Downhole Vibration

Causes of Downhole Vibration

Types of Vibration	Causes
Bit Bounce	Bit/Formation Interaction Multilobe Pattern of roller cone bits WOB Variation Mud Pressure Fluctuation Coupling
Slip Stick	Bit/Formation Interaction High WOB/Low RPM Friction between the Drillstring/BHA and Hole Wall High Wellbore Tortuosity Coupling
Bit/BHA Whirl and Bending	Mass Imbalance Lack of Axial Symmetry Component Misalignment Lateral Deflection Steerable Motor BHA/Drillstring-Wellbore Interaction Bit/Formation Interaction Uneven Vertical Loading on Bit Face Imbalanced Cutter Forces High RPM/Low WOB Rotation Off Bottom Reaming Formation Hardness/Formation Change Oversize Hole Coupling

Eliminating Downhole Vibration

Types of Elimination	Causes
Bit Whirl	Increase WOB Decrease RPM
Slip-Stick	Decrease WOB Increase RPM Increase mud lubricity

Downhole vibrations in drilling operations can significantly impact drilling performance and equipment integrity. Understanding these phenomena is crucial for optimizing drilling efficiency and preventing costly downtime. Here’s an overview of key aspects:

Bit Whirl: This occurs when a bit spirals instead of rotating around its center, often in softer formations, leading to enlarged holes and increased bit wear.

Slip Stick: A harmful vibration caused by insufficient torque to shear the formation, resulting in the bit momentarily stopping and breaking free at higher speeds, causing bit and BHA damage.

Coupling: The bending of the drill string under Weight on Bit (WOB), where linear coupling leads to additional bending in the plane of initial curvature, impacting drilling performance.

Bit Bounce: Primarily caused by bit/formation interaction, resulting in the bit bouncing off the hole bottom due to insufficient engagement with the formation, hindering smooth drilling action.

Understanding and mitigating these downhole vibrations are essential for maintaining drilling efficiency, minimizing equipment wear, and ensuring safe and productive drilling operations. Advanced drilling technologies and equipment designs aim to address these challenges and optimize drilling performance in various geological conditions.

	Identifying Vibration	Slip Stick	BHA Whirl	Bit Whirl	Bounce
	Real Tme
	Torque Fluctuation
	Torque Cyclicity
	MWD Shocks
	Torque
	High Frequency Downhole
	Lateral Torsional Vibration
	ROP
	WOB Fluctuation
	Surface Vibration
	Post Run
	Connection Over-Torque or Back-Off
	Twist-Off/Washout
	Cutter Impact Damage
	Over-Gauge Hole
	Tool Joint Wear
	Stabilizer Damage

Eliminating Vibration
Increase Weight on bit	to	Decrease Bit-Whirl
Decrease Weight on Bit	to	Decrease Slip-Stick
Increase Rotary Speed	to	Decrease Slip-Stick
Decrease Rotary Speed	to	Decrease Bit Whirl
Increase Mud Lubricity	to	Decrease Slip-Stick