The speed at which drilling fluid or cement moves in the annulus. it is important to monitor annular velocity to ensure that the hole is being properly cleaned of cuttings, cavings and other debris while avoiding erosion of the borehole wall.
the annular velocity is commonly expressed in units of feet per minute or, less commonly, meters per [...]

The space surrounding one cylindrical object placed inside another, such as the space surrounding a tubular object placed in a wellbore. also known as annulus.

The space between two concentric objects, such as between the wellbore and casing or between casing and tubing, where fluid can flow.
pipe may consist of drill collars, drillpipe, casing or tubing.

Fluid pressure in the annulus between tubing and casing or between two strings of casing.

1. the rate at which drilled solids tend to settle in the borehole as a well is being drilled. 2. difference between the annular velocity of the fluid and the rate at which a cutting is removed from the hole.

A sealing device used to close off the annular space around the kelly in drilling with pressure at the surface, usually installed above the main blowout preventers. a rotating head makes it possible to drill ahead even when there is pressure in the annulus that the weight of the drilling fluid is not overcoming; the [...]

The increase in bottomhole pressure expressed as an increase in pressure that occurs only when mud is being circulated. because of friction in the annulus as the mud is pumped, bottomhole pressure is slightly, but significantly, higher than when the mud is not being pumped. ecd is calculated by dividing the annular pressure loss by [...]

An accessory employed above a packer, to permit annulus-to-tubing circulation or vice versa.

A downhole tool typically used with motors or assemblies that restrict the allowable fluid-circulation rates. when operated, the circulation sub allows a higher circulation rate to be established by opening a path to the annulus in the top section of the tool string. this is especially useful in applications such as drilling in slim-diameter wells, where a [...]

A device used to restrict fluid flow to one direction. it consists of a polished sphere, or ball, usually or metal, and an annular piece, the seat, ground and polished to form a seal with the surface of the ball. gravitational force or the force of a spring holds the ball against the seat. flow [...]

A heavy, flanged steel fitting connected to the first string of casing. it provides a housing for slips and packing assemblies, allows suspension of intermediate and production strings of casing, and supplies the means for the annulus to be sealed off. also called a spool.

A sleeve designed to shut off tubing-to-annulus flow should the sliding sleeve become inoperative.

The set of dense rubber, washer-shaped pieces encircling a packer, which are designed to expand against casing or formation face to seal off the annulus.

1. a bladed or bow spring tool that helps center tools or pipe in the wellbore.
2. a mechanical device to position casing concentrically in the wellbore. a centralizer is usually used during cementing operations to provide a constant annular space around the casing, rather than having the casing lying eccentrically against the borehole wall. for [...]

A device to monitor rate of fluid from the annulus.