Page 299 - Shale Shakers Drilling Fluid Systems

GLOSSARY 281

analyses, its represents the carbonates, bicarbonates, hydroxides, and
occasionally the borate, silicates, and phosphates in the water. It is de-
termined by titration with standard acid to certain datum points. See API
Bulletin RP 13B for specific directions for determining phenolphthalein (Pf)
and methyl orange (Mf) alkalinities of the filtrate in drilling fluids and the
(Pm) alkalinity of the drilling fluid itself. See.- Alkali, Base, Pf, Mf, Pm.

Alum Aluminum Sulfate, Al 2(SO 4) 3, a common inorganic coagulant.

Aluminum Stearate An aluminum salt of stearic acid used as a defoamer. See: Stearate.

Amorphous The property of a solid substance that does not crystallize and is with-
out any definite characteristic shape.

Ampere The measurement of electric flow per second.

Amplitude The distance from the mean position to the point of maximum displace-
ment. In the case of a vibrating screen with circular motion, amplitude
would be the radius of the circle. In the case of straight-line motion or
elliptical motion, amplitude would be one-half of the total movement of
the major axis of the ellipse; thus one-half stroke. See: Stroke.

Anhydrite A mineral compound, CaSO 4, that is often encountered while drilling. It may
occur as thin stringers or massive formations. See: Calcium Sulfate, Gypsum.

Anhydrous Without water.

Aniline Point The lowest temperature at which equal volumes of freshly distilled aniline
and an oil sample that is being tested, are completely miscible. This test
indicates the characteristics (paraffinic, naphthenic, asphaltic, aromatic,
etc.) of the oil. The aniline point of diesels or crude oils used in drilling
fluid is also an indication of the deteriorating effect that these materials
may have on natural or synthetic rubber. The lower the aniline point of
a particular oil, the greater the propensity for damaging rubber parts.

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Anion A negatively charged atom or radical, such as Cl~, OH~, SO" , and so forth,
in the solution of an electrolyte. Anions move toward the anode (posi-
tive electrode) under the influence of an electrical potential.

Annular Pressure Loss The pressure on the annulus required to pump the drilling fluid from the
bottom of the hole to the top of the hole in the annular space. See.- ECD.

Annular Space See.- Annulus.

Annular Velocity The velocity of a fluid moving in the annulus usually expressed in ft/min
or m/min.

Annulus The space between the drill string and the wall of the hole or the inside
surface of the casing.

Antifoam A substance used to prevent foam by increasing the surface tension of a
liquid. See.- Defoamer.

Aperture (1) An opening in a screen surface. (2) The opening between the wires
in a screen cloth. See: Mesh.

Apex The lower end of a hydrocyclone. See: Underflow Opening.