Splice Housing for Fiber Optic Casing Imaging
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Solution Overview
Problem
The challenge in downhole environments is the harsh conditions faced by fiber optic sensors and splices, which require precise installation and can lead to faulty sensors being inserted before detection, resulting in wasted time for removal and replacement, especially in high-temperature, high-pressure boreholes.
Innovation Solution
A splice housing is designed to be disposed in the borehole with a sealed interior volume to protect splices and allow a functional bend of at least 90 degrees for spliced optical fibers, enabling testing before insertion and secure attachment to the casing, using a configuration with uphole and downhole ports for sealing and protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If splices are installed on the floor of a completion rig, then fiber optic sensors can be coupled to communication cables, but the installation cannot achieve the care and precision required for reliable installation
Solution Approach 1:
The splice is installed in advance on the floor of the completion rig in a controlled environment where precision tools and proper lighting are available. This preliminary splicing action allows technicians to perform the delicate fiber optic coupling work under ideal conditions before deploying the entire assembly into the harsh borehole environment, thereby ensuring both reliability and ease of operation.
2Productivity
If a faulty sensor is inserted into the borehole before a splice is made, then the sensor can be far down the borehole before the fault is detected, but this results in wasted time to remove the sensor for repair or replacement
Solution Approach 1:
The splice housing is pre-assembled with the fiber optic splice completed before the sensor is inserted into the borehole. This preliminary assembly allows for pre-testing of the sensor and splice connections on the surface, ensuring functionality before deployment. If a fault is detected during pre-testing, the sensor can be replaced without requiring retrieval from the borehole, thus eliminating wasted time for removal and replacement.
Solution Approach 2:
The splice housing serves as an intermediary component that decouples the splicing operation from the sensor insertion operation. By completing the splice in the housing first, then inserting the sensor into the assembled housing, the system allows for independent testing and validation of each component before final deployment, preventing faulty sensors from being deployed into the borehole.
3Reliability
If fiber optic sensors are used to monitor downhole structures, then harsh environments can be monitored, but the sensors require careful and precise installation that is not conducive to harsh downhole conditions
Solution Approach 1:
The splice housing is pre-assembled with the fiber optic splice completed in a controlled surface environment where precision installation can be performed. This preliminary assembly separates the delicate splicing operation from the harsh downhole deployment conditions, allowing technicians to install the splice with proper care and precision on the surface, then simply deploy the pre-assembled housing into the borehole without requiring precise installation operations in the harsh environment.
Data Source
AI summary
A method for imaging a structure disposed in a borehole penetrating the earth, the method including: selecting a splice housing having a first port configured to seal the housing to a first fiber optic cable and a second port configured to seal the housing to a fiber optic sensor configured to image the structure, wherein the housing includes a sealed interior volume sufficient to contain a splice of optical fibers for protection and to enable a functional bend of at least ninety degrees for at least one spliced optical fiber; disposing a splice between an optical fiber of the first fiber optic cable and an optical fiber of the fiber optic sensor in the splice housing; disposing the splice housing containing the splice in the borehole; attaching the fiber optic sensor to the structure; and disposing the structure in the borehole after the splice housing is disposed in the borehole.