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- Abandoned
- A
dry hole in which
no producible oil
or gas was present,
or a well that has
stopped producing.
Abandoned wells must
be plugged to prevent
seepage of oil, gas,
or water from one
formation to another.
-
- Active well
- A
well in mechanical
condition for production
or service use (i.e.,
in active production
or service use).
-
- Anticline
- An
upfold or arch of
stratified rock in
which the beds or
layers bend downward
in opposite directions
form the crest or
axis of the fold.
-
- API
- The
American Petroleum
Institute is the oil
industry's trade organization.
API's research and
engineering work provides
a basis for establishing
operating and safety
standard issues; specifications
for the manufacturing
of oil field equipment;
and furnishes statistical
and other information
to related agencies.
-
- Associated gas
- Gas
combined with oil.
Known also as gas
cap gas and solution
gas, it provides the
drive mechanism needed
to force oil to the
surface of a well.
Associated gas is
normally present in
an oil reservoir in
the early stages of
production.
-
B Back to Top
- Barrel
- The
standard unit of measure
of liquids in the
petroleum industry;
it contains 42 U.S.
standard gallons.
-
- Barrel of Oil Equivalent (BOE)
- The
amount of energy resource
(in this document,
natural gas) that
is equal to one barrel
of oil on an energy
basis. The conversion
is based on the assumption
that one barrel of
oil produces the same
amount of energy when
burned as 5,620 cubic
feet of natural gas.
-
- Basin
- A
depression of the
earth's surface into
which sediments are
deposited, usually
characterized by sediment
accumulation over
a long interval; a
broad area of the
earth beneath which
layers of rock are
inclined, usually
from the sides toward
the center.
-
- Bed
- A
layer of rock, usually
sediments, which is
homogeneous (the same)
in composition. One
bed is separated from
another by a bedding
plane.
-
- Bid
- An
offer for an OCS lease
submitted by a potential
lessee in the form
of a cash bonus dollar
amount or other commitments
as specified in the
final notice of sale.
-
- Block
- A
numbered area on an
OCS leasing map or
official protraction
diagram (OPD). Blocks
are portions of OCS
leasing maps and OPD's
that are themselves
portions of planning
areas. Blocks vary
in size, but typical
ones are 5,000 to
5,760 acres (about
9 square miles or
2,304 hectares). Each
block has a specific
identifying number,
area, and latitude
and longitude coordinates
that can be pinpointed
on a leasing map of
OPD.
-
- Blowout
- An
uncontrolled flow
of gas, oil, or other
fluids from a well
to the atmosphere.
A well may blow out
when formation pressure
exceeds the pressure
overburden of a column
of drilling fluid.
-
- Blowout preventer
- A special assembly of heavy-duty valves, commonly called the BOP stack, installed on top of a well which can be closed to prevent high-pressure oil or gas from escaping (a blowout) from the well hole during drilling operations.
- Bonus
- The
cash consideration
paid to the United
States by the successful
bidder for a mineral
lease. The payment
is made in addition
to the rent and royalty
obligations specified
in the lease.
-
- Borehole
- The
hole in the earth
made by the drill;
the uncased drill
hole from the surface
to the bottom of the
well.
-
C Back to Top
- Casing
- Steel
pipe used in oil wells
to seal off fluids
in the rocks from
the bore hole and
to prevent the walls
of the hole from caving.
-
- Casinghead
- The
top of the casing
set in a well; the
part of the casing
that protrudes above
the surface and to
which the control
valves and flow pipes
are attached.
-
- Casinghead gas
- Gas
produced from an oil
well as distinguished
from gas from a gas
well. The casinghead
gas is taken off at
the top of the well
or at the separator.
-
- Choke
- A
type of orifice installed
at the surface on
the tubing string
to adjust and control
the amount of oil
or gas flowing from
a well. It is customary
to refer to the production
of a well as so many
barrels or thousands
of cubic feet through
a 1/4-inch or 1/2-inch
choke, or whatever
the size of the opening.
The flowing pressure
exerted by the well's
production give an
indication of the
strength of the well,
and is helpful in
determining whether
a well is commercial.
