Multibore Hybrid Riser Tower with Non-Contiguous Buoyancy
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Solution Overview
Problem
Hybrid Riser Towers are large, unwieldy, and prone to vortex-induced vibration and interference issues due to their size and design, which complicates fabrication and installation, especially in deepwater environments, and requires multiple structures that can interfere with each other.
Innovation Solution
A multibore hybrid riser tower design with a water injection line as the central core, surrounded by production lines and buoyancy blocks arranged non-contiguously to minimize vortex-induced vibration and interference, featuring a chain connection for buoyancy and towing, allowing for reduced drag and simplified installation without heavy vessels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple Single Line Offset Risers (SLORs) are used for a drill centre, then each production line, injection line and gas line can have its own structure, but the number of structures increases and they interfere with each other due to wake shielding and wake instability
Solution Approach 1:
The patent combines multiple SLOR structures into a single integrated multibore HRT structure that accommodates multiple production lines, injection lines and gas lines simultaneously. This merging eliminates the wake shielding and wake instability interference between multiple separate structures while maintaining the capability to serve each line individually through multiple risers within the unified tower structure.
2Device complexity
If multiple SLOR structures are placed close to each other for a drill centre, then the number of structures is reduced, but the risk of interference increases due to wake shielding and wake instability
Solution Approach 1:
The patent merges multiple SLOR structures into a single multibore HRT tower that houses multiple risers for different production and injection lines. This unified structure eliminates the harmful wake interference between closely placed separate structures by consolidating them into one tower with a single wake profile, while still providing dedicated risers for each line through the multibore configuration.
3Adaptability or versatility
If conventional HRT structures are used, then they can support multiple risers, but they are very large and unwieldy and reach the limit of component capabilities
Solution Approach 1:
The patent segments the conventional large HRT structure into a modular multibore configuration where multiple risers are arranged around a central core in a more compact configuration. This segmentation allows the structure to support multiple risers while reducing the overall size and unwieldiness by optimizing the spatial arrangement and using a central core design that efficiently accommodates multiple lines without requiring a large tower footprint.
4Adaptability or versatility
If large HRT structures are used, then multiple risers can be supported, but fabrication becomes difficult everywhere and installation requires heavy vessels
Solution Approach 1:
The patent segments the HRT into a multibore configuration with a central core and surrounding risers that can be fabricated in more manageable sections. This segmentation enables fabrication at more locations and reduces the need for heavy installation vessels by breaking down the structure into transportable modules that can be assembled on-site, while still maintaining the capability to support multiple risers for various production and injection lines.
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
The design reduces drag and interference, simplifies fabrication and installation, and minimizes the need for heavy installation vessels, enhancing the structural integrity and operational efficiency of hybrid riser towers in deepwater environments.
Implementation Method 1
surrounded by production lines and buoyancy blocks arranged non-contiguously to minimize vortex-induced vibration and interference
Implementation Method 2
Another problem with all HRTs is vortex induced vibration (alternating shedding of trailing vortexes), which can lead to fatigue damage to drilling and production risers
Implementation Method 3
featuring a chain connection for buoyancy and towing
Data Source
Figure 1
Figure 2
Figure 3a~3b
AI summary
A riser (112,114) comprises a plurality of conduits (200) extending from the seabed towards the surface and having an upper end supported at a depth below the sea surface. At least some of the conduits (200) are arranged around a structural core (410). The conduits comprise an insulated production line (200), an uninsulated service line (500) providing a pigging loop with the insulated production line, and a water injection line (210).