Stress sensor for cement or fluid applications

Patent metadata

Field	Value
Publication number	US-10451497-B2
Application number	US-201715675473-A
Country	US
Kind code	B2
Filing date	Aug 11, 2017
Priority date	Aug 11, 2017
Publication date	Oct 22, 2019
Grant date	Oct 22, 2019

Abstract

A system and method measuring subterranean stress. The system and method includes a non-destructive sheath enveloping a tubular structure positioned in direct contact with a lateral subterranean rock formation for sensing expansive changes in the subterranean rock formation. A fiber optic is directly embedded in the non-destructive sheath positioned adjacent to the exterior surface of the tubular structure. The fiber optic transmits light and thereafter receives light in proportion to the expansive changes in the subterranean rock formation. A spectrometer connected to the fiber optic remote from the non-destructive sheath. The spectrometer measures hydrostatic stress in the subterranean rock formation without estimating acoustoelastic effects or occluding the tubular structure.

First claim

What is claimed is:

1. A system that measures subterranean stress in situ comprising:
a non-destructive sheath enveloping a tubular structure positioned in direct contact with a lateral subterranean rock formation for sensing expansive changes in the lateral subterranean rock formation;
a fiber optic directly embedded in the non-destructive sheath positioned adjacent to the exterior surface of the tubular structure for transmitting light and receiving light in proportion to the expansive changes in the lateral subterranean rock formation; and
a spectrometer coupled to the fiber optic remote from the non-destructive sheath for measuring a hydrostatic stress in the lateral subterranean rock formation without estimating the acoustoelastic effects of the lateral subterranean rock or occluding the tubular structure;
where the non-destructive sheath comprises an alumina crystalline structure heated up and until 950° C. causing it to change directly from a solid into a vapor.

2. The system of claim 1 where the non-destructive sheath is moisture resistant, stiffens and hardens when it cures, possess plasticity, and is fire resistant.

3. The system of claim 2 where the non-destructive sheath absorbs and stores energy.

4. The system of claim 3 where the non-destructive sheath comprises an alpha-alumina.

5. The system of claim 4 where the non-destructive sheath comprises a Portland cement that forms a hydraulic seal with the alpha-alumina and fiber optic in a wellbore.

6. The system of claim 3 where the non-destructive sheath comprises an alpha-alumina and a chromia.

7. The system of claim 1 where the fiber optic comprises a multi-mode fiber optic configured to allow multiple modes of light to pass through it.

8. The system of claim 1 where the fiber optic comprises a single mode fiber optic that allows only one mode of light to pass through it.

9. The system of claim 1 further comprising means to display and record the hydrostatic stress of the lateral subterranean rock formation in an electronic memory.

10. A method for measuring subterranean stress in situ comprising:
enveloping a tubular structure with a non-destructive sheath positioned in direct contact with a lateral subterranean rock formation for sensing expansive changes in the subterranean rock formation;
embedding a fiber optic cable directly in the non-destructive sheath positioned adjacent to the exterior surface of the tubular structure for transmitting light and receiving light in proportion to the expansive changes in the lateral subterranean rock formation; and
measuring a hydrostatic stress in the subterranean rock formation through the non-destructive sheath without estimating the acoustoelastic effects of the lateral subterranean rock formation or occluding the tubular structure;
where the non-destructive sheath comprises an alumina heated until it renders an R-line intensity of about one-hundred and forty times greater than the alumina unheated.

11. The method of claim 10 where the non-destructive sheath is moisture resistant, stiffens and hardens when cured, possess plasticity, and is fire resistant.

12. The method of claim 11 where the non-destructive sheath absorbs and stores energy.

13. The method of claim 12 where the non-destructive sheath comprises an alpha-alumina.

14. The method of claim 13 further comprising doping the alpha-alumina with chromia.

15. The method of claim 14 further comprising heating the alumina in a range of one and nine-tenth hours to two hours.

16. The method of claim 10 where the non-destructive sheath comprises a Portland cement that forms a hydraulic seal with the alpha-alumina and fiber optic in a wellbore.

17. A directional stress sensor for measuring subterranean stress comprising:
a stress-measuring material exposed at a proximal base in direct contact with a single surface of a subterranean media such that it senses stress at only the proximal base in a single axial direction, the stress measuring-measuring material for sensing an axial stress;
a compliant material comprising an elastomer enclosing an entire annular area between a sensor housing and the stress sensing materials that extends from the proximal base to a distal base of the stress-measuring material, the compliant material isolates the stress-measuring material from the sensor housing isolating the stress measuring material from an entire radial stress received from the subterranean media;
the sensor housing enclosing the annular surfaces of the stress measuring material and the compliant material in lateral contact with the subterranean media; and
a fiber optic directly embedded in the stress-measuring material passing through the proximal base for transmitting light and receiving light in proportion to the expansive changes in the subterranean media.

18. The system of claim 17 where the compliant material comprises an annular air gap and annular elastomer.

19. The system of claim 17 further comprising a spectrometer coupled to the fiber optic remote from the stress-measuring material for measuring stress in the subterranean media without measuring acoustoelastic effects.

20. The system of claim 19 where the spectrometer is programmed to measure birefringence.

21. The system of claim 17 further comprising a light source for transmitting light in the absorption area through the optic.

22. A sensor for measuring the local stress of a concrete structure comprising:
a fiber optic cable encased by an outer jacket, said cable having a distal end terminating at a stress measurement area within the concrete;
a light source for transmitting a light into a proximal end of said cable from a location that is remote of the stress measurement area; and
a spectrometer for receiving a signal from the proximal end that is indicative of the local stress of the concrete at the stress measurement area;
where the cement in at least the stress measurement area is doped with a solid crystalline structure that is heated up and until it reaches an R-line intensity of about one-hundred and forty times greater than solid crystalline structure when unheated.

Assignees

• Ut Battelle Llc

Inventors

• Polsky Yarom
• Lance Michael J
• Hemrick James Gordon

Classifications

• E21B33/14 Primary

  for cementing casings into boreholes · CPC title

• E21B47/135

  using light waves, e.g. infrared or ultraviolet waves · CPC title

• E21B47/005 Primary

  Monitoring or checking of cementation quality or level · CPC title

• G01L1/242 Primary

  the material being an optical fibre · CPC title

• G01L1/241

  by photoelastic stress analysis · CPC title