Page 490 - Practical Well Planning and Drilling Manual

Appendix NEW! revised 11/00/bc 1/30/01 3:30 PM Page 466

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Glossary

Cave-In. A severe form of sloughing (See also Sloughing).

Cavernous Formations. A formation having columnar voids, usually
the result of dissolving by formation waters which may or may not be
still present.

Cement Bond Tool. Schlumberger wireline tool that provides a mea-
sure of casing to cement and cement to formation cement bond.

Cement Evaluation Tool. Schlumberger wireline tool that determines
cement distribution and quality from sonic response. Also measures
casing thickness and so can detect damage or corrosion.

Cementing. The operation by which cement slurry is forced down
through the casing and out at the lower end in such a way that it fills
the space between the casing and the sides of the well bore to a pre-
determined height above the bottom of the well. This is for the pur-
pose of securing the casing in place and excluding water and other
fluids from the well bore.

Centralizers, Spring and Rigid. Spring steel guides are attached to
casing and which serve to keep it centered in the open hole. Rigid
centralizers have no “give” and are only run inside a larger casing.

Centrifuge. A machine using centrifugal force for separating sub-
stances of different densities, for removing solids or moisture or for
simulating gravitational effects.

Charles Law. This states that if the volume of a body of gas is kept
constant, pressure is inversely proportional to temperature. Usually
expressed as P1/T1 = P2/T2.

Chemical Barrel. A container in which various chemicals are mixed
prior to addition to the drilling fluid.

Chemicals. In drilling-fluid terminology a chemical is any material
that produces changes in the viscosity, yield point, gel strength and
fluid loss, as well as surface tension.

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