# US 11,029,264 B2 · Spectral analysis with spectrum deconvolution

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- Number: US 11,029,264 B2
- Document ID: US11029264B2
- Status: Granted
- Kind: B2
- Application number: 16/787,369
- Filed: 2020-02-11
- Published: 2020-07-09
- Granted: 2021-06-08
- Earliest claimed: 2013-11-08
- Assignees: Schlumberger Technology Corporation
- Applicants: Schlumberger Technology Corporation
- Inventors: Damien Chazal; Massimiliano Fiore
- Web page: https://patentgrep.com/patent/US11029264B2

## CPC

- G01N 23/083: the radiation being X-rays
- E21B 47/10: Locating fluid leaks, intrusions or movements
- G01F 1/66: by measuring frequency, phase shift or propagation time of electromagnetic or other waves, e.g. using ultrasonic flowmeters
- G01N 23/12: the material being a flowing fluid or a flowing granular solid
- G01N 33/2823: {Raw oil, drilling fluid or polyphasic mixtures}
- G01T 1/20: with scintillation detectors
- 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)
- E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- G01F: MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01T: MEASUREMENT OF NUCLEAR OR X-RADIATION (radiation analysis of materials, mass spectrometry G01N23/00; tubes for determining the presence, intensity, density or energy of radiation or particles H01J47/00)

## 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.

## Claims

### Claim 1

A method comprising:
emitting x-ray and gamma radiation into a fluid;
receiving photons of the x-ray and gamma radiation transmitted through the fluid having different energies at a detector;
physically modelling the detector by determining a detector response function based on characteristics of the detector, and
analyzing the fluid based on the photons received at the detector, wherein analyzing the fluid includes:
measuring an energy spectrum of the photons; and
inferring incident count rates by fitting the measured spectrum with a modelled spectrum, the modelled spectrum being the detector response function applied to an incident spectrum.

### Claim 2 (depends on 1)

The method of claim 1, wherein receiving the photons at the detector includes receiving photons that have passed through a multiphase fluid in a conduit.

### Claim 3 (depends on 2)

The method of claim 2, 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.

### Claim 4 (depends on 1)

The method of claim 1, wherein inferring incident count rates includes inferring count rates for a first energy level of received x-ray photons and a second energy level of received gamma-ray photons.

### Claim 5 (depends on 4)

The method of claim 4, wherein the first energy level of received x-ray photons is between 30 keV and 36 keV.

### Claim 6 (depends on 4)

The method of claim 4, wherein the second energy level of received gamma-ray photons is between 79 keV and 81 keV.

### Claim 7 (depends on 1)

The method of claim 1, wherein receiving the photons at the detector includes receiving the photons at a scintillator of the detector.

### Claim 8 (depends on 1)

The method of claim 1, wherein determining a detector response function based on the detector characteristics comprises determining a set of crystal monoenergetic response functions based on detector characteristics and determining the detector response function based on the set of crystal monoenergetic response functions.

### Claim 9

A multiphase flow meter comprising:
a fluid conduit;
an emitter and a detector of electromagnetic radiation including x-rays and gamma rays, the emitter and the detector 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 detection chain having 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 configured to physically model the detector by determining a detector response function based on characteristics of the detector, wherein the flow computer is configured to analyze the fluid, such analysis including inferring incident count rates by fitting the measured spectrum with a modelled spectrum, the modelled spectrum being the detector response function applied to an incident spectrum.

### Claim 10 (depends on 9)

The multiphase flow meter of claim 9, wherein the flow computer is configured to infer the count rates for the photons received by the detector in real time.

### Claim 11 (depends on 9)

The multiphase flow meter of claim 9, wherein the flow computer is configured to calculate phase fractions for the fluid within the fluid conduit in real time.

### Claim 12 (depends on 9)

The multiphase flow meter of claim 9, comprising a pressure sensor, wherein the flow computer is configured to determine a flow rate for the fluid.

### Claim 13 (depends on 9)

The multiphase flow meter of claim 9, wherein the emitter includes a radioactive source of electromagnetic radiation.

### Claim 14 (depends on 9)

The multiphase flow meter of claim 9, wherein the emitter includes an electric x-ray generator.

### Claim 15 (depends on 9)

The multiphase flow meter of claim 9, wherein the flow computer is further configured to determine a set of crystal monoenergetic response functions based on characteristics of the detector and determine the detector response function based on the set of crystal monoenergetic response functions.

### Claim 16

A method comprising:
transmitting electromagnetic radiation through a fluid, the electromagnetic radiation including x-ray and gamma radiation;
receiving a portion of the electromagnetic radiation transmitted through the fluid at a detector comprising a detection chain of components; and
analyzing the fluid based on the portion of the electromagnetic radiation received at the detector, wherein analyzing the fluid 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, the physical model including a detector response function that is based on physical characteristics of the detector.

### Claim 17 (depends on 16)

The method of claim 16, wherein the detector response function is also based on a component response function for each of a plurality of components of the detection chain that relates inputs at the component to corresponding outputs.

### Claim 18 (depends on 16)

The method of claim 16, wherein inferring the incident count rates is performed by optimization to fit a modeled spectrum with the measured energy spectrum, the modelled spectrum being the detector response function applied to an incident spectrum.

### Claim 19 (depends on 18)

The method of claim 18, wherein optimization includes performing least squares optimization.

### Claim 20 (depends on 19)

The method of claim 19, wherein the physical model of detector response includes models having detector-specific parameters, and the method comprises inferring the detector-specific parameters from the least squares optimization.

### Claim 21 (depends on 20)

The method of claim 20, further comprising calibrating the detector based on the inferred detector-specific parameters.

### Claim 22 (depends on 16)

The method of claim 16, further comprising characterizing a physical attribute of the fluid based on the inferred incident count rates.

### Claim 23 (depends on 22)

The method of claim 22, wherein the fluid is a multiphase fluid and characterizing a physical attribute of the fluid includes determining phase fractions for the multiphase fluid.

### Claim 24

An apparatus comprising:
an emitter and a detector of electromagnetic radiation configured to emit or detect, respectively, x-rays and gamma rays;
a multi-channel analyzer configured to measure an energy spectrum of electromagnetic radiation received by the detector; and
a controller configured to analyze a fluid through which the electromagnetic radiation is passed from the emitter to the detector, wherein such analysis includes deconvolving the measured energy spectrum using a physical model representative of the response of the detector to characterize the electromagnetic radiation received by the detector, wherein the physical model includes a detector response function that is based on physical characteristics of the detector and on a component response function for each of a plurality of components of a detection chain of the detector that relates inputs at each component to corresponding outputs.

### Claim 25 (depends on 24)

The apparatus of claim 24, wherein the controller is configured to determine count rates for photons incident on the detector based on the deconvolution of the measured energy spectrum.

### Claim 26 (depends on 24)

The apparatus of claim 24, wherein the detector is a solid-state detector.

### Claim 27 (depends on 24)

The apparatus of claim 24, comprising a multiphase flow meter having the detector, the emitter, the multi-channel analyzer, and the controller.

### Claim 28 (depends on 27)

The apparatus of claim 27, wherein the controller is a flow computer configured to calculate phase fractions of the 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.

### Claim 29 (depends on 24)

The apparatus of claim 24, wherein the detector includes a shaping amplifier for providing to the multi-channel analyzer output pulses indicative of photons received by the detector.

### Claim 30 (depends on 29)

The apparatus of claim 29, wherein the multi-channel analyzer includes a pile-up rejector.