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US-12618770-B2 - Method and system for water cut sensing in an oil-water flow

US12618770B2US 12618770 B2US12618770 B2US 12618770B2US-12618770-B2

Abstract

A method for water cut sensing in an oil-water flow involves obtaining a composite absorbance spectrum of the oil-water flow, obtaining a reference absorbance spectrum of a reference fluid, computing a slope for data points associated with the composite absorbance spectrum of the oil-water flow vs corresponding data points associated with the reference absorbance spectrum of the known fluid, and based on the slope, determining the water cut of the oil-water flow.

Inventors

  • Mhanna MHANNA
  • Muhammad ARSALAN
  • Aamir Farooq

Assignees

  • SAUDI ARABIAN OIL COMPANY
  • KING ABDULLAH UNIVERSITY OF SCIENCE AND TECHNOLOGY

Dates

Publication Date
20260505
Application Date
20231211

Claims (20)

  1. 1 . A method for water cut sensing in an oil-water flow, the method comprising: obtaining a composite absorbance spectrum of the oil-water flow; obtaining a reference absorbance spectrum of a reference fluid; computing data points, wherein each of the data points is for a specific absorbance spectrum wavelength and is based on an absorbance of the absorbance spectrum of the oil-water flow versus an absorbance of the absorbance spectrum of the reference fluid; computing a best-fit slope for the data points; and based on the best-fit slope, determining the water cut of the oil-water flow.
  2. 2 . The method of claim 1 , wherein computing the data points comprises computing a first derivative of the composite absorbance spectrum.
  3. 3 . The method of claim 1 , wherein computing the data points comprises computing a first derivative of the reference absorbance spectrum.
  4. 4 . The method of claim 1 , wherein the reference fluid is water.
  5. 5 . The method of claim 1 , further comprising, prior to determining the water cut: re-computing the best-fit slope after eliminating outliers in the data points associated with the composite absorbance spectrum.
  6. 6 . The method of claim 5 , wherein the outliers are eliminated based on exceeding a distance from a linear fit line with the best-fit slope.
  7. 7 . The method of claim 1 , wherein obtaining a composite absorbance spectrum of the oil-water flow comprises performing a laser-based absorption spectroscopy measurement.
  8. 8 . The method of claim 1 , wherein the computing of the best-fit slope is performed for a first region of the composite absorbance spectrum, and wherein the method further comprises: determining that the water cut is above 10%, and based on the determination, repeating the computing of the best-fit slope for a second region of the composite absorbance spectrum.
  9. 9 . A system for water cut sensing in an oil-water flow, the system comprising: a laser-based spectroscopy sensor; and a computer system that: obtains a composite absorbance spectrum of the oil-water flow from the laser-based spectroscopy sensor, obtains a reference absorbance spectrum of a reference fluid, computes data points, wherein each of the data points is for a specific absorbance spectrum wavelength and is based on an absorbance of the absorbance spectrum of the oil-water flow versus an absorbance of the absorbance spectrum of the reference fluid, computes a best-fit slope for the data points, and based on the best-fit slope, determines the water cut in the oil-water flow.
  10. 10 . The system of claim 9 , wherein computing the data points comprises computing a first derivative of the composite absorbance spectrum.
  11. 11 . The system of claim 9 , wherein computing the data points comprises computing a first derivative of the reference absorbance spectrum.
  12. 12 . The system of claim 9 , wherein the reference fluid is water.
  13. 13 . The system of claim 9 , wherein the computer system further, prior to determining the water cut: re-computes the best-fit slope after eliminating outliers in the data points associated with the composite absorbance spectrum.
  14. 14 . The system of claim 13 , wherein the outliers are eliminated based on exceeding a distance from a linear fit line with the best-fit slope.
  15. 15 . The system of claim 9 , wherein the computing of the best-fit slope is performed for a first region of the composite absorbance spectrum, and wherein the computer system further: determines that the water cut is above 10%, and based on the determination, repeats the computing of the best-fit slope for a second region of the composite absorbance spectrum.
  16. 16 . A non-transitory computer readable medium (CRM) storing computer readable program code for water cut sensing in an oil-water flow, the computer readable program code causing a computer system to: obtain a composite absorbance spectrum of the oil-water flow; obtain a reference absorbance spectrum of a reference fluid; compute data points, wherein each of the data points is for a specific absorbance spectrum wavelength and is based on an absorbance of the absorbance spectrum of the oil-water flow versus an absorbance of the absorbance spectrum of the reference fluid, compute a best-fit slope for the data points; and based on the best-fit slope, determine the water cut of the oil-water flow.
  17. 17 . The non-transitory computer readable medium of claim 16 , wherein computing the data points comprises computing a first derivative of the composite absorbance spectrum.
  18. 18 . The non-transitory computer readable medium of claim 16 , wherein computing the data points comprises computing a first derivative of the reference absorbance spectrum.
  19. 19 . The non-transitory computer readable medium of claim 16 , wherein the computer readable program code further causes the computer system to, prior to determining the water cut: re-compute the best-fit slope after eliminating outliers in the data points associated with the composite absorbance spectrum.
  20. 20 . The non-transitory computer readable medium of claim 16 , wherein the computing of the best-fit slope is performed for a first region of the composite absorbance spectrum, and wherein the computer readable program code further causes the computer system to: determine that the water cut is above 10%, and based on the determination, repeat the computing of the best-fit slope for a second region of the composite absorbance spectrum.

