Distributed Optical Fiber Sensing for Strain and Pressure Monitoring
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Solution Overview
Problem
Current methods lack the capability to accurately detect state changes in underground strata and do not effectively correlate pressure changes with deformation on the ground surface, making it difficult to assess geomechanical integrity.
Innovation Solution
A system that simultaneously measures distributions of pressure, temperature, and strain using Brillouin and Rayleigh frequency shifts in optical fibers, allowing for accurate monitoring and evaluation of extensive materials by analyzing Brillouin and Rayleigh frequency shifts and their correlations with pressure, temperature, and strain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electrical pressure sensors are used to detect pressure changes at specific spots, then pressure detection capability is improved, but the ability to measure distributed pressure, temperature, and strain simultaneously deteriorates
Solution Approach 1:
The patent combines multiple measurement capabilities (pressure, temperature, and strain measurement) into a single optical fiber-based distributed sensing system. By merging these functions into one system using Brillouin and Rayleigh scattering measurements, the patent achieves simultaneous measurement of multiple parameters along the entire length of the optical fiber, resolving the contradiction between specialized pressure detection and versatile simultaneous measurement.
Solution Approach 2:
The optical fiber sensing system is designed to perform multiple functions simultaneously - measuring pressure, temperature, and strain distributions along the same optical fiber. This multi-functional approach allows a single system to provide comprehensive geomechanical monitoring, making the system universally applicable for detecting various physical parameters without requiring separate specialized sensors for each parameter.
2Device complexity
If a single measurement system is used to measure multiple parameters (pressure, temperature, strain), then system complexity is reduced, but measurement precision for each individual parameter deteriorates
Solution Approach 1:
The patent segments the measurement process by utilizing two distinct scattering phenomena (Brillouin scattering for pressure and strain, Rayleigh scattering for temperature and strain) that occur simultaneously in the optical fiber. This segmentation allows different physical parameters to be measured through different scattering mechanisms, maintaining high measurement precision for each parameter while using a single integrated system, thereby reducing overall system complexity.
3Ease of operation
If optical fiber is not fixed to the object being measured, then ease of installation is improved, but the ability to measure strain of the object deteriorates
Solution Approach 1:
The patent introduces an intermediary approach where the optical fiber is coupled to the object being measured through a bonding agent or adhesive layer. This intermediary coupling mechanism allows the optical fiber to follow the strain of the object without requiring direct rigid attachment, maintaining ease of installation while enabling accurate strain measurement. The bonding agent acts as a mediator that transfers strain from the object to the optical fiber effectively.
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
Enables accurate and simultaneous measurement of pressure, temperature, and strain distributions, effectively monitoring and evaluating the state of underground materials, including geomechanical integrity and carbon dioxide sequestration processes.
Implementation Method 1
a Brillouin frequency shift measurement unit for measuring distribution of a Brillouin frequency shift in the optical fiber from the scattered waves
Implementation Method 2
a Rayleigh frequency-shift measurement unit for measuring distribution of a Rayleigh frequency shift in the optical fiber from the scattered waves
Data Source
AI summary
Distributions of a Brillouin frequency shift and a Rayleigh frequency shift in optical fibers set up in a material are measured from scattered waves of pulse laser light entered into the optical fibers, and distributions of pressure, temperature, and strain of the material along the optical fibers at a measurement time point are analyzed using coefficients that are inherent to the set up optical fibers and correlate pressure, temperature, and strain of material with the Brillouin frequency shift and the Rayleigh frequency shift.