Downhole Fluid Spectral Analysis with Merged Spectrometers
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Solution Overview
Problem
Existing downhole fluid analysis tools using a single spectrometer are limited by a small number of channels and require separate modules, and calibration in adverse conditions is challenging due to the need for light differentiation, which increases tool size.
Innovation Solution
A system employing multiple spectrometers, including filter array and grating spectrometers, with a single light source providing both measurement and reference signals for calibration, using light choppers to differentiate signals, and routing light directly to spectrometers for enhanced spectral analysis and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single filter array spectrometer is used for downhole fluid analysis, then the device complexity is reduced, but the channel density and measurement precision are limited to about 20 channels maximum
Solution Approach 1:
The patent combines multiple spectrometers (filter array spectrometer and grating spectrometer) into a single integrated downhole tool, allowing them to share common components such as the light source, sample cell, and optical pathways. This merging approach increases channel density and spectral analysis precision while controlling overall device complexity through shared infrastructure.
Solution Approach 2:
The system is designed with multi-functionality where a single light source serves multiple spectrometers, and the optical system can route light to different detectors based on analysis requirements. The filter array spectrometer provides broad spectral coverage while the grating spectrometer provides high-resolution analysis, creating a universal platform that adapts to different fluid characterization needs.
2Adaptability or versatility
If multiple spectrometers of different types are used simultaneously, then channel density and spectral analysis capability are increased, but the device complexity and tool size increase significantly
Solution Approach 1:
Multiple spectrometers are merged into a single tool architecture, sharing common components including the light source, sample cell, optical routing mechanisms, and electronic control systems. This reduces the overall tool size and complexity compared to having separate modules, while maintaining the versatility of multiple spectrometer types.
Solution Approach 2:
The patent transitions from a single-dimension spectral analysis approach to a multi-dimensional approach by combining spectrometers with different spectral resolutions and ranges. The filter array provides one dimension of spectral coverage while the grating spectrometer provides another dimension of high-resolution analysis, creating a comprehensive characterization capability without proportionally increasing tool size.
3Measurement precision
If light choppers are used to differentiate reference and measurement light signals for calibration, then calibration accuracy is improved, but the tool size increases due to the required motor
Solution Approach 1:
The patent replaces the mechanical light chopper system with an optical switching mechanism that uses electronic control to direct light signals. This substitution eliminates the motor and associated mechanical components, reducing tool volume while maintaining the ability to differentiate between reference and measurement light signals for accurate calibration.
Solution Approach 2:
An optical switching element acts as an intermediary between the light source and spectrometers, enabling temporal or spatial separation of reference and measurement signals without requiring mechanical rotation. This intermediary component achieves signal differentiation through optical routing rather than mechanical modulation, reducing the physical footprint of the calibration system.
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
This configuration increases channel density and accuracy in fluid analysis, providing detailed spectral information and improving calibration efficiency in harsh downhole conditions, reducing tool size and complexity.
Implementation Method 1
Fluids drawn from the formation into the testing chamber by a fluid admitting assembly are analyzed by directing light at the fluids, detecting the spectrum of the transmitted and/or backscattered light
Implementation Method 2
by taking optical density (OD) measurements of the fluid stream at certain predetermined energies, oil and water fractions of a two-phase fluid stream may be quantified
Data Source
AI summary
A downhole fluid analysis system comprises an input light signal that is directed through a fluid sample housed in a sample cell. The input light signal may originate from a plurality of light sources. A light signal output from the sample cell is then routed to two or more spectrometers for measurement of the represented wavelengths in the output light signal. The output of the spectrometers is then compared to known values for hydrocarbons typically encountered downhole. This provides insight into the composition of the sample fluid. Additionally, the input light can be routed directly to the two or more spectrometers to be used in calibration of the system in the high temperature and noise environment downhole.