Drill String Sub Assembly Friction Reduction
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Solution Overview
Problem
Current drill string technologies face challenges with high torque and friction issues during deep well drilling, leading to increased energy consumption, wear, and damage, as well as flexibility and deflection problems that affect drilling efficiency and accuracy.
Innovation Solution
A sub assembly with a mandrel, sleeve, and quick-lock stop mechanism that reduces friction by using a low-friction Chromium alloy coating and a simple, robust design with snap-lock engagement and removable stops for easy assembly and maintenance, allowing the sleeve to remain stationary relative to the well wall while rotating with the mandrel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a rotating collar with ball bearings is used to prevent friction against well casing, then friction is reduced, but device complexity and cost increase
Solution Approach 1:
The invention extracts the friction-reducing function from complex rotating collar mechanisms with ball bearings and implements it through a simpler bushing tool that slides within the drill string. The bushing tool achieves friction reduction without requiring rotating collar assemblies, thereby eliminating the complexity associated with bearings and rotating joint mechanisms.
Solution Approach 2:
The bushing tool is designed as a simpler, more economical component compared to rotating collars with ball bearings. The drill string bushing tool can be disposed of or replaced more easily, reducing the need for expensive maintenance and repair of complex rotating collar assemblies.
2Stability of the object's composition
If multiple drill string bushing tools are disposed on a rotary drill string to avoid deflection, then drill string flexibility is improved, but device complexity increases
Solution Approach 1:
The drill string is divided into multiple sections, each equipped with a bushing tool. This segmentation allows each segment to independently manage friction and deflection forces, improving overall drill string stability without requiring a single complex mechanism. The modular nature of multiple bushing tools simplifies maintenance and replacement compared to a unified complex system.
3Object-affected harmful factors
If a double-sleeve mounted on a mandrel via bearings is used to reduce friction, then friction is reduced, but ease of manufacture and maintenance deteriorate
Solution Approach 1:
The invention replaces the mechanical bearing system with a simpler sliding bushing mechanism. The bushing tool slides within the drill string without requiring bearing assemblies, eliminating the need for complex mechanical support structures and simplifying both manufacturing and maintenance processes.
4Object-affected harmful factors
If a double-sleeve mounted on a mandrel via bearings is used to reduce friction, then friction is reduced, but ease of repair and operation deteriorate
Solution Approach 1:
The bushing tool is extracted as a separate, standalone component that can be easily removed and replaced without disassembling complex bearing assemblies. This extraction simplifies repair operations, allowing the bushing tool to be quickly swapped out when worn, without requiring specialized maintenance procedures for bearing systems.
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 solution effectively reduces torque and friction, lowers wear on drill strings and casing, and simplifies maintenance and installation, providing a cost-effective and efficient drilling process with reduced risk of deflection and deviation.
Implementation Method 1
a low-friction Chromium alloy coating
Data Source
Figure 1
Figure 2
Figure 3A~3C
AI summary
A sub assembly for coupling to a drill string, the assembly comprising; a mandrel; a sleeve arranged to be co-axially positioned about said mandrel; a first stop arranged to prevent axial movement of the sleeve along the mandrel in a first direction; a second stop arranged to prevent axial movement of the sleeve in a second direction; wherein said second stop is releasably engageable from the mandrel.