Subsea Riser Fluid Plug Removal via Heated Assisting Liquid
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Solution Overview
Problem
Current systems for injecting environmentally harmful fluids, such as CO2, into subterranean voids beneath the seabed lack an efficient, safe, and reliable means of connecting risers between an offloading buoy and a template on the seabed.
Innovation Solution
A method involving the use of heated assisting liquids to melt and remove obstructing fluid plugs from the base section of a riser, which connects a receiving end to a subsea template on the seabed, allowing for efficient fluid injection into subterranean voids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If utilities for subsea CO2 wells and template are located onshore, then control and safety systems can be managed remotely, but the system becomes highly inflexible and costly to relocate
Solution Approach 1:
The system is divided into modular components: a subsea template with injection wells on the seabed, a floating reception facility on the water surface, and onshore control utilities. This segmentation allows the injection point to be relocated by moving the floating facility while keeping onshore control systems in place, resolving the contradiction between remote control capability and relocation flexibility.
Solution Approach 2:
The floating reception facility can be dynamically repositioned on the water surface to different locations around the subsea template. This dynamic capability enables the system to adapt to different injection points and operational requirements while maintaining continuous remote control from onshore, thus achieving both ease of operation and adaptability.
2Duration of action of stationary object
If CO2 is transported via long seabed pipelines from onshore, then continuous supply is possible, but the system design becomes highly inflexible
Solution Approach 1:
The transport system is segmented into short seabed pipelines connecting the floating facility to the subsea template, rather than one long pipeline from onshore. This allows the floating facility to be repositioned to serve different injection points while maintaining continuous CO2 supply through new short pipeline connections.
Solution Approach 2:
The floating reception facility acts as an intermediary between onshore CO2 sources and subsea injection points. It receives CO2 from various sources, stores it temporarily, and distributes it to different subsea template locations, enabling both continuous supply and flexible relocation without requiring long fixed pipelines.
3Reliability
If a reliable connection means between offloading buoy and seabed template is established, then uninterrupted fluid injection is achieved, but the system complexity increases
Solution Approach 1:
The subsea template is pre-installed on the seabed with all necessary connection interfaces and utilities before the floating facility arrives. This preliminary preparation ensures that when the floating facility needs to connect for CO2 offloading, the connection process is straightforward and reliable, minimizing system complexity while ensuring uninterrupted injection capability.
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 method provides an efficient and reliable means of removing fluid plugs, ensuring uninterrupted fluid injection into subterranean voids, thereby facilitating long-term storage of environmentally harmful fluids.
Implementation Method 1
heating at least one assisting liquid to a predetermined temperature... injecting the at least one heated assisting liquid from the storage container into at least one injection point in the base section... until any plugs in the riser have melted away
Data Source
AI summary
Obstructing fluid plugs are removed from a base section of a riser, which base section extends between a receiving end connected to an upright section of the riser and an emitting end of the riser connected to a subsea template located on a seabed over a drill hole to a subterranean void into which fluid received via the riser is to be injected from the subsea template (120). The obstructing fluid plugs are removed either by injecting heated assisting from a storage container into an injection point in the base section and injecting heated assisting liquid from the vessel in the upright section of the riser, or a heating unit is controlled to heat the base section to a predetermined temperature, and thereafter maintain a temperature level here above or equal to the predetermined temperature.