Water-Soluble Plugs for Subsea Pipeline Connection
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Solution Overview
Problem
Current methods for connecting longer pipeline bundles in the subsea oil and gas industry face challenges such as multiple underwater interfaces, complex welding processes, and the risk of seawater flooding, which increase costs and complexity, especially when using traditional solid plugs for isolation.
Innovation Solution
The method involves using water-soluble plugs made of materials like paper or organic composites that can withstand seawater pressure and maintain structural integrity for at least an hour, allowing for underwater connection of pipeline sections before being flushed away with a solvent, reducing the need for multiple valves and simplifying the assembly process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional solid plugs are used for isolation during subsea connection, then the connection can be maintained, but the risk of seawater flooding and internal corrosion increases, and the complexity of the system increases due to the need for multiple valves
Solution Approach 1:
The invention extracts and removes the temporary isolation plugs from the system after they have served their purpose. The plugs are designed to be dissolved or fragmented by flushing with fresh water or chemical solvent, completely removing the isolation component rather than requiring manual retrieval or complex valve systems
Solution Approach 2:
The isolation plugs are designed as single-use, disposable components made from water-soluble or solvent-fragmentable materials. They perform their isolation function temporarily during connection operations and then dissolve away, eliminating the need for expensive, complex, reusable valve systems and reducing overall system complexity
2Ease of manufacture
If multiple underwater interfaces are created for connecting pipeline sections, then the connection can be achieved, but the cost and complexity of the operation increases
Solution Approach 1:
The invention merges multiple isolation functions into a single integrated temporary plug system. Instead of requiring separate valves and isolation mechanisms for each bore, a single plug per bore provides complete isolation, and the plugs are removed together through a single flushing operation, reducing the number of critical interfaces and simplifying the connection process
3Strength
If conventional welding processes are used for joining pipeline sections, then mechanical strength and leak-tightness are achieved, but the difficulty of testing multiple welds increases
Solution Approach 1:
The invention extracts and removes the temporary plugs after welding is complete, allowing for simplified testing of the welded joints. By removing the plugs through flushing rather than requiring complex retrieval operations, the testing process becomes more accessible and less difficult
Solution Approach 2:
The temporary plugs serve as intermediaries during the connection and welding process, maintaining isolation while allowing the welding operations to proceed. After welding is complete, the plugs are removed to allow testing, thus facilitating the welding process without permanently complicating the testing phase
4Length of moving object
If longer pipeline bundles are fabricated, then the distance between subsea connection points can be covered, but the length is constrained by the availability of land at onshore fabrication facilities
Solution Approach 1:
The invention divides the long pipeline bundle into multiple shorter sections that can be fabricated separately at onshore facilities with limited land availability. The sections are then connected underwater using the temporary plug system, allowing the final assembled bundle to exceed the length constraints of individual fabrication sites
Solution Approach 2:
The invention performs preliminary fabrication of pipeline sections at onshore facilities before assembling them into the complete long-distance bundle. The temporary plugs are installed in advance to maintain isolation during transport and assembly operations, enabling the construction of longer pipelines than could be fabricated in a single location
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 approach reduces the complexity and cost of subsea connections by allowing for efficient underwater assembly of longer pipeline bundles with reduced risk of flooding and internal corrosion, while maintaining mechanical strength and leak-tightness, and simplifies the process of connecting multiple sections without the need for bulky valves.
Implementation Method 1
the plugs being dissolved and/or fragmented in a flushing fluid that flows along the communicating bores
Implementation Method 2
the plugs are made from a water-soluble material able to withstand contact with seawater for at least one hour before dissolving
Data Source
AI summary
A method for connecting sections of a multi-bore structure in water comprises connecting the sections to bring corresponding bores of the sections into mutual alignment while those bores are each closed by a plug that excludes the water from the bores. Then, with the sections connected and the corresponding bores sealed together in fluid communication with each other, the plugs are flushed away in a flushing fluid that flows along the communicating bores.