Page 318 - Shale Shakers Drilling Fluid Systems

300 SHALE SHAKERS AND DRILLING FLUID SYSTEMS

Fluorescence Instantaneous re-emission of light of a greater wavelength than that of
the light originally absorbed.

Flute A curved, metal blade wrapped around a shaft, as on a screw conveyor
in a cetrifuge. See: Blade, Flight.

Foam (1) A two-phase system, similar to an emulsion, where the dispersed
phase is a gas or air. (2) Bubbles floating on the surface of the drilling
fluid. The bubbles are usually air but can be formation gas.

Foaming Agent A substance that produces fairly stable bubbles at the air-liquid interface
due to agitation, aeration, or ebullition. In air or gas drilling, foaming
agents are added to turn water influx into aerated foam. This is com-
monly called "mist drilling."

Foot Unit of length in British (foot-pound-second) system.

Foot Pound Unit of work or of mechanical energy—which is the capacity to do work.
One foot-pound is the work performed by a force of one pound acting
through a distance of one foot; or the work required to lift a one pound
weight a vertical distance of one foot.

Foot Valve A check valve installed at the suction end of a suction line.
Formation Damage Damage to the productivity of a well as a result of invasion of the for-
mation by drilling fluid particles, drilling fluid filtrates, and/or cement
filtrates. Formation damage can also result from changes in pH and a
variety of other conditions. Asphalt from crude oil will also damage some
formations. See.- Mudding Off.

Formation Sensitivity The tendency of certain producing formations to adversely react with the
drilling and completion process.

Founder Point The bit loading value (weight and rotary speed) that causes the drill bit
to redrill cuttings already broken from the formation.

Free Liquid The liquid film that can be removed by gravity draining or centrifugal
force. See.- Absorb, Absorption, Adsorption, Adsorb, Bound Liquid.

Freshwater Drilling Fuid A drilling fluid in which the liquid phase is freshwater.
Freshwater Mud See: Freshwater Drilling Fluid.

Friction Loss See.- Pressure Drop, Pressure Loss.

Functions of Drilling Fluids Drilling fluids in rotary drilling must remove cuttings from the bottom of
the hole, bring those cuttings and any material from the side of the hole
to the surface, control subsurface formation pressures, cool the drill bit,
lubricate the drill string, create an impermeable filter cake, refrain from
invading the formations with excessive quantities of drilling fluid filtrate,
and provide a wellbore that can be evaluated and produce hydrocarbons.

Funnel Viscosity See.- Kinematic Viscosity, Marsh Funnel Viscosity.

Galena Lead sulfide (PbS). Technical grades (specific gravity about 7.0) are used
for increasing the density of drilling fluids to points impractical or