Eccentric Flapper Valve Seat for Downhole Tool Clearance
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Solution Overview
Problem
Existing flapper valves in oil and gas operations are limited by their internal and external diameters, preventing the flapper from pivoting away from the central axis enough to accommodate downhole tools, which reduces pressure ratings and increases costs due to the need for milled pockets.
Innovation Solution
The design includes a housing with an offset internal passage and external surfaces, allowing the flapper to pivot further and accommodate downhole tools without additional milled pockets, enhancing pressure ratings and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the internal annular recess is designed to accommodate the flapper, then the flapper can pivot away from the central axis, but the inner and outer diameters are restricted preventing sufficient pivoting distance
Solution Approach 1:
The patent introduces an eccentric seat where the internal passage is offset from the external surface, creating an asymmetric geometry. This asymmetry allows the flapper to pivot away from the central axis by a distance greater than the radius of the internal passage, enabling downhole tools to pass through while maintaining structural integrity and pressure ratings.
2Ease of operation
If a milled pocket is created in the housing to accommodate flapper pivoting, then the flapper can pivot further, but the pressure rating of the housing is reduced
Solution Approach 1:
Instead of milling a pocket that would compromise structural strength, the patent uses an eccentric seat design where the internal passage is offset from the external surface. This asymmetric configuration provides the necessary pivoting space without removing material that would reduce the pressure rating, thereby maintaining both operational capability and structural integrity.
3Ease of operation
If a milled pocket is added to the housing, then the flapper can accommodate further pivoting, but manufacturing cost increases
Solution Approach 1:
The eccentric seat design with offset internal and external passages provides the required pivoting range without the need for additional milled pockets. This eliminates complex manufacturing steps, reduces production costs, and avoids the orientation difficulties associated with milled pockets while achieving the same operational benefit.
Data Source
AI summary
A method and apparatus according to which a flow control device includes a housing and a flapper valve. The housing defines an internal passage in which the flapper valve extends. The flapper valve includes a seat and a flapper pivotably coupled to the seat. The seat includes an internal passage and an external surface. The internal passage of the seat extends along a longitudinal central axis that is offset from a longitudinal central axis along which the external surface of the seat extends and a longitudinal central axis along which the internal passage of the housing extends. This offset allows an internal annular recess of the housing to accommodate the flapper pivoting away from the longitudinal central axis of the internal passage of the seat by a distance of equal to or greater than a radius of the internal passage of the seat.