# US 11,906,282 B2 · Systems for determining at least one condition proximate the system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,906,282 B2 - Document ID: US11906282B2 - Status: Granted - Kind: B2 - Application number: 17/644,142 - Filed: 2021-12-14 - Published: 2022-04-07 - Granted: 2024-02-20 - Earliest claimed: 2014-06-30 - Assignees: Baker Hughes Holdings LLC - Applicants: Baker Hughes Holdings LLC - Inventors: Anusha Chilukuri; Othon R. Monteiro - Web page: https://patentgrep.com/patent/US11906282B2 ## CPC - G01B 11/0675: {using interferometry} - E21B 47/006: {Detection of corrosion or deposition of substances} - E21B 47/135: using light waves, e.g. infrared or ultraviolet waves - G01B 11/14: for measuring distance or clearance between spaced objects or spaced apertures (G01B11/26 takes precedence; rangefinders G01C3/00) - G01N 17/04: Corrosion probes - G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS - E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) ## Abstract Sensing systems include a tube defining a Fabry-Perot cavity and an optical fiber including a distal end disposed within the Fabry-Perot cavity and a proximal end. A corrodible material caps the Fabry-Perot cavity. Devices for sensing corrosion of downhole equipment include an optical fiber with a corrodible material disposed over a distal end of the optical fiber. Systems for sensing a condition in equipment include an optical fiber with a fiber Bragg grating proximate a distal end thereof and a mass of sensor material coupled to the distal end of the optical fiber. The mass of sensor material is suspended from above the fiber Bragg grating. Other systems for sensing a condition in a wellbore include an optical fiber and a plurality of fiber Bragg gratings along a length thereof. A plurality of sensor materials are coupled to the optical fiber and surround respective fiber Bragg gratings. ## Claims ### Claim 1 A system for sensing at least one condition proximate the system, the system comprising: at least one optical fiber comprising a distal end, a plurality of fiber Bragg gratings along a length thereof, and a proximal end; a plurality of sensor materials coupled to the at least one optical fiber and surrounding and in contact with respective fiber Bragg gratings of the plurality of fiber Bragg gratings; at least one reference optical fiber extending along the length of the at least one optical fiber, the at least one reference optical fiber including a plurality of inert materials disposed around the at least one reference optical fiber; and a light wavelength sensor coupled to a proximal end of the at least one optical fiber, the light wavelength sensor configured to sense a wavelength of light reflected from the plurality of fiber Bragg gratings. ### Claim 2 (depends on 1) The system of claim 1, wherein the plurality of sensor materials comprises a material selected to react with a reactive chemical. ### Claim 3 (depends on 2) The system of claim 2, wherein the reactive chemical comprises H2S. ### Claim 4 (depends on 2) The system of claim 2, wherein the material selected to react with a reactive chemical comprises a metal oxide material. ### Claim 5 (depends on 2) The system of claim 2, wherein the material selected to react with a reactive chemical comprises ZnO. ### Claim 6 (depends on 1) The system of claim 1, wherein the plurality of sensor materials comprises a pre-stressed corrodible material. ### Claim 7 (depends on 1) The system of claim 1, wherein the plurality of fiber Bragg gratings are spaced along the length of the at least one optical fiber at intervals of at least about 5 mm. ### Claim 8 (depends on 1) The system of claim 1, wherein the plurality of fiber Bragg gratings are spaced along the length of the at least one optical fiber at intervals between about 5 mm and about 2 cm. ### Claim 9 (depends on 1) The system of claim 1, wherein the system is configured to determine one or more of a temperature, a pressure, a presence of reactive chemicals, and a corrosion rate proximate the plurality of sensor materials. ### Claim 10 (depends on 1) The system of claim 1, wherein each sensor of plurality of sensor materials is substantially the same. ### Claim 11 (depends on 1) The system of claim 1, wherein a diameter of the sensor materials of the plurality of sensor materials is larger than a diameter of the at least one optical fiber. ### Claim 12 (depends on 1) The system of claim 1, wherein the plurality of inert materials are disposed around fiber Bragg gratings of the at least one reference optical fiber. ### Claim 13 (depends on 1) The system of claim 1, wherein the plurality of inert materials comprises one or more of a ceramic material, a diamond-like carbon material, an oxide material, a sapphire material, an alumina material, a silicon carbide material, or a silicon material. ### Claim 14 (depends on 1) The system of claim 1, wherein the light wavelength sensor is configured to isolate portions of signals from the plurality of sensor materials of the at least one optical fiber resulting from the at least one condition based on signals from the at least one reference optical fiber. ### Claim 15 (depends on 1) The system of claim 1, wherein the plurality of sensor materials comprises a metal oxide. ### Claim 16 (depends on 1) The system of claim 1, wherein the light wavelength sensor is configured to independently sense a wavelength of light reflected from each of the plurality of sensors. ### Claim 17 (depends on 1) The system of claim 1, further comprising a cladding material around the at least one optical fiber and adjacent to the plurality of sensor materials. ### Claim 18 A system for sensing at least one condition proximate the system, the system comprising: at least one optical fiber comprising a distal end, a plurality of fiber Bragg gratings along a length thereof, and a proximal end; a plurality of sensor materials coupled to the at least one optical fiber and surrounding and in contact with respective fiber Bragg gratings of the plurality of fiber Bragg gratings, wherein at least one sensor material of the plurality of sensor materials comprises a pre-stressed corrodible material that causes a respective fiber Bragg grating around which the at least one sensor material is disposed to be in axial tension or compression; and a light wavelength sensor coupled to a proximal end of the at least one optical fiber, the light wavelength sensor configured to sense a wavelength of light reflected from the plurality of fiber Bragg gratings.