-
- Commercial well
- A
well of sufficient
net production that
it could be expected
to pay out in a reasonable
time and yield a profit
from the operation.
A shallow 50-barrel-a-day
well in a readily
accessible location
onshore could be a
commercial well. Such
a well in virtually
any offshore area
where enormously expensive
producing facilities
and pipe lines would
have to be constructed
would not be considered
commercial.
-
- Completed well
- A
well that has been
mechanically completed
for production or
service use. There
may be more than one
completed zone in
the well. (See Active
well.)
-
- Concession
- Usually
used in foreign operations
and refers to a large
block of acreage granted
to the operator by
the host government
for a certain time
and under certain
government conditions
which allows the operator
to conduct exploratory
and/or development
operations. The Concession
Agreement assures
the holder of certain
rights under the law.
-
- Condensate
- A
natural gas liquid
with a low vapor pressure,
compared with natural
gasoline and liquified
petroleum gas. It
is produced from a
deep well where the
temperature and pressure
are high. Gas condenses
as it rises up the
wellbore and reaches
the surface as condensate.
Similarly, condensate
separates out naturally
in pipelines or in
a separation plant
by the normal process
of condensation.
-
- Condensate
- Liquid
hydrocarbons produced
with natural gas
which are separated
from it by cooling,
expansion, and various
other means (also
called "distillate").
-
- Continental margin
- A
zone separating the
emergent continents
from the deep sea
bottoms.
-
- Continental shelf
- A
broad, gently sloping,
shallow feature extending
from the shore to
the continental slope.
-
- Continental slope
- A
relatively steep,
narrow feature paralleling
the continental shelf;
the region in which
the steepest descent
of the ocean bottom
occurs.
-
- COST
- Continental
Offshore Stratigraphic
Test. These tests
under the direction
of the Minerals Management
Service are wells
deliberately drilled
to provide geological
information pertinent
to competitive bidding
for offshore tracts.
-
D Back to Top
- Demonstrated reserves (American Petroleum Institute)
- A
collective term for
the sum of proved
and indicated reserves.
Proved reserves are
estimated with reasonable
certainty to be recovered
under current economic
conditions. Indicated
reserves are economic
reserves in known
productive reservoirs
in existing fields
expected to respond
to improved recovery
techniques where (1)
an improved technique
has been installed
but its effect cannot
yet be fully evaluated,
or (2) an improved
technique has not
been installed but
knowledge of reservoir
characteristics and
the results of a known
technique installed
in a similar situation
are available for
use in the estimating
procedure.
-
- Development
- Activities
following exploration
including the installation
of facilities and
the drilling and completion
of wells for production
purposes.
-
- Diapir
- A
mass of rock, usually
salt, which has come
from a slightly deeper
part of the earth's
surface by piercing
through overlying
layers of sediment
through a zone of
weakness.
-
- Directional drilling
- The
technique of drilling
at an angle from the
vertical by deflecting
the drill bit. Directional
wells are drilled
to develop an offshore
lease from one drilling
platform; to reach
a pay zone where drilling
cannot be done, such
as beneath a shipping
lane.
-
- Discovery
- A
find of significant
quantities of gas
or oil.
-
- Dome
- A
roughly symmetrical
upfold of the layers
of rock in which the
beds dip in all directions
more or less equally
from a common point;
any deformation characterized
by local uplift and
approximately circular
in outline; e.g. the
salt domes of Louisiana
and Texas.
-
- Drill cuttings
- Chips
and small fragments
of drilled rock that
are brought to the
surface by the flow
of the drilling mud
as it is circulated.
-
- Drill pipe
- Heavy,
thich walled, hollow
steel pipe used in
rotary drilling to
turn the drill bit
and to provide a conduit
for the drilling mud.
-
- Drilling contractor
- A
person or company
whose business is
drilling wells. Wells
are drilled on several
contract specifications:
per foot, day rate,
or turnkey (that is,
upon completion).
Most major oil companies
do not own drilling
rigs. Exploration
and development drilling
is contracted. Personnel
manning the rigs work
for the contractor.
-
- Drilling mud
- A
special mixture of
clay, water, or refined
oil, and chemical
additives pumped downhole
through the drill
pipe and drill bit.
