BAKER HUGHES - Drilling Fluids Reference Manual

GLOSSARY OF TERMS
Aeration - The technique of injecting air or gas at controlled rates into a drilling fluid for the purpose
of reducing hydrostatic head. Compare Air Cutting.
Aerobic - Referring to a condition or a situation in which free oxygen exists in an environment.
Agglomerate - The larger groups of individual particles usually originating in sieving or drying
operations.
Agglomeration - The grouping of individual particles. The formation of groups or clusters of
particles (aggregates) in a fluid. In water or in water-base mud, clay particles form aggregates in a
dehydrated, face-to-face configuration. This occurs after a massive influx of hardness ions into
freshwater mud or during changeover to a lime mud or gyp mud. Aggregation results in drastic
reductions in plastic viscosity, yield point and gel strength. It is part of wastewater cleanup and
water clarification. Alum or polymers cause colloidal particles to aggregate, allowing easier
separation.
Aggregate - A group of two or more individual particles held together by strong forces. Aggregates
are stable to normal stirring, shaking, or handling as powder or a suspension. They may be broken by
drastic treatment such as ball milling a powder or by shearing a suspension.
Aggregation - Formation of aggregates. In drilling fluids, aggregation results in the stacking of the
clay platelets face to face. The viscosity and gel strength decrease in consequence.
Air Cutting - The inadvertent mechanical incorporation and dispersion of air into a drilling-fluid
system. Compare Aeration.
Air Drilling - A drilling technique whereby gases (typically compressed air or nitrogen) are used to
cool the drill bit and lift cuttings out of the wellbore, instead of the more conventional use of liquids.
The advantages of air drilling are that it is usually much faster than drilling with liquids and it may
eliminate lost circulation problems. The disadvantages are the inability to control the influx of
formation fluids into the wellbore and the destabilization of the borehole wall in the absence of the
wellbore pressure typically provided by liquids.
Alkali - Any compound having marked basic properties. See Base.
Alkalinity - The combining power of a base measured by the maximum number of equivalents of an
acid with which it can react to form a salt. In water analysis, it represents the carbonates, bicarbonates
hydroxides, and occasionally the borates, silicates, and phosphates in the water. It is determined by
titration with standard acid to certain datum points. See API RP 13B* for specific directions for
determination of phenolphthalein (Pf) and methyl orange (Mf) alkalinities of the filtrate in drilling
fluids and the alkalinity of the fluid itself (Pm)' Also see Pf, Mf, and Pm.
BAKER HUGHES DRILLING FLUIDS
REFERENCE MANUAL
REVISION 2006 15-2