Downhole Drill Bit Steering via Non-Cylindrical Borehole
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Solution Overview
Problem
Existing drilling technologies face challenges in efficiently steering a drill bit within a borehole to navigate towards resources or avoid obstacles while minimizing damage to the borehole wall, as current methods often result in significant wear or damage to the drill bit and borehole.
Innovation Solution
A downhole drilling apparatus with radially protruding, extendable, and revolvable cutting elements that transform the borehole shape from cylindrical to non-cylindrical by selectively extending cutting elements to create a cross-sectional shape with varying radii, allowing lateral movement without significant disturbance, and reaming back to cylindrical when necessary to maintain straight drilling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If cutting elements are extended to create a non-cylindrical borehole shape for steering, then directional control is improved, but wear and damage to the borehole wall increases
Solution Approach 1:
The cutting elements are made dynamically extendable and retractable rather than fixed. This allows the gauge pads to be extended only when steering is needed, creating a non-cylindrical borehole shape to guide the drill bit laterally, and retracted when not needed to minimize borehole wall contact and damage. The dynamic adjustment resolves the contradiction between needing contact for steering and avoiding contact to prevent damage.
Solution Approach 2:
The cutting elements operate periodically by extending during steering operations and retracting during straight drilling or when passing through formation. This periodic extension and retraction allows the system to achieve steering functionality when required while minimizing harmful contact with the borehole wall during other operations, thus reducing overall wear and damage.
2Measurement precision
If gauge pads are extended to steer the drill bit laterally, then directional accuracy is improved, but wear on the gauge pads increases
Solution Approach 1:
The gauge pads are equipped with extendable mechanisms that allow them to be deployed only when steering corrections are needed. During straight drilling sections, the pads are retracted to minimize contact with the borehole wall, significantly reducing wear accumulation. This dynamic deployment strategy maintains steering accuracy when required while extending gauge pad service life by reducing unnecessary contact hours.
Solution Approach 2:
The system changes the radial position parameter of the gauge pads dynamically. By adjusting the extension/retraction state based on real-time drilling conditions and desired trajectory, the system optimizes the balance between achieving necessary steering accuracy and minimizing wear. The parameter change allows the same physical component to serve dual purposes: high-precision steering when extended and wear-minimized travel when retracted.
3Ease of operation
If the drill bit continuously contacts the borehole wall for steering, then directional control is maintained, but energy consumption increases
Solution Approach 1:
Instead of continuous contact, the gauge pads engage the borehole wall periodically only when steering corrections are required. During straight drilling sections, the pads are retracted to eliminate unnecessary friction and contact forces, thereby reducing energy consumption. The periodic engagement maintains directional control when needed while minimizing energy waste during straight-run sections.
Solution Approach 2:
The dynamic extendable/retractable mechanism allows the system to switch between contact and non-contact states based on steering requirements. When the desired borehole trajectory aligns with the current drill bit path, the pads are retracted to minimize energy consumption. When trajectory adjustments are needed, the pads extend to provide lateral guidance. This dynamic state switching optimizes the balance between directional control and energy efficiency.
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
Enables precise steering and minimizes borehole damage by allowing the drill bit to curve within the borehole while maintaining the non-cylindrical shape, and reaming back to cylindrical when needed for straight drilling, thus enhancing directional control and reducing wear on the drill bit and borehole.
Implementation Method 1
Timed extension of the cutting elements, while the apparatus is rotating within a borehole, may allow them to degrade an inner wall of the borehole in certain places to create a non-cylindrical borehole shape.
Implementation Method 2
The sliding may cause the body to be urged laterally to form a curve in the borehole at it is being formed.
Data Source
AI summary
A downhole drilling apparatus may comprise a rotatable body with various cutting elements connected thereto, some radially protruding therefrom, some radially extendable therefrom, and some revolvable relative thereto about a common axis. In operation, when the body is rotated, the radially protruding cutting elements may bore a generally cylindrical borehole. The radially extendable cutting elements may be extended during specific portions of the body's rotation to degrade certain areas of an inner wall of the borehole transforming it into a non-cylindrical borehole. At certain times, the revolvable cutting elements may be allowed to slide against the non-cylindrical inner wall while freely revolving to minimize disturbance to the borehole shape. At other times, revolution of these revolvable cutting elements may be restrained to ream the borehole back to a cylindrical shape.