Multi-Row Drill Bit Cutters for Eccentric Drilling
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Solution Overview
Problem
Current drill bit designs for eccentric drilling modes, particularly those using rotatable bent motors, suffer from mediocre performance due to the difficulty in estimating and optimizing the bottom hole pattern, leading to reduced rate of penetration and increased wear.
Innovation Solution
A drill bit design featuring a plurality of cutters, including a primary row and a secondary row, where the secondary cutters are strategically sized, oriented, and positioned based on the bottom hole pattern generated by the primary cutters in eccentric drilling cases to enhance depth of cut and reduce wear, with the secondary cutters optionally not participating in rock cutting in concentric drilling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single row of cutters is used in drill bit design, then the structure is simple and manufacturing is easier, but the depth of cut and rate of penetration are limited in eccentric drilling cases
Solution Approach 1:
The cutter row is segmented into multiple rows (first row and second row) with different functions. The first row cutters are optimized for concentric drilling while the second row cutters are specifically designed to address blade rubbing in eccentric drilling, allowing each row to specialize in different operational conditions.
Solution Approach 2:
The solution transitions from a single-row cutter configuration to a multi-row configuration, adding a dimensional aspect to the cutter arrangement. The second row of cutters is positioned at a different radial location and orientation angle, creating a three-dimensional cutter distribution that addresses eccentric drilling challenges.
2Productivity
If cutters are positioned to maximize depth of cut in eccentric drilling, then rate of penetration improves, but wear on primary cutters increases
Solution Approach 1:
The second row of cutters acts as an intermediary element that mediates between the primary cutters and the rock formation in eccentric drilling conditions. By positioning the second row cutters to engage the rock at strategic locations, they reduce the burden on primary cutters and minimize blade rubbing, thereby extending cutter life while maintaining effective depth of cut.
3Productivity
If drill bit is designed for concentric drilling only, then cutter configuration is optimized for that mode, but performance deteriorates in eccentric drilling mode
Solution Approach 1:
The drill bit cutter configuration is designed with multi-functionality to handle both concentric and eccentric drilling modes effectively. The first row cutters handle concentric drilling optimization while the second row cutters provide additional functionality for eccentric drilling conditions, making the overall system adaptable to different drilling modes without sacrificing performance in either mode.
4Productivity
If secondary cutters are added to the drill bit, then blade rubbing is reduced and depth of cut increases, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The second row of cutters is strategically positioned at specific locations on the blade rather than uniformly distributed. The cutters are placed at radial locations and orientation angles that specifically target areas prone to blade rubbing in eccentric drilling, providing localized quality enhancement where it is most needed rather than uniform improvement throughout.
Data Source
AI summary
A drill bit (10), for example of a fixed cutter type, comprises at least one structure, for example a blade, having first and second rows of cutters (35a-h) thereon. The first row is configured to achieve suitable performance when the drill bit drills in concentric mode. The second row of cutters is configured to improve the performance of the first row of cutters when the drill bit drills in eccentric mode. For example, the second row increases depth of cut and wear resistance in eccentric mode drilling. The drill bit may be mounted on a bent motor (120) used in directional drilling.