Subsea Annulus Isolation Valve for Venting and Flood Containment
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Solution Overview
Problem
Flexible pipes used in subsea oil and gas transportation face challenges in maintaining a continuous vent path between segments, leading to potential pipe rupture due to increased annulus pressure and flooding, which can result in costly downtime and losses.
Innovation Solution
A valve system with a slidable member and biasing element that allows selective connection and disconnection of fluid communication regions between flexible pipe segments, including a flood passage to isolate flooded segments and prevent system-wide flooding, while maintaining a continuous vent path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a continuous vent path is provided between multiple segments of flexible pipe body, then annulus pressure is reduced and venting efficiency is improved, but the risk of system-wide flooding increases if one segment floods
Solution Approach 1:
The flexible pipe system is divided into multiple segments with individual vent paths. Each segment has its own vent passage that can be selectively connected or disconnected. This segmentation allows the venting function to be maintained while preventing flood propagation between segments, as each segment can be isolated independently if flooding occurs.
Solution Approach 2:
The vent path configuration is made dynamic through the use of isolatable connections between segments. The connection between the vent passage of one segment and the vent passage of another segment can be selectively opened or closed. This dynamic capability allows the system to switch between a connected state (for efficient venting) and an isolated state (for flood prevention), resolving the contradiction between venting efficiency and flood risk.
2Length of moving object
If multiple segments of flexible pipe are connected in series to reach deep water locations, then the pipe can operate at greater depths, but maintaining a continuous vent path between all segments becomes increasingly complex
Solution Approach 1:
The venting system is segmented to match the pipe segmentation. Each pipe segment has its own vent passage, and the connection points between segments provide natural isolation opportunities. This modular approach simplifies the overall vent path configuration compared to trying to create a single continuous vent path through all segments, as each segment can be independently configured and connected.
3Reliability
If the annulus is continuously vented to maintain safety, then pressure buildup is prevented, but flooded segments can propagate flooding to other segments through the vent path
Solution Approach 1:
The vent path isolation capability is made dynamic, allowing the system to switch between connected and isolated states. During normal operation, the vent paths are connected to maintain continuous venting and prevent pressure buildup. When flooding is detected in a segment, the isolation capability allows the vent path to be closed at the affected segment, preventing flood propagation while maintaining venting functionality in other segments.
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
The solution provides a continuous vent path that reduces annulus pressure and prevents system-wide flooding, ensuring operational safety and reducing downtime by isolating flooded segments and maintaining fluid communication between segments.
Implementation Method 1
at least one biasing element locatable proximate to at least one of the open channel end or closed channel end, for biasing the slidable body towards the open channel end
Implementation Method 2
the slidable member is slidable along a longitudinal axis of the channel responsive to a local environmental pressure provided at the open channel end
Data Source
AI summary
A method and apparatus for selective connection of a first fluid communication region to a further fluid communication region at a subsea location and a flexible pipe are disclosed. The apparatus comprises a valve body that includes a primary passageway extending from a first port of the valve body, and connectable to a first fluid communication region, to a further port of the valve body, connectable to a further fluid communication region, the valve body comprising a channel intersecting the primary passageway and extending between an open channel end and a closed channel end; at least one slidable member comprising a slidable body locatable in the channel and comprising a slidable member fluid passage extending through or around the slidable body; and at least one biasing element locatable proximate to at least one of the open channel end or closed channel end, for biasing the slidable body towards the open channel end; wherein the slidable member is slidable along a longitudinal axis of the channel responsive to a local environmental pressure provided at the open channel end.