Drill Bit DOCC Rolling Element Friction Reduction
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Solution Overview
Problem
Existing earth-boring drill bits face issues with friction and wear due to contact between cutting elements and downhole formations, leading to fatigued cutting elements and reduced drill bit lifespan, as they require weight on bit and rotation, which generates excessive friction and can result in over-engagement.
Innovation Solution
The integration of depth-of-cut control (DOCC) elements with rolling elements secured within a walled retainer, allowing the rolling elements to rotate freely and reduce friction, minimizing stick-slip vibration and improving drill bit stability by using a braze alloy for securement without nail-lock retention features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If cutting elements are used to drill the wellbore with weight on bit and rotation, then drilling capability and rate of penetration are improved, but friction between cutting elements and formation increases, leading to wear and reduced drill bit lifespan
Solution Approach 1:
A rolling element is introduced as an intermediary between the DOCC element and the formation. This rolling element reduces direct frictional contact by converting sliding friction into rolling friction, thereby minimizing wear on the DOCC element while maintaining effective depth control functionality
Solution Approach 2:
The patent replaces the traditional sliding contact mechanism with a rolling contact mechanism. By substituting the direct sliding interface between the DOCC element and formation with a rolling element, the mechanical interaction changes from high-friction sliding to low-friction rolling, extending component life
2Reliability
If depth-of-cut control elements are added to limit cutting element engagement, then friction and wear are reduced, but device complexity increases
Solution Approach 1:
The rolling element is nested within a walled retainer structure that is itself positioned within a pocket on the drill bit. This nested arrangement consolidates multiple components into a compact integrated assembly, reducing overall space requirements and simplifying the structural organization of the depth control system
3Reliability
If rolling elements are used in DOCC elements, then friction is reduced and wear is minimized, but the rolling element may become dislodged during operation
Solution Approach 1:
The rolling element is nested within a walled retainer that provides containment while allowing rolling motion. The retainer structure prevents the rolling element from becoming dislodged during operation while maintaining its ability to rotate and reduce friction
Solution Approach 2:
Instead of attempting to secure the rolling element through complex retention mechanisms, the design inverts the approach by using the walled retainer to contain the rolling element through its geometric structure, allowing the rolling element to remain free-moving for friction reduction while being passively retained
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The DOCC elements with rolling elements effectively reduce friction and wear, enhancing the stability and lifespan of the drill bit by allowing the rolling elements to rotate freely and minimizing contact with the downhole formations, thus improving the rate of penetration and overall drilling efficiency.
Implementation Method 1
contact between the cutting elements and downhole formations generates friction that can result in worn or fatigued cutting elements... rolling elements to rotate freely and reduce friction
Data Source
AI summary
An earth-boring drill bit with brazed-in rolling elements for depth-of-cut control. The earth-boring drill bit includes a bit body, a blade having an exterior surface and defining at least one pocket, and a DOCC element positioned within the blade. The DOCC element includes a walled retainer positioned within the pocket. The walled retainer includes retainer side walls and an endcap attached to the retainer side walls at an end of the walled retainer. The DOCC element further includes a rolling element positioned within and partially enclosed by walled retainer, with a portion thereof extending above the exterior surface of the blade. The disclosure further includes the DOCC element and a method of installing it in the pocket defined by the blade.