Speight J.G. Natural Gas: A Basic Handbook
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Glossary
219
Guard bed
A
bed (usually alumina) that serves as a pro-
tector of a more expensive bed (e.g., molecular
sieve); serves by the act of attrition and may
be referred to as an attrition catalyst.
Heat
of
combustion (energy content)
The amount of energy
that is obtained from burning natural gas;
measured in British thermal units (Btu).
HCFCs
(hydrochlorofluorocarbons)
Gaseous compounds that
meet current environmental standards for
minimizing stratospheric ozone depletion.
Horizontal drilling
Drilling method that allows producers to
extend horizontal shafts into areas that could
not otherwise be reached; especially useful
in
offshore drilling; categorized as short
(extending only
20
to
40
ft from the vertical),
medium
(300
to
700
ft from the vertical) or
long
(1,000
to
4,500
ft from vertical) radius.
Horsehead (balanced conventional beam, sucker rod) pump
A
common type of cable rod lifting equipment
for recovery of oil and gas; so-called because of
the shape of the counterweight at the end of
the beam.
Hydrocarbon
An
organic compound containing only
carbon and hydrogen. Hydrocarbons often
occur
in
petroleum products, natural gas, and
coals.
Hydraulic fracturing
The injection
of
water into the formation.
Ideal gas
A
gas in which all collisions between atoms or
molecules are perfectly elastic and
in
which
there are no intermolecular attractive forces.
IFPEXOL
process
A
methanol-based process for water removal
and hydrocarbon dew
point
control;
also
used
for acid-gas removal.
220
Glossary
Impure natural
gas
Natural gas as delivered from the well and
before processing (refining).
Independent producer
A
non-integrated company that receives
nearly all
of
its revenues from production at
the wellhead; by the
IRS
definition, a firm is
an “Independent”
if
the refining capacity is
less than
50,000
barrels per day
in
any given
day
or
their retail sales
are
less than
$5
million
for the year.
Interruptible service contracts
Contracts that allow a distrib-
uting party to temporarily suspend delivery of
gas to a buyer to meet the demands
of
cus-
tomers who purchased firm service.
Iron oxide process (iron sponge process,
dry
box method)
A
process
in
which the gas is passed through a
bed
of
wood chips impregnated with iron
oxide to scavenge hydrogen sulfide and
organic sulfur compounds (mercaptans) from
natural gas streams.
Kitchen
The underground deposit of organic debris
that is eventually converted to petroleum and
natural gas.
Landfill gas
See
Natural
gas.
Lean gas
Natural gas
in
which methane is the major
constituent.
Liquefied natural gas
The liquid form of natural gas.
Liquefied petroleum
gas
(LPG)
The term applied to certain spe-
cific hydrocarbons and their mixtures, which
exist
in
the gaseous state under atmospheric
ambient conditions but can be converted to
the liquid state under conditions
of
moderate
pressure at ambient temperature.
Glossary
221
Local distribution company
A
retail gas distribution company
that delivers natural gas to end users.
LO-CAT
process
A
wet oxidation process.
Lithology
The study
of
rocks; important for exploration
and drilling crews
to
have an understanding
of
lithology as it relates to the production
of
gas and
oil.
Lowering
of
different types
of
measuring
instruments into the wellbore and gathering
and recording data on porosity, permeability,
and types
of
fluids present near the current
well after which the data are used to construct
subsurface maps
of
a region to aid
in
further
exploration.
Lower explosive limit
The lower percent by volume
of
the gas
vapor
in
air at which the gas
will
explode or
inflame. See also
Upper explosive limit.
Lower flammability limit
The minimum concentration by
volume of a combustible substance that is
capable
of
propagating a flame under specified
conditions.
Magnetometer
A
device to measure small changes
in
the
earth’s magnetic field at the surface, which
indicates what kind
of
rock formations might
be present underground.
Marsh gas
See
Natural gas.
Mcf (thousand cubic feet)
A
unit
of
measure that is more com-
monly used in the low volume sectors
of
the
gas industry, such as stripper well production.
See also
Btu,
Bcfi
Tcfi
Quad.
MDEA
MEA
Methyldiethanolamine.
Ethanolamine (monoethanolamine).
222
Glossary
Methane
(CH4)
Commonly (often incorrectly) known as nat-
ural gas; colorless and naturally odorless, and
burns efficiently without many by products.
Methanogens
Methane-producing microorganisms.
Most efficient recovery rate
(MER)
The rate at which the
greatest amount of natural gas may be
extracted without harming the formation
itself.
Muds
Used in drilling to lubricate the drilling bit
in
rotary drilling rigs.
