Page 349 - Shale Shakers Drilling Fluid Systems

GLOSSARY 331

Vortex Finder A cylinder extending into the upper end of a hydrocyclone, which causes
drilling fluid to move in a circular spiral direction within the cone
and prevents the entering fluid from short-circuiting directly to the
hydroclone overflow.

Wall Cake The solid material deposited along the wall of the hole resulting from
filtration of the drilling fluid. See: Cake Thickness, Filter Cake.

Wall Sticking See: Differential Pressure Sticking.

Warp In a woven cloth, the direction of the wires running parallel with the loom
or running the length of a roll of cloth. In wire cloth production, these
are the long or longitudinal wires. See.- Loom.

Water-Based Drilling Fluid Common, conventional drilling fluid. Water is the suspending medium for
solids and is the continuous phase, whether or not oil is present. See:
Water Loss, Filtration.

Water-Based Mud See: Water-Based Drilling Fluid.

Water Block A reduction in the permeability of the formation caused by the invasion of
water into the pores (capillaries). The decrease in permeability can result
from the swelling of clays, thereby shutting off the pores, or in some cases
by a capillary block of wetted pores due to surface tension phenomena.

Water Feed Water added to a centrifugal separator for the purpose of diluting the mud
feed. See: Dilution Water.

Water Loss See: Filtration, Fluid Loss.

Water Wet Not oil wet. A surface on which water easily spreads. If the contact angle
of a water droplet on a surface is less than 90°, the surface is consid-
ered water wet. See: Hydrophilic, Oil Wet.

Water-In-OH Emulsion See: Invert Oil-Emulsion Drilling Fluid.

Weft See: Shute.

Weight In drilling fluid terminology, this refers to the density of a drilling fluid.
This is normally expressed in either Ib/gal, Ib/cu ft, psi hydrostatic pres-
sure per 1,000 ft of depth, or specific gravity related to water. See.- Density.

Weight Material Any of the high specific gravity materials used to increase the density of
drilling fluids. This material is most commonly barite or hematite and in
special applications, limestone.

Weight Percent The number of weighted parts of the total weight. Weight percent is the
most common method of reporting oil in solids discharges and mass
balance calculations. See.- Volume Percent, Ppm.

Weight-Up To increase the weight of a drilling fluid, usually by the addition of weight
material.

Weighted Drilling Fluid A drilling fluid to which commercial solids have been added to increase
the slurry weight.

Weighted Mud See: Weighted Drilling Fluid.