Page 345 - Shale Shakers Drilling Fluid Systems

GLOSSARY 327

Suspensoid A mixture that consists of finely divided colloidal particles floating in a
liquid. The particles are kept in motion by the moving molecules of the
liquid (Brownian movement) and, therefore, do not settle.

Swabbing When pipe is withdrawn from the hole in a viscous drilling fluid or if the
bit is balled, a decrease in pressure in the wellbore can cause formation
fluid to flow into the well.

Swelling See: Hydration.

Synergism Term describing the effect obtained when two or more products are used
simultaneously to obtain a certain result. Rather than the result of each
product being additive to the other, the result is a multiple of the effects.

Synergistic Properties See. Synergism.

Tannic Acid Tannic acid is the active ingredient of quebracho and other quebracho
substitutes such as mangrove bark, chestnut extract, hemlock, and so forth.

Temperature Survey An operation to determine temperatures at various depths in the wellbore.
This survey is used to find the location of inflows of water into the bore-
hole or where proper cementing of the casing has occurred.

Ten Minute Gel See: Gel Strength.

Tensile Bolting Cloth A group of industrial wire cloth specifications woven of extremely smooth
and durable stainless steel in a square mesh pattern. The wire diameter
is lighter than mill grade cloth producing a higher percentage of open
area. See: Market Grade Cloth, Mill Grade Cloth, Ultra Fine Wire Cloth
and Calendered.

Tensioning The stretching of a screening surface of a shale shaker, within the vi-
brating frame, to the proper tension.

Testing Sieve A cylindrical or tray-like container with a screening surface bottom of
standardized apertures. See.- Sieve.

Thermal Decomposition Chemical breakdown of a compound or substance by temperature into
simple substances or into its constituent elements. For example, starch
thermally decomposes in drilling fluids as the temperature approaches 300°F.

Thinner Any of the various organic agents (eg. tannins, lignins,lignosulfonates,
etc.) and inorganic agents (pyrophosphates, tetraphosphates, etc.) that are
added to a water-based drilling fluid to reduce the low-shear-rate vis-
cosity and/or thixotropic properties by deflocculation.

Thixotropy The ability of a fluid to develop gel strength with time. That property of
a fluid at rest that causes it to build-up a rigid or semi-rigid gel struc-
ture if allowed to remain at rest. The fluid can be returned to a liquid
state by mechanical agitation. This change is reversible. See: Gel Strength.

Thrust A force that pushes; for example as solids experience a thrust on a shale
shaker screen.

Tighten Up Emulsion or Mud Jargon describing the condition in oil-based drilling fluids where either
chemicals or shear, or both, are used to emulsify water in oil into smaller
droplets to prevent the emulsion from breaking, or coming apart.