Asymmetric Drill Bit Cutting Elements for Vibration Control
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Solution Overview
Problem
Rotary drill bits with PDC cutters face instability and damage in hard subterranean formations due to limited weight and torque, leading to vibration and borehole irregularities, despite previous stability approaches like anti-whirl and low-imbalance designs.
Innovation Solution
The design incorporates a plurality of cutting elements configured as kerfing pairs on radially extending blades, generating a directed net lateral force that stabilizes the drill bit by forming grooves in the formation, which cooperate with the bit's structure to inhibit vibration, and varying cutting element sizes and exposures to control aggressiveness and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If PDC bits are used at increased rates of rotation to achieve higher rates of penetration in hard subterranean formations, then productivity is improved, but the bit becomes prone to dynamic dysfunctions caused by instability, resulting in damage to the PDC cutters and bit body
Solution Approach 1:
The drill bit employs an asymmetric distribution of cutting elements, specifically using high-imbalance configurations where cutting elements are strategically positioned to generate controlled lateral forces. This asymmetric arrangement creates stabilizing effects that counteract the dynamic dysfunctions and vibrations that occur at high rotational speeds, allowing the bit to maintain stability while achieving high rates of penetration in hard formations
Solution Approach 2:
The invention changes the parameters of cutting element distribution and configuration, transitioning from conventional symmetric arrangements to asymmetric high-imbalance designs. By modifying the spatial parameters of cutting element placement and adjusting the imbalance characteristics, the bit achieves improved stability at high RPMs while maintaining high productivity in hard subterranean formations
2Productivity
If weight on bit and torque are increased to achieve higher rates of penetration in hard subterranean formations, then productivity is improved, but the PDC cutters and bit body may be damaged due to excessive loads
Solution Approach 1:
The asymmetric high-imbalance configuration distributes cutting forces more effectively across the bit structure. By positioning cutting elements to create controlled lateral forces, the design reduces peak torque demands and prevents excessive localized loads on individual cutters and the bit body, enabling sustained high-rate penetration without damage
Solution Approach 2:
The invention converts the potentially harmful lateral forces and vibrations that typically cause instability into a beneficial stabilizing mechanism. The controlled lateral forces generated by the asymmetric configuration create stabilizing effects that reduce overall bit vibration and prevent damage, transforming what would normally be a harmful dynamic effect into a protective mechanism
3Reliability
If conventional anti-whirl or low-imbalance designs are used to stabilize the drill bit, then bit stability is improved, but the ability to drill straight paths or maintain borehole geometry may be compromised
Solution Approach 1:
The invention optimizes the imbalance parameters within a specific range that simultaneously achieves both stability and straight drilling. By carefully selecting the degree and distribution of imbalance, the design maintains borehole geometry while providing sufficient stabilizing effects to prevent whirl and vibration at high rotational speeds
Data Source
AI summary
Earth-boring tools comprise a body having a face at a leading end. A plurality of cutting elements are disposed over the face and configured as a plurality of kerfing pairs comprising two or more cutting elements disposed at substantially the same radial position relative to a bit axis, wherein each of the at least two cutting elements follows substantially the same cutting path when the bit is rotated about its axis. Earth-boring tools are further configured so that a summation of a lateral force generated during drilling by each cutting element of the plurality of cutting elements is directed toward a side of the body.