Subsea Module Tool Hanger Sealing for Well Abandonment
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Solution Overview
Problem
The challenge in subsea well plug and abandonment operations is the high cost and complexity due to the need for heavy equipment and semi-submersible vessels, particularly in achieving permanent barriers and maintaining well integrity under varying regulatory requirements.
Innovation Solution
A subsea module and tool hanger system that includes a spool with a main bore, a component connector, and seals to securely mount and seal on a wellhead or tree, allowing for the deployment of an in-well tool string to isolate wellbore and annuli, utilizing a circulation block and return block for fluid management, and enabling wireless activation of barrier devices for efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heavy equipment and semi-submersible vessels are used for plug and abandonment operations, then well integrity and barrier reliability are improved, but operational cost and equipment complexity increase significantly
Solution Approach 1:
The system divides the plug and abandonment operation into modular components: a subsea module with barrier devices, a tool hanger with sealing mechanisms, and separate barrier valves. This segmentation allows each component to be optimized independently and deployed without requiring heavy semi-submersible vessels, reducing equipment complexity while maintaining well integrity through coordinated function of the modular segments.
Solution Approach 2:
The tool hanger acts as an intermediary mechanism between the subsea module and the wellbore, providing a sealing interface and suspension point for the in-well tool string. The barrier valves serve as intermediaries to control fluid flow independently, allowing well isolation without requiring complex heavy equipment for the entire operation.
2Reliability
If multiple plugs are placed in the well to provide redundancy, then barrier reliability is improved, but device complexity and operational difficulty increase
Solution Approach 1:
The system merges multiple barrier functions into integrated components: the subsea module incorporates both a barrier device and barrier valve, the tool hanger integrates sealing mechanisms with suspension functions, and the circulation/return blocks combine fluid control capabilities. This merging reduces the number of separate components needed while maintaining redundant barrier reliability through multi-functional design.
3Reliability
If semi-submersible vessels are used for plug and abandonment operations, then well control capability is improved, but operational cost increases
Solution Approach 1:
The subsea module and tool hanger system is designed to be self-contained with all necessary barrier devices, sealing mechanisms, and fluid control capabilities integrated onboard. This self-service capability eliminates the need for expensive semi-submersible vessels by allowing the system to perform well control operations independently at the subsea location, significantly reducing operational costs while maintaining well control reliability.
4Productivity
If a single trip isolation of upper well annuli is achieved, then productivity is improved, but sealing reliability requirements increase
Solution Approach 1:
The tool hanger is pre-configured with sealing mechanisms and barrier valves before deployment. The circulation and return blocks are pre-assembled with all necessary sealing surfaces and control mechanisms. This preliminary preparation enables single-trip isolation of the upper well annuli by having all sealing components ready for immediate operation, achieving both high productivity and reliable sealing without requiring multiple trips or additional equipment.
Data Source
AI summary
A system including a subsea module, a tool hanger, and an in-well tool string coupled to and extending from a lower portion of the tool hanger is provided. The subsea module includes a subsea spool with a main bore formed therethrough, and the main bore includes a tool hanger interface. The subsea module also includes a connector for mounting the subsea module on a subsea component, wherein the connector includes a grip configured to engage the subsea component, and a first seal coupled to the connector and configured to seal the connector against the subsea component. The tool hanger is disposed within the main bore and coupled to the tool hanger interface via at least a second seal configured to seal the tool hanger against the main bore of the subsea spool. The in-well tool string is configured to couple the tool hanger to an in-well tool.