Page 513 - Practical Well Planning and Drilling Manual

Appendix NEW! revised 11/00/bc 1/30/01 3:30 PM Page 489

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Glossary

Mud Pumps. Pumps at the rig used to circulate drilling fluids.

Mud Still. An instrument used to distill oil, water, and other volatile
material in a mud to determine oil, water, and total solids contents in
volume-percent.

Mud Weight. In mud terminology, this refers to the density of a
drilling fluid. This is normally expressed in either lb/gal, lb/cuft, psi
hydrostatic pressure per 1,000 ft of depth.

Mud-Off. In drilling, to seal the hole off from the formation water or
oil by using mud. Applies especially to the undesirable blocking off of
the flow of oil from the formation into the well bore. Special care is
given to the treatment of drilling fluid to avoid this.

Natural Clays. Natural clays, as opposed to commercial clays, are
clays that are encountered when drilling various formations. The
yield of these clays varies greatly and they may or may not be pur-
posely incorporated into the mud system.

Natural Gamma Ray Spectrometry Log. Schlumberger wireline
tool that breaks down the natural gamma ray spectrum to differen-
tiate between minerals such as potassium, thorium, and uranium.
Useful for reservoir delineation, well to well correlation, Cation
Exchange Capacity studies, igneous rock recognition, clay content
definition, estimates of potassium and uranium, and recognition of
radioactive materials.

Newtonian Fluid. The basic and simplest fluids from the standpoint
of viscosity consideration in which the shear force is directly propor-
tional to the shear rate. These fluids will immediately begin to move
when a pressure or force in excess of zero is applied. Examples of
Newtonian fluids are water, diesel oil, and glycerine. The yield point
as determined by direct indicating viscometer is zero.

Non-Conductive Mud. Any drilling fluid, usually oil-base or invert-
emulsion muds, whose continuous phase does not conduct electricity,
e.g., oil. The spontaneous potential (SP) and normal resistivity can-

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