Flow Cage Assembly Interference Fit for Downhole Pump Leak Prevention

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Solution Overview

Problem

Conventional flow cage assemblies in downhole reciprocating pumps face durability issues due to wear on sealing members and potential weak points in threaded connections, leading to leaks and fatigue, which compromise the reliability of fluid extraction in hydrocarbon recovery operations.

Innovation Solution

A method and kit for assembling a flow cage assembly using a tubular body with an expandable axial bore, a tubular insert, and a retaining element that forms an interference fit, eliminating the need for a sealing member and reducing the risk of leaks and material weakness, by heating the tubular body to expand the bore and inserting the retaining element to secure the insert in place.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a sealing member is used to prevent leaks at the threaded connection, then leak prevention is improved, but the sealing member is subject to wear from repeated ball movement and becomes a potential failure point

Engineering Contradiction:

Improveleak preventionVSAvoidsealing member service life

Core Design Contradiction:

ReliabilityVSDuration of action of moving object

Solution Approach 1:

The patent removes the sealing member from the assembly by using a tapered interference fit between the flow cage body and top bushing. The taper creates a mechanical lock and seal through friction and normal forces, eliminating the need for a separate sealing component that would be subject to wear from ball movement.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical sealing system (sealing member) with a mechanical interference fit system using tapered surfaces. The taper generates radial and axial forces that create both the seal and the mechanical retention, substituting a passive sealing component with an active mechanical coupling mechanism.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of manufacture

If threaded connections are used to connect the flow cage body to the top bushing, then assembly is simplified, but the threaded connection decreases wall thickness and creates weak points vulnerable to cracking and fatigue

Engineering Contradiction:

Improveassembly simplicityVSAvoidbody wall strength

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The patent removes the threaded connection from the design, eliminating the need for threads in the flow cage body. Instead, a tapered interference fit with a retaining element provides both connection and retention functions, preserving the full wall thickness and structural integrity of the body.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent combines the functions of connection, retention, and sealing into a single tapered interference fit mechanism with a retaining element. This eliminates the need for separate threaded connections and sealing members, reducing the number of potential failure points while maintaining assembly simplicity.

Inventive Principle:

Principle #5Merging (Combining)

3Strength

If a retaining element with outer diameter between the first and second diameters is inserted after heating, then an interference fit is formed to secure the insert, but the heating and cooling process is required

Engineering Contradiction:

Improveinterference fit strengthVSAvoidassembly process complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The patent utilizes thermal expansion of the flow cage body to temporarily increase the bore diameter, allowing the retaining element to be inserted. Upon cooling, the body contracts to create a tight interference fit, securing the insert and ball seat in place. This thermal cycling approach enables a strong mechanical connection without requiring complex assembly equipment.

Inventive Principle:

Principle #37Thermal expansion

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution enhances the durability and reliability of flow cage assemblies by preventing leaks and reducing material weaknesses, thereby improving the longevity and efficiency of fluid extraction in downhole pumps.

Implementation Method 1

heating the tubular body such that the axial bore expands to the second diameter

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

cooling the tubular body such that the tubular body and the retaining element form an interference fit

Methodology Applied

Scientific EffectThermal contraction: Thermal Contraction

Data Source

PatentUS11608709B2Methods and kits for assembling a flow cage assembly for downhole reciprocating pump

Publication Date: 2023.03.21 Q2 ARTIFICIAL ELEVATOR SERVICES ULC

AI summary

Methods and kits for assembling a flow cage assembly are provided. The flow cage assembly may be used in a traveling valve or a standing valve of a downhole pump. In some embodiments, the kit comprises a tubular body having an axial bore, a tubular insert, and a retaining element. The kit may be assembled such that the retaining element forms an interference fit with the tubular body and thereby retains the tubular insert within the axial bore. In some embodiments, the interference fit between the retaining element and the tubular body may reduce or eliminate a possible failure point within the flow cage assembly.