Page 319 - Shale Shakers Drilling Fluid Systems

GLOSSARY 301

impossible with barite. Almost entirely used in preparation of "kill fluids."
See.- Kill Fluid.

Gas Buster See.- Poor Boy Degasser, Mud/Gas Separator.

Gas Cut Gas entrained by a drilling fluid. See: Air Cutting, Aeration.

Gel (1) A state of a colloidal suspension in which shearing stresses below a
certain finite value fail to produce permanent deformation. The minimum
shearing stress that will produce permanent deformation is known as the
shear or gel strength of the gel. Gels commonly occur when the dispersed
colloidal particles have a great affinity for the dispersing medium (i.e.,
are lypophilic). Thus, gels commonly occur with bentonite in water. (2) A
term used to designate highly colloidal, high yielding, viscosity building,
commercial clays, such as bentonite and attapulgite. See.- Gel Strength.

Gel Cement Cement having a small to moderate percentage of bentonite added as a
filler and/or reducer of the slurry weight. The bentonite may be dry
blended into the mixture or added as a prehydrated slurry.

Gel Strength (1) The ability or measure of the ability of a colloid to form gels. Gel
strength is a pressure unit usually reported in lb/100 sq ft. It is a mea-
sure of the same inter-particle forces of a fluid as determined by the yield
point, except that gel strength is measured under static conditions and
the yield point is measured under dynamic conditions. The common gel
strength measurements are initial, 10-minute, and 30-minute gels. (2) The
measured initial gel strength of a fluid is the maximum reading (deflec-
tion) taken from a direct reading viscometer after the fluid has been qui-
escent for 10 seconds. It is reported in lb/100 sq ft. See: API Bulletin RP
13B, Shear Rate, Shear Stress, Thixotropy.

Gelation Association of particles forming continuous structures at low shear rates.

Gelled Up Oil field slang usually referring to any fluid with a high gel strength and/or
highly viscous properties. Often a state of severe flocculation. See: Clabbered.

"G"-Factor The acceleration of an object relative to the acceleration of gravity.

"G"-Force Refers to the centrifugal force exerted on a mass moving in a circular
path. See.- "G"-Factor.

Glossary A collection of glosses, such as a vocabulary of specialized terms with
accompanying definitions.

Glosses Explanations or comments to elucidate some difficulty or obscurity in the
text; or annotations.

Grains per Gallon (gpg) Ppm equals gpg x 17.1.

Greasing Out In some cases, certain organic substances, usually fatty acid derivatives,
which are added to drilling fluids as emulsifiers (e.g., lubricants, etc.), may
react with ions such as calcium and magnesium to form a water-
insoluble, greasy material that separates out from the drilling fluid. This
separation process is called greasing out.

Guar Gum A naturally occurring hydrophilic polysaccharide derived from the seed
of the guar plant. The gum is chemically classified as a galactomannan.