Subsea Cable Installation Tool Tension Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for deploying subsea cables at large depths face challenges with cable drift due to strong sea currents and the risk of tangling with ROV umbilicals, particularly in rough seas, where high tension solutions complicate observing the touchdown point and lead to cable damage.
Innovation Solution
A subsea installation tool with a tensioner that actively pulls down the flexible body, allowing high tension in the upper section between the vessel and the tool while maintaining low tension in the lower section to the seabed, using a main body with sufficient mass and density to create a downward force, and optionally including chutes and a trencher for efficient deployment and trenching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high tension is applied to the cable during deployment, then cable control is improved, but cable damage risk increases and touchdown point observation becomes difficult
Solution Approach 1:
The cable is divided into two sections with different tension characteristics: an upper section (from vessel to installation tool) maintained at high tension for control, and a lower section (from installation tool to seabed) maintained at low tension to reduce damage risk. The installation tool acts as a segmentation point between these two tension zones.
Solution Approach 2:
Different tension levels are applied to different sections of the cable based on local requirements. The upper section requires high tension for active control by the tensioner, while the lower section requires low tension to minimize damage risk at the touchdown point. This local differentiation resolves the contradiction between control and damage prevention.
2Object-affected harmful factors
If the cable is allowed to drift freely at the seabed, then cable damage from tension is reduced, but cable control is lost in strong currents
Solution Approach 1:
The cable system is segmented into controlled and uncontrolled zones. The upper section is actively controlled by the tensioner while the lower section is allowed to drift freely on the seabed. This segmentation enables simultaneous achievement of cable control where needed and damage reduction where control is not required.
3Stability of the object's composition
If a guide weight is used to maintain vertical cable position, then cable stability is improved, but the cable becomes trapped from top to bottom and cannot accommodate sensor stations
Solution Approach 1:
The guidance function is segmented: the installation tool provides active guidance and stability in the upper water column, while the lower section of the cable is allowed to drift freely on the seabed. This eliminates the need for continuous top-to-bottom guidance, enabling sensor stations to be accommodated in the lower section.
Solution Approach 2:
The guidance function is extracted from the lower section of the cable and concentrated in the upper section where the installation tool operates. This extraction removes the constraint that would otherwise trap the entire cable, allowing the lower section to move freely and accommodate sensor stations.
4Productivity
If the installation tool is operated from the same vessel as the ROV, then operational efficiency is improved, but cable tangling with ROV umbilical occurs
Solution Approach 1:
The cable guidance and tensioning function is extracted from the ROV system and assigned to a dedicated installation tool. This extraction eliminates the need for the ROV umbilical to run parallel to the cable, removing the source of potential tangling while maintaining operational efficiency through the dedicated installation tool.
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
This solution enhances the reliability and efficiency of cable deployment by reducing the risk of cable damage and entanglement, maintaining control over the flexible body even in strong currents, and allowing for precise placement and trenching of sensor stations.
Implementation Method 1
a main body suspended from the vessel using an umbilical and having a mass and density sufficient to create a downward force in the umbilical
Implementation Method 2
a tensioner couplable to the flexible body, e.g. by clamping, to actively pull down the flexible body. Thereby tension in a first (upper) section of the flexible body from the installation vessel to the installation tool can in a controlled manner be made larger
Implementation Method 3
A GW umbilical is strong and drag displacements are limited due to the weight of the wire and the GW itself
Data Source
AI summary
A subsea installation tool for installing a flexible body, e.g. a subsea fiber cable on a seabed from a surface vessel, and an associated method for installing the flexible body on the seabed is provided. The installation tool includes a tensioner that may be coupled to the flexible body to actively pull it down, thus increasing tension in an upper section of the cable from the installation vessel to the installation tool. High tension in the upper part of the cable gives good control even in strong sea currents. At the same time the tensioner enables lower tension in the bottom part cable from the installation tool to the seabed, giving good control of the touchdown position on the seabed.