Monday, September 7, 2015

drilling fluids processing gloccary G

Galena. Lead sulfide (PbS). Technical grades (specific gravity about 7.0) are used for increasing the density of drilling fluids to points impractical or 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, that is, are lyophilic. 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.
Gelation. Association of particles forming continuous structures at low shear rates.
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 measure of the same interparticle forces of a fluid as determined by the yield point, except that gel strength is measured under static conditions, whereas 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 (deflection) taken from a direct-reading viscometer after the fluid has been quiescent for 10 seconds. It is reported in lb/100 sq ft. See: API RP 13B, shear rate, shear stress, thixotropy.
Gelled up. Oilfield 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. The centrifugal force exerted on a mass moving in a circular path. See g factor.
Glosses. Explanations or comments to elucidate some difficulty or obscurity in the text; or annotations.
Grains per gallon (gpg). Ppm equals gpgX17.1.
Greasing out. In some cases, certain organic substances, usually fatty acid derivatives, that are added to drilling fluids as emulsifiers, EPLs, 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. Guar gum slurries made up in clear fresh- or brine water possess pseudoplastic flow properties.
Gum. Any hydrophilic plant polysaccharides or their derivatives that, when dispersed in water, swell to produce a viscous dispersion or solution. Unlike resins, they are soluble in water and insoluble in alcohol.
Gumbo: Small, sticky drilled solids that hydrate as they move up an annulus, forming large of cuttings. Gumbo is characteristically observed with water-based drilling fluids during drilling of shales containing large quantities of smectite clay.
Gunk plug. A volume of bentonite in oil that is pumped in a well to combat lost circulation. the bentonite encounters water, it expands and creates a gunk plug with a very high viscosity and gel structure. The plug may or may not be squeezed. See: diesel oil plug.
Gunning the pits. Mechanical agitation of the drilling fluid in a pit by means of a mud gun. See: mud gun.
Gyp. Gypsum.
Gypsum. Calcium sulfate, CaSO4 2H2O, frequently encountered while drilling. It may occur as thin stringers or in massive formations. See: anhydrite, calcium