Compound-Angle Bearing Assembly for Low-Friction Directional Drilling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Directional drilling operations face challenges due to increased bit orbit diameter, friction, and vibration caused by external angles introduced by bent subs in the bottom hole assembly, limiting rotary mode operation and efficiency.
Innovation Solution
A bearing assembly design featuring an upper and lower bearing housing with a driveshaft positioned within, where the bearing housings are machined to intersect at an angle, allowing for a sliding mode of operation and reducing friction through oil-lubricated radial and thrust bearings, and a control valve assembly to manage fluid pressure and rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a bent sub is used to introduce an angle in the wellbore, then directional drilling capability is improved, but bit orbit diameter increases and rotary mode operation is limited
Solution Approach 1:
Instead of bending the drill string externally with a bent sub, the invention inverts the approach by creating an internal angle within the bearing assembly itself. The bore longitudinal axis is formed at an angle to the bearing housing longitudinal axis, allowing the drive shaft to rotate concentrically while the housing provides the directional angle. This eliminates the external bend and enables rotary mode operation.
Solution Approach 2:
The invention transitions from a single-axis rotation system to a multi-axis system. The drive shaft rotates along the bore longitudinal axis while the bearing housing is oriented at an angle relative to the drill string axis. This dimensional change allows simultaneous achievement of rotary rotation and directional drilling capability without the limitations of traditional bent subs.
2Adaptability or versatility
If a bent sub is used to introduce an angle, then toolface angle adjustment is enabled, but friction and vibration increase
Solution Approach 1:
The invention extracts the angle-introduction function from the drill string configuration and relocates it to the bearing assembly internal structure. By forming the bore axis at an angle to the housing axis within the bearing assembly itself, the need for external bent subs is eliminated, thereby removing the source of increased friction and vibration.
Solution Approach 2:
The bearing assembly acts as an intermediary between the drill string and the drill bit. It receives rotational input from the drill string along one axis and transmits it to the drill bit along an angled axis through its internally angled bore configuration. This intermediary function enables toolface angle adjustment without requiring external bending, thus reducing friction and vibration.
3Adaptability or versatility
If external angles are introduced by bent subs, then directional control is achieved, but drill string friction increases
Solution Approach 1:
Rather than bending the drill string externally to achieve directional control, the invention inverts the approach by creating the angle internally within the bearing assembly. The bore longitudinal axis is formed at an angle to the bearing housing longitudinal axis, allowing directional control to be achieved through internal geometry rather than external bending, thereby reducing drill string friction.
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
Enables efficient directional drilling by reducing bit orbit diameter, increasing rotary mode rotation speed, and maintaining toolface angle stability, while allowing for both sliding and rotary drilling operations with reduced vibration and friction.
Implementation Method 1
reducing friction through oil-lubricated radial and thrust bearings
Implementation Method 2
providing fluid pressure from the interior of the upper bearing housing to the control piston cylinder through the fluid supply port, valve port, output port, and control port
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A bearing housing for a bottomhole assembly of a downhole tool includes an upper bearing housing, lower bearing housing, and a driveshaft. The upper bearing housing and lower bearing housing include a bore defining a bore longitudinal axis. The outer surface of the upper bearing housing defining a bearing housing longitudinal axis, the bearing housing longitudinal axis formed at an angle to the bore longitudinal axis. The upper bearing housing may be formed by forming a bore through an upper bearing housing blank and subsequently forming the outer surface of the upper bearing housing concentric with the bearing housing longitudinal axis.