Rotary Steerable Control Shaft Deflection for Directional Accuracy
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Solution Overview
Problem
Rotary steerable tools face challenges in maintaining directional accuracy of a drill bit during wellbore drilling, as the drill bit rotates while targeting a stationary location, requiring constant adjustments to keep the bit pointed in the correct direction.
Innovation Solution
A point the bit rotary steerable system that includes a control shaft with deflection devices, enabled and disabled by a control device to apply forces that pivot the drill bit around a universal joint, ensuring the bit remains pointed at a target direction despite rotational movement of the bottom hole assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the drill bit rotates during drilling, then drilling progress is made, but directional accuracy is lost as the bit moves away from the stationary target location
Solution Approach 1:
The system applies periodic deflection forces to the control shaft at specific rotational positions of the drill bit. Deflection devices are selectively enabled and disabled in synchronization with the rotation cycle, applying forces only when the bit passes through predetermined angular positions to correct directional drift while allowing continuous rotation for drilling progress
Solution Approach 2:
The control system predicts the rotational position of the drill bit and pre-activates deflection devices before the bit reaches the target correction position. This anticipatory activation ensures that directional corrections are applied at the optimal moment in the rotation cycle, maintaining accuracy without interrupting the drilling process
2Measurement precision
If deflection devices are continuously enabled to maintain directional accuracy, then the drill bit remains pointed at the target, but energy consumption increases and mechanical wear accelerates
Solution Approach 1:
Instead of continuous operation, deflection devices are activated in periodic pulses synchronized with the drill bit's rotation cycle. Each deflection device operates only during specific angular positions when correction is needed, then is disabled for the remainder of the rotation, dramatically reducing cumulative energy consumption and mechanical wear while maintaining directional control
Solution Approach 2:
The system applies deflection forces only partially during the rotation cycle, using minimal activation periods of deflection devices to achieve the necessary directional corrections. This partial action approach provides sufficient control to maintain accuracy while avoiding the excessive energy expenditure and wear that would result from continuous deflection device operation
Data Source
AI summary
A method, device, and system is described herein for pointing a rotary drill bit. A rotary bit pointing device is positioned between a proximal end of a control shaft and a universal joint. As the bottom hole assembly rotates, various portions of the rotary bit pointing device are enabled and subsequently disabled to apply a substantially constant force in a substantially constant direction to the control shaft. Such a force causes the distal end of the control shaft to point the rotary drill bit in a target direction.