SUBSURFACE NUCLEAR MEASUREMENT SYSTEMS, METHODS AND APPARATUS

• US 20110035151A1
• Filed: 08/06/2009
• Published: 02/10/2011
• Est. Priority Date: 08/06/2009
• Status: Active Grant

• Current Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Original Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Inventors: Botto, Tancredi
• Granted Patent: US 8,384,017 B2
• Time in Patent Office: Days
• US Class Current: 702/2
• CPC Class Codes: G01N 9/24 by observing the transmission of wave or particle radiation through the material
• CPC Class Codes: G01T 1/20 with scintillation detectors
• CPC Class Codes: G01V 5/04 specially adapted for well-logging
• CPC Class Codes: G01V 5/06 for detecting naturally radioactive minerals
• CPC Class Codes: G01V 5/107 and detecting reflected or back-scattered neutrons

Abstract

Methods and related systems are described for use for making subterranean nuclear measurements. The system can include a plurality of elongated scintillator members each generating optical signals in response to ionizing radiation. Optical detector units can be optically coupled to at least one end of each elongated scintillator member so as to detect optical signals from each elongated scintillator member. The system can be suitable for permanent or semi-permanent deployment downhole. For example, the system can operate for more than six months in a subterranean deployment measuring cosmic radiation. The system can be suited to monitor density changes in subterranean regions of interest, for example, density changes brought about by steam injection as part of a steam assisted gravity drainage operation.

Claims

1. A system for making subterranean nuclear measurements, the system comprising:

a plurality of elongated scintillator members each generating optical signals in response to ionizing radiation;

a first optical detector unit optically coupled to a first end of each elongated scintillator member of the plurality of elongated scintillator members so as to detect optical signals from each elongated scintillator member; and

a housing adapted to house the plurality of elongated scintillator members and the first optical detector and being suitable for subterranean deployment.

2. The system according to claim 1, further comprising:

a second optical detector unit optically coupled to a second end of each elongated scintillator member of the plurality of elongated scintillator members; and

a processing system adapted and programmed to calculate position information for ionizing radiation based at least in part on a comparison of optical signal arrival times at the first and second optical detector units.

3. The system according to claim 2, wherein the processing system is further adapted and programmed to calculate trajectory information for ionizing radiation based at least in part on the calculated position information from at least two scintillator members.

4. The system according to claim 3, wherein the plurality of elongated scintillator members forms a bundle having an arrangement selected from one or more of the type in the group consisting of one of a bundle of mostly collinear fibers, a bundle of fibers in a direction mostly transverse to the main longitudinal axis of the housing, a bundle of helically wound fibers, a bundle wherein one or more fibers overlap, a bundle wherein one or more fibers cross at given angles or a bundle with a rounded or polygonal cross section.

5. The system according to claim 1, wherein each elongated scintillator member of the plurality of elongated scintillator members are of one or more type selected from the group consisting of one of a plastic scintillator fiber, an inorganic crystal fiber, a liquid-based scintillator in a long aspect ratio geometry or a composite fiber.

6. The system according to claim 5, wherein each elongated scintillator member of the plurality of elongated scintillator members are of one or more type selected from the group consisting of one of a plurality of fibers with a rounded cross-section, a plurality of fibers with a polygonal cross-section or a plurality of fibers with a varying cross-section.

7. The system according to claim 6, wherein each elongated scintillator member of the plurality of elongated scintillator members are of one or more type selected from the group consisting of one of a plurality of fibers with a hollow core, a plurality of photonic-crystal fibers or microstructured fibers.

8. The system according to claim 5, wherein at least one elongated scintillator member of the plurality of elongated scintillator members is doped so as to enhance the elongated scintillator member'"'"'s detection efficiency for one or more type of particle selected from the group consisting of one of slow neutrons, fast neutrons, gamma-rays or charged particles.

9. The system according to claim 5, wherein at least one elongated scintillator member of the plurality of elongated scintillator members is one of doped so as enhance its optical properties or is doped so as to better match the optical signals to the sensitivity of the optical detector unit.

