High Permeability Cable Marker for Downhole Azimuthal Positioning
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Solution Overview
Problem
Current cable systems for downhole use, particularly those with fiber optic cables, face challenges in accurately determining the azimuthal position due to the need for extensive mapping and high uncertainty, often requiring costly wellbore upsizing and being susceptible to displacement in tight spots, which complicates the orientation of perforating guns and protection of optical cables.
Innovation Solution
A magnetically detectable cable system is introduced, featuring a magnetic-permeability element with a relative magnetic permeability of at least 2,000, allowing for precise location using a magnetic orienting tool through a metal wall, thereby reducing the number of measurement locations and uncertainty in azimuthal positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If wire ropes are used to mark cable position, then electromagnetic detectability is improved, but wellbore diameter must be increased
Solution Approach 1:
The invention changes the magnetic permeability parameter of the marker element to extremely high values (μr ≥ 2000, preferably μr ≥ 10000), which dramatically enhances electromagnetic detectability without increasing physical dimensions. This allows the marker to be detected through the metal wall with high precision while maintaining a compact size that fits within the existing wellbore diameter.
Solution Approach 2:
The invention applies high magnetic permeability material locally at the cable position rather than using large-diameter wire ropes throughout. The marker element is positioned adjacent to the optical cable, creating a localized high-contrast electromagnetic signature that can be detected through the casing wall without requiring wellbore upsizing.
2Measurement precision
If wire ropes are used for cable location, then electromagnetic signal strength is improved, but susceptibility to displacement increases
Solution Approach 1:
The invention merges the marker function with the cable protection structure itself. The marker element is integrated into the cable assembly and positioned adjacent to the optical cable, ensuring that the marker and cable move together as a single unit. This eliminates the relative displacement problem between separate wire ropes and cables.
Solution Approach 2:
The marker element is pre-positioned adjacent to the optical cable during cable deployment, ensuring correct azimuthal orientation is established before the cable enters the wellbore. This preliminary positioning prevents subsequent displacement issues that occur with separate wire rope markers.
3Measurement precision
If extensive mapping is performed to locate cable, then measurement coverage is improved, but time and cost increase
Solution Approach 1:
The extremely high magnetic permeability (μr ≥ 2000) of the marker element creates a strong electromagnetic contrast against the metal wall and surrounding environment. This enhanced parameter allows the magnetic orienting tool to detect the cable position with high precision using minimal measurement locations, dramatically reducing the extent of mapping required compared to conventional low-permeability markers.
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 enhances the accuracy of azimuthal position determination, reduces the need for extensive mapping, and maintains the integrity of the optical cable by providing a clear signal contrast against the metal wall, enabling precise oriented perforation without damaging the cable.
Implementation Method 1
a magnetic-permeability element configured along a length of the cable, wherein the magnetic-permeability element comprises a material having a relative magnetic permeability μr of at least 2,000
Data Source
AI summary
A system for providing information through a metal wall employs a device adapted to be arranged on one side of the metal wall and a magnetic-permeability element, provided at, near or connected to the device. The magnetic-permeability element is based on a material having a relative magnetic permeability of at least 2000. The disclosure also provides use of said system. The use may involve the step of optimizing the magnetic-permeability element using equivalent inductive mass (EIm). The system can for example be used to magnetically sense the location of a cable present on the outside of a wellbore tubular using a magnetic orienting tool that is located within the wellbore tubular.