Subsea Vessel Mobile Deck Heave Compensation Riser Elimination
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Solution Overview
Problem
Existing offshore drilling vessels require a riser for subsea wellbore activities, which is time-consuming to build and remove, and necessitates a large vessel, limiting their versatility for wellbore-related tasks without a riser.
Innovation Solution
A vessel equipped with a heave-compensated mobile working deck and hoisting device that allows for subsea wellbore activities without a riser, using hydraulic cylinders for heave compensation and a hoisting system to lift and lower objects along a firing line, enabling the mobile deck to move between lowered and elevated positions for enhanced operational flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a riser is used for subsea wellbore activities, then stable operations are achieved, but time consumption increases and vessel size requirements increase
Solution Approach 1:
The patent removes the riser from the system entirely, replacing it with a mobile working deck that can be directly positioned over the wellhead. This extraction of the riser component eliminates the time-consuming building and removal operations while maintaining operational stability through the heave-compensated mobile deck platform.
Solution Approach 2:
The patent employs a mobile working deck that can dynamically adjust its position and provide heave compensation to counteract wave motions. This dynamic positioning system replaces the static riser structure, enabling stable operations without requiring a fixed riser installation, thus reducing the time needed for setup and teardown.
2Reliability
If a riser is used for subsea wellbore activities, then operational stability is provided, but vessel size increases
Solution Approach 1:
By removing the riser from the system, the patent eliminates the need for large vessels that would be required to support and maneuver a riser. The mobile working deck operates independently without requiring the extensive space and structural support of a traditional riser system, thereby reducing vessel size requirements.
Solution Approach 2:
The patent changes the operational parameters by using a heave-compensated mobile working deck that can stabilize itself against wave motions. This eliminates the need for large vessel size to provide stability, as the mobile deck actively compensates for heave motions through hydraulic cylinders, allowing smaller vessels to perform the same operations.
3Adaptability or versatility
If a mobile working deck is used without riser, then versatility improves, but heave compensation complexity increases
Solution Approach 1:
The mobile working deck is designed as a multi-functional platform that can perform various wellbore activities including workovers, maintenance, and installation operations. The same heave compensation system serves all these diverse functions, making the complexity worthwhile by enabling versatile operations that would otherwise require multiple specialized vessels or systems.
Solution Approach 2:
The heave compensation system is integrated into the mobile working deck itself, allowing the deck to self-stabilize against wave motions without requiring external support systems. This self-service capability, achieved through hydraulic cylinders that actively counteract heave, enables the deck to operate independently and perform multiple functions without adding proportional complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables a wide range of subsea wellbore activities, including workover and maintenance, with reduced time and vessel size requirements by eliminating the need for a riser, while maintaining heave compensation for stable operations in wave conditions.
Implementation Method 1
a mobile deck compensator configured to lift the mobile working deck out of the lowered position into an elevated position and configured to provide a heave compensated motion of the mobile working deck when lifted in the elevated position
Implementation Method 2
a hoisting device configured for lowering and lifting an object along the firing line below the mobile working deck
Data Source
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AI summary
The invention relates to a vessel (1) for performing subsea wellbore related activities such as workover activities, well maintenance, installing an object on a subsea well bore (2), wherein the vessel comprises a floating hull (3), a hoisting device (7), a mobile working deck (15) and a mobile deck compensator (18). According to the invention, the vessel is configured to enable the hoisting device to lower and lift objects in a firing line below the mobile working deck.