Mid-Infrared CO2 Sensor with Phase-Independent Filters
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Solution Overview
Problem
Current mid-infrared sensors face challenges in accurately monitoring carbon dioxide (CO2) concentrations in various fluid phases, particularly in downhole environments, due to temperature sensitivity and limitations in measuring uncondensed phases, which affects the reliability and flexibility of CO2 monitoring in hydrocarbon industries.
Innovation Solution
A mid-infrared sensor system with a set of three narrow-bandpass filters configured to transmit radiation over specific wavelengths corresponding to water, oil, and CO2 absorbance peaks, combined with a processor to determine CO2 concentrations, allowing measurement in liquid, gas, or mixed phases, and featuring temperature-invariant filters to reduce environmental temperature effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional mid-infrared sensors are used, then CO2 monitoring is possible, but measurement accuracy deteriorates in various fluid phases and temperature conditions
Solution Approach 1:
The sensor divides the mid-infrared spectrum into multiple wavelength bands using narrow bandpass filters, each targeting specific absorption peaks of different substances (CO2 at 4.26 μm, water at 3.00 μm, oil at 3.45 μm). This segmentation allows selective measurement of CO2 while compensating for interference from other substances, improving measurement accuracy across different fluid phases.
Solution Approach 2:
The invention uses temperature-invariant filters with transmission bands that remain stable across a wide temperature range (−50°C to +150°C). This parameter change approach ensures that the filter characteristics do not shift with temperature, maintaining measurement reliability in varying thermal conditions while enabling accurate CO2 monitoring.
2Adaptability or versatility
If conventional mid-infrared sensors are used, then CO2 monitoring is possible, but flexibility deteriorates due to inability to measure uncondensed phases
Solution Approach 1:
The sensor is designed with a universal detection capability that works across all fluid phases (gas, liquid, vapor) by utilizing the strong absorption of CO2 at 4.26 μm in the mid-infrared region. The use of temperature-invariant filters and multi-component absorption analysis enables the same sensor configuration to reliably measure CO2 in diverse phases including uncondensed gas phases, enhancing adaptability and versatility.
3Ease of manufacture
If standard bandpass filters are used, then filter design is simple, but temperature sensitivity increases causing measurement errors
Solution Approach 1:
The invention specifies narrow bandpass filters with transmission bands centered at 4.26 μm for CO2, 3.00 μm for water, and 3.45 μm for oil, each with a bandwidth of 0.05 μm or less. These filters are designed to be substantially temperature-invariant across the range of −50°C to +150°C, maintaining stable transmission characteristics without requiring complex temperature compensation mechanisms, thus balancing manufacturing feasibility with thermal stability.
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 sensor system provides accurate and flexible CO2 monitoring across different fluid phases and temperatures, enhancing the reliability of CO2 concentration measurements in hydrocarbon well management and reservoir monitoring.
Implementation Method 1
narrow bandpass filters that are each configured to preferentially transmit mid-infrared radiation over bands of wavelengths corresponding to respective absorbance peaks of water, oil and CO2
Implementation Method 2
the beam undergoes attenuated internal reflection at an interface between the window and the fluid
Implementation Method 3
the CO2 is strongly absorbing in the mid-infrared at a wavelength of about 4.3 μm
Data Source
AI summary
A sensor for monitoring CO2 in a fluid regardless of the phase properties of the fluid, i.e., regardless of whether the fluid contacting the 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. The sensor includes an internal reflection window for contacting with the fluid. A mid-infrared light source directs a beam of mid-infrared radiation into the window and the beam is internal reflected at an interface between the window and the fluid. The reflected beam is passed through three narrow bandpass filters which preferentially transmit mid-infrared radiation over bands of wavelengths corresponding to absorbance peaks of water, oil and CO2. The amount of CO2 is determined from the intensities of the mid-infrared radiation passing through the three filters.