Spool Tree Well Access System with Segmented Tubing Hanger
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Solution Overview
Problem
Current well access systems, such as vertical and horizontal trees, face challenges in efficient maintenance and dual barrier protection, leading to high costs and unreliable downhole valves, especially in offshore operations, where predicting maintenance needs is difficult and requires significant equipment and time for tree and completion removal.
Innovation Solution
A well completion system with a spool tree configuration that allows for independent removal and maintenance of the tubing hanger and tree, utilizing adjustable fluid barriers and valves to provide dual barrier protection without relying on downhole valves, enabling direct downhole access and reducing maintenance costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If vertical or horizontal trees are used for well access, then well control and production are achieved, but maintenance costs and time increase significantly due to difficulty in accessing downhole components
Solution Approach 1:
The system divides the well access structure into separable modules: a tree assembly and a completion assembly that can be independently removed. The tubing hanger with barriers can be detached from the tree, allowing maintenance of downhole components without removing the entire tree structure, thus reducing maintenance time and improving accessibility.
2Ease of operation
If trees are removed for maintenance, then downhole access is improved, but dual barrier protection becomes unreliable
Solution Approach 1:
The barriers are extracted from the tree structure and integrated into the tubing hanger assembly. This allows the barriers to remain with the completion components when the tree is removed, ensuring that dual barrier protection is maintained independently of the tree's presence. The barriers can be tested and verified before tree removal.
Solution Approach 2:
The barriers are installed and tested in the tubing hanger before the tree is removed from the well. This preliminary establishment of barrier protection ensures that safety requirements are met before downhole access is enabled, maintaining reliability while improving accessibility.
3Adaptability or versatility
If downhole valves are used for well control, then operational flexibility is improved, but reliability decreases due to valve failure risks
Solution Approach 1:
The system removes reliance on downhole valves by extracting the control function to surface-operated barriers integrated in the tubing hanger. This eliminates the reliability issues associated with downhole valve failure while maintaining operational flexibility through surface control of the barrier system.
4Ease of repair
If complete tree and completion removal is performed for maintenance, then thorough inspection is possible, but productivity loss increases
Solution Approach 1:
The system segments the maintenance scope by allowing removal of only the completion assembly (tubing hanger with barriers) while leaving the tree in place. This enables thorough inspection and maintenance of downhole components without the extended downtime required for complete tree removal, thus maintaining productivity while achieving adequate repair capability.
Data Source
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AI summary
A system and method for accessing a well, in certain embodiments, includes a production tree, a cap, and a spool including a longitudinal bore configured to receive a tubing hanger. The tubing hanger includes a longitudinal bore configured to transfer product between the spool and the production tree. At least one adjustable fluid barrier is included in the tubing hanger and/or the cap. The adjustable fluid barrier can be used to open and close the longitudinal passage and allow access through the tubing hanger and/or the cap.