Page 342 - Geology and Geochemistry of Oil and Gas

GLOSSARY 303
compose the outer skeletal remains of coccospheres
(skeletons of marine, planktonic protists).
Coefficient of correlation A dimensionless quantity measuring the degree of
linear association between two variables and taking
values in the range from 1 to +1: value of 1
indicates a perfect negative linear relationship; +1, a
perfect positive relationship; 0 denotes the absence of
relationship. Symbol: r.
Coefficient of A measure of the proportion of each other’s
determination variability that two variables share; the squared
2
coefficient of correlation. Symbol: r .
Coefficient of variation A dimensionless quantity measuring the relative
dispersion of a set of observations, calculated as the
ratio of the standard deviation to the mean of the
data values (sometimes as a percentage). Syn:
Coefficient of variability.
Collapse breccia Sedimentary breccia formed as a result of collapse of
indurated strata due to dissolution of underlying
strata, or commonly, cave-roof collapse.
Combination drive Two or three natural drives moving the reservoir
fluids toward the wellbore.
Compaction Reduction in bulk volume and/or thickness of a
sedimentary deposit resulting from either physical
processes of grain readjustment (closed packing) in
response to an increased weight of overburden
(mechanical compaction), or chemical processes such
as dissolution, grain interpenetration, and
stylolitization (chemical compaction).
Completion Finishing a well. Installation of necessary equipment
to produce a well. Includes placing the casing,
cementing and perforation opposite the productive
zone.
Composite sample Oil sample composed of equal portions of samples
obtained from two or more points in the tank.
Composite grain Aggregate carbonate grain composed of discrete
particles bound together by cement or organic
mucilage.
Condensate Liquid hydrocarbons, generally clear or pale straw-
colored and of high API gravity (above 601), that are
produced with wet gas. Syn: Distillate, Natural
gasoline.
Conduction log Measurement of the formation electric conductivity.
Conductor Casing pipe in a wellbore attached to the BOP.
Confidence level [stat] The probability (prescribed in advance and expressed
as decimals or percentage) that true value of an