Downhole Rotational Lock Mechanism for Torque Transfer
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Solution Overview
Problem
Drill bit speed slows down due to increased weight or formation resistance, leading to motor stall, which causes mechanical loading and high pressure fluid erosion, reducing the working life and efficiency of downhole drilling equipment.
Innovation Solution
A downhole rotational lock mechanism comprising a tubular housing with a driving gear and a driven gear, along with a ball-end screw, that engages and disengages to transfer additional rotational torque to the drill bit by changing the relative rotational speeds of the components, allowing the drill bit to overcome resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the drill bit encounters increased weight or formation resistance, then the drilling depth and productivity are improved, but the drill bit speed slows down causing motor stall and mechanical damage
Solution Approach 1:
The patent applies a dynamic locking mechanism that transitions between engaged and disengaged states based on operational conditions. The locking element automatically engages when the drill bit encounters resistance and disengages when the bit clears the formation, allowing the motor to dynamically adjust its operation and prevent stall while maintaining drilling progress
Solution Approach 2:
The locking element acts as an intermediary between the motor and the drill bit. It transmits torque to the drill bit when needed and decouples the motor from the bit when the bit clears the formation, preventing back-lashing and mechanical damage while maintaining drilling productivity
2Force
If the locking mechanism engages to deliver additional torque, then the rotational torque is improved, but the mechanical complexity of the system increases
Solution Approach 1:
The locking mechanism is designed to be self-regulating and automatically responds to operational conditions without external control. The locking element engages and disengages based on the relative motion between the motor and drill bit, eliminating the need for complex control systems while delivering the required torque
Solution Approach 2:
The locking function is extracted as a separate, simple locking element that can be independently engaged or disengaged. This modular approach allows the torque transmission function to be added without complicating the overall motor-drill bit system, as the locking element operates independently based on operational needs
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 mechanism effectively delivers additional torque to the drill bit during stall conditions, preventing motor stall and reducing damage from mechanical loading and erosion, thereby enhancing drilling efficiency and equipment longevity.
Implementation Method 1
a ball-end screw fixed to the tubular housing of the rotational lock mechanism, said ball-end screw being disposed in a circular circumferential groove connected to a helical cam groove disposed on an outer cylindrical surface of the driven gear
Implementation Method 2
passing the ball-end screw from the circular circumferential groove to the helical cam groove; and rotating the output shaft and the driven gear at the second rotational speed less than the first rotational speed and in the first rotational direction to urge the ball-end screw along the helical cam groove
Implementation Method 3
transferring rotational torque from the driving gear to the driven gear, wherein engaging the driven gear with the driving gear comprises: passing the ball-end screw from the circular circumferential groove to the helical cam groove
Data Source
Figure 1
Figure 2A~2B
Figure 3A~6B
AI summary
The subject matter of this specification can be embodied in, among other things, a method that includes a downhole rotational lock mechanism including a tubular housing having a longitudinal bore with an internal wall. A driving gear is disposed in the longitudinal bore of the tubular housing and has a peripheral edge secured to the internal wall of the longitudinal bore of the tubular housing. The driving gear has an upper portion including a plurality of gear teeth arranged around a central longitudinal bore through the driving gear. A driven gear is movably disposed in the longitudinal bore of the tubular housing, and has a central longitudinal bore and a lower portion including a plurality of gear teeth. An output drive shaft is disposed longitudinally in the longitudinal bore of the tubular housing and in the longitudinal bore of the driven gear.