Determining structural tomographic properties of a geologic formation

• US 10,444,065 B2
• Filed: 02/27/2019
• Issued: 10/15/2019
• 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., Servin, Jesus Manuel Felix, Hveding, Frode, Colombo, Daniele
• Primary Examiner(s): Rahman, Md M
• Application Number:
  US16/286,916
• Publication Number:
  US 20190195682A1
• Time in Patent Office: 230 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 method comprising:

directing a modulating frequency light beam with a variable frequency light source along a fiber optic cable placed within a borehole;

inducing a deformation in the fiber optic cable with a subsurface detection device that is responsive to a specified stimulus;

detecting a backscatter of multiple frequencies within the fiber optic cable with a plurality of optical detectors attached to the fiber optic cable, each of the optical detectors configured to detect a specified frequency of light; and

determining physical property of a geologic formation in which the borehole is formed in response to detecting the backscatter of multiple frequencies;

wherein inducing a deformation in the fiber optic cable comprises;

expanding a hydrophilic gel in response to a moisture content within the borehole; and

inducing the deformation within the fiber optic cable with the expanded hydrophilic gel.

2. The method of claim 1, wherein inducing a deformation in the fiber optic cable comprises:

detecting a change in an electromagnetic field with an antenna; and

inducing the deformation within the fiber optic cable with a transducer coupled to the antenna in response to the change in the electromagnetic field.

3. The method of claim 1, further comprising:

harvesting energy from changes in magnetic fields within the borehole with an antenna;

storing the harvested energy within an energy storage device; and

powering equipment within the borehole with the stored energy.

4. The method of claim 3, wherein the energy storage device comprises a super capacitor or a battery.

5. The method of claim 1, further comprising:

harvesting energy from ambient noise within the borehole with a transducer;

storing the harvested energy within an energy storage device; and

powering equipment within the borehole with the stored energy.

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