Expandable Downhole Tool Ratchet Locking Mechanism

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Solution Overview

Problem

Existing expandable downhole tools face logistical and cost challenges in achieving a secure seal around the wellbore due to limitations in controlling the sealing contact of resilient sleeves, requiring multiple versions of tools with different sleeve thicknesses for varying borehole sizes.

Innovation Solution

The tool employs progressive mandrel expansion to move and lock an exterior ring against a sleeve, allowing for enhanced sealing without the need for multiple sleeve thicknesses, using a ratchet mechanism to maintain the ring's position and prevent springback, enabling better wellbore contact and fluid passage or filtration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a thicker resilient sleeve is used to achieve a tighter seal against the borehole, then the sealing contact is improved, but the device complexity and cost increase due to needing multiple tool versions with different sleeve thicknesses

Engineering Contradiction:

Improvesealing contactVSAvoidmultiple tool versions

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent employs a dynamic expansion system where a swage mechanism progressively expands the mandrel, which in turn expands the resilient sleeve to match the borehole diameter. This dynamic adjustment allows a single tool design to adapt to various borehole sizes and maintain reliable sealing contact without requiring multiple fixed-thickness sleeve versions.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention changes the physical state and dimensions of the resilient sleeve from a fixed thickness to a variable thickness through mechanical expansion. The swage mechanism applies radial force to expand the mandrel and sleeve, transforming the sleeve from its initial compact state to an expanded state that conforms to the borehole wall, thereby achieving reliable sealing with a universal tool design.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the mandrel is expanded to engage the seal with the surrounding wellbore, then the sealing capability is improved, but the swage may bind during expansion

Engineering Contradiction:

Improvesealing capabilityVSAvoidswage binding

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent divides the expansion function into two independent components: the mandrel that provides structural support and the resilient sleeve that provides sealing. The swage expands the mandrel, which then expands the sleeve radially outward to engage the wellbore. This segmentation allows the swage to expand the mandrel without directly binding against the sealing interface, as the sleeve absorbs the radial expansion forces.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The resilient sleeve acts as an intermediary between the mandrel and the surrounding wellbore. The swage expands the mandrel, and the mandrel in turn expands the sleeve, which then contacts the wellbore wall. This intermediary relationship prevents direct binding between the swage and the sealing surface, allowing smooth operation while maintaining reliable sealing capability.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If the exterior sleeve is compressed to enhance sealing contact, then the seal tightness is improved, but the sleeve may spring back longitudinally after expansion

Engineering Contradiction:

Improveseal tightnessVSAvoidsleeve position

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent incorporates a locking mechanism that is activated during the expansion process to preliminarily secure the sleeve in its expanded position. As the swage expands the mandrel and sleeve, the locking mechanism engages to prevent longitudinal spring-back of the sleeve. This preliminary action ensures that once the sleeve is compressed and expanded to achieve tight sealing contact, it remains stable in that position without rebounding.

Inventive Principle:

Principle #10Preliminary action

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

This solution provides a cost-effective and practical means to achieve a secure seal across varying borehole sizes by utilizing progressive mandrel expansion to compress and lock the exterior sleeve, ensuring effective sealing and fluid management without the need for multiple tool versions.

Implementation Method 1

a mandrel that is expanded from within by a swage or other technique

Methodology Applied

Scientific EffectMandrel expansion:

Implementation Method 2

The ring engages a ratchet mechanism to hold its position with respect to the mandrel

Methodology Applied

Scientific EffectRatchet mechanism: Ratchet

Data Source

PatentUS7730941B2Expandable tool with enhanced expansion capability

Publication Date: 2010.06.08 BAKER HUGHES CO

AI summary

An expandable downhole tool features a mandrel that is expanded from within by a swage or other technique. The expansion of the mandrel advances an exterior ring or comparable slidably mounted object against an exterior sleeve that can be impervious or porous. The ring engages a ratchet mechanism to hold its position with respect to the mandrel as the swage advances through the mandrel and expands the ring and the exterior sleeve. The locking of the ring to the mandrel keeps the exterior sleeve from springing back longitudinally as the expansion is concluded.