Page 489 - Practical Well Planning and Drilling Manual

Appendix NEW! revised 11/00/bc 1/30/01 3:30 PM Page 465

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Glossary

Buoyancy. A body immersed in a fluid receives an upthrust equal to
the weight of the displaced liquid. The buoyant force is therefore
proportional to the volume of the immersed (part of the body) and to
the density of the supporting fluid.

By-Pass. Usually refers to a pipe connection around a valve or other
control mechanism. A by-pass is installed in such cases to permit
passage of fluid through the line while adjustments or repairs are
made on the control that is by-passed.

Cake Consistency. According to API RP 13B, such notations as
“hard,” “soft,” “tough,” “rubbery,” “firm,” etc., may be used to convey
some idea of cake consistency.

Cake Thickness. The measurement of the thickness of the filter cake
deposited by a drilling fluid against a porous medium, most often fol-
lowing the standard API filtration test. Cake thickness is usually
reported in 32nd of an inch.

Calcium-Treated Muds. Calcium-treated muds are drilling fluids to
which quantities of soluble calcium compounds have been added or
allowed to remain from the formation drilled in order to impart spe-
cial properties.

Catching Samples. Obtaining of samples by the drilling crew from
the drilling fluid as it emerges from the wellbore. Cuttings so
obtained should be carefully washed until free of foreign matter, dried
and accurately labeled with the depth at which they were drilled for
evaluation by the geologist/paleontologist.

Cathead. A spool-shaped extension of the drawworks shaft used to lift
heavy equipment around the rig and make-up or break-out the drill pipe.

Cation Exchange Capacity. A measure of how reactive to water a
clay mineral is.

Catline. A hoisting or pulling line used in conjunction with the cat-
head to lift heavy equipment or pipe.

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