Downhole Cable Retainer with Deflecting Detent
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Solution Overview
Problem
Existing methods for securing fiber optic and other cables downhole are not sufficiently effective, particularly when crossing sand screens, as they require a more rigid retention mechanism to maintain cable integrity and prevent deflection or escape.
Innovation Solution
A cable retainer design featuring a tapered body with a detent and relief area that allows cable passage, combined with a detent lip and optional relief occupier, such as a set screw, to ensure secure engagement and prevent radial movement of the cable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rigid retention mechanism is used to secure the cable, then the cable is firmly held and prevented from deflection or escape, but the cable cannot pass through the retainer structure
Solution Approach 1:
The detent is designed as a movable component that can deflect from its initial position to allow cable passage, then return to its original position to secure the cable. This dynamic behavior allows the retainer to transition between two functional states: open for cable insertion and closed for cable retention, resolving the contradiction between allowing cable passage and providing firm retention.
Solution Approach 2:
The detent's position parameter is changed dynamically - it deflects to a different position during cable passage and returns to its original position for retention. This parameter change enables the retainer to provide both cable passage capability and secure retention, as the detent moves between two states to satisfy different functional requirements.
2Ease of operation
If the detent deflects to allow cable passage, then the cable can be installed, but the cable may escape or move radially outwardly
Solution Approach 1:
The relief occupier is pre-installed in the relief area before cable installation to prevent unintended detent deflection. This preliminary anti-action counteracts any potential cable escape by blocking the relief path, ensuring the detent remains in its cable-retaining position and preventing radial outward movement of the cable.
Solution Approach 2:
The relief occupier acts as an intermediary element between the detent and the relief area. It mediates the interaction by occupying the relief space, preventing the detent from deflecting unintentionally, and thus ensuring the cable remains securely held without allowing radial escape.
3Device complexity
If a simple retainer design is used, then the device complexity is reduced, but the cable cannot be reliably secured across sand screens
Solution Approach 1:
The retainer is segmented into distinct functional components: the body, the detent, the relief area, and the optional relief occupier. This segmentation allows each component to perform its specific function - the detent provides retention, the relief area allows controlled deflection, and the occupier prevents unintended escape - achieving reliable cable security through a modular yet integrated structure.
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 retainer effectively secures cables, including DTS and deformation-measuring cables, by allowing deflection of the detent for cable passage while maintaining a rigid hold, protecting against impact and ensuring reliable deformation sensing across sand screens.
Implementation Method 1
urging the cable against the retainer at a portion thereof to cause a detent to deflect into a relief allowing passage of the cable; and allowing the detent to rebound to a natural position
Data Source
AI summary
A cable retainer for a downhole tubing string includes a body; a detent extending from the body; a relief between the detent and the body facilitating deflection of the detent to allow passage of a cable; and a detent lip extending from the detent. A method for securing a cable to a tubular.