Axial Load Device for Drill String Assembly
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Solution Overview
Problem
Existing drilling technologies face challenges in maintaining optimal axial load on drill bits during directional drilling, particularly in ultra-small boreholes, leading to premature wear, reduced drilling speed, and increased sticking probabilities due to uneven or insufficient load distribution, which affects the reliability and efficiency of drilling operations.
Innovation Solution
An axial load device is integrated into the drill string assembly, featuring a hollow cylinder body with a spring-loaded flow-type piston rod and a profiled key with two-way longitudinal slots, allowing for axial movement and self-excited vibrations, optimizing the axial load distribution and enhancing drilling efficiency by generating flexural waves and vortex flows that intensify rock crushing and reduce sticking risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the load on the drill bit is created by the weight of the pipe string rigidly connected to the bottom hole assembly, then the axial load is maintained, but the drilling assembly experiences reciprocal and oscillating movement that negatively affects performance
Solution Approach 1:
The patent applies mechanical vibration principle by creating self-excited vibrations in the drill string assembly through controlled axial load variations. The system generates vibrations at frequencies that resonate with the drill bit-rock interaction, intensifying rock crushing while reducing reciprocal movements that harm assembly performance. This is achieved through the dynamic interaction between the axial load device and the drilling system.
Solution Approach 2:
The patent implements periodic action by introducing pulsating axial load to the drill bit through a controlled mechanism. The axial load varies periodically, creating cycles of increased and decreased force application that enhance rock fragmentation efficiency while preventing sticking. The periodic variation in load creates the necessary dynamic conditions for improved drilling performance.
2Productivity
If uneven or exceedingly high load is applied on the drill bit, then rock crushing is intensified, but tooth and bearing chipping occurs causing premature wear
Solution Approach 1:
The patent applies dynamics principle by transitioning from static axial load to dynamic axial load with controlled variations. The system maintains average load levels that protect drill bit components while introducing dynamic fluctuations that intensify rock crushing during specific phases of the vibration cycle. This dynamic approach allows the drill bit to experience high instantaneous loads for rock fragmentation while maintaining lower average loads that prevent cumulative damage.
3Strength
If insufficient axial load is applied on the drill bit, then mechanical drilling strength decreases, but the risk of BHA sticking increases
Solution Approach 1:
The patent uses periodic action to alternately apply high axial load for rock crushing and reduced axial load for preventing sticking. The pulsating nature of the axial load creates cycles where increased force intensifies drilling during active phases, while reduced force during other phases prevents the bottom hole assembly from adhering to the borehole wall, thus maintaining both drilling strength and preventing sticking.
4Productivity
If high-pressure mud pulse is used for rock crushing, then drilling speed increases, but fluid consumption and pressure loss in small tubings increase significantly
Solution Approach 1:
The patent replaces the hydraulic rock crushing system with a mechanical vibration-based system. Instead of using high-pressure mud jets to fragment rock, the system uses mechanically generated vibrations and axial load variations to intensify rock crushing. This substitution eliminates the need for high fluid consumption and associated pressure losses in small tubings while maintaining enhanced drilling performance.
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 improves drilling efficiency, reduces sticking and tool lock-in probabilities, stabilizes the drilling trajectory, and enhances performance in ultra-small boreholes by optimizing axial load distribution and generating self-excited vibrations, thereby increasing mechanical drilling speed and reliability.
Implementation Method 1
a spring-loaded flow-type piston rod
Implementation Method 2
generating self-excited vibrations, thereby increasing mechanical drilling speed and reliability
Implementation Method 3
generating flexural waves and vortex flows that intensify rock crushing
Implementation Method 4
generating flexural waves and vortex flows that intensify rock crushing
Implementation Method 5
rock crushing tool (a drill bit or a mill)
Implementation Method 6
rock crushing process
Data Source
AI summary
The invention relates to drilling equipment. A device for generating an axial load in a drill string assembly with a bottomhole motor powered by drilling fluid comprises a hollow cylinder barrel and a spring-loaded flow-through plunger rod with a key, the rod and key forming a subassembly. The hollow cylinder barrel is provided with a sealing collar and with bilateral longitudinally oriented grooves that are arranged along the internal generatrix of the cylinder barrel and receive with longitudinal and transverse clearance the key, having a profiled surface, such that the key is capable of moving along the grooves together with the flow-through plunger rod. The length of the bilateral longitudinally oriented grooves is dependent on the maximum length of the working stroke of the flow-through plunger rod. The result is an improvement in the operating efficiency of the drill string together with expanded functional capabilities.