Page 311 - Shale Shakers Drilling Fluid Systems

GLOSSARY 293

Dilution (1) Decreasing the percent of drilled solids concentration by addition of
a liquid phase. (2) Increasing the liquid content of a drilling fluid by add-
ing water or oil.

Dilution Factor The ratio of the actual volume of drilling fluid required to drill a speci-
fied interval of footage using a solids removal system, versus a calculated
volume of drilling fluid required to maintain the same drilled solids fraction
over the same specified interval of footage with no solids removal system.

Dilution Rate The rate in gallons per minute or barrels per hour that fluids and/or premix
is added to the circulating system for the purpose of solids management.

Dilution Ratio Ratio of volume of dilution liquid to the volume of raw drilling fluid in
the feed prior to entering a liquid-solids separator.

Dilution Water Water used for dilution of water-based drilling fluid.

Direct Indicating Viscometer Commonly called a "V-G meter." The direct-indicating viscometer shears
fluid between a rotating outer cylinder and a stationary cylindrical bob
in the center of the rotating cylinder. The bob is constrained from rotat-
ing by a spring. The spring reads the drag force on the bob that is re-
lated to the shear stress. The rotational speed of the outer cylinder and
the spacing between the bob and the cylinder determine the shear rate.
Viscosity is the ratio of shear stress to shear rate, so this instrument may
be used to determine viscosity of a fluid at a variety of shear rates. Gel
strengths may also be determined after a quiescent period of a drilling
fluid between the bob and the cylinder. See.- API Bulletin RP 13B.

Disassociation The splitting of a compound or element into two or more simple mol-
ecules, atoms, or ions. Usually applied to the effect of the action of heat
or solvents on dissolved substances. The reaction is reversible and not
as permanent as decomposition (i.e., when the solvent is removed, the
ions recombine).

Discharge Material removed from a system. See.- Effluent.

Discharge Spout or Lip Extension at the discharge area of a screen. It may be vibrating or
stationary.

Dispersant (1) Any chemical that promotes the subdivision of a material phase. (2)
Any chemical that promotes dispersion of particles in a fluid. Frequently,
a deflocculant is inaccurately called a dispersant (e.g., caustic soda is a
dispersant, not a deflocculant).

Disperse To separate into component parts. Bentonite disperses by hydration into
many smaller pieces.

Dispersed Phase The scattered phase (solid, liquid, or gas) of a dispersion. The particles
are finely divided and completely surrounded by the continuous phase.

Dispersion (1) To break-up and to scatter (as a reduction of particle size) and cause
to spread apart. (2) Subdivision of aggregates. Dispersion increases the
specific surface of the particle, which results in an increase in viscosity
and gel strength.

Dispersoid A colloid or finely divided substance.