Subsea Annulus Stab Flow Isolation for Sensitive Components
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing subsea completion systems expose fragile components like sensors and electronics to deleterious well fluids due to open plenum regions between tubing hangers and subsea trees, which are not suitable for housing these components.
Innovation Solution
An isolated annulus flow path is created by positioning an annulus stab between the tubing hanger and subsea tree, extending through the plenum region and defined by a passageway through the tubing hanger, protecting components from exposure to well fluids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an open plenum region is used between tubing hanger and subsea tree, then the structure is simple and easy to manufacture, but fragile components are exposed to deleterious well fluids
Solution Approach 1:
The patent divides the flow path into separate segments: a production flow path and an annulus flow path. The annulus flow path is isolated within an annulus stab that extends through the plenum region, preventing mixing with well fluids while maintaining structural simplicity. This segmentation allows fragile components in the plenum to be protected from deleterious fluids.
Solution Approach 2:
The annulus stab acts as an intermediary structure that carries the annulus flow path through the plenum region without exposing it to well fluids in the production path. This mediator structure enables the coexistence of simple open plenum design with protected fluid pathways.
2Reliability
If components are protected from well fluids using expensive materials and seals, then reliability improves, but manufacturing cost increases
Solution Approach 1:
The patent extracts the annulus flow path from the main production environment and places it within a dedicated annulus stab. This extraction allows the use of standard, cost-effective materials in the plenum region while maintaining fluid isolation, eliminating the need for expensive protective materials.
Solution Approach 2:
The design allows the use of simpler, more economical materials and seals in components exposed to the plenum region, since the critical fluid isolation function is handled by the dedicated annulus stab structure rather than requiring expensive protective measures on all components.
3Reliability
If complex fluid isolation structures are used to protect components, then component protection improves, but device complexity increases
Solution Approach 1:
The annulus stab serves multiple functions: it provides the annulus flow path, acts as a structural support element, and creates fluid isolation boundaries. This multi-functionality reduces the need for separate protective structures, maintaining simplicity while ensuring component protection.
Solution Approach 2:
The annulus flow path is nested within the annulus stab structure, which itself is positioned within the larger subsea tree assembly. This nested arrangement creates efficient fluid isolation using concentric structures, reducing overall system complexity compared to separate isolation mechanisms.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A technique facilitates protection of potentially susceptible components from unwanted exposure to well fluids or other fluids in a monobore subsea installation. The subsea installation may comprise various components, e.g. a tubing hanger and a subsea tree which form a plenum region therebetween. An annulus stab (or stabs) is positioned to extend between the tubing hanger and the subsea tree so as to provide an isolated flow path within the annulus stab and through the plenum region. The isolated flow path also may extend longitudinally through the tubing hanger until exiting through a side of the tubing hanger. The annulus stab and overall isolated flow path are thus able to accommodate an annulus flow within the monobore subsea installation while protecting components exposed to the plenum region from contact with deleterious fluids in the annulus flow path.