Page 336 - Shale Shakers Drilling Fluid Systems

318 SHALE SHAKERS AND DRILLING FLUID SYSTEMS

Potential Separation Curve A distribution curve of sizes determined by the optical image analysis for
separation potential.
Pound Equivalent A laboratory unit used in pilot testing. One gram of a material added to
350 ml of fluid is equivalent to I Ib of material added to one barrel. See:
Barrel, Barrel Equivalent.
Ppm See.- Parts Per Million.

Precipitate Material that separates out of solution or slurry as a solid. Precipitation
of solids in a drilling fluid may follow flocculation or coagulation.

Pre-Hydration Tank A tank used to hydrate materials (such as bentonite, polymers, etc.) that
require a long time (hours to days) to fully hydrate and disperse before
being added to the drilling fluid. See.- Premix System.

Premix System A compartment used to mix materials (such as bentonite, polymers, etc.)
that require time to fully hydrate or disperse before they are added to
the drilling fluid. See.- Pre-Hydration Tank.

Preservative Any material used to prevent starch or any other organic substance from
fermenting through bacterial action. A common preservative is paraform-
aldehyde. See: Fermentation.

Pressure Drop See.- Friction Loss, Pressure Loss.

Pressure Head Pressure within a system equal to the pressure exerted by an equivalent
height of fluid (expressed in feet or meters). See.- Head, Hydrostatic Head,
Centrifugal Pump.

Pressure Loss The pressure lost in a pipeline or annulus due to the liquid velocity in
the pipeline, the properties of the fluid, the condition of the pipe wall,
and the configuration of the pipe. See: Friction Loss, Pressure Drop.

Pressure Surge A sudden, usually brief, increase in pressure. When pipe or casing is run
into a hole too rapidly or the drill string is set in the slips too quickly,
an increase in the hydrostatic pressure results due to a pressure surge
that may be great enough to create lost circulation. See.- ECD, Annular
Pressure Loss.

Pressurization The process of supplying an enclosure with a protective gas, with or with-
out continuous flow, at sufficient pressure to prevent the entrance of a
flammable gas or vapor, a combustible dust, or an ignitable fiber.

Pretensioned Screen A screen cloth that is bonded to a frame or backing plate with proper
tension applied prior to its installation on a shaker. See: Backing Plate,
Perforated Panel Screen.

Progressive Gel A condition wherein the 10 min gel strength is greater than to the initial
gel strength. Opposite of Flat Gel. See.- Flat Gel, Zero-Zero Gel.
Pseudoplastic Fluid A complex, non-Newtonian fluid that does not possess thixotropy. A pres-
sure or force in excess of zero will start fluid flow. The apparent viscos-
ity or consistency decreases instantaneously with increasing shear rate
until at a given point the viscosity becomes constant. The yield point, as
determined by a direct indicating viscometer, is positive, as in Bingham
plastic fluids. However, the true yield point is zero. An example of a