Reverse Circulation Drill Bit Assembly for Bearing Cooling
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Solution Overview
Problem
Existing roller cone drill bits often have drilling fluid bypassing the working face, reducing efficiency and potentially damaging the drill bit during fluid redirection attempts, which complicates directing more fluid to the face without affecting the longevity of the bit.
Innovation Solution
A drill bit assembly that includes a bit sub with legs and fluid delivery passages to direct drilling fluid to the working face of the roller cone bit, using a skirt and nut section to secure the bit sub, and a check valve section to manage fluid flow, allowing for reverse circulation without overheating the bearings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If drilling fluid is redirected to flow across the working face of the roller cone bit, then fluid circulation and cooling improve, but the bearings and seals of the roller cones are heated and damaged
Solution Approach 1:
The patent inverts the conventional fluid flow direction by implementing reverse circulation, where drilling fluid flows up the annulus and down through the drill bit interior rather than the traditional down-annulus flow. This reversal allows fluid to cool the roller cone bearings from the inside out, preventing overheating while maintaining effective cooling of the working face.
Solution Approach 2:
The patent introduces a specialized bit sub assembly with fluid delivery passages that act as an intermediary system. This intermediary directs drilling fluid through the drill bit interior and across the working face without allowing direct contact between high-velocity fluid and the roller cone bearings, thus mediating the thermal interaction to prevent bearing damage.
2Productivity
If more drilling fluid is directed to the working face, then drilling efficiency improves, but fluid bypassing the face increases without effective circulation
Solution Approach 1:
The patent segments the fluid circulation system into distinct pathways: an annular path for upward flow and an internal bit path for downward flow across the working face. This segmentation ensures that drilling fluid is systematically distributed to where it is most needed (the working face) while preventing bypassing and maximizing circulation effectiveness.
Solution Approach 2:
The reverse circulation system creates a feedback loop where fluid flow across the working face is continuously monitored and adjusted. The system responds to drilling conditions by optimizing fluid distribution, ensuring that sufficient fluid reaches the face for effective cooling and cuttings removal without excessive bypassing that would waste energy.
3Ease of operation
If a bit sub with fluid delivery passages is added to direct fluid to the working face, then fluid distribution improves, but device complexity increases
Solution Approach 1:
The patent merges the fluid delivery function with the existing bit sub structure by integrating fluid delivery passages into the bit sub body. This consolidation achieves effective fluid distribution control while minimizing additional complexity, as the bit sub serves both structural support and fluid delivery functions simultaneously.
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
Enhances drilling fluid distribution across the working face of the roller cone bit, improving drilling efficiency and longevity by ensuring effective fluid circulation without detrimental heat effects on the drill bit components.
Implementation Method 1
a check valve section to manage fluid flow
Data Source
AI summary
A drill bit assembly for boring including a drill bit and a bit sub. A front bit end has a plurality cutting elements at a forward face of the front bit end and a first fluid return passage extending through the drill bit to a rear bit end. The bit sub couples to the rear bit end. The bit sub includes a bore disposed at a front sub end sized and shaped to receive the rear bit end of the drill bit. A plurality of legs extends from a mid-sub region toward the front sub end between pairs of cutting elements. The plurality of legs has a fluid delivery passage disposed therein with the fluid delivery passage extending from the plurality of legs to a rear sub bit end. The bit sub has a second fluid return passage connecting the first fluid return passage to the rear sub bit end.