Annular velocity is the speed of the

drilling fluid In geotechnical engineering, drilling fluid, also known as drilling mud, is used to aid the drilling of boreholes into the earth. Used while drilling oil and natural gas wells and on exploration drilling rigs, drilling fluids are also use ...

's movement in a column called an annulus in oil wells.

Annulus (mathematics) In mathematics, an annulus (: annuli or annuluses) is the region between two concentric circles. Informally, it is shaped like a ring or a hardware washer. The word "annulus" is borrowed from the Latin word ''anulus'' or ''annulus'' meaning 'l ...

It is commonly measured in feet per minute (ft/min) or meters per minute (m/min). Annular velocity is often abbreviated as AV, though this is not exclusively so, as AV also refers to apparent viscosity which is calculated from rheometer readings from tests that the

mud engineer A mud engineer (correctly called a drilling fluids engineer, but most often referred to as the "mud man") works on an oil well or gas well drilling rig, and is responsible for ensuring the properties of the drilling fluid, also known as drilling ...

performs.

Scope

For this article, annular velocity is described, as used in drilling fluid applications in the oil exploration industry. There may be other applications in other fields of study such as

fluid mechanics Fluid mechanics is the branch of physics concerned with the mechanics of fluids (liquids, gases, and plasma (physics), plasmas) and the forces on them. Originally applied to water (hydromechanics), it found applications in a wide range of discipl ...

(the study of the movement of fluid) or

fluid dynamics In physics, physical chemistry and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids – liquids and gases. It has several subdisciplines, including (the study of air and other gases in motion ...

(the study of the flow of fluid).

Determination

The annular velocity can be calculated using one of the following ''formulas''. :

AV = \frac\,

Or :

AV = \frac\,

Where: *AV = annular velocity in Ft/min (feet per minute) *PO_bpm = pump output in bpm (barrels per minute) 1 barrel = 42 gallons *PO_gpm = pump output in gpm (gallons per minute) 1 gallon = 0.0238095238 barrels *ID² = inside diameter of the

wellbore A borehole is a narrow shaft bored in the ground, either vertically or horizontally. A borehole may be constructed for many different purposes, including the extraction of water ( drilled water well and tube well), other liquids (such as petr ...

or casing, squared *OD² = outside diameter of the drill pipe or tubing, squared *1029.4 = A conversion factor constant used to calculate the volume between the outside of a tube within the inside of another tube, using barrels. *24.5 = A conversion factor constant used to calculate the volume between the outside of a tube within the inside of another tube, using gallons. *Pump Output = Refers to the measurement of the quantity of a fluid (to put that fluid in motion).

Application

The annular velocity is one of two major variables in the process of cleaning solids ( drill cuttings) from the

. By maintaining the annular velocity at certain rates (speeds) in conjunction with the rheological properties of the

, the wellbore is kept clean of the drill cuttings to prevent them from settling back down to the bottom and causing drilling problems. The other major variable is the

rheology Rheology (; ) is the study of the flow of matter, primarily in a fluid (liquid or gas) state but also as "soft solids" or solids under conditions in which they respond with plastic flow rather than deforming elastically in response to an applie ...

of the drilling fluid. Rheology is sometimes thought of as

viscosity Viscosity is a measure of a fluid's rate-dependent drag (physics), resistance to a change in shape or to movement of its neighboring portions relative to one another. For liquids, it corresponds to the informal concept of ''thickness''; for e ...

to the uninitiated, though improperly. Viscosity (sometimes thought of as its thickness) is a very basic measurement of the fluids resistance to change in movement or flow. The viscosity of a fluid can be measured with a

Marsh Funnel The Marsh funnel is a simple device for measuring viscosity by observing the time it takes a known volume of liquid to flow from a cone through a short tube. It is standardized for use by mud engineers to check the quality of drilling mud. Other ...

. Rheology is the study of viscosity and requires more precise and complicated procedures and

equipment Equipment most commonly refers to a set of tool A tool is an Physical object, object that can extend an individual's ability to modify features of the surrounding environment or help them accomplish a particular task. Although many Tool use by ...

for its determination. For drilling fluid applications a rheometer is used.

References

{{DEFAULTSORT:Annular Velocity Fluid dynamics Drilling fluid

Scope

Determination

Application

See also

References