Steerable Drill Bit with Movable Cutters for Directional Control
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Solution Overview
Problem
Current directional drilling methods, such as positive displacement mud motors and rotary steerable systems, face limitations in controlling drilling direction and rate of penetration, leading to slower operations and increased complexity and cost.
Innovation Solution
A directional drilling device with movable cutting members that can be remotely controlled to alter their position between engaged and retracted states, synchronized with the rotational position of the drill bit, creating an eccentric channel to steer the drill bit and maintain directional control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If positive displacement mud motors are used for directional drilling, then directional control is achieved, but the rate of penetration is reduced due to torque limitations and alternating sliding/rotating modes
Solution Approach 1:
The patent employs movable cutting members that can dynamically change position between retracted and extended states during drill string rotation. This dynamic adjustment allows the system to maintain continuous rotation while achieving directional control, eliminating the need to alternate between sliding and rotating modes and thereby improving rate of penetration
Solution Approach 2:
The cutting members are activated periodically during each rotation of the drill string to create eccentric channels at controlled intervals. This periodic action provides directional control through cumulative deviation while allowing continuous rotation, resolving the contradiction between directional precision and drilling speed
2Productivity
If continual rotation of the drill string is used for directional drilling, then higher rates of penetration and smoother well bores are achieved, but device complexity increases
Solution Approach 1:
The directional control function is segmented into discrete movable cutting members that can be independently activated. Each cutting member operates as a separate unit during rotation, simplifying the overall system architecture while enabling continuous rotation for higher rates of penetration
Solution Approach 2:
The system changes the operational parameters of cutting members during rotation - specifically their radial position (inward/outward) and angular position relative to the drill string axis. This parameter modulation enables directional control through continuous rotation without requiring complex mechanical steering mechanisms
3Measurement precision
If movable cutting members are used to create eccentric channels, then directional control precision is improved, but the device complexity increases due to additional control mechanisms
Solution Approach 1:
The patent combines the directional control function with the existing drill string rotation mechanism. The movable cutting members utilize the rotational motion already present in the system, merging steering functionality with the primary drilling operation and reducing overall system complexity
Solution Approach 2:
The movable cutting members are designed to be actuated by the rotational motion of the drill string itself. The system uses its own operational parameters (rotation) to activate the steering mechanism, eliminating the need for separate complex control systems while maintaining directional precision
Data Source
AI summary
A directional drilling apparatus for use in the directional drilling of bore holes is disclosed. The apparatus comprises a plurality of cutting elements movably mounted with respect to a rotatable body member, wherein the cutting elements are movable between first, radially retracted, positions and radially extended, positions for cutting. A rotary valve is provided for synchronising the movement of the cutting elements between their respective extended and retracted positions in accordance with the rotational position of the body member in the bore hole being drilled. Control of the directional drilling system is affected by synchronised movement of the cutting elements from an inner to an outer radial position in accordance with the angular position of the drill bit. A near bit stabiliser contacts with the portion of the well bore which was not removed with the dynamic cutters and this contact exerts a force onto the drill bit.