Retractable Bolt Retention System for Whipstock Release
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Solution Overview
Problem
The existing systems for securing and releasing a lead mill of a bottom hole assembly from a whipstock in wellbore operations face reliability risks due to high frictional forces, which can lead to premature shear of shear bolts and incorrect positioning, increasing costs and risks in well completion operations, especially in highly deviated wellbores.
Innovation Solution
A retention system that includes a retractable bolt biased to a retracted position with a retraction actuator capable of opposing its bias, and meshing features on the bottom hole assembly and whipstock that slideably mesh and release without rotation, allowing secure coupling and release without destruction of the bolt.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a shear bolt is used to secure the lead mill to the whipstock, then the lead mill can be released by shearing the bolt, but the high frictional forces in highly deviated wellbores can cause premature shear of the bolt or prevent proper release
Solution Approach 1:
The patent extracts the harmful frictional forces from the load path by removing the shear bolt from the system. Instead of relying on a shear bolt that must withstand friction, the invention uses a frictionless release mechanism where the lead mill is held by engagement features and released by disengaging these features, completely eliminating the friction problem that caused premature shear or failure to release.
Solution Approach 2:
The patent transforms the static shear bolt connection into a dynamic engagement system. The lead mill is secured through engagement features that can be actively disengaged, allowing the system to transition from a fixed connection to a controlled release. This dynamic mechanism eliminates the frictional issues inherent in static shear bolt connections by using movable engagement surfaces rather than relying on bolt shear strength.
2Ease of operation
If weight is applied to the drill string to shear the shear bolt, then the lead mill should release, but frictional forces may prevent proper weight transfer to the bolt
Solution Approach 1:
The patent removes the shear bolt from the release mechanism, eliminating the need to transfer weight to a bolt that must shear. The new system uses engagement features that are disengaged through a different mechanism, removing the unreliable weight transfer step and replacing it with a more dependable release method that is not compromised by frictional forces.
Solution Approach 2:
The patent introduces engagement features as an intermediary mechanism between the lead mill and whipstock. Instead of directly relying on shear bolt failure, the system uses these engagement features to secure and release the lead mill. This intermediary mechanism provides a more reliable and controllable release process that is not dependent on friction-compromised weight transfer to a shear bolt.
3Adaptability or versatility
If the whipstock is anchored to direct the drill string, then the drill string can be directed in the second direction, but the frictional forces may cause incorrect positioning of the whipstock
Solution Approach 1:
The patent extracts the problematic frictional forces from the whipstock positioning system. By removing the shear bolt connection that was subject to friction, the system achieves more reliable positioning. The engagement features provide a frictionless connection that maintains whipstock position and orientation without the harmful effects of friction that caused incorrect positioning.
Solution Approach 2:
The patent employs engagement features that are designed for single-use or limited-use operations. These features secure the whipstock during the critical positioning and milling operations, then can be discarded or replaced. This approach ensures precise positioning during operation without the long-term reliability issues of friction-affected shear bolts.
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 reduces the risks and costs associated with well completion operations by ensuring reliable and secure release of the lead mill from the whipstock, maintaining bolt integrity and preventing incorrect positioning, thereby enhancing operational efficiency in deviated wellbores.
Implementation Method 1
a retractable bolt at least partially disposed in the bottom hole assembly and biased to a retracted position by the bias mechanism
Data Source
AI summary
Methods and apparatus for releasing a lead mill of a BHA from a whipstock in a wellbore include slideably releasing the BHA from the whipstock without relative rotation and without destruction of a retractable bolt. A system includes: a bias mechanism; a retractable bolt at least partially disposed in the bottom hole assembly and biased to a retracted position by the bias mechanism; and a retraction actuator capable of selectably opposing the bias of the retractable bolt. A method includes: coupling a whipstock to a BHA with a retention system, including: a retractable bolt biased to retract into the BHA; and a retraction actuator configured to resist the bias of the retractable bolt; and after the whipstock and BHA have been disposed in a wellbore, activating the retraction actuator so that retraction of the retractable bolt ensues.