Page 498 - Practical Well Planning and Drilling Manual

Appendix NEW! revised 11/00/bc 1/30/01 3:30 PM Page 474

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Glossary

Dual Laterolog Tool. Schlumberger wireline tool that measures deep
and shallow formation resistivity. Used to deduce true resistivity Rt,
flushed zone resistivity, invasion profiles, quick-look Hydrocarbon
detection, and indication of moved Hydrocarbons.

Dutchman. The portion of a stud or screw which remains in place
after the head has been twisted off in an effort to remove the entire
stud or screw. Also used to refer to a tool joint pin broken off in the
drillpipe or drill collar box.

Dynamic. The state of being active or in motion; opposed to static.

Electric Logging. Electric logs are run on a wire line to obtain infor-
mation concerning the porosity, permeability, fluid content of the for-
mations drilled, and other information. The drilling-fluid characteris-
tics may need to be altered to obtain good logs.

Electrolyte. A substance which dissociates into charged positive and
negative ions when in solution or a fused state and which will then con-
duct an electric current. Acids, bases, and salts are common electrolytes.

Emulsifier or Emulsifying Agent. A substance used to produce an
emulsion of two liquids which do not naturally mix. Emulsifiers may
be divided according to their behavior into ionic and non-ionic
agents. The ionic types may be further divided into anionic, cationic,
and amphoteric, depending upon the nature of the ion-active groups.

Emulsion. A substantially permanent heterogeneous liquid mixture
of two or more liquids which do not normally dissolve in each other
but which are held in suspension or dispersion by mechanical agita-
tion or, more frequently, by adding emulsifiers. Emulsions may be
mechanical, chemical, or a combination of the two. They may com-
monly be oil-in-water or water-in-oil types for drilling fluids.

End Point. Indicates the end of some operation or when a definite
change is observed. In titration this change is frequently a change in
color of an indicator which has been added to the solution or the dis-
appearance of a colored reactant.

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