Rotary Drill Bit Back-Up Cutting Elements Segmentation
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Solution Overview
Problem
Conventional rotary drill bits with back-up cutting elements have a short bit life due to inadequate exposure and ineffective engagement of back-up cutting elements, leading to inefficient drilling as primary cutting elements wear out.
Innovation Solution
A multi-layer downhole drilling tool design with primary and back-up cutting elements, where back-up cutting elements are strategically positioned on different blades and configured based on the wear characteristics of primary cutting elements to ensure optimal engagement and depth of cut control, using methods that estimate wear and adjust under-exposure to maximize bit life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If back-up cutting elements are placed on the same blade directly behind primary cutting elements with small under-exposure, then they can act as depth of cut controllers, but they result in ineffective engagement and shorter bit life
Solution Approach 1:
The patent divides the back-up cutting elements into multiple groups, with each group placed on a different blade rather than concentrating them on a single blade. This segmentation allows more uniform distribution of cutting engagement across all blades, ensuring that back-up elements engage the formation effectively when primary elements wear, thereby extending bit life while maintaining depth of cut control.
Solution Approach 2:
The patent applies different under-exposure values to different back-up cutting elements based on their specific locations and the wear characteristics of corresponding primary cutting elements. This localized optimization ensures that each back-up element engages at the appropriate depth, maximizing cutting effectiveness and bit life without compromising depth of cut control.
2Productivity
If back-up cutting elements are placed with larger under-exposure, then they engage the formation more effectively when primary elements wear, but they may never engage if primary elements are not worn
Solution Approach 1:
The patent optimizes the under-exposure parameter for each back-up cutting element based on the wear characteristics of the corresponding primary cutting element. By carefully selecting under-exposure values that are neither too small nor too large, the patent ensures that back-up elements engage the formation effectively when primary elements wear, while avoiding situations where they never engage or engage inconsistently.
3Duration of action of moving object
If back-up cutting elements are placed on different blades, then bit life is extended through more uniform engagement, but device complexity increases
Solution Approach 1:
The patent segments back-up cutting elements across multiple blades in a systematic manner. This segmentation approach, while increasing structural complexity, distributes the cutting load more uniformly across all blades, preventing any single blade from bearing excessive wear and thereby extending overall bit life.
Solution Approach 2:
The patent designs the blade configuration so that each blade can serve both as a primary cutting blade and potentially as a back-up cutting surface. This multi-functionality approach allows the drill bit to maintain effectiveness across all blades throughout the drilling operation, extending bit life without requiring entirely separate primary and back-up blade systems.
Data Source
AI summary
A multi-layer downhole drilling tool designed for drilling a wellbore including a plurality of formations is disclosed. The drilling tool includes a bit body including a rotational axis extending therethrough. A plurality of blades are disposed on exterior portions of the bit body. A plurality of primary cutting elements and a plurality of back-up cutting elements are disposed on exterior portions of the plurality of blades. The back-up cutting elements are track set with corresponding primary cutting elements, and each back-up cutting element is disposed on a different blade than the corresponding primary cutting element.