Spectral analysis with spectrum deconvolution

Patent metadata

Field	Value
Publication number	US-2016290846-A1
Application number	US-201415034824-A
Country	US
Kind code	A1
Filing date	Nov 7, 2014
Priority date	Nov 8, 2013
Publication date	Oct 6, 2016
Grant date	—

Abstract

A method for inferring incident count rates of electromagnetic energy at a detector is provided. In one embodiment, the method includes transmitting electromagnetic radiation through a fluid and receiving a portion of the electromagnetic radiation at a detector. The method also includes measuring the energy spectrum of the portion of the electromagnetic radiation received by the detector and using the measured energy spectrum and a physical model of detector response to electromagnetic radiation to infer incident count rates for discrete energy levels of the portion of the electromagnetic radiation received by the detector. Additional systems, devices, and methods are also disclosed.

First claim

1 . A method comprising:
transmitting electromagnetic radiation through a fluid; receiving a portion of the electromagnetic radiation at a detector; measuring the energy spectrum of the portion of the electromagnetic radiation received by the detector; and using the measured energy spectrum and a physical model of detector response to electromagnetic radiation to infer incident count rates for discrete energy levels of the portion of the electromagnetic radiation received by the detector.

2 . The method of claim 1 , wherein using the measured energy spectrum and the physical model of detector response includes comparing the measured energy spectrum to a detector response function of the physical model to infer the incident count rates.

3 . The method of claim 2 , wherein comparing the measured energy spectrum to the detector response function includes performing least squares optimization of the detector response function with respect to the measured energy spectrum to infer the incident count rates.

4 . The method of claim 3 , wherein the physical model of detector response includes energy and resolution response models having detector-specific parameters, and the method comprises inferring the detector-specific parameters from the least squares optimization between the measured energy spectrum and the detector response function.

5 . The method of claim 4 , comprising calibrating the detector based on the inferred detector-specific parameters.

6 . The method of claim 1 , comprising characterizing a physical attribute of the fluid based on the inferred incident count rates.

7 . The method of claim 6 , wherein the fluid is a multiphase fluid and characterizing a physical attribute of the fluid includes determining phase fractions for the multiphase fluid.

8 . The method of claim 4 , further comprising: monitoring the health status of the detector using the measured spectrum.

9 . An apparatus comprising:
a detector of electromagnetic radiation; a multi-channel analyzer configured to measure an energy spectrum of electromagnetic radiation received by the detector; and a controller configured to deconvolve the measured energy spectrum using a physical model representative of the response of the detector to characterize the electromagnetic radiation received by the detector.

10 . The apparatus of claim 9 , wherein the controller is configured to determine count rates for photons incident on the detector based on the deconvolution of the measured energy spectrum.

11 . The apparatus of claim 9 , wherein the detector is a solid-state detector.

12 . The apparatus of claim 9 , comprising a multiphase flow meter having the detector, the multi-channel analyzer, and the controller.

13 . The apparatus of claim 12 , wherein the controller is a flow computer operable to calculate phase fractions of a fluid passing through the multiphase flow meter based on the deconvolution of the measured energy spectrum using the physical model representative of the response of the detector.

14 . The apparatus of claim 9 , wherein the detector includes a shaping amplifier for providing to the multi-channel analyzer output pulses indicative of photons received by the detector.

15 . The apparatus of claim 14 , wherein the multi-channel analyzer includes a pile-up rejector configured to discard a shaping amplifier output pulse from the detector that is indicative of multiple photons received by the detector within a width of the shaping amplifier output pulse if a time interval between receipt of the multiple photons exceeds a threshold duration.

16 . A method comprising:
receiving photons having different energies at a detector; measuring an energy spectrum of the photons; using multiple monoenergetic response functions to derive spectral components of the energy spectrum for multiple energy levels of the photons; and measuring count rates for at least two energy levels of the received photons based on the derived spectral components.

17 . The method of claim 16 , wherein receiving the photons at the detector includes receiving photons that have passed through a multiphase fluid in a conduit.

18 . The method of claim 16 , comprising:
calculating attenuation rates of the photons by the multiphase fluid for the at least two energy levels; and calculating phase fractions of the multiphase fluid using the calculated attenuation rates.

19 . A multiphase flow meter comprising:
a fluid conduit; an emitter and a detector of electromagnetic radiation arranged with respect to the fluid conduit so as to enable the detector to receive photons transmitted from the emitter through a fluid within the fluid conduit, wherein the detector includes a scintillator, a photomultiplier tube, and an amplifier; a multi-channel analyzer coupled to the detector to receive electrical signals from the amplifier and output a measured energy spectrum of the photons received by the detector; and a flow computer encoded with a response model for the detector, the response model based on characteristics of the emitter and the detector, wherein the flow computer is operable to compare the measured energy spectrum with the response model to infer count rates for the photons received by the detector.

20 . The multiphase flow meter of claim 18 , wherein the response model includes detector energy and resolution functions having detector-specific parameters and a set of monoenergetic response functions that model response of the scintillator to photons incident on the scintillator.

Assignees

• Schlumberger Technology Corp

Inventors

• Chazal Damien
• Fiore Massimiliano

Classifications

• E21B47/10

  Locating fluid leaks, intrusions or movements · CPC title

• G01F1/66 Primary

  by measuring frequency, phase shift or propagation time of electromagnetic or other waves, e.g. using ultrasonic flowmeters · CPC title

• G01T1/20

  with scintillation detectors · CPC title

• G01N23/083 Primary

  the radiation being X-rays · CPC title

• G01N23/12

  the material being a flowing fluid or a flowing granular solid · CPC title