# US 10,865,638 B2 · Mid-infrared sensor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,865,638 B2 - Document ID: US10865638B2 - Status: Granted - Kind: B2 - Application number: 16/695,671 - Filed: 2019-11-26 - Published: 2020-05-28 - Granted: 2020-12-15 - Earliest claimed: 2014-09-15 - Assignees: Schlumberger Technology Corporation - Applicants: Schlumberger Technology Corporation - Inventors: Timothy Jones; Nathan Lawrence; Go Fujisawa; Sheng Chao; Rolf Rustad - Web page: https://patentgrep.com/patent/US10865638B2 ## CPC - E21B 47/135: using light waves, e.g. infrared or ultraviolet waves - E21B 47/002: by visual inspection - E21B 47/003: Determining well or borehole volumes - E21B 47/07: Temperature - G01N 21/552: Attenuated total reflection - G01N 33/24: Earth materials (G01N33/42 takes precedence) - 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 A sensor for monitoring a species which is a component of a fluid. The sensor includes an internal reflection window which, in use, is in direct contact with the fluid. The sensor further includes a mid-infrared light source which directs a beam of mid-infrared radiation into said window for attenuated internal reflection at an interface between the window and the fluid. The sensor further includes a first narrow bandpass filter which preferentially transmits mid-infrared radiation over a band of wavelengths corresponding to an absorbance peak of the species. The sensor further includes an infrared detector which detects filtered mid-infrared radiation transmitted through the first filter and a processor for measuring the intensity of the detected mid-infrared radiation transmitted through the first filter, and determines therefrom an amount of the species in the fluid. ## Claims ### Claim 1 A sensor for monitoring a hydrate inhibitor dissolved in a liquid, the sensor comprising: an internal reflection window configured to contact the liquid in use; a mid-infrared light source configured to direct a beam of mid-infrared radiation into the internal reflection window to provide for attenuated internal reflection at an interface between the internal reflection window and the liquid; a first narrow bandpass filter configured to preferentially transmit mid-infrared radiation over a band of wavelengths corresponding to an absorbance peak of the dissolved hydrate inhibitor to provide for filtering internally reflected mid-infrared radiation received from the internal reflection window; an infrared detector configured to detect the filtered mid-infrared radiation transmitted through the first filter, wherein the first narrow bandpass filter is located in between the internal reflection window and the infrared detector; and a processor arrangement, operably coupled to the infrared detector and configured to measure intensity of the detected mid-infrared radiation transmitted through the first narrow bandpass filter and determine an amount of the hydrate inhibitor dissolved in the liquid from the measured intensity. ### Claim 2 (depends on 1) The sensor according to claim 1, wherein the first narrow bandpass filter is configured to preferentially transmit mid-infrared radiation over at least one of a band of wavelengths corresponding to: a 1040 cm−1 absorbance peak for monoethylene glycol; a 1084 cm−1 absorbance peak for monoethylene glycol; a 1020 cm−1 absorbance peak for methanol; a 1045 cm−1 absorbance peak for ethanol; and a 1295 cm−1 absorbance peak for polyvinylpyrrolidone. ### Claim 3 (depends on 1) The sensor according to claim 1, further comprising: a second narrow bandpass filter in between the internal reflection window and the infrared detector, the second narrow bandpass filter being configured to transmit mid-infrared radiation over a band of wavelengths corresponding to a reference portion of the absorbance spectrum of the liquid. ### Claim 4 (depends on 3) The sensor according to claim 3, further comprising: the or a further infrared detector configured to detect filtered mid-infrared radiation transmitted through the second filter, wherein the processor arrangement is configured to measure a reference intensity of the detected mid-infrared radiation transmitted through the second filter and use the measured reference intensity in the determination of the amount of the hydrate inhibitor in the liquid. ### Claim 5 (depends on 1) The sensor according to claim 1, wherein the first narrow bandpass filter comprises a plurality of the first narrow bandpass filters each configured to transmit mid-infrared radiation over a band of wavelengths corresponding to an absorbance peak of a respective hydrate inhibitor, and wherein the or a respective further infrared detector is configured to detect the filtered mid-infrared radiation transmitted through each of the plurality of the first narrow bandpass filters and the processor arrangement is configured to measure intensity of the detected mid-infrared radiation transmitted through each first narrow bandpass filter and determine therefrom an amount of each hydrate inhibitor in the liquid. ### Claim 6 (depends on 4) The sensor according to claim 4, wherein the determined amounts of the hydrate inhibitor in the liquid is in the form of a ratio of the concentrations of the hydrate inhibitors. ### Claim 7 (depends on 1) The sensor according to claim 1, wherein the beam of mid-infrared light is pulsed. ### Claim 8 (depends on 1) The sensor according to claim 1, wherein the internal reflection window comprises one of a diamond window or a sapphire window. ### Claim 9 (depends on 1) The sensor according to claim 1, further comprising: a heater configured to heat the internal reflection window. ### Claim 10 (depends on 1) The sensor according to claim 1, further including: a pressure pulse arrangement configured to produce a pressure pulse in the fluid at the internal reflection window to clean a surface of the internal reflection window in contact with the fluid. ### Claim 11 (depends on 1) The sensor according to claim 1, wherein the sensor is located subsea. ### Claim 12 (depends on 1) A method of monitoring a hydrate inhibitor dissolved in a liquid, the method including: providing the sensor of claim 1 such that the internal reflection window is in direct contact with the liquid; and operating the sensor to determine an amount of the hydrate inhibitor dissolved in the liquid. ### Claim 13 (depends on 1) A well or pipeline tool including the sensor of claim 1. ### Claim 14 A method for monitoring a hydrate inhibitor dissolved in a liquid, comprising: directing a beam of mid-infrared radiation into an internal reflection window that is in contact with the liquid; passing an attenuated internal reflection of the beam from an interface between the internal reflection window and the liquid through a narrow bandpass filter configured to preferentially transmit mid-infrared radiation over a band of wavelengths corresponding to an absorbance peak of the dissolved hydrate inhibitor; detecting the filtered mid-infrared radiation transmitted through the first filter; measuring an intensity of the detected mid-infrared radiation transmitted through the first filter; and determining an amount of the hydrate inhibitor dissolved in the liquid from the measured intensity. ### Claim 15 (depends on 14) The method according to claim 14, wherein the narrow bandpass filter is configured to preferentially transmit mid-infrared radiation over at least one of a band of wavelengths corresponding to: a 1040 cm−1 absorbance peak for monoethylene glycol; a 1084 cm−1 absorbance peak for monoethylene glycol; a 1020 cm−1 absorbance peak for methanol; a 1045 cm−1 absorbance peak for ethanol; and a 1295 cm−1 absorbance peak for polyvinylpyrrolidone. ### Claim 16 (depends on 14) The method according to claim 14, further comprising: passing the attenuated internal reflection of the beam from the interface between the internal reflection window and the liquid through a reference narrow bandpass filter configured to transmit mid-infrared radiation over a band of wavelengths corresponding to a reference portion of the absorbance spectrum of the liquid. ### Claim 17 (depends on 16) The method according to claim 16, further comprising: detecting a portion of the attenuated internal reflection of the beam from the interface between the internal reflection window and the liquid transmitted through the reference filter; measuring a reference intensity of the portion of the attenuated internal reflection of the beam from the interface between the internal reflection window and the liquid transmitted through the reference filter; and using the measured reference intensity in the determination of the amount of the hydrate inhibitor in the liquid.