Fiber Bragg Grating Calibration for Accurate DTS Profiles
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Solution Overview
Problem
Existing distributed temperature sensing (DTS) systems face accuracy issues due to degradation of optical fibers under high temperatures, pressures, and moisture, necessitating the use of additional calibration lines which increase complexity.
Innovation Solution
Integrating fiber Bragg gratings (FBGs) within the optical fiber to calibrate temperature profiles by computing temperature data at specific locations and adjusting the computed profile based on FBG readings, using a processor to enhance accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a calibration line is added adjacent to the sensing line, then temperature measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The patent combines the calibration function and sensing function into a single optical fiber by integrating FBG sensors within the sensing fiber itself. This eliminates the need for a separate calibration line while maintaining temperature measurement accuracy, as the FBG sensors provide discrete calibration points along the distributed sensing fiber.
Solution Approach 2:
The optical fiber serves dual purposes: it acts as both the distributed temperature sensing medium and the calibration reference through integrated FBG sensors. The FBG sensors provide discrete calibration measurements while the fiber itself provides continuous distributed temperature profiling, making the single fiber universally functional for both calibration and sensing.
2Measurement precision
If multiple FBGs are integrated within the optical fiber, then calibration precision is improved, but manufacturing complexity increases
Solution Approach 1:
The calibration function is segmented into multiple discrete FBG sensors distributed along the optical fiber. Each FBG sensor provides an independent calibration point at a specific location, allowing for multi-point calibration that improves precision while maintaining a manageable manufacturing process through standard FBG fabrication techniques.
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
Enhances the accuracy of temperature profiling by utilizing FBGs as internal calibration points, reducing complexity and improving precision in DTS systems.
Implementation Method 1
providing at least one fiber Bragg grating (FBG) within the optical fiber; computing a temperature datum for a location of each of the at least one FBG based on signals generated by the fiber optic transceiver in response to light reflections from the FBG
Implementation Method 2
The local temperature conditions at different depths of the well bore affect the local optical characteristics of the optical fiber, which results in reflections with different local shifts due to the Raman scattering effect
Data Source
AI summary
A system and method for calibrating a distributed temperature sensing (DTS) system having a fiber optic receiver coupled to an optical fiber, includes fiber Bragg gratings (FBGs) integrally formed within the optical fiber, and a processor configured to compute a temperature datum for a location of each FBG based on signals generated by the fiber optic receiver in response to light reflections from the FBG; and adjusting a computed temperature data profile along the optical fiber segment, based on the computed temperature datum for each location of an FBG.