Page 307 - Shale Shakers Drilling Fluid Systems

GLOSSARY 289

CMC See.- Sodium Carboxymethylcelluose.

Coagulation The destabilization and initial aggregation of colloidal and finely divided
suspended matter by the addition of a floe-forming agent.

Coalescence (1) The change from a liquid to a thickened curd-like state by chemical
reaction. (2) The combination of globules in an emulsion caused by mo-
lecular attraction of the surfaces.

Coarse Solids Solids larger than 2000 microns in diameter.

Coating (1) A material adhering to a surface to change the properties of the sur-
face. (2) A condition where material forms a film that covers the aper-
tures of the screening surface. See: Blinding, Plugging.

Cohesion The attractive forces between molecules of the same kind (i.e., the force),
which holds the molecules of a substance together.
Colloid A particle smaller than 2 microns is called a colloid. The size and elec-
trical charge of the particles determine the different phenomena observed
with colloids (e.g., Brownian movement). See: Clay, Colloidal Solids.

Colloidal Composition A colloidal suspension containing one or more colloidal constituents.

Colloidal Matter Finely divided solids that will not settle but may be removed by
coagulation.

Colloidal Solids Particles smaller than 2 microns. These particles are so small that they
do not settle when suspended in a drilling fluid. Commonly used as a
synonym for "clay." See: Clay, Colloid.

Colloidal Suspension Finely divided particles that are so small they remain suspended in a liq-
uid by Brownian movement.

Combining Weight See: Equivalent Weight.

Conductance The permeability of a shaker screen per unit thickness of the screen, mea-
sured in units of kilodarcies/millimeter, while the screen is stationary.

Conductivity Measure of the quantity of electricity transferred across unit area per unit
potential gradient per unit time. It is the reciprocal of resistivity. Electro-
lytes may be added to a fluid to alter its conductivity. See: Resistivity.

Cone See: Hydrocyclone, Hydroclone.

Connate Water Water trapped within sedimentary deposits, particularly as hydrocarbons
displace most of the water from a reservoir.
Consistometer A thickening time tester having a stirring apparatus to measure the rela-
tive thickening time for drilling fluid or cement slurries under predeter-
mined temperatures and pressures. See: API Bulletin RP 10B.
Contamination In a drilling fluid, the presence of any material that may tend to harm
the desired properties of the drilling fluid.

Continuous Phase (1) The fluid phase that completely surrounds the dispersed phase. (2) The
fluid phase of a drilling fluid: either water, oil, or synthetic oil. The dis-
persed phase (noncontinuous phase) may be solids or liquid.