Drill Bit Cross-Section Steering for Low-Energy Borehole Curving
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing drill bit steering techniques require significant energy expenditure to form curving boreholes, especially those with small radii of curvature, and instrumentation on drill bits is complex and prone to wear, complicating measurements and communication across drill-string-to-drill-bit connections.
Innovation Solution
A drill bit assembly that forms a borehole with a cross-sectional shape comprising two circular arcs of different radii, using extendable cutting elements and a stabilizer to steer the drill bit laterally, and a mechanism for communication across the drill-string-to-drill-bit connection that is independent of rotational orientation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional pad pushing techniques are used to steer the drill bit, then the drill bit can be directed toward valuable resources or away from obstacles, but great amounts of energy are expended downhole and the useful life of the tool is shortened
Solution Approach 1:
Instead of pushing the drill bit forward with pads, the invention removes material from the borehole wall to create an asymmetric cross-sectional shape. This causes the drill bit to be pushed laterally by the reaction force from the borehole wall, effectively reversing the steering mechanism from active pushing to passive steering through shape control.
Solution Approach 2:
The invention changes the cross-sectional shape parameters of the borehole by selectively removing material at specific locations. By controlling the radius and curvature of the borehole cross-section through strategic material removal, the drill bit steering direction and curvature radius are controlled without requiring continuous high-energy pad engagement.
2Adaptability or versatility
If the desired radius of curvature of the borehole is decreased to achieve tighter turns, then the drill bit can navigate more complex pathways, but the amount of energy required increases significantly
Solution Approach 1:
The invention performs preliminary material removal from the borehole wall at strategically selected locations before the drill bit reaches those sections. This pre-shaping of the borehole cross-section creates the lateral pushing force needed to steer the drill bit along the desired curved path, reducing the energy required during actual drilling.
Solution Approach 2:
The asymmetric borehole cross-sectional shape acts as an intermediary mechanism between the drilling system and the steering objective. By controlling the borehole geometry, the system indirectly controls drill bit direction and curvature, avoiding the need for direct high-energy pad pushing and enabling tighter turns with reduced energy consumption.
3Measurement precision
If instrumentation is added to the drill bit for measurements and functions, then valuable data can be collected close to the drill string end, but the complexity and cost of replacement increases due to wear and damage
Solution Approach 1:
The invention separates the instrumentation from the drill bit by placing it on the stabilizer, which is a distinct component. This segmentation allows the drill bit to be replaced without affecting the instrumentation, reducing complexity and cost while maintaining measurement capabilities close to the drill string end.
Solution Approach 2:
The stabilizer serves multiple functions: it provides structural support, enables measurements and functions through instrumentation, and facilitates drill bit replacement. By making the stabilizer a multi-functional component, the system reduces overall complexity while maintaining measurement precision.
Data Source
Figure 1
Figure 2
Figure 3-1~3-4
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 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.