Earth-Boring Tool Asymmetric Blade Configuration for Bit Stability
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Solution Overview
Problem
Conventional earth-boring tools with PDC cutting elements face instability and damage in hard subterranean formations, leading to reduced drilling efficiency and increased mechanical specific energy due to bit whirl and imbalance issues.
Innovation Solution
The selective placement of shaped inserts on specific blades of the earth-boring tool enhances imbalance forces by positioning them on blades farthest from the natural imbalance force, creating an asymmetric configuration that stabilizes the bit and reduces mechanical specific energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If PDC bits are used at increased rates of rotation to obtain higher rate-of-penetration in hard subterranean formations, then the rate-of-penetration is improved, but the bit becomes particularly prone to dynamic dysfunctions caused by instability
Solution Approach 1:
The patent applies asymmetry by configuring blades with different numbers of cutting elements. Specifically, a first blade has a different number of cutting elements than second and third blades, creating an asymmetric distribution of cutting elements around the bit. This asymmetric configuration generates controlled imbalance forces that counteract the natural tendency toward whirl and instability, thereby maintaining bit stability at high rotation rates while preserving high rate-of-penetration in hard formations
2Reliability
If weight-on-bit and torque-on-bit are limited to protect PDC cutting elements in harder subterranean formations, then the cutting elements are protected, but the drilling efficiency is reduced
Solution Approach 1:
The patent applies local quality by creating different blade configurations where at least one blade has a different number of cutting elements compared to other blades. This localized variation in cutting element distribution generates specific imbalance forces that stabilize the bit during drilling operations. The stabilization effect allows higher weight-on-bit to be applied without causing instability, thereby protecting cutting elements while maintaining or improving drilling efficiency in hard formations
3Stability of the object's composition
If anti-whirl or high-imbalance designs are used to increase drilling stability, then bit stability is improved, but the device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the bit into multiple blades with different cutting element configurations. Instead of using a single complex stabilization mechanism, the bit is segmented into blades where at least one blade has a different number of cutting elements than others. This segmented approach to creating imbalance forces simplifies the overall design compared to traditional anti-whirl devices, while effectively stabilizing the bit during drilling operations
Data Source
AI summary
An earth-boring tool includes a body, blades extending longitudinally and generally radially from the body, and cutting elements located on each blade. The earth-boring tool may also include a first group of at least two adjacent blades comprising the cutting elements proximate a front cutting edge of the blades and one or more shaped inserts located rotationally following the cutting elements, and a second group of one or more additional blades comprising the cutting elements proximate the front cutting edge of the blades while being entirely free of the one or more shaped inserts. Methods include drilling a subterranean formation including engaging a formation with the cutting elements and the shaped inserts of the earth-boring tool, the shaped inserts secured at selected locations on two or more adjacent blades of the first group of blades while the second group of blades is entirely free of the shaped inserts.