Method and apparatus for elemental analysis of a fluid downhole

• US 20070068242A1
• Filed: 09/26/2005
• Published: 03/29/2007
• Est. Priority Date: 09/26/2005
• Status: Active Grant

• Current Assignee: Baker Hughes Incorporated (Baker Hughes Company)
• Original Assignee: Baker Hughes Incorporated (Baker Hughes Company)
• Inventors: DiFoggio, Rocco
• Granted Patent: US 7,530,265 B2
• Time in Patent Office: Days
• US Class Current: 73/152.550
• CPC Class Codes: E21B 47/113 using electrical indications; using light radiations
• CPC Class Codes: E21B 49/087 Well testing, e.g. testing for reservoir productivity or formation parameters
• CPC Class Codes: G01J 3/443 Emission spectrometry
• CPC Class Codes: G01N 2021/8528 Immerged light conductor
• CPC Class Codes: G01N 2021/855 Underground probe, e.g. with provision of a penetration tool
• CPC Class Codes: G01N 21/6402 Atomic fluorescence; Laser induced fluorescence
• CPC Class Codes: G01N 21/67 using electric arcs or discharges
• CPC Class Codes: G01N 21/69 specially adapted for fluids , e.g. molten metal
• CPC Class Codes: G01N 21/718 Laser microanalysis, i.e. with formation of sample plasma
• CPC Class Codes: G01N 21/8507 Probe photometers, i.e. with optical measuring part dipped into fluid sample
• CPC Class Codes: G01N 33/2823 raw oil, drilling fluid or polyphasic mixtures hydrocarbon content of earth materials G01N33/241; prospecting G01V; drilling per se E21B
• CPC Class Codes: G01N 33/2835 specific substances contained in the oil or fuel

Abstract

The present invention provides a method and apparatus for performing elemental analysis of a formation fluid downhole. The present invention provides elemental analysis of a formation fluid downhole using breakdown spectroscopy. In one aspect of the invention, a method and apparatus are provided for performing laser induced breakdown on a formation fluid sample is provided. In another aspect of the invention a method and apparatus are provided for performing spark induced breakdown spectroscopy. Plasma is induced in a fluid under test downhole. Emissions from the plasma are analyzed to determine the elemental composition of the fluid under test. Emissions include but are not limited to light in the ultraviolet, visible, and near infrared regions of the spectrum. A spectrometer is provided for elemental analysis of a fluid downhole. Elemental analysis yields information about the fluid and the formation from which the fluid originated.

Claims

1. A method for estimating composition of a fluid downhole, comprising:

inducing plasma in the fluid downhole;

collecting a light emissions from the plasma; and

analyzing the light emissions to estimate the composition of the fluid downhole.

2. The method of claim 1, wherein inducing the plasma further comprises generating a laser pulse in the fluid.

3. The method of claim 1, wherein inducing the plasma further comprises generating a spark in the fluid.

4. The method of claim 1, wherein collecting the light emission from the plasma further comprises receiving light in a fiber optic cable.

5. The method of claim 1, wherein analyzing the light emission further comprises performing an elemental analysis of the light emission.

6. The method of claim 1, further comprising:

estimating a characteristic of a formation associated with the fluid.

7. The method of claim 6, wherein the characteristic is compartmentalization.

8. The method of claim 1, further comprising:

injecting a tracer in the fluid.

9. The method of claim 1, wherein inducing the plasma in the fluid further comprises sending energy through a window into the fluid.

10. The method of claim 1, wherein the light emissions further comprises light that is one of visible light, near infrared light and ultra violet light.

11. The method of claim 4, wherein generating a spark in the fluid further comprises;

generating an electric field through a substantially metal coated fiber tip coated with an optically transparent and electrically conductive coating.

23. The method of claim 1, wherein estimating the composition includes estimating presence of at least one of:

Be, Mg, Cr, Fe, Ag, Hg, Li, B, Na, Cl, Ca, Ti, Mn, Ni, Cu, Zn, Sr, Ba, Pb, Th, C, F, Al, Si, S, K, Co, Ga, Rb, Zr, Nb, Tc, Pd, Cd, Sn, Cs, Eu, Pt, Tl, P, V, Ge, As, Mo, I, Au, Bi, Y, In, Sb, Te, Hf. W, H, N, O Ar, Sc, Ru, Rh, GD, Er Re, U, Pu and Am.

24. The method of claim 1, wherein analyzing the light emission is done by a spectrometer downhole.

12. An apparatus for estimating composition of a fluid downhole, comprising:

a plasma generator in communication with the fluid downhole;

an optical sensor in optical communication with a plasma generated in the fluid downhole; and

a processor configured to process output from the optical sensor to estimate the composition of the fluid downhole.

13. The apparatus of claim 12, wherein the plasma generator further comprises an optical conduit to deliver a laser pulse to the fluid downhole.

14. The apparatus of claim 12, wherein the plasma generator further comprises an electrode to generate a spark in the fluid downhole.

15. The apparatus of claim 12, further comprising:

a window between the plasma generated in the fluid downhole and the optical sensor.

16. The apparatus of claim 12, wherein the processor is further configured to perform elemental analysis of the light emission.

17. The apparatus of claim 12, wherein the processor is further configured to estimate a characteristic of a formation associated with the fluid downhole.

18. The apparatus of claim 16, wherein the processor is further configured to determine compartmentalization of a formation.

19. The apparatus of claim 16, wherein the processor is further configured to determine an origin of the fluid from the analysis.

20. The apparatus of claim 12, wherein the plasma generator further includes a fiber tip coated with optically transparent and electrically conductive coating for generating a spark.

22. The downhole tool of claim 19, wherein the plasma generator comprises at least one of an optical conduit to deliver a laser pulse to the fluid downhole and an electrode to generate a spark in the fluid downhole.

21. A downhole tool for estimating composition of a fluid downhole, comprising:

a plasma generator in communication with the fluid downhole;

an optical sensor in optical communication with a plasma generated in the fluid downhole by the plasma generator; and

a spectrometer configured to analyze output from the optical sensor to estimate the composition of the fluid downhole.