Optical Phase Fraction Measurement in Multiphase Flowmeters
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Solution Overview
Problem
Current multiphase flowmeters used in hydrocarbon production, which include radioactive sources, are undesirable due to regulatory challenges and are expensive for low-production wells, necessitating a non-radioactive and cost-effective solution for phase fraction measurement.
Innovation Solution
A multiphase flowmeter system with a transparent window structure and collimated light sources emitting wavelengths absorptive to specific phases, combined with photodetectors and processing circuitry to continuously adjust light power, enabling accurate phase fraction measurement beyond the photodetector's dynamic range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a radioactive source is used in a multiphase flowmeter, then measurement accuracy is improved, but regulatory compliance becomes problematic and cost increases
Solution Approach 1:
The patent removes the radioactive source from the measurement system entirely, replacing it with an optical-based detection system using light sources and photodetectors. This extraction eliminates the harmful regulatory aspects while maintaining measurement capability through alternative physical principles (optical absorption and scattering).
Solution Approach 2:
The patent substitutes the radioactive measurement mechanism with an optical measurement system. Instead of using radiation detection, the system employs light transmission through the fluid with photodetectors measuring absorption and scattering properties to determine phase fractions, replacing a mechanical/radioactive system with an optical one.
2Measurement precision
If a radioactive source is used in a multiphase flowmeter, then measurement accuracy is improved, but device cost increases
Solution Approach 1:
The patent replaces expensive radioactive sources with inexpensive optical components (light-emitting diodes, photodetectors, lenses) that have no regulatory licensing costs and can be manufactured at low cost. The optical components are replaceable and do not require special handling or disposal procedures.
Solution Approach 2:
The substitution of radioactive sources with optical components eliminates the need for expensive radiation shielding, licensing, and specialized handling equipment, significantly reducing overall system cost while maintaining measurement functionality.
3Loss of information
If a photodetector measures light through multiphase fluid, then phase fraction information is obtained, but the photodetector's limited dynamic range restricts measurement capability
Solution Approach 1:
The patent employs multiple light sources with different wavelengths (e.g., infrared, visible, ultraviolet) that can be dynamically selected or combined based on the specific measurement requirements and fluid composition. This dynamic multi-wavelength approach allows the system to adapt to varying absorption characteristics and extend the effective measurement dynamic range beyond what a single photodetector could achieve alone.
Solution Approach 2:
The patent uses a multi-wavelength light source system where different wavelengths serve different measurement functions - some wavelengths are more sensitive to gas phases, others to liquid phases, and others to solid particles. This multi-functional optical system allows a single measurement device to characterize multiple phases simultaneously, effectively extending the dynamic range for different phase fractions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively determines phase fractions of multiphase fluids, including gas, oil, water, and solids, without the need for radioactive sources, providing accurate and cost-effective measurements across a wide dynamic range.
Implementation Method 1
A collimated light source is configured to emit light through the transparent window structure and into the pipe with the emitted light having a wavelength at which a component of a desired phase of the multiphase fluid is absorptive
Implementation Method 2
A photodetector is positioned such that the emitted light passes through the multiphase fluid in the pipe and out through the transparent window structure to impinge upon the photodetector
Data Source
AI summary
An apparatus includes a pipe through which a multiphase fluid flows, with a transparent window structure formed in the pipe. A collimated light source emits light through the transparent window structure into the pipe having a wavelength at which a component of a desired phase of the multiphase fluid is absorptive. A photodetector is positioned such that the emitted light passes through the multiphase fluid in the pipe to impinge upon the photodetector. The photodetector has an actual dynamic range for collimated light detection. Processing circuitry is configured to continuously adjust a power of the collimated light source dependent upon an output level of the photodetector so as to cause measurement of the emitted light over an effective dynamic range greater than the actual dynamic range, and determine a property of the multiphase fluid as a function of the power of the collimated light source.