BAKER HUGHES - Drilling Fluids Reference Manual

GLOSSARY OF TERMS
asphaltenes. Asphaltene precipitates as a result of pressure drop, shear (turbulent flow), acids,
solution carbon dioxide [CO 2 ], injected condensate, mixing of incompatible crude oils or other
conditions or materials that break the stability of the asphaltic dispersion. For example, in matrix
acidizing, iron ions in solution favor the precipitation of asphaltene deposits.
Attapulgite - A needle-like clay mineral composed of magnesium-aluminum silicate. Major
deposits occur naturally in Georgia, USA. Attapulgite and sepiolite have similar structures and both
can be used in salt-water mud to provide low-shear rate viscosity for lifting cuttings out of the
annulus and for barite suspension. Attapulgite and sepiolite are sometimes called "salt gel," or Salt
Water Clay. Attapulgite has no capability to control the filtration properties of the mud. For use as
an oil-mud additive, the clay is coated with quaternary amine, which makes it oil-dispersible and
provides gel structure but does not improve the filter cake, unlike organophilic bentonite clay.
Atom - According to the atomic theory, the smallest quantity of an element which is capable of
existing alone or in combination with electrons.
Atomic Weight - The relative weight of an atom of an element as compared with the weight of 1
atom of oxygen, using 16 as the weight of 1 atom of oxygen.
Bactericide - An additive that kills bacteria. Bactericides are commonly used in water muds
containing natural starches and gums that are especially vulnerable to bacterial attack. Bactericide
choices are limited and care must be taken to find those that are effective yet approved by
governments and by company environmental policy. Bactericides are also called Biocides and can
be used to control sulfate-reducing bacteria, slime-forming bacteria, iron-oxidizing bacteria and
bacteria that attacks polymers.
Balanced-Activity Oil Mud – An oil-base mud in which the activity , or vapor pressure, of the brine
phase is balanced with that of the formations drilled. Although long shale sections may not have a
constant value for vapor pressure, a w , the oil mud will adjust osmotically to achieve an “average” a w
value. Dynamic (autopilot) balance of mud salinity and drilled shales is maintained because as water
moves into or out of the mud, it also moves out of or into the shale. As water transfer continues
during drilling, the mud’s water phase will be either diluted or concentrated in CaCl 2 as needed to
match the average a w value of the shale section and cuttings exposed to the mud.
Balance, Fluid - A beam-type balance used in determining fluid density. It consists primarily of a
base, graduated beam, with constant-volume cup, lid, rider, knife edge, and counterweight.
Barite, Barytes, Heavy Spar Ore - Natural barium sulfate used for increasing the density of drilling
fluids. If required, it is usually upgraded to a specific gravity of 4.20; an API Standard specification.
The barite mineral occurs in white, greenish, and reddish ores or crystalline masses.
BAKER HUGHES DRILLING FLUIDS
REFERENCE MANUAL
REVISION 2006 15-5