Description

BACKGROUND Effective oil production is indispensable to fulfill the increasing energy demands of the world. Enhanced recovery methods, along with the presence of perforated rocks near the oil reservoir, can be a cause of water becoming mixed into the oil. Water cut (WC) measurement is essential in the oil industry as it is key for production allocation, reservoir management, and early water breakthrough detection. WC varies with the age and geolocation of oil wells, which requires WC sensors to span near full dynamic range (0-100%), and thus cover wide industrial applications. A myriad of WC sensors exists in literature based on various technologies. Dielectric properties of oil-water (OW) mixtures have been exploited, especially at high frequencies (MHz), by measuring microwave resonance and transmission to detect WC. However, microwave resonance suffers poor sensitivity to WC, and microwave transmission is obfuscated in saline OW mixtures. WC can be measured intrusively by several methods, but these cannot be utilized for inline WC sensing. Multi-energy gamma rays which use radioactive sources can be used, but they are associated with handling and disposal safety concerns. Planar microwave resonance has been implemented on a pipeline surface to provide in situ, non-intrusive WC sensing. However, calibration was needed to know what oils were present in the OW flow. Near-infrared (NIR) spectroscopy has been employed based on adapting Beer-Lambert law for non-homogeneous immiscible mixtures, and although the resulting WC sensor was proven to be more accurate than other sensors, it needs frequent well-specific calibration which gets tedious with well-aging and changing geolocation. Accordingly, alternative WC sensors that operate in the full dynamic range (0-100%), and that do not require any calibration would be highly desirable and beneficial. SUMMARY This summary is provided to introduce a selection of concepts that are further described below in the detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter. In general, in one aspect, embodiments relate to a method for water cut sensing in an oil-water flow, the method comprising: obtaining a composite absorbance spectrum of the oil-water flow; obtaining a reference absorbance spectrum of a reference fluid; computing a slope for data points associated with the composite absorbance spectrum of the oil-water flow vs corresponding data points associated with the reference absorbance spectrum of the known fluid; and based on the slope, determining the water cut of the oil-water flow. In general, in one aspect, embodiments relate to a system for water cut sensing in an oil-water flow, the system comprising: a laser-based spectroscopy sensor; and a computer system that: obtains a composite absorbance spectrum of the oil-water flow from the laser-based spectroscopy sensor, obtains a reference absorbance spectrum of a reference fluid, computes a slope for data points associated with the composite absorbance spectrum of the oil-water flow vs corresponding data points associated with the reference absorbance spectrum of the known fluid, and based on the slope, determines the water content in the oil-water flow. In general, in one aspect, embodiments relate to a non-transitory machine-readable medium comprising a plurality of machine-readable instructions executed by one or more processors, the plurality of machine-readable instructions causing the one or more processors to perform operations comprising: obtaining a composite absorbance spectrum of the oil-water flow; obtaining a reference absorbance spectrum of a reference fluid; computing a slope for data points associated with the composite absorbance spectrum of the oil-water flow vs corresponding data points associated with the reference absorbance spectrum of the known fluid; and based on the slope, determining the water cut of the oil-water flow. In light of the structure and functions described above, embodiments of the disclosure may include respective means adapted to carry out various steps and functions defined above in accordance with one or more aspects and any one of the embodiments of one or more aspect described herein. Other aspects and advantages of the claimed subject matter will be apparent from the following description and the appended claims. BRIEF DESCRIPTION OF DRAWINGS Specific embodiments of the disclosed technology will now be described in detail with reference to the accompanying figures. Like elements in the various figures are denoted by like reference numerals for consistency. FIG. 1 shows a well environment in accordance with one or more embodiments. FIGS. 2A and 2B show systems for water cut sensing in an oil-water flow in accordance with one or more embodiments. FIG. 3 shows a flowchart for a method in accordance with one or more