PASSIVE CASED WELL IMAGE LOGGING

• US 20180164469A1
• Filed: 01/12/2017
• Published: 06/14/2018
• Est. Priority Date: 12/14/2016
• Status: Active Grant

• Current Assignee: Rock Visualization Technology, LLC
• Original Assignee: Rock Visualization Technology, LLC
• Inventors: Kuespert, Jonathan
• Granted Patent: US 10,641,919 B2
• Time in Patent Office: Days
• CPC Class Codes: G01T 1/20 with scintillation detectors
• CPC Class Codes: G01V 5/04 specially adapted for well-logging
• CPC Class Codes: G01V 5/045 Transmitting data to recording or processing apparatus; Recording data
• CPC Class Codes: G01V 5/06 for detecting naturally radioactive minerals
• CPC Class Codes: G01V 5/232 having relative motion between the source, detector and object other than by conveyor G01V5/226 takes precedence

Abstract

A method of creating a well image log of a cased well is provided. A passive cased well image logging tool assembly including a logging tool body, a plurality of gamma ray radiation sensors and a spatial positioning device is moved through at least a portion of the wellbore at a logging speed of no greater than 750 feet per hour. Corrected gamma ray radiation data is vertically sampled at a vertical distance sampling rate of once every vertical distance sampling interval, wherein the vertical distance sampling interval is no greater than 1.75 inches. Based on the sampled data, a well image log is prepared. A passive cased well image logging tool assembly for use in a cased well is also provided.

Claims

1. A method of creating a well image log of a cased well, comprising:

providing a passive cased well image logging tool assembly, said logging tool assembly including;

a logging tool body;

a plurality of gamma ray radiation sensors attached to said logging tool body, each gamma ray radiation sensor being capable of continuously collecting gamma ray radiation data from one or more geologic units surrounding or adjacent to the wellbore as said logging tool assembly is moved through the wellbore; and

at least one spatial positioning device attached to said logging tool body that is capable of continuously collecting sensor position data reflecting the xyz spatial position of said gamma ray radiation sensors in the wellbore relative to the wellbore and the Earth as said logging tool assembly is moved through the wellbore;

moving said logging tool assembly through at least a portion of the wellbore at a logging speed of no greater than 750 feet per hour;

as said logging tool assembly is being moved through the wellbore, using said gamma ray radiation sensors to continuously collect gamma ray radiation data that is emitted by the geologic unit(s);

as said logging tool assembly is being moved through the wellbore, using said spatial positioning device to continuously collect sensor position data reflecting the xyz spatial position of said gamma ray radiation sensors within the wellbore relative to the wellbore and the Earth;

using said collected sensor position data to correct said collected gamma ray radiation data;

vertically sampling said corrected gamma ray radiation data at a vertical distance sampling rate of once every vertical distance sampling interval, wherein said vertical distance sampling interval is no greater than 1.75 inches; and

preparing a well image log based on said sampled gamma ray radiation data.

2. The method of claim 1, wherein said well image log is a spectral gamma ray log.

3. The method of claim 1, wherein said spatial positioning device is a gyroscope.

4. The method of claim 1, wherein said gamma ray radiation data that is continuously collected by said gamma ray radiation sensors is naturally emitted by the geologic unit(s).

5. The method of claim 1, wherein said logging tool assembly is moved through at least a portion of the wellbore at a logging speed in the range of from about 30 feet per hour to about 600 feet per hour.

6. The method of claim 5, wherein said logging tool assembly is moved through at least a portion of the wellbore at a logging speed in the range of from about 60 feet per hour to about 300 feet per hour.

7. The method of claim 1, wherein said vertical distance sampling interval is in the range of about 0.5 inches to about 1.75 inches.

8. The method of claim 7, wherein said vertical distance sampling interval is in the range of about 0.5 inches to about 1 inch.

9. The method of claim 1, wherein the counting time associated with each gamma ray radiation sensor attached to said logging tool body is in the range of from about 0.40 seconds per inch to about 60.00 seconds per inch.

10. The method of claim 1, wherein said gamma ray radiation sensors are attached to and equally spaced around said logging tool body.

11. The method of claim 10, wherein a sufficient number of gamma ray radiation sensors are attached to and equally spaced around and along the logging tool body to allow gamma ray radiation data to be collected at sufficient points around the circumference of the wellbore and an image log of an entire geologic unit surrounding the wellbore to be prepared.