Multiple completions
The result of drilling several different
depths from a single well
to
increase the rate
of
production or the amount
of
recoverable
gas.
Natural gas
Also called
marsh gas, swamp gas,
and
landfill
gas;
a gaseous fossil fuel that is found in oil
fields, natural gas fields, and in coal beds; a
mixture of hydrocarbon and small quantities
of
non-hydrocarbons that exists either
in
the
gaseous phase or is
in
solution in crude oil
in
natural underground reservoirs, and which is
gaseous at atmospheric conditions of pressure
and temperature.
NaturalGas Act
Passed
in
1938
and gives the Federal Power
Commission (now the Federal Energy Regula-
tory Commission or FERC) jurisdiction over
companies engaged in interstate sale or trans-
portation
of
natural gas.
Natural gas co-firing
The injection
of
natural gas with pulver-
ized coal or oil into the primary combustion
zone
of
a boiler.
Glossary
223
Natural gas liquids
(NGLs)
A
hydrocarbon liquid stream gas
condensate); higher molecular weight hydro-
carbons that exist in the reservoir as constitu-
ents of natural gas but which are recovered as
liquids in separators, field facilities
or
gas-
processing plants.
Natural Gas Policy
Act
of
1978
One of the first efforts to dereg-
ulate the gas industry and to determine the
price of natural gas as dictated by market
forces, rather than regulation.
Natural gas resource base
An
estimate of the amount of natural
gas available, based
on
the combination of
proved reserves, and those additional volumes
that have not yet been discovered, but are esti-
mated to be “discoverable” given current tech-
nology and economics.
Natural gas vehicle
(NGV)
A
car, bus, or truck that is powered by
a natural gas, either
in
compressed or liquefied
form, rather than the traditional gasoline or
diesel fuel.
NES
(National Energy Strategy)
A
1991 federal proposal that
focused
on
national security, conservation,
and regulatory reform, with options that
encourage natural gas use.
Non-associated natural gas
Sometimes called
gas
well
gas;
gas
produced from geological formations that
typ-
ically do not contain much,
if
any, crude oil,
or higher boiling hydrocarbons
(gas
liquids)
than methane; can contain non-hydrocarbon
gases such as carbon dioxide and hydrogen
sulfide.
NOx (nitrogen oxides)
Produced during combustion; precursors
to acid deposition (acid rain).
NPC
(National Petroleum Council)
An
advisory body
of
appointed
members whose
purpose
is
to
advise the secretary
of
energy.
224
Glossary
Off-peak period
The time during a day, week, month or year
when
gas
use
on
a particular system is not at
its maximum.
Olamineprocess
A
process that used an amine derivative (an
olamine)
to
remove acid gas from natural gas
streams.
Olamines
Compounds such as ethanolamine (monoeth-
anolamine, MEA), diethanolamine (DEA), tri-
ethanolamine (TEA), methyldiethanolamine
(MDEA), diisopropanolamine (DIPA), and dig-
lycolamine (DGA) that are widely used in gas
processing.
Order
636
The Federal Energy Regulatory Commission’s
1992
order that required pipelines to
unbundle their transportation, sales, and
storage services.
Peak load requirements (peak load storage)
The design to
have high-deliverability for short periods
of
time during which the natural gas can be
withdrawn from storage quickly as the need
arises.
Peak shaving
Peak-use period
Permeability
Petroleum
PIGS
Use of natural gas from storage to supplement
the normal amounts delivered to customers
during peak-use periods.
The period
of
time when gas use
on
a partic-
ular system is at its maximum.
A
measure of the ease that a fluid can pass
through a section
of
rock.
Crude oil.
Robotic agents used to inspect pipeline inte-
rior walls for corrosion and defects, measure
pipeline interior diameters, remove accumu-
lated debris and for other specialty tasks.
Glossarv
225
Porosity
Producer
Production rate
Propping agents
Proved Resources
The spaces between grains
of
sediment
in
sedi-
mentary rock.
The company generally involved in explora-
tion, drilling, and refining of natural gas.
The rate
of
production of oil and/or gas from a
well; usually given
in
barrels per day @bls/day)
for oil or standard cubic feet (scft/day) for gas.
Sand, glass beads, epoxy,
or
silica sand that
serve to prop open the newly widened fissures
in the formation.
Part of the resource base that includes the
working inventory of natural gas; volumes
that have already been discovered and are
readily available for production and delivery.
Proved amount in place
The volume originally occurring
in
known natural reservoirs that has been care-
fully measured and assessed as exploitable
under present and expected local economic
conditions with existing available technology.
