Page 363 - Geology and Geochemistry of Oil and Gas

324 APPENDIX C

Mound Organic or inorganic sediment buildup with low
depositional relief; or organic buildup composed of
non-framework building (but commonly gregarious),
in-place organisms or allochthonous organisms.
Mud [sed] Fine-grained particles, by various definitions less than
20 microns or 4 microns in size. Syn: Particulate
micrite.
Mud [drill] See: Drilling mud.
Mudbank Accumulation of mud [sed].
Mud cake A clay layer formed where the drilling mud lost water
by filtration into a porous and permeable formation
during rotary drilling and adhered to the walls of the
borehole. See also: Filter cake.
Mud logging A continuous analysis of the drilling mud and
cuttings to determine the presence or absence of oil,
gas, or water in the formations penetrated by
borehole, and to ascertain the depths of any oil- and
gas-bearing formations using geochemical analysis,
chromatograph interpretation, and sample
description.
Mud program Plan of supplying and using drilling fluids and their
additives during the drilling operations.
Mudstone (a) Argillaceous or clay-bearing sedimentary rock
which is non-plastic and has a massive or non-foliated
structure. See: Claystone.
(b) Carbonate rock textural type composed
dominantly of mud (micrite) with less than 10%
grains. See: Lime mud.
Multiple completion Several producing zones completed for production
through one well.

N

Nannofossil General term for small fossils, the resolution of which
is near the limits of the light microscope.
Naphtha Petroleum distillate used as a cleaning fluid, for
example.
Naphthene See: Cycloparaffin.
Natural gas A naturally occurring mixture of hydrocarbon and
non-hydrocarbon gases found in porous media at
depth. It is often associated with crude oil. Composed
mainly (E70 to 90%) of methane gas.
Neomorphism General petrologic term that encompasses both
recrystallization (increase in crystal size in case where