Hybrid Drill Bit Balancing Torque and Penetration Rate
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Solution Overview
Problem
Existing hybrid earth-boring bits struggle to achieve a balance between cutting aggressiveness and durability, particularly in harder formations, as they often exceed torque or weight-on-bit limits, and previous designs have only marginal improvements over rolling-cutter bits in such conditions.
Innovation Solution
A hybrid drill bit design featuring a combination of fixed blade cutters and rolling-cutters, where the cutting aggressiveness is adjusted by varying the angular relationship and effective projection of cutting elements, allowing for optimal balance between penetration rate and bit durability through configurations such as 'cutter-leading', 'blade-leading', and 'cutter-opposite' arrangements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fixed blade cutters are used to increase cutting aggressiveness, then penetration rate is improved, but torque capacity is exceeded
Solution Approach 1:
The patent combines fixed blade cutters and rolling-cutters in a hybrid bit configuration. The fixed blade cutters provide aggressive cutting action for high penetration rates, while the rolling-cutters reduce torque requirements through their rolling mechanism. This merging of two different cutter types allows the system to achieve both high productivity and acceptable torque levels that would not be possible with either cutter type alone.
2Force
If rolling-cutters are used to reduce torque requirements, then torque capacity is maintained, but penetration rate is reduced
Solution Approach 1:
The hybrid bit merges fixed blade cutters and rolling-cutters to compensate for the low penetration rate of rolling-cutters alone. The fixed blade cutters provide the aggressive cutting action needed for high penetration rates, while the rolling-cutters maintain torque within acceptable limits. The synergistic combination allows the system to overcome the weaknesses of each individual cutter type.
3Reliability
If hybrid bit configuration is optimized for harder formations, then durability is improved, but cutting aggressiveness is reduced
Solution Approach 1:
The patent applies local quality by assigning different functions to different parts of the hybrid bit. Fixed blade cutters with specific geometries and materials are positioned for aggressive cutting in harder formations, while rolling-cutters are positioned to provide durability and stability. The angular relationships and radial positions of different cutter types are optimized locally to achieve both durability and cutting aggressiveness in hard formations.
Data Source
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AI summary
A hybrid earth boring bit comprising a bit body having a central axis, at least one, preferably three fixed blades, depending downwardly from the bit body, each fixed blade having a leading edge, and at least one rolling cutter, preferably three rolling cutters, mounted for rotation on the bit body. A rolling cutter is located between two fixed blades.