Subsea Buoyancy String Insertion for Deepwater Pipeline Weight Reduction
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Solution Overview
Problem
Existing methods for controlling the buoyancy of large submerged pipeline bundles, especially in deep and ultra-deep water, are hindered by the need for thick-walled carrier pipes to withstand hydrostatic pressure, which increases weight and complexity, and require external buoyancy modules that are difficult to manage and retrieve.
Innovation Solution
An elongate articulated buoyancy string housed within a tubular buoyancy holder that can be easily inserted or withdrawn to alter the buoyancy of the structure, eliminating the need for a closed carrier pipe and external buoyancy modules, allowing for more flexible and efficient buoyancy management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If thick-walled carrier pipes are used to withstand hydrostatic pressure in deep water, then the strength and pressure resistance are improved, but the weight and complexity of the buoyancy system increase
Solution Approach 1:
The buoyancy system is divided into multiple discrete buoyancy modules distributed along the pipeline bundle length. Each module is a separate unit that can be independently managed, allowing the system to achieve necessary buoyancy without requiring a single heavy thick-walled carrier pipe to withstand all hydrostatic pressures.
Solution Approach 2:
The buoyancy function is extracted from the carrier pipe structure itself and implemented through separate buoyancy modules. This separation allows the carrier pipe to be optimized for pressure resistance while the buoyancy modules provide the necessary buoyant force, reducing the overall weight and complexity of the system.
2Adaptability or versatility
If external buoyancy modules are attached to the pipeline bundle, then the buoyancy control capability is improved, but the device complexity and difficulty of management increase
Solution Approach 1:
The buoyancy modules are designed to be nested within or attached to the pipeline bundle structure in an organized manner. Each module contains integrated components for buoyancy control, and the modular design allows for systematic arrangement that reduces overall system complexity while maintaining adaptability.
Solution Approach 2:
The buoyancy system incorporates dynamic adjustment capabilities through individually controllable buoyancy modules. Each module can be independently adjusted or released, allowing the system to adapt to different operational conditions (towing, installation, retrieval) without requiring complex centralized control mechanisms.
3Strength
If a closed carrier pipe is used to enclose buoyancy chamber, then the structural integrity is improved, but the ease of insertion and withdrawal of buoyancy elements is reduced
Solution Approach 1:
The carrier pipe structure incorporates segmented or sectioned openings at strategic locations that allow buoyancy modules to be inserted and withdrawn while maintaining the overall structural integrity of the closed pipe. The segmentation enables access points without compromising the pressure-containing capability of the carrier pipe.
Solution Approach 2:
The invention introduces intermediary structures such as access hatches, removable end caps, or flexible seals that facilitate the insertion and withdrawal of buoyancy modules while preserving the closed carrier pipe structure. These intermediaries provide temporary openings that can be sealed when not in use, maintaining structural integrity.
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 pipeline bundles in deeper waters using the controlled-depth tow method by reducing the weight and complexity of buoyancy systems, facilitating easier deployment and retrieval of buoyancy modules, and eliminating the need for buoyancy fluid management.
Implementation Method 1
An elongate articulated buoyancy string housed within a tubular buoyancy holder that can be easily inserted or withdrawn to alter the buoyancy of the structure
Data Source
Figure 1~2
Figure 3~6
Figure 7
AI summary
A subsea structure comprises: an elongate articulated buoyancy string comprising a longitudinal series of buoyancy elements; and at least one elongate buoyancy holder that is fixed relative to the structure and is capable of housing the buoyancy string. The buoyancy of the structure may be altered by moving the buoyancy string along a transit path that extends along and within the buoyancy holder and through an end opening of the buoyancy holder. The buoyancy string passes through that end opening on being inserted into or withdrawn from the buoyancy holder.