Active surface cleaning for a sensor

Patent metadata

Field	Value
Publication number	US-10539500-B2
Application number	US-201515511437-A
Country	US
Kind code	B2
Filing date	Sep 9, 2015
Priority date	Sep 15, 2014
Publication date	Jan 21, 2020
Grant date	Jan 21, 2020

Abstract

An integrated approach for cleaning an active surface of a petrochemical sensor. Sensors in the petrochemical industry are often deployed in locations where they are prone to fouling. By heating the active surface fouling substances may be removed from the active surface. Heating the surface above a supercritical point of a fluid being sensed may create a fluid that may serve to clean the active surface. Limiting the duration of the applied heating and/or pulsing the heating may mitigate adverse effects of use of high temperatures. A doped active surface, such as a doped diamond window may be designed to have conductive areas in the window that may be used for resistive heating of the window.

First claim

The invention claimed is:

1. A sensor for monitoring a species which is a component of a fluid, the sensor including:
an internal reflection window configured in use for contacting with the fluid;
a mid-infrared light source configured to direct a beam of mid-infrared radiation into the internal reflection window and produce attenuated internal reflection of the beam at an interface between the internal reflection window and the fluid;
a first narrow bandpass filter configured to receive from the internal reflection window the attenuated internal reflection of the beam and to filter the received attenuated internal reflection of the beam, wherein the first narrow bandpass filter is configured to preferentially transmit mid-infrared radiation over a band of wavelengths corresponding to an absorbance peak of the species;
an infrared detector for detecting filtered mid-infrared radiation transmitted through the first narrow bandpass filter;
a processor arrangement, operably coupled to the infrared detector and configured to measure an intensity of the detected mid-infrared radiation transmitted through the first narrow bandpass filter and determine from the measured intensity an amount of the species in the fluid; and
a heater configured to locally heat the internal reflection window to clean the surface of the internal reflection window in contact with the fluid, wherein the internal reflection window includes a conductive or semiconductive material and the heater comprises an electrical power supply for sending a current through the internal reflection window to induce resistive heating of the internal reflection window.

2. The sensor according to claim 1 , wherein the heater heats the internal reflection window to a peak temperature of at least about 400° C.

3. The sensor according to claim 1 , wherein the heater maintains a peak temperature for less than one microsecond.

4. The sensor according to claim 1 , further comprising:
a second 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 fluid, wherein the or a further infrared detector is configured to detect filtered mid-infrared radiation transmitted through the second narrow bandpass filter, and wherein the processor arrangement is configured to measure a reference intensity of the detected mid-infrared radiation transmitted through the second narrow bandpass filter and use the measured reference intensity in the determination of the amount of the species in the fluid.

5. The sensor according to claim 1 , comprising:
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 species, the or a respective further infrared detector configured to detect the filtered mid-infrared radiation transmitted through each first narrow bandpass filter, and the processor arrangement configured to measure the intensity of the detected mid-infrared radiation transmitted through each first narrow bandpass filter and determine from the measured intensity an amount of each species in the fluid.

6. The sensor according to claim 5 , wherein the determined amounts of the species in the fluid is in the form of a ratio of the concentrations of the species.

7. The sensor according to claim 1 , wherein the beam of mid-infrared light is pulsed.

8. The sensor according to claim 1 , wherein the internal reflection window is a diamond internal reflection window or a sapphire internal reflection window.

9. The sensor according to claim 1 which is configured for use downhole.

10. The sensor according to claim 1 which is adapted for monitoring one or more of a hydrocarbon species which is a component of a hydrocarbon liquid, a hydrate inhibitor species which is dissolved in a liquid, or a mineral acid species which is dissolved in a liquid.

11. The sensor according to claim 1 which is adapted for monitoring CO 2 concentration in the fluid, the sensor having three first narrow bandpass filters corresponding to respective absorbance peaks of water, oil and CO 2 ,
wherein the processor arrangement determines an amount of CO 2 notwithstanding whether the fluid contacting the internal reflection window is a liquid water-based phase, a liquid oil-based phase, a mixture of liquid water and liquid oil-based phases, or a gas phase.

12. A well tool including the sensor of claim 1 .

13. The sensor according to claim 1 , wherein the first narrow bandpass filter comprises a substrate having opposing surfaces, and wherein alternating dielectric layers of high and low refractive index are stacked on the opposing surfaces of the substrate.

14. The sensor according to claim 13 , wherein the high refractive index layers are formed of one or more of PbTe, PbSe, PbS, or Ge.

15. The sensor according to claim 13 , wherein the low refractive index layers are formed of one or more of ZnS or ZnSe.

16. The sensor according to claim 13 , wherein each layer in the stacks of alternating layers of high and low refractive index has an optical thickness of about one quarter wavelength.

17. The sensor according to claim 13 , wherein the first narrow bandpass filter is configured such that its wavelength transmission band is substantially temperature invariant over all temperatures in the range of about 25° C. to about 150° C.

Assignees

• Schlumberger Technology Corp

Inventors

• Jones Timothy
• Lawrence Nathan
• Fujisawa Go
• Chao Sheng
• Gahlings Steven

Classifications

• G01N21/3577

  for analysing liquids, e.g. polluted water · CPC title

• B08B7/0071

  by heating (B08B7/0035 takes precedence) · CPC title

• G02B1/02

  made of crystals, e.g. rock-salt, semi-conductors (G02B1/08 takes precedence) · CPC title

• G01N21/552

  Attenuated total reflection · CPC title

• G01N21/15 Primary

  Preventing contamination of the components of the optical system or obstruction of the light path · CPC title