Hybrid Tower Seabed Connections Using Distributed Buoyancy
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Solution Overview
Problem
Current bottom-to-surface connection systems for subsea oil and gas production face challenges in deep waters, including high costs, complex manufacturing, and interference issues with multiple flexible pipes, which increase the risk of collisions and require extensive lengths that compromise stability and thermal insulation.
Innovation Solution
A hybrid tower system comprising multiple rigid vertical risers connected to flexible pipes with distributed buoyancy elements, allowing for a reduced number of large floats and optimized spacing, which reduces the length of flexible pipes, minimizes interference, and enhances thermal insulation by using syntactic foam or glass microbeads for buoyancy and insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple flexible pipes are used to connect subsea wellheads to the FPSO reel, then more bottom-to-surface connections can be established, but the pipes interfere with each other and collide, increasing complexity and reducing reliability
Solution Approach 1:
The system divides the connection path into two segments: rigid risers that extend vertically from the seabed to near the surface, and flexible pipes that connect from the reel to the risers. This segmentation allows the rigid risers to maintain fixed positions while the flexible pipes operate in a controlled zone, reducing interference and collision risks between multiple connections
Solution Approach 2:
The invention introduces a vertical dimension by using tall rigid risers that extend upward from the seabed, creating a three-dimensional tower structure. This vertical arrangement separates multiple connections in the vertical space rather than having them all at the same level, reducing horizontal interference and collision risks between flexible pipes
2Length of stationary object
If extensive lengths of flexible pipes are used to reach from the reel to subsea wellheads, then deep water connections are achieved, but the pipe length increases interference and collision risk
Solution Approach 1:
The connection system is segmented into rigid risers providing the vertical reach to deep water, and shorter flexible pipes connecting only from the reel to the risers. This eliminates the need for extremely long flexible pipes, reducing interference and collision risk while still achieving deep water connections
Solution Approach 2:
The rigid risers act as intermediary structures between the seabed wellheads and the surface reel. They provide the necessary vertical reach to deep water while the flexible pipes only need to bridge the remaining gap to the risers, significantly reducing the flexible pipe length and associated interference problems
3Force
If large floats are used to provide buoyancy for the flexible pipes, then the pipes can be supported, but the floats occupy space and increase the risk of collisions
Solution Approach 1:
The invention extracts the buoyancy function from large floats and redistributes it along the flexible pipes through distributed buoyancy elements. This eliminates the need for large concentrated floats that occupy space and increase collision risk, while still providing the necessary buoyancy support
Solution Approach 2:
Instead of using large floats that provide buoyancy at single points, the invention applies buoyancy locally along the entire length of the flexible pipes through distributed buoyancy elements. This provides continuous support while minimizing the space occupied by buoyancy devices, reducing collision risk
4Productivity
If multiple flexible pipes are used for multiple connections, then more wellheads can be connected, but thermal insulation efficiency is compromised
Solution Approach 1:
The system segments the connection into rigid risers that can be heavily insulated for efficient thermal transport, and flexible pipes that are minimized in length. This allows the majority of the thermal transport path to be through well-insulated rigid structures, maintaining thermal efficiency while supporting multiple connections
Solution Approach 2:
The rigid risers serve as thermal intermediary structures that can be extensively insulated along their length. They transfer thermal energy efficiently from the seabed wellheads to the surface, while the minimized flexible pipe section reduces thermal losses, maintaining overall insulation efficiency across multiple connections
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 configuration enables a higher number of bottom-surface connections in a compact space, reduces manufacturing and installation costs, improves stability by eliminating large floats, and maintains thermal insulation efficiency, thus supporting long-term operation in deep waters.
Implementation Method 1
at least one said hybrid tower comprises: at least two said first flexible pipes with positive buoyancy... and said risers are equipped with second peripheral coaxial floats surrounding said risers and integral with said risers... all of said second coaxial floats compensating at least for the total weight l1 of said risers
Implementation Method 2
improves thermal insulation by using syntactic foam or glass microbeads for buoyancy and insulation
Data Source
Figure 1
Figure 2
Figure 3~3C
AI summary
The present invention relates to an installation comprising seabed-to-surface connections, including a so-called floating support comprising a reel (1a), and comprising: a plurality of risers (10), the upper ends of which are solidly connected to a supporting structure (3a), and a plurality of flexible pipes (4a-4b, 4a1-4a2, 4b1-4b2) extending from the reel to the upper ends (10a) of the risers, including at least two so-called first positive-buoyancy flexible pipes positioned at different heights and guiding modules (20) solidly connected to a tendon and capable of sliding along the floats (11) of the risers.