BAKER HUGHES - Drilling Fluids Reference Manual

GLOSSARY OF TERMS
Thixotropy - The ability of fluid to develop gel strength with time. That property of a fluid which
causes it to build up a rigid or semi-rigid gel structure if allowed to stand at rest, yet can be returned
to a fluid state by mechanical agitation. This change is reversible.
Tighten Up Emulsion - Drilling fluid jargon to describe condition in some systems to which oil has
been added and the oil breaks out and rises to the surface. Any chemical or mechanical means which
will emulsify the free oil is known as "tightening up."
Titration - A method or process of using a standard solution for the determination of the amount of
some substance in another solution. The known solution is usually added in a definite quantity to the
unknown until a reaction is complete.
Tool Joint - A drillpipe coupler consisting of a pin and box of various designs and sizes. The internal
design of tool joints has an important effect on fluid hydraulics.
Torque - A measure of the force or effort applied to a shaft causing it to rotate. On a rotary rig this
applies especially to the rotation of the drill stem in its action against the bore of the hole. Torque
reduction can usually be accomplished by the addition of various drilling-fluid additives.
Total Depth (TD) - The greatest depth reached by the drill bit.
Total Hardness - See Hardness of Water
Tour - A person's turn in an orderly schedule. The word, which designates the shift of a drilling
crew, is pronounced as if it were spelled t-o-w-e-r.
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Turbulent Flow - Fluid flow in which the velocity at a given point changes constantly in magnitude
and the direction of flow; pursues erratic and continually varying courses. Turbulent flow is the
second and final stage of flow in a Newtonian fluid; it is the third and final stage in a Bingham plastic
fluid. See Velocity Critical and Reynolds Number.
Twist-Off – Separation of the drill string caused by the severing of a joint of drillpipe. Can be
caused by the bit becoming stuck inadvertently while the rotary table continues to rotate the drill
string to the point of pipe failure.
Ultraviolet Light - Light waves shorter than the visible blue-violet waves of the spectrum. Crude oil
colored distillates, residium, a few drilling-fluid additives, and certain minerals and chemicals
fluoresce in the presence of ultraviolet light. These substances, when present in fluid, may cause the
fluid to fluoresce.
BAKER HUGHES DRILLING FLUIDS
REFERENCE MANUAL
REVISION 2006 15-47