10. The system according to claim 1, wherein the plurality of elongated scintillator members are arranged around a hollow core volume which contains detector bias and data memory.

11. The system according to claim 1, wherein the plurality of elongated scintillator members are arranged around a hollow core volume through which a fluid flow channel is positioned.

12. The system according to claim 1, wherein the plurality of elongated scintillator members are arranged around a hollow core volume which contains a Cerenkov or a transition radiation detector adapted to tag incoming ultra-relativistic cosmic ray muons.

13. The system according to claim 1, wherein the first optical detector unit includes one or more optical detector with one or more independent optical amplification channel and each elongated scintillator member of the plurality of elongated scintillator members is optically coupled with a different optical amplification channel.

14. The system according to claim 13, wherein the one or more optical detector is a solid-state optical detector.

15. The system according to claim 14, wherein the one or more optical detector is of a type selected from the group consisting of one of a photo-diode or a solid-state photo-multiplier.

16. The system according to claim 13, wherein the one or more optical detector is an electron avalanche optical detector.

17. The system according to claim 16, wherein the one or more optical detector is of a type selected from the group consisting of one of photo-multipliers or multi-channel plates.

18. The system according to claim 1, wherein the ionizing radiation includes gamma-rays, cosmic-ray muons, slow or fast neutrons.

19. The system according to claim 1, further comprising a data storage system housed within the housing adapted to store data generated by the first detector unit.

20. The system according to claim 1, further comprising a battery system housed within the housing and adapted to supply power to the first detector unit for at least six months of operation.

21. The system according to claim 1, further comprising a cable link from a surface of the earth adapted to supply power to the first detector unit for at least six months of operation.

22. The system according to claim 1, further comprising a radionuclide gamma ray nuclear source or a gamma ray electronic generator housed within the housing, and wherein the ionizing radiation is primarily gamma ray radiation backscattered by a subterranean formation and originating from the source.

23. A method for making subterranean nuclear measurements comprising:

deploying a tool housing into a subterranean formation, the housing containing a plurality of elongated scintillator members each generating optical signals in response to ionizing radiation; and

detecting optical signals from one or more elongated scintillator member of the plurality of elongated scintillator members using a first optical detector unit that is optically coupled to a first end of each elongated scintillator member.

24. The method according to claim 23, further comprising:

detecting optical signals from one or more elongated scintillator member of the plurality of elongated scintillator members using a second optical detector unit that is optically coupled to a second end of each elongated scintillator member; and

calculating position information for ionizing radiation based at least in part on a comparison of optical signal arrival times at the first and second optical detector units.

25. The method according to claim 23, further comprising calculating trajectory information for ionizing radiation based at least in part on the calculated position information and on information relating to which of the plurality of scintillator members generates optical signals.

26. The method according to claim 23, further comprising monitoring density changes in an underground formation based at least in part on monitoring ionizing radiation in the form of cosmic-rays traversing one or more regions of interest.

27. The method according to claim 26, wherein the density changes are brought about by the injection, movement or displacement of fluids caused at least in part by injection of fluid from one or more injection wells.

28. The method according to claim 27, wherein the injection of fluid is primarily for a purpose selected from the group consisting of one of a storage of the injected fluid in an underground reservoir, stimulation of a reservoir by injection of water, or stimulation of a reservoir by injections of gases.

29. The method according to claim 28, wherein the injection of fluid is steam as part of a steam assisted gravity drainage operation.

30. The method according to claim 23, wherein the housing further contains a battery system housed within the housing and adapted to supply power to the first detector unit for at least six months of operation.

31. The method according to claim 23, wherein the housing further contains a data storage system adapted to store data generated by the first detector unit.

32. The method according to claim 23, wherein the housing further contains a radionuclide gamma ray nuclear source or a gamma ray electronic generator, the ionizing radiation is primarily gamma ray radiation, and the method further comprises measuring back-scattered gamma rays by detecting the optical signals.

33. The method according to claim 32, wherein the back-scattered gamma rays are measured at different distances and/or angles so as to minimize, separate and/or correct for bore-hole density effects.