12. The method of claim 1, wherein said cased well is inactive.

13. The method of claim 12, wherein said cased well is an inactive well for which a well image log is not available.

14. A method of creating a well image log of a cased well, comprising:

providing a passive cased well image logging tool assembly, said logging tool assembly including;

a logging tool body;

a plurality of gamma ray radiation sensors attached to and equally spaced around said logging tool body, each gamma ray radiation sensor being capable of continuously collecting gamma ray radiation data that is naturally emitted by one or more geologic units surrounding or adjacent to the wellbore as said logging tool assembly is moved through the wellbore; and

at least one gyroscope attached to said logging tool body that is capable of continuously collecting sensor position data reflecting the xyz spatial position of said gamma ray radiation sensors in the wellbore relative to the wellbore and the Earth as said logging tool assembly is moved through the wellbore;

moving said logging tool assembly through at least a portion of the wellbore at a logging speed of about 30 feet per hour to about 600 feet per hour;

as said logging tool assembly is being moved through the wellbore, using said gamma ray radiation sensors to continuously collect gamma ray radiation data that is emitted by the geologic unit(s);

as said logging tool assembly is being moved through the wellbore, using said spatial positioning device to continuously collect sensor position data reflecting the xyz spatial position of said gamma ray radiation sensors within the wellbore relative to the wellbore and the Earth;

using said collected sensor position data to correct said collected gamma ray radiation data;

vertically sampling said corrected gamma ray radiation data at a vertical distance sampling rate of once every vertical distance sampling interval, wherein said vertical distance sampling interval in the range of about 0.5 inches to about 1.75 inches; and

preparing a well image log based on said sampled gamma ray radiation data.

15. The method of claim 14, wherein said well image log is a spectral gamma ray log.

16. The method of claim 14, wherein said logging tool assembly is moved through at least a portion of the wellbore at a logging speed in the range of from about 60 feet per hour to about 300 feet per hour.

17. The method of claim 14, wherein said vertical distance sampling interval is in the range of about 0.5 inches to about 1 inch.

18. The method of claim 14, wherein the counting time associated with each gamma ray radiation sensor attached to said logging tool body is in the range of from about 0.40 seconds per inch to about 60.00 seconds per inch.

19. The method of claim 14, wherein a sufficient number of gamma ray radiation sensors are attached to and equally spaced around and along the logging tool body to allow gamma ray radiation data to be collected at sufficient points around the circumference of the wellbore and an image log of an entire geologic unit surrounding the wellbore to be prepared.

20. The method of claim 14, wherein said cased well is an inactive well for which a well image log is not available.

21. A passive cased well image logging tool assembly for use in a cased well, comprising:

a logging tool body;

a plurality of gamma ray radiation sensors attached to said logging tool body, each gamma ray radiation sensor being capable of continuously collecting gamma ray radiation data from one or more geologic units surrounding or adjacent to the wellbore as said logging tool assembly is moved through the wellbore; and

at least one spatial positioning device attached to said logging tool body that is capable of continuously collecting sensor position data reflecting the xyz spatial position of said gamma ray radiation sensors in the wellbore relative to the wellbore and the Earth as said logging tool assembly is moved through the wellbore.

22. The passive cased well image logging tool assembly of claim 21, further comprising at least one receptor arm assembly attached to said logging tool body.

23. The passive cased well image logging tool assembly of claim 22, further comprising at least three extendable arm sets attached to said receptor arm assembly and equally spaced radially around and equidistantly offset along the longitudinal axis of said logging tool body.

24. The passive cased well image logging tool assembly of claim 23, further comprising a pad subassembly attached to each extendable arm set, each pad subassembly including a pad housing having an outer flat face, wherein at least one gamma ray radiation sensor is attached to said outer flat face of each pad subassembly.

25. The passive cased well image logging tool assembly of claim 24, wherein said receptor arm subassembly is operable to move said extendable arm sets and pad subassemblies attached thereto between a retracted position an extended position.

26. The passive cased well image logging tool assembly of claim 25, wherein said extendable arm sets are configured to extend from said receptor arm subassembly and said logging tool body in a manner that can place said outer faces of said pad housings of said pad subassemblies into contact with the inside surface of the casing.

27. The passive cased well image logging tool assembly of claim 26, wherein at least one gamma ray radiation sensor is positioned inside each of said pad housings, and wherein a radiation shield is attached to said outer flat face of each of said paid housings over the gamma ray radiation sensor(s) therein, said radiation shield including a window therein to allow gamma ray radiation to reach the gamma ray radiation sensor(s) in the pad housing.

28. The passive cased well image logging tool assembly of claim 21, wherein said spatial positioning device is a gyroscope.

29. The passive cased well image logging tool assembly of claim 21, further comprising a signal processing unit attached to said logging tool body.

30. The passive cased well image logging tool assembly of claim 21, further comprising an omnidirectional gamma ray device attached to said logging tool body.

31. The passive cased well image logging tool assembly of claim 21, further comprising a centralized gamma ray radiation sensor attached to said logging tool body.