Cladded Sensor Wire for Downhole Optical Fiber Durability
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Solution Overview
Problem
Existing optical fibers used in downhole measurements lack durability and are susceptible to gas intrusion and mechanical stress, leading to inadequate signal transmission and reduced working load in harsh wellbore conditions.
Innovation Solution
A cladded sensor wire design featuring optical fibers positioned within a grooved conductor and surrounded by cladding, with a welded connection and optional silicone filling to enhance mechanical durability and prevent gas intrusion, improving signal-to-noise ratio and power delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If optical fibers are used in downhole measurements, then signal transmission capability is improved, but mechanical durability and resistance to gas intrusion deteriorate
Solution Approach 1:
The cable is divided into distinct functional segments: a grooved conductor portion providing mechanical protection, a cladding layer providing hermetic sealing, and optical fiber portions for signal transmission. This segmentation allows each component to specialize in its function, with the conductor handling mechanical stress and the cladding handling gas intrusion prevention.
Solution Approach 2:
The optical fibers are nested within the grooved conductor, which is itself nested within the cladding. This nested structure provides multiple layers of protection: the conductor protects the fibers from mechanical stress, while the cladding protects the entire assembly from gas intrusion, thereby improving reliability without compromising signal transmission.
2Ease of operation
If optical fibers are exposed in the cable structure, then ease of installation is improved, but susceptibility to mechanical stress and gas intrusion increases
Solution Approach 1:
The optical fibers are pre-positioned within the grooved conductor during cable manufacturing, and the cladding is pre-applied to provide hermetic sealing. This preliminary protection eliminates the need for post-installation protection measures and ensures the fibers are immediately protected against mechanical stress and gas intrusion upon deployment.
Solution Approach 2:
The grooved conductor acts as an intermediary structure between the optical fibers and the external environment. It provides a protected pathway for the fibers while the cladding serves as a secondary intermediary providing hermetic sealing. This dual-intermediary approach maintains ease of installation while effectively blocking harmful factors.
3Ease of manufacture
If traditional cable structures are used, then manufacturing simplicity is maintained, but durability and protection against harsh conditions deteriorate
Solution Approach 1:
The cladding is implemented as a thin-walled tubular structure that provides hermetic sealing and gas intrusion prevention. This thin-film approach maintains manufacturing simplicity compared to bulky protective structures, while effectively protecting the optical fibers from harsh downhole conditions through its continuous sealed barrier.
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 increases the mechanical durability and resistance to gas intrusion of optical fibers, enhancing the signal-to-noise ratio and power delivery, thereby improving the reliability and performance of downhole measurements.
Implementation Method 1
the cladding provides increased resistance to mechanical stress
Implementation Method 2
the cladding includes a welded connection along a first end and a second end of the cladding
Data Source
AI summary
Sensors for imaging boreholes via the detection of electrical and optical properties may be subject to harsh conditions downhole, such as from pressure and temperature. In addition, these sensors may be subject to impact, such as tension, elongation, and compression forces, along the wall of the borehole. The harsh conditions downhole and impacts on the sensor can lead to premature wear and even breaking. The present disclosure generally relates to an apparatus for measuring electrical and optical properties of the borehole and methods for manufacturing the apparatus.