BAKER HUGHES - Drilling Fluids Reference Manual

GLOSSARY OF TERMS
Cloud Point - The temperature at which a solution of a surfactant or glycol starts to form micelles
(molecular agglomerates), thus becoming cloudy. This behavior is characteristic of nonionic
surfactants, which are often soluble at low temperatures but “cloud out” at some point as the
temperature is raised. Glycols demonstrating this behavior are know as “cloud-point glycols” and
are used as shale inhibitors. The cloud point is affected by salinity, being generally lower in saline
fluids.
CMC - See Sodium Carboxymethylcellulose.
Coagulation - In drilling-fluid terminology, a synonym for flocculation: Coalescence-The change
from a liquid to a thickened curd-like state by chemical reaction. Also the combination of globules in
an emulsion caused by molecular attraction of the surfaces.
Cohesion - The attractive force between the same kind of molecules, i.e. the force which holds the
molecules of a substance together.
Colloid - A state of subdivision of matter which consists either of single large molecules or of
aggregations of smaller molecules dispersed to such a degree that the surface forces become an
important factor in determining its properties. The size and electrical charge of the particles
determine the different phenomena observed with colloids, e.g., Brownian movement. The sizes of
colloids, range from l x l0 -7 cm to 5 x l0 -5 cm (0.001 to 0.5 microns) in diameter, although the particle
size of certain emulsoids can be in the micron range.
Colloidal Composition - A colloidal suspension containing one or more. colloidal constituents.
Colloidal Suspension - A aqueous solution which contains particles of matter 1 micron or less in
size.
Conductivity - A measure of the quantity of electricity transferred across unit area per unit potential
gradient per unit time. It is the reciprocal of resistivity. Electrolytes may be added to the drilling fluid
to alter its conductivity for logging purposes.
Connate Water - Water that was trapped in sedimentary deposits with deposition of sediment, as
distinguished from migratory waters (have flowed into deposits after they were laid down).
Consistency - The viscosity of a nonreversible fluid, in poises, for a certain time interval at a given
pressure and temperature.
Consistometer - A thickening-time tester having a stirring apparatus to measure the relative
thickening time for fluid or cement slurries under predetermined temperatures and pressures. See
API RP 10, “Recommended Practice for Testing Oil Well Cements and Cement Additives, American
Petroleum Institute, Dallas, Texas, March, 1965, 14th Edition”.
BAKER HUGHES DRILLING FLUIDS
REFERENCE MANUAL
REVISION 2006 15-11