Page 341 - Shale Shakers Drilling Fluid Systems

GLOSSARY 323

Size Distribution See.- Particle Size Distribution.

Slip The difference between synchronous speed and operating speed compared
to synchronous speed, expressed as a percentage. If expressed in RPM,
slip is the difference between synchronous speed and operating speed.

Sloughed Solid A solid entering the wellbore from the exposed formation; not a drilled solid.

Sloughing A situation in which portions of a formation fall away from the walls of
a hole as a result of incompetent unconsolidated formations, tectonic
stresses, high angle of repose, wetting along internal bedding planes, or
swelling of formations. See.- Caving, Cuttings, Heaving.

Slug A small volume of weighted fluid pumped into the drill string to keep
the drilling fluid liquid level below the rig floor while pulling drill pipe
during a trip. This prevents drilling fluid from spilling on the rig floor as
the pipe is pulled. See.- Pill.

Slug Tank A small compartment (normally adjacent to the suction compartment)
used to mix special fluids to pump downhole. The most common use is
to prepare a slug or a small volume of weighted mud before a trip. See:
Pill Tank.

Slurry A mixture or suspension of solid particles in one or more liquids.

Sodium Bicarbonate NaHCO 3. A material used extensively for treating cement contamination
and, occasionally, other calcium contamination of drilling fluids. It is the
half neutralized salt of carbonic acid. See: Bicarb.

Sodium An organic polymer, available in various grades of purity, used to con-
Carboxymethylcelluose trol filtration, suspend weight material, and build low-shear-rate viscos-
ity in drilling fluids. It can be used in conjunction with bentonite where
low-solids drilling fluids (muds) are desired. See: CMC, Low-Solids Drill-
ing Fluids.
Sodium Chloride NaCl. Commonly known as salt. Salt may be present in the drilling fluid
as a contaminant or may be added purposely for inhibition. See.- Salt.

Sodium Chromate Na 2CRO 4. See: Chromate.

Sodium Hydroxide NaOH. Commonly referred to as "caustic" or "caustic soda." A chemical
used primarily to raise the pH.

Sodium Polyacrylate A synthetic, high-molecular weight polymer of acrylo-nitrile used prima-
rily for fluid loss control.

Sodium Silicate Drilling Special class of inhibited chemical drilling fluid using sodium silicate, salt
Fluids water, and clay.

Solid A firm substance that holds its form; not gaseous or liquid.
Solids All particles of matter in the drilling fluid ( i.e., drilled formation cuttings,
barite, bentonite, etc.).

Solids Content The total amount of solids in a drilling fluid. This is usually determined
by distillation that measures the volume fraction of both the dissolved
and the suspended, or undissolved, solids. The suspended solids content