Determining structural tomographic properties of a geologic formation

• US 10,612,969 B2
• Filed: 06/18/2019
• Issued: 04/07/2020
• Est. Priority Date: 12/06/2017
• Status: Active Grant

• Current Assignee: Saudi Arabian Oil Company (Government of Saudi Arabia)
• Original Assignee: Saudi Arabian Oil Company (Government of Saudi Arabia)
• Inventors: Schmidt, Howard K., Felix Servin, Jesus Manuel, Hveding, Frode, Colombo, Daniele
• Primary Examiner(s): Rahman, Md M
• Application Number:
  US16/444,646
• Publication Number:
  US 20190301925A1
• Time in Patent Office: 294 Days
• Field of Search: 356 731
• CPC Class Codes: E21B 41/0085 Adaptations of electric power generating means for use in boreholes
• CPC Class Codes: E21B 47/12 Means for transmitting measuring-signals or control signals from the well to the surface, or from the surface to the well, e.g. for logging while drilling
• CPC Class Codes: G01D 5/35358 using backscattering to detect the measured quantity
• CPC Class Codes: G01D 5/35393 using frequency division multiplexing
• CPC Class Codes: G01H 9/004 using fibre optic sensors light guides per se G02B6/00, acousto-optical devices specially adapted for gating or modulating in optical wave guides G02F1/125
• CPC Class Codes: G01V 1/226 Optoseismic systems
• CPC Class Codes: G01V 11/00 Prospecting or detecting by methods combining techniques covered by two or more of main groups G01V1/00 - G01V9/00
• CPC Class Codes: G01V 3/26 operating with magnetic or electric fields produced or modified either by the surrounding earth formation or by the detecting device with electromagnetic waves G01V3/30
• CPC Class Codes: H02J 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
• CPC Class Codes: H02N 2/18 producing electrical output from mechanical input, e.g. generators for measurement devices G01

Abstract

A variable-frequency light source is configured to emit a light beam and modulate a frequency of the light beam. A fiber optic cable is attached to the variable frequency light source. The fiber optic cable is configured to receive the light beam at an inlet and pass the light beam to an exit. Multiple optical detectors are attached to the fiber optic cable. Each of the optical detectors is configured to detect a specified frequency of light that is backscattered through the fiber optic cable. An actuation mechanism is attached to the fiber optic cable. The actuation mechanism is configured to deform the fiber optic cable in response to a stimulus.

Claims

1. A sub-surface detection device comprising:

a variable-frequency light source configured to emit a light beam and modulate a frequency of the light beam;

a fiber optic cable attached to the variable frequency light source, the fiber optic cable configured to receive the light beam at an inlet and pass the light beam to an exit;

a plurality of optical detectors attached to the fiber optic cable, each of the optical detectors configured to detect a specified frequency of light that is backscattered through the fiber optic cable; and

an actuation mechanism attached to the fiber optic cable, the actuation mechanism configured to deform the fiber optic cable in response to a stimulus.

2. The sub-surface detection device of claim 1, wherein each of the plurality of optical detectors is configured to detect a different frequency of light.

3. The sub-surface detection device of claim 1, wherein the actuation mechanism comprises:

an antenna configured to detect changes in an electromagnetic field; and

an electromechanical transducer that is connected to the antenna, the electromechanical transducer configured to deform the fiber optic cable in response to detecting changes in the electromagnetic field.

4. The sub-surface detection device of claim 3, wherein the electromechanical transducer comprises a piezoelectric element.

5. The subsurface detection device of claim 3, further comprising:

a filtering circuit configured to filter out noise detected by the antenna;

an amplifier configured to amplify the filtered signal; and

an energy storage device configured to supply power to at least one of the amplifier or the filtering circuit.

6. The subsurface detection device of claim 5, wherein the energy storage device comprises a battery or capacitor.

7. The subsurface detection device of claim 6, wherein the energy harvesting device comprises:

an antenna configured to harvest electromagnetic energy within the borehole;

a rectification circuit coupled to the antenna, the rectification circuit configured to condition the harvested energy for storage; and

an energy storage device coupled to the rectification circuit, the energy storage device configured to store the harvested energy.

8. The subsurface detection device of claim 6, wherein the energy harvesting device comprises:

a piezoelectric device configured to harvest mechanical energy within the borehole;

a rectification circuit coupled to the piezoelectric device, the rectification circuit configured to condition the harvested energy for storage; and

an energy storage device coupled to the rectification circuit, the energy storage device configured to store the harvested energy.

9. The subsurface detection device of claim 1, wherein the actuation mechanism comprises:

a hydrophilic gel configured to expand in the presence of moisture; and

a diaphragm connected to the hydrophilic gel and the fiber optic cable, wherein an expansion in the hydrophilic gel induces the diaphragm to deform the fiber optic cable.

10. The subsurface detection device of claim 1, further comprising:

an energy harvesting device configured to harvest energy from an ambient environment; and

an energy storage device configured to store the harvested energy.