Drill String Agitator Radial Vibration Friction Reduction
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Solution Overview
Problem
Downhole tools face challenges in minimizing friction forces along the drill string as it advances within the wellbore, particularly due to increasing static and dynamic friction, which can lead to sticking and reduced movement efficiency, and existing vibration devices may cause resonance or sympathetic vibrations when multiple units are used.
Innovation Solution
Radial vibration of the drill string using agitators with rotatable agitation masses and rotors, which create localized vibrations to reduce friction and prevent resonance, allowing for efficient movement and formation property measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If multiple vibration generating devices are coupled to the drill string to reduce friction, then friction forces are minimized and drill string movement is maintained, but resonance or sympathetic vibrations occur which can damage the drill string
Solution Approach 1:
The patent applies local quality by creating localized radial vibrations at specific positions along the drill string using distributed agitators. Each agitator generates vibrations in its immediate vicinity rather than uniform axial vibrations throughout the entire drill string. This localized approach reduces friction at specific high-friction zones without propagating resonance waves through the entire drill string structure, thereby maintaining reliability while minimizing friction forces.
Solution Approach 2:
The patent transitions from axial vibration (one dimension along the drill string length) to radial vibration (perpendicular dimension outward from the drill string axis). This dimensional change allows multiple agitators to operate simultaneously at different axial positions without their vibration fields interfering with each other through resonance, as the radial vibrations are localized and do not couple into global drill string modes that cause sympathetic vibrations.
2Length of stationary object
If the drill string is advanced deeper into the wellbore to reach target formations, then drilling depth increases, but friction forces increase proportionally making advancement more difficult
Solution Approach 1:
The patent segments the drill string into multiple sections with agitators distributed at specific intervals along its length. This segmentation allows the long drill string to be treated as a series of shorter segments, each with localized vibration control. The agitators create radial vibrations in local segments to reduce friction forces at each position along the extended drill string, enabling deep wellbore penetration without the cumulative friction that would otherwise prevent advancement.
Solution Approach 2:
By introducing radial vibrations perpendicular to the drill string axis, the patent enables friction reduction at multiple positions along the extended drill string length without the vibrations coupling together to create harmful resonance. This dimensional approach allows the drill string to be progressively lengthened for deeper drilling while maintaining manageable friction forces through distributed localized radial vibration zones.
3Ease of operation
If axial vibration is used to reduce friction and maintain drill string movement, then dynamic friction is overcome, but resonance and sympathetic vibrations are induced that can damage the drill string
Solution Approach 1:
The patent replaces global axial vibration with localized radial vibrations at distributed positions. Each agitator creates radial vibration quality in its local zone that reduces friction and maintains movement ease, while the localized nature prevents the propagation of resonant waves that would compromise drill string structural integrity through sympathetic vibrations.
Solution Approach 2:
The patent transitions from axial vibration (parallel to drill string axis) to radial vibration (perpendicular to axis). This dimensional change enables friction reduction and maintained drill string movement while preventing resonance, because radial vibrations at different axial positions do not couple into the global axial modes that cause sympathetic vibrations and structural damage.
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 radial vibration effectively decreases friction forces along the drill string, preventing sticking and allowing for smoother advancement without causing resonance, while also enabling the measurement of formation properties.
Implementation Method 1
Radial vibration of the drill string using agitators with rotatable agitation masses and rotors, which create localized vibrations to reduce friction
Data Source
AI summary
An agitator for vibrating a drill string includes an agitator housing, a rotor and an agitation mass. The drill string has a central axis. The rotor is coupled to the agitator housing and being rotatable about an agitator axis. The agitation mass is coupled to the rotor and is rotatable about the agitator axis. During rotation, a center of mass of the agitation mass is spaced apart from the agitator axis to cause deflection of the agitator axis relative to the central axis to produce vibration in the drill string.