Mid-infrared acid sensor

Patent metadata

Field	Value
Publication number	US-10345480-B2
Application number	US-201515511336-A
Country	US
Kind code	B2
Filing date	Sep 9, 2015
Priority date	Sep 15, 2014
Publication date	Jul 9, 2019
Grant date	Jul 9, 2019

Abstract

A sensor is provided for monitoring a mineral acid dissolved in a liquid. The sensor includes an internal reflection window which, in use, is in direct contact with the liquid. 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 liquid. 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 dissolved mineral acid to filter internally reflected mid-infrared radiation received from the window. The sensor further includes an infrared detector which detects filtered mid-infrared radiation transmitted through the first filter. The sensor further includes a processor arrangement, operably coupled to the infrared detector, which measures the intensity of the detected mid-infrared radiation transmitted through the first filter, and determines therefrom an amount of the mineral acid dissolved in the liquid.

First claim

The invention claimed is:

1. A sensor for monitoring a mineral acid dissolved in a liquid, the sensor comprising:
an internal reflection window which, in use, is in contact with the liquid;
a mid-infrared light source configured to direct a beam of mid-infrared radiation into the internal reflection window 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 mineral acid to filter internally reflected mid-infrared radiation received from the internal reflection window and configured such that its band of wavelengths is substantially temperature invariant over temperatures in a range from about 25° C. to about 150° C.;
an infrared detector configured to detect filtered mid-infrared radiation transmitted through the first narrow bandpass filter; and
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 an amount of the mineral acid dissolved in the liquid from the measured intensity.

2. The sensor according to claim 1 , wherein the first narrow bandpass filter preferentially transmits mid-infrared radiation over a band of wavelengths corresponding to an absorbance peak of about 1050 cm −1 .

3. 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 liquid,
the or a further infrared detector configured to detect filtered mid-infrared radiation transmitted through the second filter, and
the processor arrangement configured to measure the 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 mineral acid in the fluid.

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

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

6. The sensor according to claim 1 , further comprising
a heater which is-operable to locally heat the internal reflection window, thereby cleaning the surface of the internal reflection window in contact with the liquid.

7. The sensor according to claim 1 , further comprising
a pressure pulse arrangement which is operable to produce a pressure pulse in the fluid at the internal reflection window, thereby cleaning the surface of the internal reflection window in contact with the fluid.

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

9. Use of the sensor of claim 1 to determine an amount of a mineral acid dissolved in a liquid.

10. A method of monitoring a mineral acid dissolved in a liquid, the method comprising:
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 mineral acid dissolved in the liquid.

11. A method of stimulating production from a well, the method comprising:
injecting a liquid containing dissolved mineral acid into the well to stimulate production from a carbonate formation;
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 the amount of mineral acid deployed into the formation.

12. The method of claim 11 , further comprising:
providing a further sensor for monitoring CO 2 in a fluid, the further sensor including:
a further internal reflection window which, in use, is in direct contact with a fluid;
a further mid-infrared light source configured to direct a beam of mid-infrared radiation into the further internal reflection window for attenuated internal reflection at an interface between the further internal reflection window and the fluid;
three further first narrow bandpass filters configured to preferentially transmit mid-infrared radiation over bands of wavelengths corresponding to respective absorbance peaks of water, oil and CO 2 to filter internally reflected mid-infrared radiation received from the internal reflection window;
one or more further infrared detector(s) which detect filtered mid-infrared radiation transmitted through the further first narrow bandpass filters; and
a further processor arrangement, operably coupled to the infrared detector(s), configured to measure the intensity of the detected mid-infrared radiation transmitted through the first narrow bandpass filters and determine an amount of CO 2 in the fluid from the measured intensity notwithstanding whether the fluid contacting the further 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; and

operating the further sensor to determine an amount of CO 2 in the fluid produced by the formation.

13. A method for monitoring a mineral acid dissolved in a liquid, the method comprising:
directing a beam of mid-infrared radiation into an internal reflection window contacting the liquid;
passing an attenuated internal reflection from the internal reflection window of the mid-infrared radiation through a narrow bandpass filter to produce a filtered output beam of mid-infrared radiation, wherein the narrow bandpass filter is configured to preferentially transmit mid-infrared radiation over a band of wavelengths corresponding to an absorbance peak of the dissolved mineral acid and is configured such that its band of wavelengths is substantially temperature invariant over temperatures in a range from about 25° C. to about 150° C.;
measuring an intensity of the filtered output beam; and
determining an amount of the mineral acid dissolved in the liquid from the measured intensity.

14. The method according to claim 13 , wherein the narrow bandpass filter is configured to preferentially transmit mid-infrared radiation over a band of wavelengths corresponding to an absorbance peak of 1050 cm −1 .

15. The method according to claim 13 , further comprising:
passing the attenuated internal reflection from the internal reflection window through 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 liquid to produce a reference output; and
measuring an intensity of the reference output,
wherein: determining an amount of the mineral acid dissolved in the liquid from the measured intensity comprises determining an amount of the mineral acid dissolved in the liquid from the measured intensity and the reference intensity.

16. The method according to claim 13 , wherein the beam of mid-infrared light is pulsed.

17. The method according to claim 13 , further comprising:
rapidly heating the internal reflection window to remove contaminants from the internal reflection window.

18. The method according to claim 13 , further comprising:
applying a pressure pulse to the liquid to remove contaminants from the internal reflection window.

19. The method according to claim 13 , further comprising:
determining an amount of CO 2 in the liquid.

Assignees

• Schlumberger Technology Corp

Inventors

• Jones Timothy
• Lawrence Nathan
• Fujisawa Go
• Chao Sheng
• Jiang Li

Classifications

• G01V8/14 Primary

  using reflectors · CPC title

• G01N33/004

  CO or CO2 · CPC title

• G01N2201/0696

  Pulsed · CPC title

• G01N2021/154

  Ultrasonic cleaning · CPC title

• Y02A50/244

  Cross-Sectional Technologies · mapped topic