Optical Fiber Temperature Sensor Jacket Design
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Solution Overview
Problem
Existing optical fiber temperature sensors in gas and oil exploration processes face challenges in accurately measuring temperatures due to tension and bending strains during installation and use, which can induce errors in temperature readings.
Innovation Solution
A temperature sensor system with an elongated sensing element, featuring an optical fiber mounted in a flexible jacket with excess fiber length and a specific cross-sectional area, allowing for minimal interaction and stress reduction between the fiber and the jacket, enabling accurate temperature measurements over long spans with reduced error.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the optical fiber is installed in the well, then temperature measurements can be obtained, but tension and bending strains are introduced that cause measurement errors
Solution Approach 1:
The patent introduces a jacket as an intermediary element between the optical fiber and the harsh well environment. The jacket protects the fiber from external mechanical stresses while allowing the fiber to maintain its optical sensing function. This mediator isolates the sensitive optical fiber from direct exposure to tension and bending forces during installation and operation.
Solution Approach 2:
The patent modifies the physical parameters of the optical fiber system by controlling the fiber-to-jacket diameter ratio and specifying minimum jacket inner diameter values. These parameter changes ensure adequate clearance between the fiber and jacket walls, preventing mechanical contact that would transmit harmful strains to the fiber during bending or tension events.
2Length of stationary object
If the optical fiber is made longer to cover more area, then more temperature data points are obtained, but the fiber becomes more susceptible to tension and bending strains
Solution Approach 1:
The patent establishes specific parameter thresholds: the jacket inner diameter must be at least 0.6 mm, and the fiber-to-jacket diameter ratio must not exceed 0.4. These parameter specifications ensure that even long optical fibers remain protected from mechanical strains, maintaining measurement precision across extended measurement ranges.
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 achieves an average temperature error of less than 2°C, providing precise temperature measurements by minimizing the impact of tension and bending strains, ensuring reliable data in harsh environments.
Implementation Method 1
an optical fiber that establishes an optical path
Implementation Method 2
When the optical fiber undergoes expansion or contraction resulting from temperature changes, the optical properties of the gratings are altered
Implementation Method 3
Gratings are formed at spaced apart intervals along that path. When the optical fiber undergoes expansion or contraction resulting from temperature changes, the optical properties of the gratings are altered. The optical properties can be measured by sending in the optical fiber an interrogation signal and then reading the responses of the individual gratings
Data Source
AI summary
A method for measuring a physical parameter at a plurality of spaced locations in a subterranean formation using a temperature sensor that has an elongated sensing element having a length of at least 10 m, measured at a temperature of 20° C. The elongated sensing element includes an elongated jacket and an optical fiber mounted in the jacket and having an EFL of at least 0.35%, wherein the elongated sensing element has an average temperature error of less than 2° C.