Terminos Petroleros

IADC Glossary

A.

Abnormal Pressure - Reservoir pore fluid pressure that

is not similar to normal saltwat er gradient pressure. The term
is usually associated with higher than normal pressure,
increased complexity for the well designer and an increased
risk of well control problems . Abnormal pressure gradients
exceed a 10-ppg equivalent fluid density (0.52 psi per foot).
Gradientsbelow normal are called subnormal.
Absolute Pressure - pressure measured with respect to
zero pressure; the sum of atmospheric pressure and gaug e
pressure.
Absolute Temperature - temperature measured with
respect to absolute zero, in degrees Rankine or degrees Kelvin.
Absolute Viscosity - dynamic relationship between a
force and the fluid motion.
Absolute Zero Temperature - temperaturethat
prevents molecular motion.
Acceleration - rate of change in velocity.
Active data - continually updated data, based on latest
operational data.
Actuators - part of a control system, which regulates speed,
power, valve position, etc. to match a set point.
Adiabatic – process that is at constant temperature without
loss or gain of heat.
Adiabatic Efficiency - ratio of theoreticaltemperature
increase to actual temperature increase; a measure of the work
done by a compressor that is not lost as heat.
Adapter Spool - connects blowout preventers of different
sizes or pressure ratings to the casing head.
Adequately Ventilated Area – is an area having a
natural or artificial ventilation system to prevent the
accumulation of gases to an explosive level. API Recommends
12 airvolume changes per hour or 1.5 CFM per square foot of
floor area whichever is greater.
Adjustable Choke - A choke with a conical needle and
seat vary the rate of flow. See also chokes
Aeration – injecting gases in varying amounts into a fluid..
Aftercooler - Heat exchanger used post compression to
reduce gas temperatures.
Air Cutting - inadvertently incorporating and dispersing
air(mechanically) into a drilling fluid system.
Anchor - Device used to secure items of equipment,
important in the context of UBD where vibration is a factor
or concern.
Affinity Laws - equations that correlate the relationship of
head, speed, impeller diameter, flow, and efficiency for turbo
machinery.
Ambient Temperature - temperature of the
surroundings.

American Standard Code for InformationInterchange. (ASCII) – A different byte represents each

number, letter, symbol and punctuation mark. Replaced by
Unicode.
ASME – American Society of Mechanical Engineers.
ANSI – American National Standards Institute.
Aniline Point – The aromatics content of a hydrocarbon
mixture.

September 2002
API – American Petroleum Institute. .
API Gravity - arbitrary measurement of density adoptedin

1921 by the American Petroleum Institute and the Bureau of
Standards.
Apparent Power - com bination of real and reactive
power.
Apparent Viscosity - Slope of the shear stress versus
velocity gradient for a fluid. For Newtonian fluids, the
apparent viscosity equals the absolute viscosity.
Aromatics – Ring group chemical structure. Most
common are benzene, toluene, and xylene.

B.Back Pressure Valve - A flow control valve to provide

backflow control when running or pulling a string.
Backup – Redundant equipment available to complete an
operation in the event the primary equipment fails.
Balance - steady state of flow line or vessel has three critical
characteristics: a) a single flow rate from node to node; (b) an
even pack throughout the system; and (c)approximately equal
volumes entering and leaving the line or vessel.
Ball Check Valve - A valve permitting flow in one
direction only by lifting a spring-loaded ball off its seat. Valv e
opens when pressure differential acts in the desired flow
direction. The valve seals by forcing the ball tightly against the
seat when a pressure differential acts opposite the desired flow
direction.
Ball Valve...