Tubing-Retrievable Safety Valve Assembly With Secondary Flapper Backup
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Solution Overview
Problem
Existing subsurface safety valves (TRSVs) in oil and gas wells are prone to failure, leading to potential leaks or inability to properly open, necessitating a secondary means for blocking fluid flow, which current wireline retrievable safety valves (WRSVs) complicate with complex installation processes, flow restrictions, and limited setting depth.
Innovation Solution
A TRSV assembly with a primary and secondary flapper, where the secondary flapper is activated by shifting a protective sleeve downhole, allowing the secondary flapper to close and prevent fluid flow without the need for additional equipment or complex control line modifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a WRSV is inserted inside an existing TRSV to provide secondary safety function, then reliability is improved, but device complexity increases due to complicated installation requiring multiple wireline trips and control line modifications
Solution Approach 1:
The patent combines the primary TRSV and secondary safety valve functions into a single integrated assembly. The secondary flapper valve is incorporated within the same housing as the primary flapper, eliminating the need for separate WRSV installation. This merging reduces device complexity while maintaining the secondary safety function.
Solution Approach 2:
The single TRSV assembly performs multiple functions: it provides both primary safety valve operation and secondary safety backup. The assembly can function as either primary or secondary valve depending on operational needs, eliminating the requirement for separate WRSV installation and control line modifications.
2Reliability
If a WRSV is inserted inside an existing TRSV, then secondary safety function is provided, but flow path is restricted due to smaller flow diameter
Solution Approach 1:
The patent arranges the primary and secondary flappers in a configuration where they operate in different spatial dimensions or planes within the same housing. This allows both flappers to be positioned such that they do not obstruct each other's flow paths, maintaining full flow capacity when either valve is open.
Solution Approach 2:
The flow path is segmented into multiple channels or zones within the housing, allowing simultaneous or alternative flow through primary and secondary flapper pathways. This segmentation ensures that the presence of the secondary flapper does not constrict the overall flow diameter.
3Adaptability or versatility
If setting depth of WRSV is increased to reach deeper locations, then adaptability is improved, but control mechanism reliability deteriorates due to increased formation fluid pressure
Solution Approach 1:
The patent employs a balanced flapper mechanism where the flapper is counterbalanced by springs or counterweights that compensate for formation fluid pressure. This counterbalancing allows the flapper to remain controllable at greater depths where higher formation pressures would otherwise prevent proper operation.
Solution Approach 2:
The patent replaces traditional mechanical control mechanisms (springs, hydraulic systems) with an alternative control method such as magnetic actuation or cable-driven mechanical advantage systems. This substitution enables reliable control at greater depths where conventional mechanical systems would fail under high formation pressure.
Data Source
AI summary
A tubing retrievable safety valve assembly and related methods are disclosed herein. The assembly includes a primary flapper, a secondary flapper, a flow tube, and a protective sleeve. The flow tube is shiftable between a downhole position that holds the primary flapper in an open position and an uphole position that allows the primary flapper to move to a closed position. The protective sleeve, when positioned in an uphole position, holds the secondary flapper valve in an open position. The protective sleeve is shiftable to a downhole position to allow the secondary flapper to move to a closed position, for example, upon failure of the primary flapper.