarized electromagnetic radiation through said sample; and

a detector for detecting the magneto-optical shift of said beam of polarized electromagnetic radiation passed through the sample.

28. Apparatus as defined by claim 27, wherein said property is the dielectric permittivity of the fluid of said earth formations.

29. Apparatus as defined by claim 27, wherein said property is the Verdet constant of the fluid of said earth formations.

30. Apparatus as defined by claim 27, wherein said property is a molecular property of the fluid of said earth formations.

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

deriving a database that relates a number of known parameters of test fluid samples to test measurements of the magneto-optical shift of light passed through the test samples;

deriving a fluid sample downhole in the borehole;

subjecting the sample while downhole to a magnetic field and measuring a magneto-optical shift of a beam of electromagnetic radiation passed through said sample; and

determining said property of the earth formations by using said measured magneto-optical shift and said database.

32. The method as defined by claim 31, wherein said property corresponds to one of the known parameters of the test fluid samples.

34. The method as defined by claim 31, wherein said property is the dielectric permittivity of the fluid.

35. The method as defined by claim 31, wherein said property is the Verdet constant of the fluid.

33. (canceled)