Torque Key Whipstock Assembly for Mill Rotation Control
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Solution Overview
Problem
Conventional single-trip whipstock designs for multilateral wells face premature shear bolt failure due to torsional and tensile stresses, leading to premature detachment of the lead mill from the whipstock, as they are not effectively designed to handle rotational torque loads.
Innovation Solution
The implementation of a whipstock assembly with a bearing support or a torque key that is movable between extended and retracted positions, allowing for enhanced torque transmission without compromising the shear bolt, by preventing the lead mill from rotating with respect to the whipstock and allowing easy milling through the bearing support or retracting to avoid obstruction during operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a shear bolt and torque lug design is used to anchor the lead mill to the whipstock, then the mill can be securely anchored during run-in, but the shear bolt is subjected to tensile and torsional stress that causes premature fatigue and shearing
Solution Approach 1:
A torque key is introduced as an intermediary component between the lead mill and whipstock. The torque key receives and transfers torsional loads, preventing these forces from being applied to the shear bolt. This mediator component allows the shear bolt to only bear axial tensile loads, eliminating the harmful torsional stress that caused premature failure.
Solution Approach 2:
The anchoring system is segmented into distinct functional components: the shear bolt handles only axial tension, while the torque key handles torsional loads. This functional segmentation separates the load paths, allowing each component to be optimized for its specific purpose and preventing the shear bolt from being overloaded by combined stresses.
2Power
If the torque key is positioned in an extended position to prevent mill rotation, then torque transmission is enhanced, but the torque key may obstruct the milling operation
Solution Approach 1:
The torque key is designed to be movable between extended and retracted positions rather than fixed. During run-in, it extends to provide torque support. During milling, it can be retracted to clear the path. This dynamic positioning allows the system to adapt its configuration to different operational phases, optimizing both torque transmission and milling smoothness at different times.
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
An example whipstock assembly includes a whipstock providing a ramped surface and a longitudinal groove defined in the ramped surface. A lead mill is coupled to the whipstock with a shear bolt and having a slot defined therein, and a torque key is movable between an extended position, where the torque key is partially positioned within both the slot and the longitudinal groove, and a retracted position, where the torque key retracts into the slot. When the torque key is in the extended position, the torque key prevents the lead mill from rotating with respect to the whipstock.