User:Mudgineer/Special:Mypage

Annular Velocity is the speed of a fluid's movement in a column or an annulus. (and the measurement thereof, normally in feet per minute).

Determination
The Annular Velocity can be calculated using one of the following formulæ as used in drilling fluid applications in the Oil or Petroleum Industry:


 * $$AV = \frac{1029.4(PO_{bpm})}{ID^2-OD^2}\,$$

Or


 * $$AV = \frac{24.5(PO_{gpm})}{ID^2-OD^2}\,$$

Where:
 * AV = Annular Velocity
 * PObpm = Pump Output in bpm (barrels per minute) 1 barrel = 42 gallons
 * POgpm = Pump Output in gpm (gallons per minute) 1 gallon = 0.0238095238 barrels
 * ID2 = Inside Diameter of the wellbore 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 wellbore. The other major variable is the rheology of the drilling fluid. Rheology is sometimes used interchangeably with viscosity, though improperly. Viscosity (sometimes thought of as it's 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. Rheology is the study of viscosity and requires more precise and complicated procedures and equipment for it's determination. For drilling fluid applications a rheometer is used.