Fiber Optic Cable Annular Sealing for Downhole Fluid Ingress
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Fiber optic cables used in harsh downhole oil and gas applications face challenges such as high temperatures, pressures, and hydrogen exposure, leading to fluid ingress, corrosion, and hydrogen darkening, which conventional designs fail to adequately address.
Innovation Solution
The development of a fiber optic cable with a fluid-tight mechanical annular seal between the armor layer and the inner tube, along with polymer sealing features and feedthrough-encapsulated filler materials, to prevent fluid flow and confine any breaching fluid to a small region, reducing the effects of corrosion and hydrogen darkening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fiber optic cable designs are used in downhole applications, then the cable structure is simple and easy to manufacture, but the cable fails to prevent fluid ingress and hydrogen darkening in harsh environments
Solution Approach 1:
The cable is divided into multiple functional layers including an inner tube containing optical fibers, an outer tube, and sealing features disposed in the annulus between them. This segmentation allows each layer to perform its specific function (protection, sealing, structural support) independently, achieving reliable fluid prevention while maintaining manufacturing feasibility through modular construction
Solution Approach 2:
Polymer sealing features are introduced as intermediary elements between the inner tube and outer tube. These sealing features specifically address the fluid ingress problem by creating barrier layers that prevent hydrogen and other fluids from reaching the optical fibers, thereby improving reliability without requiring fundamental changes to the overall cable architecture
2Reliability
If polymer sealing features are added to prevent fluid flow, then fluid ingress is reduced, but manufacturing complexity increases
Solution Approach 1:
The sealing features utilize polymer materials with specific physical and chemical parameters (temperature resistance, chemical inertness, sealing properties) that enable them to function effectively in harsh downhole environments. By selecting materials with appropriate parameters, the sealing performance is enhanced while the manufacturing process remains compatible with existing cable assembly techniques
3Object-affected harmful factors
If filler material is used to impede fluid flow, then hydrogen darkening is reduced, but the cable structure becomes more complex
Solution Approach 1:
The harmful effect of hydrogen on optical fibers is isolated by introducing filler material in the annulus that specifically addresses hydrogen ingress. This extraction approach contains the hydrogen barrier function in a dedicated component, reducing hydrogen darkening while maintaining overall structural simplicity through functional specialization
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 solution effectively inhibits fluid propagation, reducing corrosion and hydrogen-related issues, thereby enhancing the reliability and performance of fiber optic cables in harsh environments by confining breaching fluids and minimizing hydrogen darkening effects.
Implementation Method 1
one or more polymer sealing features disposed in an annulus between the outer tube and the inner tube and bonded to at least one of the inner tube or the outer tube to prevent fluid flow in the annulus
Implementation Method 2
the filler material is configured to impede the flow of an ingressing fluid along the at least the portion of the length of the optical cable
Implementation Method 3
an outer tube surrounding the inner tube and configured to form one or more fluid-tight annular seals with the inner tube to prevent fluid flow in an annulus between the outer tube and the inner tube
Data Source
AI summary
Fiber optic cables suitable for use in downhole applications, with one or more features for inhibiting flow of any fluid breaching an armor layer of the optical cable are provided. By preventing, or at least impeding, fluid flow along the cable length, any breaching fluid may be confined to a small region of the cable, which may significantly reduce the deleterious effects (e.g., hydrogen darkening) of an armor layer breach. One example optical cable generally includes one or more optical fibers, an inner tube surrounding the one or more optical fibers, an outer tube surrounding the inner tube, and one or more polymer sealing features disposed in an annulus between the outer tube and the inner tube and bonded to at least one of the inner tube or the outer tube to prevent fluid flow in the annulus along at least a portion of a length of the optical cable.