Expandable Downhole Tool Spline Bar Guide
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Solution Overview
Problem
Existing expandable downhole tools, such as under-reamers and stabilizers, face challenges with increased complexity and cost due to integral angled channels, difficulty in replacing worn parts, and vibration issues caused by unlocked cutter blocks, leading to inconsistent borehole sizing.
Innovation Solution
An expandable downhole tool design featuring a mandrel and spline bar system that allows for easy assembly and adjustment between activated and deactivated modes, using a separate spline bar as the primary guide for movement, with lock mechanisms to secure the working component in place, reducing reliance on internal tool body design and simplifying maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If integral angled channels are formed in the recesses to guide arm movement, then the tool achieves reliable expansion and retraction, but the manufacturing complexity and cost increase
Solution Approach 1:
The guide function is segmented from the tool body by introducing a separate spline bar component. The spline bar contains the angled channels as a distinct element that can be manufactured independently and then assembled into the tool body, reducing the complexity of forming integral channels in the tool body recesses.
Solution Approach 2:
The spline bar acts as an intermediary component between the tool body and the movable arms. It provides the angled guide channels as a separate mechanical element that mediates the interaction between the tool body structure and the arm movement, eliminating the need for complex integral channel formation in the tool body.
2Reliability
If integral angled channels are formed in the recesses to guide arm movement, then the tool achieves reliable expansion and retraction, but the cost increases
Solution Approach 1:
The guide function is segmented from the tool body by introducing a separate spline bar component. The spline bar contains the angled channels as a distinct element that can be manufactured independently and then assembled into the tool body, reducing the complexity of forming integral channels in the tool body recesses.
Solution Approach 2:
The spline bar acts as an intermediary component between the tool body and the movable arms. It provides the angled guide channels as a separate mechanical element that mediates the interaction between the tool body structure and the arm movement, eliminating the need for complex integral channel formation in the tool body.
3Ease of repair
If angled channels are made replaceable, then maintenance ease improves, but the structural complexity increases
Solution Approach 1:
The spline bar is designed as a separate, removable component that can be easily extracted from the tool body for replacement. This segmentation allows the guide channels to be replaced independently without disassembling the entire tool, improving maintenance ease while keeping the overall structure relatively simple.
Solution Approach 2:
The guide channel function is extracted from the tool body and placed in a separate spline bar component. This extraction allows the worn or damaged angled channels to be replaced by removing and replacing the spline bar as a complete unit, simplifying the maintenance process.
4Adaptability or versatility
If cutter blocks are allowed to float on inclined planes for movement, then the tool achieves expandability, but vibration and wear increase
Solution Approach 1:
The lock block mechanism provides feedback to the cutter block assembly, detecting when the cutter blocks have moved to the expanded position and automatically engaging the lock blocks to secure them. This feedback mechanism prevents continuous floating and vibration while maintaining the expandable function.
Solution Approach 2:
The system transitions from a static rigid connection to a dynamic controlled movement. The cutter blocks can move freely during expansion but are automatically locked when in position, providing dynamic control that eliminates vibration and wear associated with continuous floating.
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 tool achieves reliable expansion and retraction without internal guidance, reduces vibration and wear, and allows for easy replacement of components, ensuring consistent borehole sizing and reduced manufacturing and maintenance costs.
Implementation Method 1
The tool alternates between collapsed and expanded positions in response to differential fluid pressure between the flowbore and the wellbore annulus
Implementation Method 2
a spline bar mountable in a recess in the tool body and defining a first linear guide path extending parallel to the axis of movement of the mandrel, and a second outwardly extending guide path
Implementation Method 3
at least one lock block engageable with the cutter blocks to secure the cutter blocks in the outward position
Data Source
AI summary
An expandable downhole tool such as an under-reamer or a stabiliser includes a mandrel mounted for linear slidable movement relative to a main body. The mandrel, together with one or more travel blocks, cause movement of a working component in an axial direction. One or more outwardly extending guide paths slidably interact with the working component to cause the working component to move between a withdrawn inoperative position and an outwardly deployed operative position. Upon increase of hydraulic pressure from below the tool, the mandrel is urged against a spring biasing the deactivated position to move axially and cause the working component to take its operative position. Upon decrease of hydraulic pressure, the spring moves the mandrel axially to cause the working component to take its withdrawn inoperative position.