Page 372 - Geology and Geochemistry of Oil and Gas

GLOSSARY 333
(b) Semisolid or solid complex, amorphous mixture of
organic compounds having no definite melting point
or tendency to crystallize.
Resistivity log Defines the reservoir contents. Electric current flows
in the formation between two electrodes on a logging
tool and measures resistivity between those two
points.
Reynolds number The dimensionless number defined as R e ¼ rvd/Z
where r is the density of a fluid with viscosity Z
traveling at velocity v in a pipe of diameter d.
Above R e ¼ 2,000, flow is turbulent. Below, it is
laminar.
Rheology The study of fluid flow, esp. of fluid elasticity,
viscosity, and plasticity, which is of special
importance to mud engineers and reservoir engineers.
Rhizoconcretion, rhizolith An accumulation of calcium carbonate around plant
roots.
Rhodolite An accretionary carbonate particle, larger than sand-
size, with or without a nucleus surrounded by a
laminated to massive cortex constructed by red
(rhodophyte) algae. Syn: Rhodolith, Rhodoid.
Rimmed shelf/platform A shallow water platform of deposition, the seaward
edge of which is defined by a submarine topographic
high constructed by carbonate sands or reef buildups.
Rod Sucker rod is attached to the downhole pump, usually
having a length of 16–1/2 ft.
Rod lift Use of solid metal rods to activate the downhole
pump.
Root mean square (RMS) Square root of sum of squares of individual
observations divided by total number of observations.
Rotary drilling A drilling method that imparts a turning or rotary
motion to the drill string to drill the hole.
Rotary table The principal component of rotary machine used to
turn the drill string and support the drilling assembly.
Rudstone Reef rock composed of grain-supported texture of
allochtonous (transported) rather than in-place
organic particles.
Running sample Oil sample taken by lowering an unstoppered beaker
from the top outlet level to the bottom outlet and
returning it at a uniform rate of speed so that it is
about three quarters full when returned.
S

Salt dome A dome that is caused by an intrusion or piercing of
rock salt into overlying deposits, which are usually