BORON LINER FOR NEUTRON DECTECTORS FOR WELL LOGGING APPLICATIONS

• US 20130068941A1
• Filed: 09/20/2011
• Published: 03/21/2013
• Est. Priority Date: 09/20/2011
• Status: Abandoned Application

• Current Assignee: Baker Hughes Incorporated (Baker Hughes Company)
• Original Assignee: Baker Hughes Incorporated (Baker Hughes Company)
• Inventors: Nikitin, Anton
• Application Number:
  US13/237,301
• Publication Number:
  US 20130068941A1
• Time in Patent Office: Days
• US Class Current: 250/269.4
• CPC Class Codes: G01V 5/107 and detecting reflected or back-scattered neutrons

Abstract

Disclosed is an apparatus for detecting neutrons. The apparatus includes a plurality of neutron detector cells, each detector cell comprising a cathode surrounding an anode wherein the cathode of each cell is common to an adjacent detector cell. A neutron interaction material covers an interior surface of the cathode in each neutron detector cell, the neutron interaction material being configured to emit a charged particle between the cathode and the anode upon interacting with a neutron.

Claims

1. An apparatus for detecting neutrons, the apparatus comprising:

a plurality of neutron detector cells, each detector cell comprising a cathode surrounding an anode wherein the cathode of each cell is common to an adjacent cell; and

a neutron interaction material covering an interior surface of the cathode in each neutron detector cell, the neutron interaction material being configured to emit a charged particle between the cathode and the anode upon interacting with a neutron.

2. The apparatus according to claim 1, wherein each detector cell comprises a hexagonal shape.

3. The apparatus according to claim 2, wherein a distance between two parallel cathode surfaces is about two millimeters.

4. The apparatus according to claim 1, wherein each anode is disposed along a centerline of the corresponding cell.

5. The apparatus according to claim 1, wherein the plurality of detector cells is disposed in a casing.

6. The apparatus according to claim 5, wherein the casing is cylindrical.

7. The apparatus according to claim 5, wherein the cathode of each neutron detector cell is electrically tied to the casing.

8. The apparatus according to claim 5, wherein the anodes of the neutron detector cells are electrically tied together outside of the casing.

9. The apparatus according to claim 5, further comprising a lid configured to seal an end of the casing, the lid comprising a plurality of electrical feed-throughs configured to receive corresponding anodes.

10. The apparatus according to claim 5, further comprising a mixture of an inert gas and a quenching compound disposed within the casing, the inert gas being configured to be ionized by the charged particle.

11. The apparatus according to claim 1, wherein the neutron interaction material comprises Boron-10.

12. The apparatus according to claim 1, wherein the plurality of neutron detector cells comprises a first assembly of neutron detector cells and a second assembly of neutron detector cells, each assembly comprising an integrated cathode structure.

13. An apparatus for estimating a property of an earth formation penetrated by a borehole, the apparatus comprising:

a carrier configured to be conveyed through the borehole;

a neutron source disposed at the carrier and configured to irradiate the formation with neutrons;

a plurality of neutron detector cells disposed at the carrier, each detector cell comprising a cathode surrounding an anode wherein the cathode of each cell is common to an adjacent cell; and

a neutron interaction material covering an interior surface of the cathode in each neutron detector cell, the neutron interaction material being configured to emit a charged particle upon interacting with a received neutron to generate an electrical pulse between the cathode and the anode in the neutron detector cell that received the neutron;

wherein the electrical pulse is used to estimate the property.

14. The apparatus according to claim 13, wherein the carrier comprises a wireline, a drill string or coiled tubing.

15. The apparatus according to claim 13, wherein the electrical pulse is a current pulse.

16. The apparatus according to claim 13, wherein the property is density or porosity.

17. The apparatus according to claim 13, further comprising a processor coupled to the plurality of neutron detector cells and configured to estimate the property from electrical pulses generated in the plurality of neutron detector cells.

18. A method for estimating a property of an earth formation penetrated by a borehole, the method comprising:

conveying a carrier through the borehole;

irradiating the formation with neutrons emitted from a neutron source disposed at the carrier;

receiving neutrons resulting from an interaction of emitted neutron with the formation with a plurality of neutron detector cells disposed at the carrier, each detector cell in the plurality comprising a cathode surrounding an anode wherein the cathode of each cell is common to an adjacent detector cell;

emitting charged particles from neutron interaction material covering an interior of the cathode in each detection cell receiving a neutron wherein the neutron interaction material is configured to emit a charged particle upon interacting with a neutron;

generating electrical pulses using the charged particles; and

estimating the property using the electrical pulses.

20. The method according to claim 18, further comprising counting the generated electrical pulses to estimate the property.

19. The method according to claim 187, further comprising ionizing a gas disposed between the anode and cathode with the charged particles to generate ions and collecting the ions at the cathodes to generate the electrical pulses.