Casing Removal Gripper with Switcher Locking Mechanism

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Solution Overview

Problem

Existing methods for removing sections of casing or lining from wellbores are inefficient and costly, as they often require separate trips for cutting and pulling operations, and existing pulling tools suffer from wear, complexity, and interference with the cutting process.

Innovation Solution

A tubular mandrel with a sliding assembly and gripper system that allows for gripping and releasing from the casing without rotation, using a switcher mechanism to automatically engage and disengage the gripper, and fluid actuation to move the gripper away from the wall, enabling simultaneous cutting and pulling operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If pulling tools are deployed together with cutting tools in the same trip, then operational efficiency is improved, but the pulling tools suffer wear and damage from rotating the string during cutting operations

Engineering Contradiction:

Improveoperational efficiencyVSAvoidtool wear and damage

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The pulling tool is segmented into modular components including a body, grippers, and a biasing mechanism. This segmentation allows each component to be optimized independently - the grippers can be designed to engage casing internally without requiring external rotation, while the biasing mechanism provides automatic engagement force, reducing overall tool wear during combined cutting and pulling operations

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of using external rotation to actuate the pulling tool (as in conventional spear tools), this invention inverts the actuation mechanism by using internal biasing springs that automatically engage the grippers with the casing wall. This eliminates the need for rotation-dependent actuation, protecting the pulling tool from wear during cutting operations while maintaining reliability

Inventive Principle:

Principle #13The other way round (Inversion)

2Ease of operation

If conventional spear tools with selective actuation are used, then the pulling function can be performed, but it is difficult to determine whether actuation has successfully taken place, resulting in delays and operational uncertainty

Engineering Contradiction:

Improvepulling functionVSAvoiddelays and operational uncertainty

Core Design Contradiction:

Ease of operationVSLoss of time

Solution Approach 1:

The pulling tool incorporates a mechanical feedback mechanism where the biasing springs provide immediate tactile and visual indication of gripper engagement status. When the grippers engage the casing wall, the compression of the biasing springs creates a noticeable mechanical resistance and position change that can be detected in real-time, eliminating uncertainty about actuation success and preventing delays

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The biasing mechanism provides self-service actuation where the springs automatically engage and disengage the grippers based on the tool's position and operational state, without requiring complex external control systems. This self-actuating mechanism provides inherent feedback through its mechanical state, allowing operators to immediately determine engagement status without additional sensing or communication systems

Inventive Principle:

Principle #25Self-service

3Adaptability or versatility

If the pulling tool remains on hand during cutting operations, then it can perform pulling when required, but it interferes with the cutting process and fluid circulation

Engineering Contradiction:

Improvepulling capability during cuttingVSAvoidinterference with cutting process

Core Design Contradiction:

Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The pulling tool employs dynamic grippers that can automatically engage and disengage based on operational conditions. During cutting operations, the grippers can be positioned to clear the cutting path while maintaining the capability to engage quickly when pulling is required. This dynamic positioning eliminates interference with the cutting process and fluid circulation while preserving pulling adaptability

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The harmful interference is extracted by separating the cutting and pulling functions into distinct spatial and temporal domains. The grippers are designed to engage only when needed for pulling, clearing the cutting path during cutting operations. This extraction of the pulling function from the cutting path eliminates interference while maintaining the versatility to perform both operations with the same tool

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS10907432B2Apparatus for removing a section of casing or lining from a well-bore, and methods

Publication Date: 2021.02.02 WEATHERFORD TECHNOLOGY HOLDINGS LLC

AI summary

Apparatus and method for removing a section of casing or lining from a wellbore. A tubular mandrel has a sliding assembly mounted thereon with grippers coupled to the assembly so that the grippers can be moved between an engaged configuration were they grip the inner wall of the casing section and a disengaged position were they are held away from the inner wall. A switcher is mounted on the mandrel which operates on entering the casing section to lock the grippers in the disengaged position so that cutting of the casing may be done. On pulling the switcher from the casing section, the grippers are automatically engaged and grip the upper end of casing section so that it can be removed. Additional locking arrangements are described which, by rotation, maintain the grippers in the disengaged position regardless of the location of the switcher.