Well Barrier Flapper Valve Axial Retention Design
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Solution Overview
Problem
Conventional flapper valves for well barriers require multiple control lines for bidirectional sealing and constant hydraulic pressure to maintain the open position, leading to potential interruptions in production and increased risk of moving part damage.
Innovation Solution
A well barrier design featuring a housing with a flapper valve and actuator that allows axial movement, incorporating retention devices to maintain the flapper in open or closed positions, minimizing exposure to hydrocarbons and enabling bi-directional sealing with a single actuator force, and utilizing biasing means to ensure the valve is normally open or closed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional flapper valve is used for bidirectional sealing, then sealing capability is improved, but device complexity increases due to requiring multiple control lines
Solution Approach 1:
The patent inverts the conventional flapper valve operation by making the valve normally open and using a single control line to close it rather than requiring multiple control lines for bidirectional control. The retention device holds the flapper in the open position, and a single actuator can close the valve when needed, eliminating the need for complex multi-line control systems while maintaining bidirectional sealing capability.
Solution Approach 2:
The retention device serves multiple functions: it retains the flapper valve in the open position, protects the seal seat from hydrocarbon exposure, and works with the single control line system to enable bidirectional sealing. This multi-functional component reduces overall device complexity while maintaining reliable sealing.
2Ease of operation
If constant hydraulic pressure is applied to maintain the flapper valve open, then valve operability is improved, but reliability worsens due to potential pressure failure and production interruptions
Solution Approach 1:
The retention device enables the valve to maintain its open position without requiring constant external hydraulic pressure. The mechanical retention mechanism holds the flapper in place, and the valve can be opened again automatically or with minimal intervention after closing, making the system self-sufficient and eliminating the need for continuous pressure maintenance.
Solution Approach 2:
Instead of using constant pressure to keep the valve open (conventional approach), the patent uses a retention device to mechanically hold the valve open and applies pressure only momentarily to close it. This inverted approach eliminates the risk of pressure failure causing unintended valve closure and production interruptions.
3Adaptability or versatility
If the flapper valve is exposed to hydrocarbon flow, then valve functionality is maintained, but reliability decreases due to potential damage to moving parts
Solution Approach 1:
The retention device creates a protected zone around the seal seat and moving parts, shielding them from direct hydrocarbon exposure. The flapper valve remains functional for sealing when needed, but the retention mechanism prevents hydrocarbons from continuously contacting and potentially damaging the seal seat and other sensitive components.
Data Source
AI summary
A well barrier for sealing a downhole conduit is described. The well barrier comprises a housing defining a throughbore having a longitudinal axis, a valve actuator and a flapper valve. The flapper valve includes a flapper attached to the valve actuator. The flapper valve and the valve actuator are axially movable with respect to the housing in a direction parallel to the longitudinal axis. The flapper is adapted to move from one of a throughbore open and throughbore closed positions to the other of said open and closed positions when the actuator and flapper valve move a predetermined axial distance.