Drill String Eddy-Current Damping for Stick-Slip Vibrations
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Solution Overview
Problem
Current drill string vibration damping solutions primarily focus on bit-rock interaction, failing to address the distributed sources of vibrations along the string, such as mechanical friction, hydraulic forces, and centrifugal accelerations, leading to instability and premature wear.
Innovation Solution
A device comprising brake means with brake parts and roller wheels that utilize eddy currents generated by magnetic fields to resist rotational and longitudinal vibrations, allowing the drill string to move freely while damping vibrations without requiring external activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If active vibration control systems are used to reduce stick-slip oscillations, then drilling performance and BHA longevity are improved, but the system complexity and cost increase significantly
Solution Approach 1:
The patent converts the harmful stick-slip vibrations into beneficial effects by using the same vibrational energy to fracture rock formations. The system intentionally induces controlled vibrations that, while similar to harmful stick-slip, are used to break rock and improve drilling performance, thereby transforming a harmful phenomenon into a useful one
Solution Approach 2:
The patent introduces a vibration isolation element as an intermediary component between the drill bit and the BHA. This element acts as a mediator that filters and attenuates harmful high-frequency vibrations while allowing beneficial drilling forces to pass through, reducing the need for complex active control systems
2Productivity
If high-weight-on-bit is applied to maintain drill bit engagement, then drilling efficiency is improved, but stick-slip oscillations are intensified
Solution Approach 1:
The patent segments the drill string into functional zones with different vibration characteristics. By creating sections with varying mass, stiffness, and damping properties, the system can maintain high WOB for productivity while different segments absorb and attenuate stick-slip oscillations, preventing them from amplifying throughout the entire BHA
Solution Approach 2:
The patent changes physical parameters of the BHA components, such as mass distribution, stiffness, and damping coefficients, to optimize the system's response to WOB variations. By adjusting these parameters, the system maintains drilling efficiency at high WOB while suppressing the generation and propagation of stick-slip oscillations
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
Effectively damps a wide range of vibrations along the drill string, improving drilling performance by reducing rotational and longitudinal vibrations, and maintaining weight on the bit, while being passive and mechanical, suitable for high-temperature environments.
Implementation Method 1
a vibration isolation element arranged between the drill bit and the sub. The vibration isolation element may be configured to reduce the strength of harmful vibrations and/or oscillations
Data Source
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AI summary
A device for damping vibrations of a rotary drill string in motion in a wellbore, a related method, drill string and drill string sub or section, where at least one component of motion of the drill string is communicated to the device, and brake means counter the vibrations, resisting the motion in dependence upon the speed of motion. Examples include using eddy current braking. In examples, the device has an outer sleeve arranged on an inner, tubular body which is rotatably arranged within the outer sleeve, roller wheels support the sleeve on the wellbore wall and facilitate longitudinal movement of the device and prevent rotational slipping of the outer sleeve relative to the wall upon rotating the tubular body and drill string, one brake part of the brake means on the outer sleeve and another on the tubular body operating to resist rotational vibration components. (Figure 1)