Offset Core Optical Fiber Shape Sensing
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Solution Overview
Problem
Conventional distributed strain sensing systems require continuous and rigid attachment to components in boreholes, which is time-consuming and inefficient, especially when deploying equipment downhole for hydrocarbon exploration and production.
Innovation Solution
An optical shape-sensing system using an optical fiber with a light-guiding core offset from its centerline, featuring fiber Bragg gratings that change optical characteristics with shape deformations, allowing for non-rigid attachment and estimation of shape changes without experiencing the same strains as the component.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If continuous rigid attachment of optical fiber to component is used, then measurement precision is improved, but deployment time increases
Solution Approach 1:
The patent changes the attachment parameter from continuous rigid attachment to discrete flexible attachment points. The optical fiber is attached to the component at multiple discrete locations rather than being continuously rigidly attached, allowing the fiber to flex with the component while maintaining sufficient strain transfer for measurement.
Solution Approach 2:
The patent employs a flexible attachment mechanism that allows the optical fiber to conform to the component shape through discrete attachment points. This flexible attachment enables the fiber to move with the component without requiring continuous rigid bonding, reducing deployment time while maintaining measurement capability.
2Reliability
If continuous rigid attachment of optical fiber to component is used, then reliability is improved, but ease of operation deteriorates
Solution Approach 1:
The patent changes the attachment parameter from continuous rigid attachment to discrete flexible attachment points. This parameter change maintains measurement reliability by preserving strain transfer capability while significantly improving deployment ease through faster installation.
Solution Approach 2:
The patent segments the continuous attachment into discrete attachment points along the optical fiber length. This segmentation allows for faster deployment while maintaining sufficient strain transfer at each point to ensure reliable measurements, balancing reliability with operational ease.
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 rapid and efficient monitoring of shape changes in borehole components without the need for continuous rigid attachment, reducing deployment time and improving operational efficiency in harsh downhole environments.
Implementation Method 1
the first core having an optical characteristic configured to change due to a change in shape of the optical fiber
Implementation Method 2
a linear series of fiber Bragg gratings is etched into an optical fiber. Each fiber Bragg grating (FBG) in the series acts as a strain sensor. A beam of light reflected from the optical fiber is used to interrogate each of the FBGs
Data Source
AI summary
An apparatus for estimating a shape, the apparatus including: an optical fiber configured to conform to the shape and having a first core offset from a centerline of the optical fiber, the first core having an optical characteristic configured to change due to a change in shape of the optical fiber wherein a change in the optical characteristic is used to estimate the shape. A method for estimating a shape is also disclosed.