Proved recoverable reserves
The volume within the proved
amount in place that can be recovered in the
future under present and expected local eco-
nomic conditions with existing available
technology.
Psi (pounds per square inch, lb/in.2)
Pressure measured with
respect to that
of
the atmosphere.
PUHCA
(Public Utility Holding Company Act
of
1935)
Amended by EPACT, to allow power genera-
tion by independent power producers
(IPPs)
without restrictions
on
corporate structure.
226
Glossarv
Quad
An
abbreviation for a quadrillion
(1,000,000,000,000,000)
Btu; roughly equiva-
lent to one trillion
(1,000,000,000,000)
cubic
feet, or
1
Tcf. See also
Bcf;
Mcf,
Tcf.
Raw natural gas
Impure natural gas as delivered from the well
and before processing (refining).
Rectisol
process
A
process that used a physical (non-reactive)
solvent for gas cleaning.
Redox process
A
sulfur recovery process that involves liquid-
phase oxidation; uses a dilute aqueous solu-
tion of iron or vanadium to remove hydrogen
sulfide selectively by chemical absorption
from sour gas streams; can be used
on
rela-
tively small or dilute hydrogen sulfide stream
to recover sulfur from the acid gas stream or,
in
some cases, they can be used in place
of
an
acid gas removal process.
Reserves
Residue gas
The amount
of
a resource available for
recovery and/or production; the recoverable
amount
is
usually tied to economic aspects
of
production.
Natural gas from which the higher molecular
weight hydrocarbons have been extracted;
mostly methane.
Rich gas
A
gaseous stream is traditionally very rich
in
natural gas liquids
(NGLs);
see
NaturaZ
gas
liquids.
R/P
(reserves/production) ratio
Calculated by dividing proved
recoverable reserves by production (gross less
re-injected)
in
a given year.
Reburning
An
effective and economic means
of
reducing
NO,
emissions from
all
types
of
industrial and
electric utility boilers.
Glossary
227
Reserve additions
Reservoir
Reservoir energy
Rod pumping
Salt
caverns
Volumes of the resource base that are continu-
ously moved from the resource category to the
proved resources category.
A
geological formation that retains
or
traps
the gas.
The underground pressure
in
a reservoir that
will push the petroleum and natural gas up
the wellbore to the surface
The use of a lifting (pumping) method to
recover oil from a reservoir.
Caverns formed out of existing salt deposits.
SCADA
(supervisory control and data acquisition)
Remote-
controlled equipment used by pipelines and
LDCs to operate their gas systems.
SCOT
(Shell Claus Off-gas Treating) process
A
tail-gas treating
process.
Seismograph
An instrument used to detect and record
earthquakes; is able to pick up and record the
vibrations of the earth that occur during an
earthquake; when seismology is applied to the
search for natural gas, seismic waves, emitted
from a source, are sent into the earth and the
seismic waves interact differently with the
underground formation (underground layers),
each with its own properties.
Seismology
The study
of
the movement of energy,
in
the
form
of
seismic waves, through the earth’s
crust.
Selexol process
A
process that used a physical (non-reactive)
solvent for gas cleaning.
Separator tank
Tanks are usually located at the wellsite
to
sep-
off to be processed at different locations.
arate
oil,
gas, and water before sending
each
228
Glossarv
~~
-
~~
~
Shale
gas
Gas that occurs in low permeability shale; see
Unconventional
gas.
A
process that uses a slurry
of
iron oxide to
selectively absorb hydrogen sulfide.
Slurry process
SO,
(sulfur dioxide)
A
precursor to acid deposition (acid rain);
produced when sulfur is combusted
to
sulfur
dioxide.
Sour
gas
Specific gravity
Spot market
Spot purchase
Stretford process
Stripper wells
SulfaTreat process
Sulfinol
process
SulFerox process
swamp
gas
Natural gas that contains hydrogen sulfide.
The relationship of the density
of
a substance
to the density
of
water.
A
method
of
contract purchasing whereby
commitments by the buyer and seller are
of
a
short duration at a single volume price.
Gas purchased on the spot market, which
involves short-term contracts for specified
amount
of
gas, at a one-time purchase price.
A
wet oxidation process.
Natural gas wells that produce less than
60,000
ft3 of gas per day.
A
batch-type process for the selective removal
of
hydrogen sulfide and mercaptans from nat-
ural gas; the process is dry, using
no
free liq-
uids, and can be used for all natural gas
applications where a batch process is suitable.
A
combination process that uses a mixture
of
amines and a physical solvent (an aqueous
amine and sulfolane).
A
wet oxidation process.
See
Natural
gas.