Borehole Cross-Section Steering via Extendable Cutting Elements
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Solution Overview
Problem
Existing drill bit steering techniques require significant energy to alter the direction of a drill bit as it forms a borehole, especially when creating curves with small radii of curvature, which is inefficient and energy-intensive.
Innovation Solution
A borehole with a cross-sectional shape comprising two circular arcs of different radii, where an extendable cutting element enlarges the borehole radius in certain areas, allowing the drill bit to be steered by adjusting the relative radii and angular sizes of these arcs, reducing energy expenditure by urging the drill bit laterally rather than relying on direct pushing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional drill bit steering techniques are used to alter the direction of the drill bit, then the drill bit can be steered toward valuable resources or away from obstacles, but great amounts of energy are expended downhole
Solution Approach 1:
The borehole itself is shaped to provide lateral urging to the drill bit through its non-circular cross-sectional geometry. The irregular borehole shape, created by selective cutting element engagement, causes the drill bit to be pushed laterally by the borehole walls rather than requiring active steering mechanisms, thus making the steering system self-powered
Solution Approach 2:
Instead of using active mechanisms to push the drill bit in the desired direction, the invention inverts the approach by shaping the borehole to passively push the drill bit. The lateral urging force is generated by the borehole geometry rather than by an active steering device, reversing the traditional cause-effect relationship
2Manufacturing precision
If the desired radius of curvature of the borehole is decreased to create sharper curves, then the drill bit can be steered more precisely, but the amount of energy required increases
Solution Approach 1:
The invention changes the geometric parameters of the borehole cross-section, specifically creating a non-circular shape with varying radii of curvature. By controlling the relative radii and angular sizes of the circular arcs that form the borehole cross-section, precise curvature control is achieved without the energy penalty associated with traditional steering methods
3Ease of operation
If a drilling tool is used to push against the interior surface of the borehole to steer the drill bit, then direction control is achieved, but significant energy is required for this pushing action
Solution Approach 1:
The borehole is shaped to provide lateral urging to the drill bit through its non-circular cross-sectional geometry. The irregular borehole shape, created by selective cutting element engagement, causes the drill bit to be pushed laterally by the borehole walls rather than requiring active steering mechanisms, thus making the steering system self-powered
Solution Approach 2:
The invention extracts the steering function from active drilling tools and transfers it to the passive borehole geometry. By removing the need for active pushing mechanisms and using the borehole shape itself to provide steering forces, energy consumption is significantly reduced
Data Source
AI summary
A drill bit forming a borehole in the earth may be urged sideways, creating a curve in the borehole, by a cross-sectional shape of the borehole. For example, a borehole with a cross-sectional shape comprising two circular arcs of distinct radii, one larger and one smaller than a gauge of the drill bit, may push the drill bit away from the smaller circular arc and into the larger circular arc. Forming a borehole with such circular arcs may be accomplished by extending a cutting element from a side of the drill bit for only a portion of a full rotation of the drill bit.The relative radii and angular ranges occupied by the circular arcs may affect a radius of curvature formed in the borehole. The radii and angular ranges occupied by these circular arcs may be adjusted by altering the timing of extension and retraction of the extendable cutting element.