Subsea Tree Radial Spool Assembly for Independent Maintenance
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Solution Overview
Problem
Current mineral extraction systems, such as those using vertical and horizontal trees, face high maintenance costs and inefficiencies due to the need for complex and costly operations when retrieving or replacing subsea trees and tubing hangers, particularly in offshore environments, where predicting maintenance needs is challenging over the life of a well.
Innovation Solution
A subsea tree and spool assembly configuration where the subsea tree is positioned radially outward from the spool assembly, allowing independent retrieval and maintenance, with a longitudinal passage for the tubing hanger and lateral flow passages for product transfer, enabling reduced maintenance duration and costs by avoiding the need for robust lifting equipment and minimizing the exchange of pressure-control devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of repair
If subsea tree and tubing hanger are retrieved using conventional vertical or horizontal tree configurations, then maintenance can be performed, but robust lifting equipment and multiple vessels are required, increasing costs and time
Solution Approach 1:
The system divides the subsea completion into separable modules: the subsea tree can be independently detached from the tubing hanger and spool assembly. This segmentation allows the tree to be retrieved separately using simpler equipment, eliminating the need for complex coordinated operations required in conventional configurations where the tree and tubing hanger are interconnected.
Solution Approach 2:
The subsea tree is extracted from the conventional integrated configuration and positioned radially outward from the spool assembly. This extraction enables the tree to be removed and maintained independently without requiring the tubing hanger to be disturbed, simplifying maintenance operations and reducing equipment requirements.
2Ease of operation
If conventional tree configurations are used, then product flow can be controlled, but the subsea tree blocks access to the longitudinal passage, preventing independent tubing hanger retrieval
Solution Approach 1:
The subsea tree is repositioned from a vertical/conventional configuration to a radial configuration relative to the spool assembly. This dimensional change in positioning allows the tree to be located at the side rather than blocking the longitudinal passage, enabling independent access and retrieval of the tubing hanger while maintaining product flow control functions.
3Productivity
If subsea tree is positioned radially outward, then independent retrieval is enabled, but the configuration must accommodate additional spatial requirements
Solution Approach 1:
The system incorporates a movable platform that can dynamically reposition the subsea tree between a first position (radially outward for independent retrieval) and a second position (for product transfer). This dynamic positioning capability allows the system to optimize the configuration for different operational modes, accommodating spatial requirements only when needed for maintenance operations.
Data Source
AI summary
A system, in some embodiments, for producing well production fluids through a tubing hanger connected with a production tubing string. The system includes a subsea tree with a production flow passage and a tree annulus flow passage. The system also includes a spool assembly separate from the subsea tree that includes a body with a longitudinal passage configured to receive and support the tubing hanger, there being an annulus between the production tubing string and the body. The spool assembly also includes a lateral flow passage extending from the spool longitudinal passage and configured to transfer the production fluids. Further, the system includes an annulus flow passage extending externally from the spool assembly and in fluid communication with the annulus.