Subsea Rigid Tie-in Connection Transport Frame
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Solution Overview
Problem
The transportation and installation of long rigid tie-in connections in the subsea oil and gas industry are hindered by their bulky and heavy nature, which exceeds the capacity of conventional vessels and requires complex support structures, leading to challenges in fabrication, transportation, and installation without risking plastic deformation.
Innovation Solution
A method and system that decouples the transport and installation of rigid spools and jumpers from surface vessel architecture, utilizing a specialized spreader or support frame with adjustable buoyancy and towing arrangements to enable towing and subsurface deployment, allowing for longer connections to be handled and installed efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the length of rigid tie-in connection is increased to reduce the use of expensive flexible pipe, then the cost is reduced, but the difficulty of fabrication, transportation and installation increases due to the heavy and awkward assembly
Solution Approach 1:
The rigid tie-in connection is divided into multiple modular sections that can be fabricated separately and then assembled on the seabed. Each module has standardized connection interfaces that allow for easy assembly using ROV-operated tools, reducing the complexity of handling extremely long single-piece rigid pipes while maintaining the cost advantage of rigid pipe over flexible pipe.
2Quantity of substance
If the length of rigid tie-in connection is increased to exceed flexible pipe application limits, then flexible pipe cost is avoided, but the assembly becomes too heavy and awkward for conventional installation vessels
Solution Approach 1:
Buoyancy modules are attached to the rigid tie-in connection assembly to counterbalance its weight during transportation and installation. These buoyancy modules can be inflated or filled with gas to provide the necessary lift, allowing conventional installation vessels to handle assemblies that would otherwise be too heavy, while still using cost-effective rigid pipe instead of expensive flexible pipe.
3Adaptability or versatility
If complex bends are added to rigid tie-in connection to impart flexibility, then the ability to accommodate seabed movement is improved, but the assembly becomes heavier and more difficult to fabricate
Solution Approach 1:
Instead of creating one complex bent rigid pipe, the connection is segmented into multiple straight or lightly-bent modules with standardized factory-made bends. Each module can be fabricated using conventional pipe bending equipment, and the overall flexibility is achieved through the articulated assembly of multiple modules on the seabed, reducing fabrication difficulty while maintaining adaptability.
Solution Approach 2:
The rigid tie-in connection uses articulated joints or flexible coupling sections between modular segments that allow relative movement. This dynamic configuration enables the assembly to accommodate seabed movement, thermal expansion, and installation tolerances while each individual module remains relatively simple to fabricate, avoiding the need for complex bends in every module.
4Ease of operation
If supporting structure is added to handle long rigid tie-in connection, then the installation capability is improved, but the combination becomes particularly bulky and heavy
Solution Approach 1:
The rigid tie-in connection modules are pre-assembled into compact configurations onshore or on a support vessel before deployment. Supporting structures such as cradles and fixtures are used during fabrication to maintain proper alignment and configuration, but these supports are removed or jettisoned before sea transport, reducing the volume and weight of the assembly during transportation while ensuring installation readiness.
Solution Approach 2:
The supporting structure is designed to be collapsible or retractable, allowing it to compact during transportation to minimize volume, and then deployed or extended during installation operations to provide the necessary support and handling capability. This dynamic supporting structure reduces the overall volume of the assembly during transport while maintaining installation capability when needed.
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 the installation of significant-sized spools or jumpers by towing them from shore to a subsea site, reducing the risk of deformation and accommodating complex shapes, while minimizing the need for flexible pipes, thus overcoming the limitations of conventional vessel capacities and support structures.
Implementation Method 1
supporting the tie-in connection in the water by buoyancy acting on a frame that supports the tie-in connection until installation
Data Source
Figure 1a~1b
Figure 2
Figure 3
AI summary
A method of transporting a rigid tie-in connection across a body of water for installation underwater. The method comprises: supporting the tie-in connection in the water by buoyancy acting on a frame that supports the tie-in connection until installation; lowering the buoyancy- supported frame and the tie-in connection into a sub-surface transit configuration; and in the transit configuration, towing the buoyancy-supported frame and the tie-in connection behind a towing vessel toward an installation site. A System for implementing the method comprises: a towable frame arranged to support the tie-in connection until installation; and external buoyancy attached to the frame by an extensible suspension link arranged to suspend the frame from the buoyancy in water in use, the link being extensible to lower the frame from a raised surface-tow configuration into a lowered sub-surface transit configuration.