Subsea Plug Handling Tractor for Tubing Hanger Installation
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Solution Overview
Problem
Existing subsea wellhead assembly systems face challenges in efficiently installing and removing plugs from tubing hangers, particularly due to the need for a riser to the surface and the complexity of handling large, heavy production trees with multiple valves and controls.
Innovation Solution
A system and method utilizing a housing with a tractor and end effector to maneuver plugs in and out of tubing hangers, where the tractor is deployed from within the housing and controlled remotely, allowing for plug installation and removal without the need for a riser, using a remotely operated vehicle (ROV) for guidance and control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a riser is used to install and remove plugs from tubing hangers, then plug handling can be performed, but system complexity and operational time increase
Solution Approach 1:
The invention extracts the plug handling function from the complex riser system and relocates it to a subsea housing unit. The housing contains a tractor that can deploy and retrieve plugs directly at the wellhead, eliminating the need to bring equipment through the riser to the surface and back. This separation of the plug handling function from the riser infrastructure resolves the contradiction by maintaining operational capability while reducing system complexity.
Solution Approach 2:
The invention introduces a subsea housing unit as an intermediary between the plug and the external control system. The housing contains the tractor and plug handling mechanisms, acting as a local base that enables plug operations without requiring direct riser access. This intermediary structure allows plug handling to occur subsea, eliminating the need for complex riser-based operations while maintaining controllability through the ROV and control line.
2Adaptability or versatility
If production trees are installed with multiple valves and controls, then well control capability is improved, but handling and installation difficulty increase
Solution Approach 1:
The invention segments the production tree into modular components that can be handled and installed separately. The tractor-based plug handling system allows individual components to be manipulated independently, making it easier to manage the complexity of multiple valves and controls. Each valve and control can be installed and tested separately before final assembly, reducing the overall difficulty of handling the complete production tree system.
3Reliability
If plugs are removed through open water riser after tree installation, then safety barrier function is maintained, but operational time and cost increase
Solution Approach 1:
The invention performs preliminary action by installing the plug handling tractor and housing system during the initial wellhead assembly phase. This allows the plug to be removed quickly through the housing chamber when needed, rather than requiring complex riser operations. The safety barrier function is maintained because the plug can be rapidly deployed or retrieved through the pre-positioned housing, significantly reducing operational time compared to traditional riser-based removal methods.
Data Source
AI summary
A system for maneuvering a plug in and out of a tubing hanger mounts to a subsea wellhead assembly. The system includes a tractor and an end effector that are sheltered in a housing. A control cable spools from a reel mounted on the housing and attaches to the tractor. The control cable provides communication from a remotely operated vehicle (ROV) to the tractor and end effector so that commands from the ROV via the control cable control the tractor and end effector. After the housing connects to the wellhead assembly, control signals from the ROV activate the tractor to drive the end effector into the wellhead assembly and command the end effector to set the plug in the tubing hanger, or to remove the plug from the tubing hanger.