The mud cools the
rapidly rotating bit;
lubricates the drill
pipe as it turns in
the well bore; carries
rock cuttings to the
surface; serves as
a plaster to prevent
the wall of the borehole
from crumbling or
collapsing; and provides
the weight or hydrostatic
head to prevent extraneous
fluids from entering
the well bore and
to control downhole
pressures that may
be encountered.
-
- Dry hole
- A
well drilled to a
certain depth without
finding commercially
exploitable hydrocarbons.
-
- Dry gas
- Natural
gas from the well
that is free of liquid
hydrocarbons; gas
that has been treated
to remove all liquids;
pipeline gas.
-
E Back to Top
- Economically Recoverable Resource Estimate
- An
assessment of hydrocarbon
potential that takes
into account (1) physical
and technological
constraints on production
and (2) the influence
of exploration and
development costs
and market price on
industry investment
in OCS exploration
and production.
-
- Electric logging tool
- A
tool attached to a
cable which is lowered
into a well to survey
the borehole before
it is cased. An electrical
impulse is emitted
which is reflected
from the rock strata.
The degree of resistance
to the current allows
geologists to determine
the nature of the
rock penetrated by
the drill and some
indication of its
permeability, porosity,
and content (gas,
oil, or water).
-
- Environmental impact statement
- A
statement required
by the National Environmental
Policy Act of 1969
(NEPA) or similar
state law in relation
to any action significantly
affecting the environment,
including certain
exploration and drilling
activities.
-
- Erosion/scour
- The
removal or dissolution
of parts of the seabed
by bottom currents,
particularly those
by storms. Transportation
by currents of the
removed material
can result in significant
movement of masses
of sand, silt , and
mud on the sea floor.
This migration of
sediment can "strand" drilling
platform supports
or wellhead plumbing
by erosion of the
surrounding support
sediments.
-
- Exclusive Economic Zone (EEZ)
- An
area contiguous to
the territorial sea
of the United States,
the Commonwealth of
Puerto Rico, the Commonwealth
of Northern Mariana
Islands, and the U.S.
overseas territories
and possessions and
extending 200 nautical
miles from the coastline.
-
- Exploration
- The
process of searching
for minerals preliminary
to development. Exploration
activities include
(1) geophysical surveys,
(2) drilling to locate
an oil or gas reservoir,
and (3) the drilling
of additional wells
after a discovery
to delineate a reservoir.
It enables the lessee
to determine whether
to proceed with development
and production.
-
F Back to Top
- Field
- A
geographical area
in which one or more
oil or gas wells produce.
A field may refer
to surface area only
or to underground
productive formation.
A single field may
include several reservoirs
separated either horizontally
or vertically.
Glossary
- Gas lost
- Avoidably
lost natural gas which
is flared or vented
(i.e., natural gas
not retained in the
production system
for sale or use).
G Back to Top
- Lease
- A
legal document executed
between a landowner,
as lessor, and a company
or individual (as
lessee) that conveys
the right to exploit
the premises for minerals
or other products
for a specified period
of time over a given
area.
- Lease Sale (also called lease offering)
- An
MMS proceeding by
which leases of certain
OCS tracts are offered
for lease by competitive
sealed bidding and
during which bids
are received, announced,
and recorded.
L Back to Top
- Marginal probability of hydrocarbons (MPHC)
- The
probability that oil
and gas occur in commercial
quantities, using
existing recovery
technology under current
economic conditions.
- Minimum royalty
- The
lowest payment a lessee
can pay on an OCS
lease after production
begins. It is equivalent
to the yearly rental,
typically $3 per acre
or $8 per hectare.
Rentals are paid annually
before a discovery;
royalties are paid
on production after
a discovery. If the
total royalty payments
amount to less than
the yearly rental,
the minimum royalty
payments make up the
difference. (See Rent
and Royalty.)
M Back to Top
- Net Profit Share lease
- An
OCS lease that provides
for payment to the
U.S. of a percentage
share of the net profits
for production of
oil and gas from the
tract. The percentage
share may be fixed
in the notice of the
lease sale or may
be a variable of the
bid, depending on
the bidding system
used for the lease
sale.
