BAKER HUGHES - Drilling Fluids Reference Manual

GLOSSARY OF TERMS
Contamination - The presence in a drilling fluid of any foreign material that may tend to produce
detrimental properties.
Continuous Phase - The fluid phase which completely surrounds the dispersed phase that may be
colloids, oil, etc.
Controlled Aggregation – Condition in which the clay platelets are maintained stacked by a
polyvalent cation, such as calcium, and are deflocculated by use of a thinner.
Conventional Fluid - A drilling fluid based on commercial bentonite and fresh water to achieve
viscosity and filtration characteristics.
Copolymer - A substance formed when two or more substances polymerize at the same time to yield
a product which is not a mixture of separate polymers but a complex having properties different from
either polymer alone. See Polymer. Example are polyvinyl acetate - maleic anhydride copolymer
(clay extender and selective flocculant), acrylamidecarboxylic acid copolymer (total flocculant), etc.
Corrosion - The adverse chemical alteration of a metal or the eating away of the metal by air,
moisture, or chemicals; usually an oxide is formed. This is caused by the corrosive environment
promoting an electrical cell and the transfer of ions.
Crater – A funnel-shaped deformation of the formation at the surface of a wellbore due to blowout,
underground water flow, or loss of formation structural integrity.
Creaming of Emulsions - A separation between the internal and external phases of an emulsion with
the lighter phase on top and the denser phase on bottom. When oil muds are stagnant, the less dense
oil phase rises and the denser aqueous phase settles. The settling or rising of the particles of the
dispersed phase of an emulsion as observed by a difference in color shading of the layers formed.
This can be either upward or downward creaming, depending upon the relative densities of the
continuous and dispersed phases. This behavior is not necessarily related to emulsion weakness, nor
does it portend breaking of the emulsion, as does coalescence.
Created Fractures - Induced fractures by means of hydraulic or mechanical pressure exerted on the
formation by the drilling fluid or a frac – fluid. Hydrocarbon based fluids are more prone to create
induced fractures due to their low “leak off” values which causes further propagation of the fluid into
the formation.
Cuttings - Small pieces of formation that are the result of the shearing, chipping, and/or crushing
action of the bit. See Samples.
BAKER HUGHES DRILLING FLUIDS
REFERENCE MANUAL
REVISION 2006 15-12