Pivotable Marine Riser Guide Structure for Offshore Stability
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Solution Overview
Problem
Existing guide arrangements for marine risers, particularly in offshore oil and gas operations, face challenges in stabilizing light and flexible risers under dynamic conditions, requiring large bending stiffeners that increase costs and complexity.
Innovation Solution
The guide structure is pivotably supported by a frame assembly with a horizontal pivot axis, allowing for angular movement and reducing bending stress, eliminating the need for large bend stiffeners, and featuring a lighter steel structure with easy installation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a fixed guide structure with upward curvature is used to stabilize risers, then the riser stability is improved, but the bending stress and required stiffener size increase significantly
Solution Approach 1:
The guide structure is made movable relative to the frame assembly, allowing it to pivot and adjust its position dynamically. This dynamic capability enables the guide structure to accommodate riser movements without imposing large bending stresses, resolving the contradiction between stability and stress reduction.
Solution Approach 2:
The guide structure is separated from the frame assembly as an independent movable component. This segmentation allows the guide structure to move independently, reducing the transmission of bending stresses to the riser while maintaining stabilizing function through the frame assembly and anchor means.
2Stability of the object's composition
If a fixed guide structure with upward curvature is used to stabilize risers, then the riser stability is improved, but the device complexity and cost increase due to large bend stiffeners
Solution Approach 1:
The movable guide structure eliminates the need for large fixed bend stiffeners by allowing dynamic adjustment. This reduces device complexity while maintaining stability, as the guide structure can adapt to riser movements without requiring oversized stiffening components.
Solution Approach 2:
The guide structure's position and orientation parameters are made variable rather than fixed. This allows the structure to adapt to different riser configurations and movement conditions, reducing the need for large stiffeners and simplifying the overall device design.
3Stress or pressure
If a movable guide structure with horizontal pivot axis is used, then the bending stress is reduced, but the device complexity increases due to pivot mechanism
Solution Approach 1:
The pivot mechanism provides simple dynamic adjustment capability with minimal complexity. The horizontal pivot axis allows the guide structure to move freely in the necessary direction, reducing bending stress while introducing only the essential mechanical complexity required for movement.
Solution Approach 2:
The pivot mechanism is extracted as a simple, dedicated component rather than being integrated into a complex structure. This allows the pivot function to be implemented with minimal complexity, achieving stress reduction without proportionally increasing overall device complexity.
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 reduces bending stress and strain on risers, eliminates the need for large stiffeners, and simplifies installation while maintaining stability against lateral movements caused by sea currents and waves.
Implementation Method 1
a buoyancy element for keeping said guide structure at a desired level in the sea during operation
Implementation Method 2
the guide structure pivotably supported by said frame assembly with a pivot axis being substantially horizontal
Data Source
AI summary
Guide arrangement for marine risers, in particular for offshore oil and gas operations. The guide arrangement has at least one guide structure (21, 22) for a length of riser, a frame assembly (10, 10A-D) for supporting said guide structure, anchor means (11, 12) at the seabed, tether means (13, 14) connecting said frame assembly to said anchor means, and a buoyancy element (1) for keeping said guide structure (21, 22) at a desired level in the sea during operation. The guide structure (21, 22) is pivotably supported by said frame assembly (10, 10A-D) with a pivot axis (21P, 22P) being substantially horizontal.