34. A long-term subterranean nuclear monitoring system comprising:

a housing suitable for subterranean deployment for at least six months;

a nuclear detection unit housed in the housing; and

a power supply system adapted to supply power to the detection unit for at least six months of operation.

35. The system according to claim 34, wherein the power supply system includes a battery system housed within the housing.

36. The system according to claim 34, wherein the power supply system includes a cable link between a surface of the earth and the housing adapted to supply power to the detection unit.

37. The system according to claim 34, further comprising a data storage system housed within the housing adapted to store data from the nuclear detection unit.

38. The system according to claim 34, further comprising a communication system adapted to provide communication between a surface of the earth and the housing including one or more antennae for wireless communication.

39. The system according to claim 34, further comprising a communication system adapted to provide communication between a surface of the earth and the housing including a cable between the housing and the surface of the earth.

40. The system according to claim 34, wherein the nuclear detection unit comprises:

a plurality of elongated scintillator members each generating optical signals in response to ionizing radiation;

a first optical detector unit optically coupled to a first end of each elongated scintillator member of the plurality of elongated scintillator members so as to detect optical signals from each elongated scintillator member;

a second optical detector unit optically coupled to a second end of each elongated scintillator member of the plurality of elongated scintillator members; and

a processing system adapted and programmed to calculate position information for ionizing radiation based at least in part on a comparison of optical signal arrival times at the first and second optical detector units.

41. The system according to claim 40, wherein the processing system is further adapted and programmed to calculate trajectory information for ionizing radiation based at least in part on the calculated position information and on information relating to which of the plurality of scintillator members generates optical signals.

42. The system according to claim 41, wherein the first and second optical detector units consist of one or more solid-state based detector or one or more electron avalanche based detector, such that each solid-state based detector or each avalanche based detector includes at least one or more independent optical channel.

43. The system according to claim 34, further comprising a processing system housed within the housing and adapted and programmed to compress data collected downhole so as to reduce data storage and/or data transmission needs.

44. A method for long term subterranean nuclear monitoring, the method comprising:

deploying a tool housing into a subterranean formation, the housing containing a nuclear detection unit; and

measuring nuclear radiation over a time period of at least six months.

45. The method according to claim 44, wherein the tool housing further contains a battery system adapted to supply power to the nuclear detection unit for at least six months of operation.

46. The method according to claim 44, wherein the tool housing further contains a data storage system adapted to store data from the nuclear detection unit.

47. The method according to claim 44, further comprising communicating with the nuclear detection unit via a cable connection.

48. The method according to claim 44, further comprising communicating with the nuclear detection unit via a wireless connection.

49. The method according to claim 44, wherein the nuclear detection unit contains a plurality of elongated scintillator members, each generating optical signals in response to ionizing radiation, and the method further comprises:

detecting optical signals from one or more of the elongated scintillator member of the plurality of elongated scintillator members using a first optical detector unit that is optically coupled to a first end of each elongated scintillator member;

detecting optical signals from one or more of the elongated scintillator member of the plurality of elongated scintillator members using a second optical detector unit that is optically coupled to a second end of each elongated scintillator member; and

calculating position information for ionizing radiation based at least in part on a comparison of optical signal arrival times at the first and second optical detector units.

50. The method according to claim 49, further comprising calculating trajectory information for ionizing radiation based at least in part on the calculated position information and on information relating to which of the plurality of elongated scintillator members generates optical signals.

51. The method according to claim 44, further comprising monitoring density changes along certain directions in an underground formation based at least in part on the measured muon radiation along the directions.

52. The method according to claim 51, wherein the nuclear detection unit monitors muon radiation along directions that traverse a region of interest of changing density and along directions traversing a region of non-changing density outside the region of interest.

53. The method according to claim 51, wherein the density changes are brought about by the injection, movement or displacement of fluids caused at least in part by injection of fluid from one or more injection wells.

54. The method according to claim 53, wherein the injection of fluid is steam as part of a steam assisted gravity drainage operation.

55. The method according to claim 44, further comprising cementing or other permanent installation of the tool housing into position as part of the deployment.

56. The method according to claim 44, further comprising compressing data collected downhole so as to reduce data storage and/or data transmission needs.