Fiber Optic Splice Protector for High-Temperature Wells
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Solution Overview
Problem
Existing optical fiber splice protectors fail to provide adequate mechanical and thermal protection in harsh environments like oil and gas wells due to weak mechanical connections and limited temperature tolerance, leading to reliability issues and mechanical stress on the optical fibers.
Innovation Solution
A splice protector with a metallic body and heat shield, fusion-welded to an Inconel outer jacket, which absorbs and dissipates thermal energy during welding, and has a design that minimizes thermal stress on the optical fiber, along with Excess Fiber Length to accommodate thermal expansion differences, ensuring the optical fiber is secured at a temperature that reduces mechanical stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fusion splicing is used to join optical fiber strands, then the optical fiber connection is achieved, but the mechanical connection strength is weak with only 15% of original fiber axial strength
Solution Approach 1:
The splice protector is designed with a V-shaped clamp structure that pre-positioned to cradle and support the fusion splice before environmental stresses occur. This predetermined mechanical support structure cushions the weak fusion joint from bending and tensile forces, preventing failure before it can occur.
Solution Approach 2:
The splice protector divides the protection function into separate components: the V-shaped clamp for mechanical support, the heat shrink tube for thermal protection and bonding, and the rod for bend prevention. This segmentation allows each component to optimize its specific function while collectively strengthening the overall splice assembly.
2Temperature
If heat shrinkable material is used to protect the splice, then thermal protection is provided, but the temperature range is limited and thermal expansion differences create axial stress
Solution Approach 1:
The patent changes the material parameter of the heat shrink tube from conventional polymers to high-temperature materials such as PTFE (polytetrafluoroethylene) or other fluoropolymers that can withstand temperatures up to 260°C or higher. This parameter change in material composition allows the splice protector to function in high-temperature environments like steam-assisted gravity drainage (SAGD) wells while the oversized design accommodates thermal expansion differences.
3Strength
If a metal rod is placed in the heat shrink tube to protect from bends, then mechanical protection is improved, but thermal expansion differences between metal rod and optical fiber create axial stress
Solution Approach 1:
The patent changes the material parameter of the support rod from conventional metals to materials with thermal expansion coefficients matched to optical fiber, such as certain ceramics or specialized alloys. This parameter change in material composition allows the rod to expand and contract at similar rates to the fiber during temperature cycles, eliminating differential thermal expansion stresses while maintaining bend protection functionality.
4Reliability
If the splice protector is placed in a capillary tube for chemical protection, then hermeticity is achieved, but the protector moves around due to vibrations and shocks creating failure points
Solution Approach 1:
The patent employs the capillary tube as a flexible hermetic barrier that conforms to the splice protector assembly. The capillary tube's flexible nature allows it to accommodate minor movements and vibrations without creating stress concentrations or failure points, while maintaining chemical protection. The tube is sized to provide a snug fit that minimizes movement of the protector within the wellbore environment.
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 provides enhanced mechanical and thermal protection, allowing the optical fiber to withstand high temperatures and mechanical stresses, reducing the risk of damage and ensuring reliable operation in extreme environments.
Implementation Method 1
a heat shield positioned between the passageway and outer region to prevent heat damage to the optical fiber when the body is fusion welded to the metallic jacket
Implementation Method 2
The body has an outer region configured to be joined by a fusion weld to the outer metallic jacket
Implementation Method 3
These splices are done by aligning the strand and melting them locally, usually by an arc effect, to fuse them
Implementation Method 4
U.S. Pat. No. 5,731,051 to Fahey et al. proposes a sleeve for protecting a fusion splice with a support element made of polymer having a coefficient of thermal expansion which is approximately equal to the coefficient of thermal expansion of the optical fiber
Data Source
AI summary
An optical fiber cable for installation in a subterranean formation, where the temperature could be in excess of 150 degrees C. The optical fiber cable has an outer metallic jacket defining an elongated conduit with an internal elongated channel that receives an optical fiber. The optical fiber has two strands joined by a splice. A splice protector has a body with a passageway receiving the splice. The body has an outer region configured to be joined by a fusion weld to the outer metallic jacket.