Multi-Cable Abandonment and Recovery System for Deepwater Load Control
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Solution Overview
Problem
Existing abandonment and recovery (A&R) systems for deepwater pipeline laying face challenges with high load requirements, limited cable diameter, and inadequate control over cable rotation and tension, particularly in ultra-deepwater applications where heavy tension equipment and specialized buoyant members are needed.
Innovation Solution
A multi-cable system with at least two cables, each with a length adapted for deep water, connected to a winch system with traction regulating means and a cable connector that allows controlled rotation and tension distribution, using a combination of storage and traction winches, and a rotation-measuring device for precise control, along with a cable connector featuring hooks and connection members for efficient load handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a single thick cable is used to handle heavy loads in deepwater, then the load-bearing capacity is sufficient, but the cable diameter becomes too large and winch capacity requirements increase
Solution Approach 1:
The single thick cable is divided into multiple thinner cables (typically 2-4 cables) that work together to support the load. Each cable carries a portion of the total load, allowing the use of thinner, more manageable cables while maintaining the required load-bearing capacity. This segmentation reduces the diameter of individual cables and distributes the winch capacity requirements across multiple lines.
2Ease of operation
If cables are used for abandonment and recovery operations, then the load can be transported, but the cables tend to rotate and intermingle during movement
Solution Approach 1:
The cables are pre-configured with fairleads and guide rollers that constrain their movement paths before the abandonment or recovery operation begins. These guide elements are installed in advance to prevent cables from rotating or intermingling during the actual load movement, ensuring stable cable arrangement throughout the operation.
Solution Approach 2:
Fairleads and guide rollers act as intermediary elements between the cables and the load/vessel. These intermediaries control the cable paths, prevent direct contact between cables that would cause intermingling, and maintain proper cable orientation during dynamic operations.
3Force
If traditional A&R systems are used in ultra-deepwater, then heavy tension equipment is required, but the system becomes expensive and less adaptable
Solution Approach 1:
The tension handling capability is segmented across multiple cables rather than requiring a single heavy-duty cable system. This allows the use of standard, off-the-shelf cable and winch components that are more adaptable and cost-effective while collectively providing the required ultra-deepwater tension handling capability.
Solution Approach 2:
The multi-cable system is designed to be universally applicable to various deepwater and ultra-deepwater applications. The same basic configuration can be used for different load types and water depths by adjusting cable length and tension, reducing the need for specialized expensive equipment and improving system adaptability.
Data Source
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AI summary
Method for abandoning or recovering a load, typically a pipeline or sub-sea structure, at sea, using a multi-cable assembly with at least two cables for lowering, respectively raising a load during abandonment, respectively recovery of a load, wherein the traction in each of said at least two cables is adjusted in function of the desired rotation of the load end of the multi-cable assembly.