Gamma ray measurement apparatus, systems, and methods

Patent metadata

Field	Value
Publication number	US-10042082-B2
Application number	US-201415023211-A
Country	US
Kind code	B2
Filing date	Dec 4, 2014
Priority date	Dec 4, 2014
Publication date	Aug 7, 2018
Grant date	Aug 7, 2018

Abstract

In some embodiments, an apparatus and a system, as well as a method and article, may operate to detect gamma radiation as detected gamma radiation, and to determine a relative level of potassium decay energy within a selected band of energy levels, with respect to a combination of at least two of potassium, uranium, or thorium. Further operations may include adjusting at least one of a detector supply voltage or an analyzer gain to place the potassium decay energy at a selected energy level location when the relative level of potassium decay energy exceeds a predetermined threshold, the threshold based on an energy level of a combination of detected gamma radiation within the selected band of energy levels. Additional apparatus, systems, and methods are disclosed.

First claim

What is claimed is:

1. A method, comprising:
detecting gamma radiation as detected gamma radiation;
determining a relative level of potassium decay energy within a selected band of energy levels, with respect to a combination of at least two of potassium, uranium, or thorium; and
adjusting at least one of a detector supply voltage or an analyzer gain to place the potassium decay energy at a selected energy level location when the relative level of potassium decay energy exceeds a predetermined threshold, the threshold based on an energy level of a combination of detected gamma radiation within the selected band of energy levels.

2. The method of claim 1 , further comprising:
separating the detected gamma radiation according to a preselected number of energy levels.

3. The method of claim 1 , further comprising:
displaying the relative level of potassium decay energy along with the combination of at least two of potassium, uranium, or thorium, in a visible format.

4. The method of claim 1 , wherein the selected band of energy levels include a measured energy level of 1460 keV.

5. The method of claim 1 , wherein the selected band of energy levels has an energy level width sufficient to include an expected amount of energy level measurement drift with respect to the potassium decay energy.

6. The method of claim 1 , further comprising:
repeating the detecting, the determining, and the adjusting on a periodic basis to provide operational stabilization of a gamma radiation detection system.

7. The method of claim 1 , wherein the selected band of energy levels forms a portion of a set of numbered channels that approximately evenly divide a detected energy spectrum into a fixed number of bins.

8. The method of claim 7 , wherein placing the potassium decay energy at a selected energy level location comprises:
moving a measured or simulated peak potassium decay energy location associated with one of the bins to another one of the bins associated with the selected energy level location.

9. The method of claim 1 , further comprising:
measuring actual or simulated energy decay levels of the combination of at least two of potassium, uranium, or thorium, to determine the relative level of potassium decay energy.

10. The method of claim 1 , wherein determining the relative level of potassium decay energy within the selected band of energy levels comprises:
comparing individual potassium decay energy level counts over a predetermined spectrum channel bandwidth to an integrated energy count over the predetermined spectrum channel bandwidth comprising multiple channels that occupy at least the selected band of energy levels.

11. The method of claim 1 , further comprising:
logging the detected gamma radiation as part of a downhole logging operation.

12. An apparatus, comprising:
a gamma radiation detector to receive a detector supply voltage, the gamma radiation detector to detect gamma radiation as detected gamma radiation;
a pulse height analyzer coupled to the gamma radiation detector, the pulse height analyzer to determine a relative level of potassium decay energy within a selected band of energy levels, with respect to a combination of at least two of potassium, uranium, or thorium; and
a feedback control to adjust at least one of the detector supply voltage or an analyzer gain of the pulse height analyzer to place the potassium decay energy at a selected energy level location when the relative level of potassium decay energy exceeds a predetermined threshold, the threshold based on an energy level of a combination of detected gamma radiation within the selected band of energy levels.

13. The apparatus of claim 12 , further comprising:
a high voltage power supply to supply the detector supply voltage.

14. The apparatus of claim 12 , wherein the analyzer gain is associated with the pulse height analyzer having an energy analysis spectrum comprising a number of channels into which energy is approximately equally divided.

15. The apparatus of claim 12 , wherein the selected band of energy levels correspond to a set of channels on the pulse height analyzer.

16. The apparatus of claim 15 , wherein the selected energy level location corresponds to a single channel on the pulse height analyzer, the single channel included in the set of channels.

17. An apparatus, comprising:
a gamma radiation detector to receive a detector supply voltage, the gamma radiation detector to detect gamma radiation as detected gamma radiation;
a signal processor comprising a pulse height analyzer to determine a relative level of potassium decay energy within a selected band of energy levels with respect to a combination of at least two of potassium, uranium, or thorium, the signal processor comprising a feedback control to adjust at least one of the detector supply voltage or an analyzer gain of the pulse height analyzer to place the potassium decay energy at a selected energy level location when the relative level of potassium decay energy exceeds a predetermined threshold, the threshold based on an energy level of a combination of detected gamma radiation within the selected band of energy levels; and
a housing to attach to the gamma radiation detector.

18. The apparatus of claim 17 , wherein the gamma radiation detector, the pulse height analyzer, and the feedback control, when powered, can operate together to stabilize detection gain of the apparatus downhole without using an on-board radioactive source as a reference gain source.

19. The apparatus of claim 17 , further comprising a memory coupled to the gamma radiation detector, wherein the memory is used to store a log of the gamma radiation detected by the gamma radiation detector.

20. The apparatus of claim 17 , wherein the housing comprises one of a wireline tool housing or a downhole tool housing coupled to a drill string.

Assignees

• Halliburton Energy Services Inc

Inventors

• Luo Da
• Guo Weijun

Classifications

• G01T1/40

  Stabilisation of spectrometers · CPC title

• G01V5/06 Primary

  for detecting naturally radioactive minerals · CPC title

• E21B49/00

  Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to earth drilling or wells · CPC title

• G01T1/2018

  Scintillation-photodiode combinations · CPC title