Sliding Buoyancy Modules for Offshore Tower Buckling

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Solution Overview

Problem

Existing bottom-surface connection installations for multi-riser hybrid towers in offshore oil and gas production require expensive floats and foundations to manage buoyancy and tension, leading to compressive stresses that cause lateral buckling and increased costs.

Innovation Solution

The implementation of sliding buoyancy and guidance modules along the tendon and risers, which distribute buoyancy uniformly and eliminate the need for top floats and foundations, allowing the tower to remain vertical without permanent tensioning, reducing the required buoyancy and foundation tension.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional floats and foundations are used to manage buoyancy and tension in multi-riser hybrid towers, then the tower can remain stable and vertical, but the compressive stresses cause lateral buckling and installation costs increase significantly

Engineering Contradiction:

Improvetower stabilityVSAvoidlateral buckling and compressive stresses

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The tower structure is divided into multiple independent sections with individual risers connected to the seabed, allowing each segment to bear loads independently rather than concentrating stresses on a single foundation-point, thereby reducing lateral buckling risks

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system allows dynamic adjustment of buoyancy modules along the tendon, enabling the tower to adapt its tension distribution in real-time to prevent compressive stresses that lead to lateral buckling, while maintaining vertical stability

Inventive Principle:

Principle #15Dynamics

2Reliability

If traditional floats and foundations are used to provide buoyancy and tension support, then the tower structure can be maintained, but the installation and maintenance costs increase

Engineering Contradiction:

Improvetower support capabilityVSAvoidinstallation and maintenance cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The buoyancy modules are designed to slide along the tendon and self-adjust to optimal positions, eliminating the need for expensive external floats and foundations, thereby reducing both installation and maintenance costs while maintaining tower support capability

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The invention extracts and eliminates the traditional float and foundation components from the system, replacing them with sliding buoyancy modules that perform the same support function at lower cost, directly reducing installation and maintenance expenses

Inventive Principle:

Principle #2Taking out (Extraction)

3Ease of manufacture

If sliding buoyancy modules are implemented to distribute buoyancy uniformly, then the need for top floats and foundations is eliminated, but the complexity of the buoyancy distribution system increases

Engineering Contradiction:

Improvereduction of float and foundation requirementsVSAvoidbuoyancy distribution mechanism

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The complex mechanical buoyancy distribution system is replaced with a sliding module mechanism that uses simple gravitational and buoyant forces to automatically distribute buoyancy uniformly along the tendon, reducing device complexity while eliminating the need for traditional floats and foundations

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 the tension and buoyancy demands on the float and foundation, lowering installation and maintenance costs while preventing lateral buckling, allowing for more efficient and cost-effective operation of the multi-riser hybrid tower.

Implementation Method 1

buoyancy elements cooperating with said tendon, distributed along said tendon, preferably buoyancy elements resistant to underwater hydrostatic pressure, more preferably syntactic foam buoyancy elements

Methodology Applied

Scientific EffectBuoyancy: Archimedes' Principle (Buoyancy)

Data Source

PatentEP2401468B1Bottom-surface connecting installation of the multi-riser hybrid tower type, comprising sliding buoyancy modules

Publication Date: 2015.03.04 SAIPEM SA

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Figure 3A

AI summary

The present invention relates to a bottom-surface connecting installation (1) for connecting a plurality of sub-sea pipes (2- 1,2-2) resting on the sea bottom (12) to a floating support (10) on the surface (13), of the multi-riser hybrid tower type, comprising: 1) a tower (3) comprising : a) a vertical tendon (4), and b) a plurality of vertical rigid pipes (3- 1,3-2), c) a plurality of guide means (22) for guiding said risers, and d) buoyancy elements (21) collaborating with said tendon and 2) a plurality of flexible connecting pipes (6- 1,6-2) characterized in that the said tower (3) comprises a plurality of buoyancy and guide modules (20,20- 1,20-n) constituting a plurality of independent structures able to slide along the said tendon and along the said risers, the said structure (20) supporting the said buoyancy elements (21) and guiding the said risers into a position preferably uniformly and symmetrically distributed about the said tendon.