Downhole Tool Controller with Toggle Actuation for Underreamer
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Solution Overview
Problem
The challenge in wellbore drilling is the need for multiple drill bits of different sizes as casing/liner strings are installed with progressively smaller diameters, reducing the production flow area, and the inefficiency of current underreamers in enlarging the borehole for larger casing installation and enhanced production.
Innovation Solution
A controller for a downhole tool that includes a tubular body with a seat for receiving pump-down plugs, a catcher for the plugs, and a toggle mechanism to alternate between locked and unlocked positions, allowing the underreamer to extend and retract, enabling efficient enlargement of the wellbore without requiring multiple drill bits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple drill bits of different sizes are used as casing/liner strings are installed with progressively smaller diameters, then the drilling operation can proceed through multiple casing strings, but the production flow area is reduced
Solution Approach 1:
The underreamer is deployed in advance through the casing string in a retracted state, then extended below the casing to enlarge the borehole before drilling continues. This preliminary enlargement action allows larger casing strings to be installed later, thereby increasing the production flow area while maintaining the ability to drill through multiple casing strings
Solution Approach 2:
The underreamer arms are designed to be movable between a retracted position (for passing through casing) and an extended position (for enlarging the borehole). This dynamic transformation allows the same tool to serve multiple functions: navigating through existing casing and creating enlarged boreholes for larger future casing installations
2Area of stationary object
If an underreamer with movable arms is used to enlarge the wellbore, then the borehole can be enlarged for larger casing installation, but the device complexity increases
Solution Approach 1:
The underreamer arms are actuated using hydraulic pressure transmitted through fluid-conveying drill string members. This hydraulic actuation system allows the complex movement of multiple arms to be controlled through a simple fluid pressure input, reducing the mechanical complexity compared to purely mechanical actuation systems
Solution Approach 2:
The underreamer is designed as a multi-functional tool that can: (1) pass through existing casing strings in a retracted state, (2) extend arms to enlarge the borehole, (3) provide stabilization during drilling, and (4) be controlled through standard hydraulic systems. This multi-functionality reduces the need for multiple separate tools, thereby managing overall system complexity
3Area of stationary object
If the underreamer arms are extended to enlarge the wellbore, then the production flow area is enhanced, but the force required to extend the arms increases
Solution Approach 1:
The underreamer arms are designed to be self-supporting when extended, bearing their own weight and the stabilizing forces during operation. The hydraulic system only needs to provide the force to overcome static friction and initiate movement, not to continuously support the arms, thereby reducing the total force requirement
Solution Approach 2:
The arm extension is achieved through periodic hydraulic pressure pulses rather than continuous force application. The arms are extended in controlled stages, allowing the hydraulic system to build pressure incrementally and overcome the force requirement through repeated pressure cycles
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 allows for efficient enlargement of the wellbore, reducing the need for multiple drill bits and enhancing the production flow area by enabling the use of larger casing/liner strings, while also reducing equivalent circulation density during drilling.
Implementation Method 1
at least a portion of one of the seat and the plugs being radially displaceable to pass through or allow passage of the other of the seat and the plugs at a first threshold pressure differential
Implementation Method 2
a toggle linked to the seat to alternate between a locked position and an unlocked position in response to seating of the plugs; and a control mandrel for engaging a piston of the downhole tool and linked to the toggle: to be longitudinally movable between a first position and a second position when the toggle is unlocked
Implementation Method 3
a bottomhole assembly connected to the drill string and comprising an underreamer operable to extend between a first configuration in which the underreamer is constrained within a casing and a second configuration in which the underreamer enlarges a wellbore below the casing
Data Source
AI summary
A controller for operating a downhole tool includes a tubular body; a seat disposed in the body for receiving first and second pump-down plugs, at least a portion of one of the seat and the plugs being radially displaceable to pass through or allow passage of the other at a first threshold pressure differential; a catcher located below the seat for receiving the plugs after passing through the seat; a toggle linked to the seat to alternate between a locked position and an unlocked position in response to seating of the plugs; and a control mandrel for engaging a piston of the downhole tool and linked to the toggle: to be longitudinally movable between a first position and a second position when the toggle is unlocked, and to be prevented from movement from the first position to the second position when the toggle is locked.