Determining fluid chemistry of formation fluid by downhole reagent injection spectral analysis

• US 20040129874A1
• Filed: 09/22/2003
• Published: 07/08/2004
• Est. Priority Date: 11/22/2002
• Status: Active Grant

• Current Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Original Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Inventors: Torgersen, Torleif, Mullins, Oliver C., Raghuraman, Bhavani, Rabbito, Philip, Vasques, Ricardo Reves, Harrigan, Edward, Gustavson, Gale
• Granted Patent: US 7,427,504 B2
• Time in Patent Office: Days
• US Class Current: 250/255
• CPC Class Codes: E21B 47/11 using tracers; using radioactivity
• CPC Class Codes: E21B 49/08 Obtaining fluid samples or testing fluids, in boreholes or wells
• CPC Class Codes: G01N 33/18 Water

Abstract

A method for analyzing formation fluid in earth formation surrounding a borehole includes storing analytical reagent in a reagent container in a fluids analyzer in a formation tester and moving the formation tester, including the reagent, downhole. Reagent from the reagent container is injected into formation fluid in the flow-line to make a mixture of formation fluid and reagent. The mixture is moved through a spectral analyzer cell in the fluids analyzer to produce a time-series of optical density measurements at a plurality of wavelengths. A characteristic of formation fluid is determined by spectral analysis of the time-series of optical density measurements.

Claims

1. A method for determining fluid chemistry of formation fluid in earth formation surrounding a borehole, the method comprising:

storing analytical reagent in a reagent container coupled to a fluids analyzer via a flow-line in a formation tester;

transporting the formation tester downhole;

drawing formation fluid into the flow-line;

moving a mixture of formation fluid and analytical reagent through a spectral analyzer cell in the fluids analyzer; and

performing reagent injection spectral analysis on the mixture.

2. A method according to claim 1, wherein performing reagent injection spectral analysis includes injecting reagent into formation fluid within the flow-line to create a mixture of formation fluid and reagent in the flow-line.

3. A method according to claim 2, wherein injecting reagent includes injecting reagent using a syringe pump.

4. A method according to claim 2, further comprising establishing and storing baseline optical density values for at least one wavelength prior to injecting reagent.

5. A method according to claim 2, wherein injecting reagent includes injecting a predetermined volume of reagent.

6. A method according to claim 5, further including adjusting the predetermined volume.

7. A method according to claim 6, wherein adjusting the predetermined volume includes adjusting an injection period of time.

8. A method according to claim 6, wherein adjusting the predetermined volume includes adjusting an injection pump rate.

9. A method according to claim 5, wherein injecting reagent includes injecting reagent into a stopped formation fluid.

10. A method according to claim 5, wherein injecting reagent includes injecting reagent into a flowing formation fluid.

11. A method according to claim 2, wherein injecting reagent includes injecting reagent using wellbore overpressure.

12. A method according to claim 11, wherein injecting reagent includes injecting reagent at a controlled rate using a restrictor.

13. A method according to claim 11, wherein injecting reagent includes injecting reagent at a controlled rate using a throttle valve.

14. A method according to claim 11, wherein injecting reagent includes injecting reagent for a controlled period of time.

15. A method according to claim 2, wherein injecting reagent includes extracting formation fluid from a stopped flow-line.

16. A method according to claim 15, wherein injecting reagent includes injecting a predetermined volume of reagent.

17. A method according to claim 16, further including adjusting the predetermined volume.

18. A method according to claim 17, wherein adjusting the predetermined volume includes setting an extraction pump rate.

19. A method according to claim 17, wherein adjusting the predetermined volume includes setting an extraction time.

20. A method according to claim 15, wherein extracting formation fluid includes using a syringe piston.

21. A method according to claim 15, wherein extracting formation fluid includes using a flow-line pump.

22. A method according to claim 15, wherein extracting formation fluid includes using a step piston.

23. A method according to claim 22, wherein extracting formation fluid includes adjusting metering valve settings.

24. A method according to claim 1, wherein storing reagent includes storing different reagents in first and auxiliary reagent containers.

25. A fluids analyzer for analyzing formation fluid in earth formation surrounding a borehole, comprising:

a probe for receiving downhole formation fluid from earth formation.

a flow-line coupled to receive formation fluid downhole from said probe;

a reagent container in fluid communication with said flow-line;

spectral analyzer means, coupled to receive a mixture of formation fluid and reagent from said flow-line downhole, for analyzing said mixture to produce time-series optical density data at a plurality of wavelengths; and

computing means for determining a characteristic of formation fluid from said optical density data.

26. A fluids analyzer according to claim 25, wherein said reagent container is a syringe pump.

27. A fluids analyzer according to claim 25, wherein reagent in said reagent container is exposed to wellbore pressure.

28. A fluids analyzer according to claim 27, further comprising a syringe pump fluid container coupled to extract fluid from said flow-line.

29. A fluids analyzer according to claim 27, wherein said reagent container is coupled to said flow-line by a restrictor.

30. A fluids analyzer according to claim 27, wherein said reagent container is coupled to said flow-line by a throttle valve.

31. A fluids analyzer according to claim 27, further comprising a step piston coupled to extract fluid from said flow-line.

32. A fluids analyzer according to claim 31, further comprising a metering valve between said step piston and said flow-line.

33. A fluids analyzer according to claim 25, further comprising an auxiliary reagent container in communication with said flow-line independently of a first reagent container.