Lubricated Superhard Bearing Assemblies for Borehole Drilling
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Solution Overview
Problem
Subterranean drilling systems face significant wear and reduced operational life due to high thrust loads and abrasive drilling fluids, which challenge the durability of thrust-bearing apparatuses.
Innovation Solution
The use of a bearing apparatus with superhard polycrystalline diamond bearing elements and a separate lubricating fluid, such as oil, that transfers heat from the bearing elements to the drilling fluid, reducing friction and wear by enabling hydrodynamic operation at lower RPMs and enhancing the operational life of the bearing apparatus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If drilling fluid is used to lubricate bearing elements, then cooling is provided, but wear and friction increase due to abrasiveness
Solution Approach 1:
The system divides the fluid environment into two separate domains: a sealed internal enclosure containing lubricating oil for the bearing elements, and the external drilling fluid in the borehole. This segmentation allows each fluid to perform its optimal function without compromising the other.
Solution Approach 2:
The sealed housing acts as an intermediary barrier between the lubricating oil and drilling fluid. It enables heat transfer from the oil to the drilling fluid while preventing direct contact between the two fluids, thus protecting the bearing elements from abrasive contamination.
2Device complexity
If conventional drilling fluid is used for lubrication, then system simplicity is maintained, but operational life is reduced due to high wear
Solution Approach 1:
The bearing apparatus is segmented into a sealed internal enclosure and the external drilling environment. This allows the use of superior lubricating oil internally while maintaining relatively simple integration with the existing drilling fluid system externally.
3Reliability
If high RPM operation is used to maintain hydrodynamic lubrication, then lubrication is improved, but wear on bearing elements increases
Solution Approach 1:
The invention changes the lubrication parameter from drilling fluid to lubricating oil, which has superior lubricating properties. This allows hydrodynamic lubrication to be maintained at lower RPMs, reducing the speed-related wear on bearing elements while preserving adequate lubrication film formation.
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
This configuration significantly increases the operational life of the bearing apparatus by reducing wear and friction, allowing hydrodynamic operation at lower RPMs and effectively cooling the lubricating fluid through the drilling fluid, thus extending the useful life of the subterranean drilling system.
Implementation Method 1
The bearing apparatus is configured for transferring heat from a lubricating fluid substantially sealed within the bearing apparatus to a drilling fluid (e.g., within the borehole) during use
Implementation Method 2
Heat may be generated during operation of the bearing apparatus due to friction at an interface of first and second bearing surfaces of the respective bearing assemblies. The heat generated during operation of the bearing apparatus may be transferred from the superhard bearing elements to the lubricating fluid. The heat may then be transferred from the lubricating fluid to the drilling fluid outside of the housing
Implementation Method 3
the present inventors have found that hydrodynamic operation of the bearing apparatus may occur at significantly lower revolutions per minute ('RPM') than where conventional drilling fluids (e.g., drilling mud) are used to lubricate the superhard bearing elements
Data Source
AI summary
Embodiments to bearing apparatuses for placement into a borehole containing a drilling fluid in which the apparatus is configured for transferring heat to the drilling fluid from a lubricating fluid substantially sealed within the apparatus. The apparatus includes a substantially sealed housing, first and second bearing assemblies disposed about a rotatable shaft extending through the housing, where the bearing assemblies are within the substantially sealed housing. Each bearing assembly includes superhard bearing elements. One bearing assembly is fixed relative to the shaft so as to rotate therewith, while another bearing assembly is fixed relative to the housing. In an embodiment, a lubricating fluid for lubricating the superhard bearing elements may circulate from within a circulation cavity of the housing or shaft between the superhard bearing elements, and be recirculated back into the circulation cavity. In other embodiments, the lubricating fluid may not be recirculated.