Thermoplastic Valve Cage Inserts for Downhole Fluid Flow

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Solution Overview

Problem

Downhole ball and seat valves in hydrocarbon well applications face issues with wear and corrosion due to repeated operation in corrosive environments, and existing cage inserts impede fluid flow and require additional sealing, which can lead to compression set and leakage.

Innovation Solution

A valve cage design featuring a thermoplastic cylindrical insert with radially inward vane members forming the ball stop and no structural members across the opening, combined with bushing seals that eliminate the need for o-rings, enhancing fluid flow and durability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If openings are provided in the insert wall to allow fluid passage, then fluid flow is improved, but fluid enters between the insert and shell causing corrosion and erosion

Engineering Contradiction:

Improvefluid flowVSAvoidcorrosion and erosion

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The insert is divided into functionally distinct zones: an upper fluid passage section with radial vanes that allows fluid flow, and a lower seal section with no openings that prevents fluid contact with the shell. This segmentation resolves the contradiction by allowing fluid flow where needed while preventing corrosion in critical areas.

Inventive Principle:

Principle #1Segmentation

2Reliability

If structural members are added to the top of the cage to form ball stops, then ball positioning is improved, but fluid flow through the cage is impeded

Engineering Contradiction:

Improveball positioningVSAvoidfluid flow

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The ball stop function is localized to specific radial vanes positioned at the top of the insert, rather than using comprehensive structural members. This allows ball positioning control at the critical location while maintaining open fluid passages in the remaining areas of the insert.

Inventive Principle:

Principle #3Local quality

3Reliability

If elastomer seals are used at the ball seat to prevent leakage, then sealing is improved, but compression set and wash out occur during lengthy operation

Engineering Contradiction:

ImprovesealingVSAvoidservice life

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The insert uses a composite construction combining elastomer seal elements with a rigid thermoplastic or metal body. The elastomer provides initial sealing capability while the rigid material provides structural support and resistance to compression set, extending service life under differential pressure.

Inventive Principle:

Principle #40Composite materials

4Reliability

If o-rings are added to seal between bushing member and shell, then sealing is improved, but device complexity increases

Engineering Contradiction:

ImprovesealingVSAvoidnumber of sealing components

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The sealing function is merged into the bushing member itself through integral sealing surfaces or built-in seal features, eliminating the need for separate o-ring components. This reduces device complexity while maintaining sealing reliability.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS10184314B1Downhole valve with cage inserts

Publication Date: 2019.01.22 BLACK GOLD PUMP & SUPPLY INC

AI summary

A thermoplastic cage insert for a downhole valve utilized in oil production rod pumps and other downhole equipment has a full open bore with no structural member spanning across the bore of the cage insert. This design allows fluid to flow freely at the trailing end of the ball of the valve, maximizing the cross sectional flow area at the trailing end of the ball.