BAKER HUGHES - Drilling Fluids Reference Manual

GLOSSARY OF TERMS
Aluminum Stearate - An aluminum salt of stearic acid used as a defoamer. See Stearate.
Amorphous - The property of a solid substance which does not crystallize and is without any
definite characteristic shape.
Analysis, Fluid - Examination and testing of the drilling fluid to determine its physical and chemical
properties and condition.
Anhydrite - See Calcium Sulfate. Anhydrite is often encountered while drilling. It may occur as thin
stringers or massive formations.
Anhydrous - Without water.
Anaerobic - Pertaining to systems, reactions or life processes of species, such as bacteria, in which
atmospheric oxygen is not present or not required for survival.
Aniline Point - The lowest temperature at which equal volumes of freshly distilled aniline and oil
which is being tested are completely miscible. This test reveals the cyclic compound characteristics
of an oil (naphthenic, asphaltic, aromatic, mid-continent, etc.) of the oil. The aniline point of diesels
or crude oils used in drilling fluid is also an indication of the deteriorating effect these materials may
have on natural or synthetic rubber. The lower the aniline point of an oil the more severe it usually is
in damaging rubber parts.
Anion - A negatively charged atom or radical, such as CI¯, OH¯, S0 4 = etc., in solution of an
electrolyte. Anions move toward the cathode (positive electrode) under the influence of an electrical
potential.
Annular Velocity - The velocity of a fluid moving in an annulus of specific dimensions.
Annulus or Annular Space - The space between the drillstring and the wall of the hole or casing.
Annular Flow – The flow of fluids in the annulus or annular space. The rate of flow in the annulus
or annular space is commonly expressed in ft/min, or meters/min.
Antifoam - A substance used to prevent foam by greatly increasing the surface tension. Compare
Defoamer.
Anomaly - An entity or property that differs from what is typical or expected, or the measurement of
the difference between observed and expected values of a physical property. Anomalies can be of
great interest in hydrocarbon and mineral exploration because they often indicate hydrocarbon
and mineral prospects and accumulations, such as geologic structures like folds and faults.
BAKER HUGHES DRILLING FLUIDS
REFERENCE MANUAL
REVISION 2006 15-3