What are the three types of drillstring vibration?

What are the three types of drillstring vibration?

Drillstring vibrations can be divided into three types, or modes: axial, torsional, and lateral (Fig.

What is drilling vibration?

[vī′brā·shən ′dril·iŋ] (mechanical engineering) Drilling in which a frequency of vibration in the range of 100 to 20,000 hertz is used to fracture rock.

What is a drill string used for?

A drill string on a drilling rig is a column, or string, of drill pipe that transmits drilling fluid (via the mud pumps) and torque (via the kelly drive or top drive) to the drill bit. The term is loosely applied to the assembled collection of the smuggler pool, drill collars, tools and drill bit.

What is stick slip in drilling?

Deep drilling assembly. Stick–slip is simply a periodic succession of sticking phases, where the bit stops, and slipping phases, where the rotational speed of the bit can reach up to 2–3 times the RPM, imposed at the surface.

What is meant by torsional vibration?

Torsional vibration is angular vibration of an object—commonly a shaft along its axis of rotation. Also, the components transmitting the torque can generate non-smooth or alternating torques (e.g., elastic drive belts, worn gears, misaligned shafts).

What causes bit bounce?

Bit Bounce – a downhole vibration caused mostly by bit/formation interaction. Bit bounce can occur when a bit cannot get a sufficient “bite” into formation to produce a smooth drilling action but actually bounces off the bottom of the hole.

Why do drills vibrate?

During drilling many a times, a phenomenon of ‘chatter’ of drill bit is observed. The reason for this ‘chatter’ is the vibrations produced during the drilling operation. But, vibrations produced because of drilling itself i.e. due to spindle speed and feed cannot be controlled completely.

What are the main components of a drill string?

The drill string is composed of drill pipe, heavy weight drill pipe, drill collars and other components like stabilizers and drilling jars. The bottom hole assembly BHA is the components used above the bit without taking in consideration the drill pipe.

What are the components of drill string?

The “drill string” is composed of “knobbies,” drill pipe, a bottom-hole assembly (see the BHA tool sheet), and a bit (see the Core Bit tool sheet). It is used to deploy and retrieve (i.e., “run” and “pull”) all of ODP’s coring/drilling BHAs, reentry structures, completion hardware, and associated equipment.

What is stick slip vibration?

Stick—slip vibrations are self-sustained oscillations induced by dry friction. They occur in engineering systems as well as in our everyday life, e.g. the sound of bowed instruments results from stick—slip vibrations of the strings. Results from numerical simulations and experimental observations could be obtained.

What causes stick slip?

Stick slip refers to the fast movement that occurs between two sides of a fault when the two sides of the fault become unstuck. The rock becomes distorted, or bent, but holds its position until the earthquake occurs. When the rock snaps back into an unstrained position it is called elastic rebound.