- Nonassociated gas
- Dry
gas that is not associated
with oil in a productive
reservoir, as opposed
to associated gas
or solution gas.
N Back to Top
- Oil lost
- Oil
that is spilled or
burned (i.e., oil
not retained in the
production system
for sale).
- Operator
- The
individual, partnership,
firm, or corporation
having control or
management of operations
on a leased area or
a portion thereof.
The operator may be
a lessee, designated
agent of the lessee,
holder of rights under
an approved operation
agreement, or an agent
of an operating rights
holder.
- Outer Continental Shelf (OCS)
- All
submerged lands seaward
and outside the area
of lands beneath navigable
waters. Lands beneath
navigable waters are
interpreted as extending
from the coastline
3 nautical miles into
the Atlantic Ocean,
the Pacific Ocean,
the Arctic Ocean,
and the Gulf of Mexico
excluding the coastal
waters off Texas and
western Florida. Lands
beneath navigable
waters are interpreted
as extending from
the coastline 3 marine
leagues into the Gulf
of Mexico off Texas
and western Florida.
O Back to Top
- Planning area
- A
subdivision of an
offshore area used
as the initial basis
for considering blocks
to be offered for
lease.
- Plugged and abandoned
- Wells
in which casings have
been removed, and
the well bore sealed
with mechanical or
cement plugs.
- Producible lease
- A
lease where one well
or several wells have
discovered hydrocarbons
in paying quantities,
but for which there
is no production during
the reporting period.
- Producible zone completion
- The
interval in a wellbore
that has been mechanically
prepared to produce
oil, gas, or sulphur.
There can be more
than one zone completed
for production in
a wellbore.
- Producing lease
- A
lease that is producing
oil, gas, or sulphur
in quantities sufficient
to generate royalties.
- Production
- The
phase of oil and gas
operations involved
with well fluids extraction,
separation, treatment,
measurement, etc.
- Proven reserves (Society of Petroleum Engineers)
- Reserves
that can be estimated
with reasonable certainty
to be recovered under
current economic conditions.
Current economic conditions
include processing
costs prevailing at
the time of the estimate.
Proved reserves must
either have facilities
that are operational
at the time of the
estimate to process
and transport those
reserves to market,
or a commitment of
reasonable expectation
to install such facilities
in the future. Proved
reserves can be subdivided
into undeveloped and
developed.
P Back to Top
- Rent
- Periodic
payments made by the
holder of a lease,
during the primary
lease term for the
right to use the land
or resources for purposes
established in the
lease.
- Royalty
- Payment,
in value (money) or
in kind, of a stated
proportionate interest
in production from
mineral deposits by
the lessees to the
lessor. The royalty
rate may be an established
minimum, a sliding-scale,
or a step-scale. A
step-scale royalty
rate increases by
steps as the average
production on the
lease increases. A
sliding-scale royalty
rate is based on average
production and applies
to all production
from the lease.
R Back to Top
- Sales value
- The
proceeds received
for the sale of the
mineral.
- Service zone completion
- The
interval in a well
bore that has been
mechanically prepared
for service use, usually
water or gas injection
to stimulate production
from other wells or
for water or other
waste disposal.
- Shut-in payments
- Payments
made for any producible
well on the Federal
OCS that is temporarily
closed down. (See
Shut-in zone completion.)
- Sulphur
- A
nonmetallic element
that occurs in association
with salt diapirs
throughout much of
the onshore and offshore
Gulf of Mexico region.
All offshore sulphur
is mined by the Frasch
process, which uses
hot brine to melt
sulphur out of the
enclosing rock so
the molten sulphur
can be recovered.
- Suspended well
- A
well on which operations
have been discontinued.
The usual context
is an uncompleted
well in which operations
ceased during drilling
but which has not
been plugged and abandoned
permanently.
S Back to Top
- Well
- A
hole drilled or bored
into the earth, usually
cased with metal pipe,
for the production
of gas or oil. A hole
for the injection
under pressure of
water or gas into
a subsurface rock
formation.
- Workover
- Operation on a shut-in or producing well to restore or increase its production.
W Back to Top