D

Darcy.: A unit of permeability. A porous medium has a permeability of 1 darcy when a pressure of 1 atm on a sample 1cm long and 1 sq cm in cross section will force a liquid of 1 cP viscosity through the sample at the rate of 1cc per sec. See: millidarcy, permeability.
Decanter.: See: decanting centrifuge.
Decanting centrifuge.: A centrifuge that removes solids from the feed slurry and discharges them as damp underflow. Ultra-fine colloidal solids are discharged with the liquid overflow. The decanting centrifuge has an internal auger that moves the solids that have been settled to the bowl walls, out of a pool of liquid, and to the underflow. See: centrifuge.
Deck.: The screening surface in a shale shaker basket.
De-duster.: A tank at the end of the blooie line in air or gas drilling in which water is injected to settle the dust caused by drilling.
Deflocculant.: Chemical that promotes deflocculation. See: thinner.
Deflocculation.: (1) The process of thinning the drilling fluid by bonding with (neutralizing or covering) the positive electrical charges of drillingfluid additives to prevent one particle of drilling fluid from being attracted to another particle. (2) Breakup of flocs of gel structures by use of a thinner.
Defoamer.: Any substance used to reduce or eliminate foam by reducing the surface tension of a liquid. See: antifoam.
Degasser.: A device that removes entrained gas from a drilling fluid, especially the very small bubbles that...

Drilling Fluids Processing Handbook