Subsea Guide Tool for Pipeline Catenary Control
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Solution Overview
Problem
Positioning lightweight elongate articles such as pipelines and umbilicals underwater is challenging, especially in deepwater areas with strong currents, due to issues like over-bending, compression, unintended contact with installation vessels, excessive tension, and maintaining a desired catenary shape, especially when visibility is poor due to sediment.
Innovation Solution
An ROV-controlled guide tool with a sleeve that allows the elongate article to slide axially, equipped with a grab handle for a submersible vehicle to apply guide forces and maintain the desired catenary shape, and a method for automatically controlling the guide tool's position along a predefined lay path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a depressor unit is used to control the catenary shape, then the position control is improved, but the device complexity and handling difficulty increase due to the bulky and heavy structure supported by wires
Solution Approach 1:
The invention extracts the essential function of the depressor unit (controlling catenary shape) and implements it through a simplified ROV-guided article that can be easily deployed and positioned without the bulky wire-supported structure. The ROV provides direct guidance forces eliminating the need for complex wire support systems.
Solution Approach 2:
The invention replaces the mechanical wire-supported depressor unit with an ROV (remotely operated vehicle) that uses thrusters and manipulators to apply guidance forces directly to the article. This substitutes a complex mechanical wire support system with a more agile and controllable robotic system.
2Productivity
If traditional laying methods are used, then the installation process is simple, but the lay accuracy decreases in deepwater areas with strong currents and poor visibility
Solution Approach 1:
The invention incorporates ROV-based real-time monitoring and feedback control to track the article's position and adjust guidance forces dynamically. This feedback mechanism enables accurate laying in deepwater and strong current conditions while maintaining installation productivity.
Solution Approach 2:
The ROV-guided system enables the article to be actively guided and positioned by itself through the ROV's manipulators and thrusters, rather than relying on passive wire-supported depressor units. This self-service capability improves both accuracy and efficiency in challenging environments.
3Ease of operation
If lightweight articles are used to reduce handling difficulty, then the ease of operation improves, but the stability worsens due to adverse influence from subsea currents
Solution Approach 1:
The invention introduces the ROV as an intermediary between the installation system and the lightweight article. The ROV provides active guidance and stabilization forces to counteract current effects, enabling lightweight articles to be handled easily while maintaining stability through dynamic control.
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
Improves lay accuracy and speed by actively controlling the catenary shape and position, reducing the risk of over-bending and contact with installation vessels, while allowing installation in higher sea states and faster currents without the need for depressor units or deployment wires.
Implementation Method 1
equipped with a grab handle for a submersible vehicle to apply guide forces and maintain the desired catenary shape
Implementation Method 2
a sleeve through which the article can move axially during laying
Data Source
AI summary
A method of controlling subsea laying of an elongate article includes guiding the article using a submersible vehicle such as an ROV that carries a guide tool. The guide tool has a sleeve through which the article moves axially during laying, while the vehicle applies cross-axial guide forces to the article via the sleeve. Also disclosed is a guide tool including a sleeve through which the article can move axially during laying, and a grab handle whereby a submersible vehicle may hold the tool using a grabber. Alternatively, the guide tool can be attached to or integrated with the vehicle.