Telescopic Riser Section Actuator for Subsea Tension Control
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Solution Overview
Problem
Existing subsea riser systems face challenges in maintaining continuous tension and efficient disconnection from wellheads, especially at great depths, due to the large mass of the riser requiring significant lifting capacity and increasing vessel costs.
Innovation Solution
A telescopic riser section device with an actuator-pressurizing circuit that applies a downward tensile force, using a combination of pressure fluid and hydraulic cylinders to maintain tension and allow for controlled contraction, enabling safe disconnection from the wellhead without lifting the entire riser.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the riser is suspended directly from the surface vessel without heave compensation, then the lifting capacity requirement is reduced, but the riser cannot maintain continuous tension during vessel movement
Solution Approach 1:
The riser is divided into a fixed section and a telescopic section. The telescopic section can extend and contract independently to maintain tension during vessel movement, while the fixed section provides stable connection points. This segmentation allows the system to maintain continuous tension without requiring excessive lifting capacity from the surface vessel.
Solution Approach 2:
The telescopic section provides dynamic adjustment capability, allowing the riser length to change in response to vessel heave movements. This dynamic structure maintains continuous tension by absorbing vertical movements, eliminating the need for complex heave compensation systems while ensuring reliable tension maintenance.
2Force
If a telescopic section is arranged at the lower end portion of the riser, then the lifting capacity requirement is reduced, but the riser cannot be easily disconnected from the wellhead
Solution Approach 1:
The riser is segmented into a fixed section connected to the wellhead and a telescopic section that can be independently controlled. This segmentation allows the telescopic section to be contracted to provide clearance for disconnection operations, while the fixed section remains connected to the wellhead, enabling easy and safe disconnection without requiring excessive lifting capacity.
Solution Approach 2:
The telescopic section can be pre-contracted before disconnection operations to create the necessary clearance. This preliminary action prepares the riser configuration in advance, allowing the surface vessel to be moved away from the wellhead safely and efficiently without requiring high lifting capacity during the disconnection process.
3Force
If heave compensation is provided by the telescopic movability of the riser, then the lifting capacity requirement is reduced, but the riser mass must be sufficiently large to maintain tension
Solution Approach 1:
The riser is divided into a fixed section and a telescopic section. The telescopic section provides the necessary movability for heave compensation while the fixed section can be designed with optimized mass. This segmentation allows the system to achieve heave compensation capability without requiring the entire riser to have excessive mass, as only the telescopic section needs to provide the necessary flexibility and movement.
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
The solution effectively maintains riser tension and allows for safe disconnection, reducing the need for high lifting capacity and vessel costs, while enabling remote control and efficient operation during varying load conditions.
Implementation Method 1
an actuator-pressurizing circuit being connected to the at least one actuator and being arranged on the riser section and/or on the riser
Implementation Method 2
a possibility of contracting the telescopic riser section if the riser has to be disconnected from the wellhead
Data Source
AI summary
A telescopic riser section device for a riser which is arranged to connect a wellhead to a surface vessel, the telescopic riser section being placed between the wellhead and the riser and being provided with at least one actuator arranged to apply a downward tensile force to the riser; an actuator-pressurizing circuit being connected to the at least one actuator and being arranged on the riser section and/or on the riser.