Helical Cable Conduit for Consistent Fiber Positioning
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Solution Overview
Problem
Existing real-time casing imaging systems using optic fibers with fiber bragg gratings in hydrocarbon recovery are not entirely reliable due to inconsistent fiber positioning within conduits, leading to errors and reduced sensitivity in strain measurements.
Innovation Solution
A cable with a conduit having a helical curvature is used to consistently position the fiber along the shortest path, minimizing bend radius and stress, and secured with a hardenable material to ensure accurate strain measurement, while also allowing for the use of a spacer to maximize distance from the tubular surface for enhanced sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the fiber is pumped into the conduit with pumping fluid or epoxy, then the fiber can be installed inside the conduit, but the fiber positioning becomes inconsistent leading to measurement errors
Solution Approach 1:
The conduit is pre-formed with a helical curvature before fiber installation. This preliminary shaping of the conduit ensures that when the fiber is pumped in with epoxy, it naturally follows the curved path and becomes consistently positioned along the inner surface, eliminating positioning inconsistencies without requiring complex installation procedures
Solution Approach 2:
The conduit is given a helical curvature instead of being straight. This curvature causes the fiber to naturally follow the curved path when installed, ensuring consistent positioning at the point of greatest distance from the tubular surface. The curved geometry transforms the installation process into a self-positioning system that maintains measurement precision
2Reliability
If the conduit is bent into shape after fiber installation, then the fiber positioning consistency is improved, but the pumping pressure required increases
Solution Approach 1:
The conduit is pre-bent into its final helical shape before fiber installation. This eliminates the need to bend the conduit after fiber installation, allowing the fiber to be pumped in easily through the curved conduit without encountering high bending stresses or requiring excessive pumping pressure
3Measurement precision
If the fiber is positioned closer to the tubular surface, then the bend radius decreases improving sensitivity, but the stress on the fiber increases reducing reliability
Solution Approach 1:
The helical curvature of the conduit positions the fiber at the optimal location - at the point of greatest distance from the tubular surface along the curved path. This geometry provides the smallest practical bend radius for enhanced sensitivity while maintaining fiber integrity and reducing stress through the distributed curved configuration
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 approach enhances the reliability and sensitivity of strain measurements by maintaining the fiber in a consistent position within the conduit, reducing stress, and improving the accuracy of strain sensing, thereby overcoming the limitations of prior art systems.
Implementation Method 1
Real time casing imaging (RTCI) is known in the hydrocarbon recovery arts and comprises an optic fiber with fiber bragg gratings (FBG) disposed within a conduit
Implementation Method 2
The fiber is fixed within the conduit using a hardenable material such as epoxy to promote the transfer of strain in the conduit to the fiber
Data Source
AI summary
A method for making a cable includes creating a curvature in a conduit; pumping one or more fibers into the conduit; and securing at least one of the one or more fibers to a shortest pathway within the conduit and cable.