402 IPCC Special Report on Carbon dioxide Capture and Storage
Note: the definitions in this Annex refer to the use of the terms
in the context of this report. It provides an explanation of
specific terms as the authors intend them to be interpreted in
this report.
Abatement
Reduction in the degree or intensity of emissions or other
pollutants.
Absorption
Chemical or physical take-up of molecules into the bulk of a
solid or liquid, forming either a solution or compound.
Acid gas
Any gas mixture that turns to an acid when dissolved in water
(normally refers to H2S + CO2 from sour gas (q.v.)).
Adiabatic
A process in which no heat is gained or lost by the system.
Adsorption
The uptake of molecules on the surface of a solid or a liquid.
Afforestation
Planting of new forests on lands that historically have not
contained forests.
Aluminium silicate mineral
Natural mineral – such as feldspar, clays, micas, amphiboles
– composed of Al2O3 and SiO2 plus other cations.
Amine
Organic chemical compound containing one or more nitrogens
in -NH2, -NH or -N groups.
Anaerobic condition
Reducing condition that only supports life which does not
require free oxygen.
Anhydrite
Calcium sulphate: the common hydrous form is called
gypsum.
Antarctic Treaty
Applies to the area south of 60 degrees South, and declares
that Antarctica shall be used for peaceful purposes only.
Anthracite
Coal with the highest carbon content and therefore the highest
rank (q.v.).
Anthropogenic source
Source which is man-made as opposed to natural.
Anticline
Folded geological strata that is convex upwards.
API
American Petroleum Institute; degree API is a measure of oil
density given by (141.5/specific gravity) -131.5.
Aquifer
Geological structure containing water and with significant
permeability to allow flow; it is bound by seals.
Assessment unit
A geological province with high petroleum potential.
Assigned amount
The amount by which a Party listed in Annex B of the Kyoto
Protocol agrees to reduce its anthropogenic emissions.
ATR
Auto thermal reforming: a process in which the heat for the
reaction of CH4 with steam is generated by partial oxidation of
CH4.
Autoproduction
The production of electricity for own use.
Basalt
A type of basic igneous rock which is typically erupted from a
volcano.
Basel Convention
UN Convention on the Control of Transboundary Movements
of Hazardous Wastes and their Disposal, which was adopted at
Basel on 22 March 1989.
Baseline
The datum against which change is measured.
Basin
A geological region with strata dipping towards a common
axis or centre.
Bathymetric
Pertaining to the depth of water.
Benthic
Pertaining to conditions at depth in bodies of water.
Bicarbonate ion
The anion formed by dissolving carbon dioxide in water,
HCO3
-.
Biomass
Matter derived recently from the biosphere.
Biomass-based CCS
Carbon capture and storage in which the feedstock (q.v.) is
biomass
Annex II: Glossary, acronyms and abbreviations 403
Bituminous coal
An intermediate rank of coal falling between the extremes of
peat and anthracite, and closer to anthracite.
Blow-out
Refers to catastrophic failure of a well when the petroleum
fluids or water flow unrestricted to the surface.
Bohr effect
The pH-dependent change in the oxygen affinity of blood.
Bottom-up model
A model that includes technological and engineering details in
the analysis.
Boundary
In GHG accounting, the separation between accounting units,
be they national, organizational, operational, business units or
sectors.
Break-even price
The price necessary at a given level of production to cover all
costs.
Buoyancy
Tendency of a fluid or solid to rise through a fluid of higher
density.
Cap rock
Rock of very low permeability that acts as an upper seal to
prevent fluid flow out of a reservoir.
Capillary entry pressure
Additional pressure needed for a liquid or gas to enter a pore
and overcome surface tension.
Capture efficiency
The fraction of CO2 separated from the gas stream of a source
Carbon credit
A convertible and transferable instrument that allows an
organization to benefit financially from an emission reduction.
Carbon trading
A market-based approach that allows those with excess
emissions to trade that excess for reduced emissions
elsewhere.
Carbonate
Natural minerals composed of various anions bonded to a
CO3
2- cation (e.g. calcite, dolomite, siderite, limestone).
Carbonate neutralization
A method for storing carbon in the ocean based upon the
reaction of CO2 with a mineral carbonate such as limestone to
produce bicarbonate anions and soluble cations.
Casing
A pipe which is inserted to stabilize the borehole of a well
after it is drilled.
CBM
Coal bed methane
CCS
Carbon dioxide capture and storage
CDM
Clean development mechanism: a Kyoto Protocol mechanism
to assist non-Annex 1 countries to contribute to the objectives
of the Protocol and help Annex I countries to meet their
commitments.
Certification
In the context of carbon trading, certifying that a project
achieves a quantified reduction in emissions over a given
period.
Chemical looping combustion
A process in which combustion of a hydrocarbon fuel is split
into separate oxidation and reduction reactions by using a
metal oxide as an oxygen carrier between the two reactors.
Chlorite
A magnesium-iron aluminosilicate sheet silicate clay mineral.
Class “x” well
A regulatory classification for wells used for the injection of
fluids into the ground.
Claus plant
A plant that transforms H2S into elemental sulphur.
Cleats
The system of joints, cleavage planes, or planes of weakness
found in coal seams along which the coal fractures.
CO2 avoided
The difference between CO2 captured, transmitted and/or
stored, and the amount of CO2 generated by a system without
capture, net of the emissions not captured by a system with
CO2 capture.
CO2 equivalent
A measure used to compare emissions of different greenhouse
gases based on their global warming potential.
Co-benefit
The additional benefits generated by policies that are
implemented for a specific reason.
404 IPCC Special Report on Carbon dioxide Capture and Storage
COE
Cost of electricity, value as calculated by Equation 1 in
Section 3.7.
Co-firing
The simultaneous use of more than one fuel in a power plant
or industrial process.
Completion of a well
Refers to the cementing and perforating of casing and
stimulation to connect a well bore to reservoir.
Congruence
The quality of agreement between two entities.
Conservative values
Parameter values selected so that a parameter, such as CO2
leakage, is over-estimated.
Containment
Restriction of movement of a fluid to a designated volume
(e.g. reservoir).
Continental shelf
The extension of the continental mass beneath the ocean.
COREX
A process for producing iron.
Cryogenic
Pertaining to low temperatures, usually under about -100°C.
D, Darcy
A non-SI unit of permeability, abbreviated D, and
approximately = 1μm2.
Dawsonite
A mineral: dihydroxide sodium aluminium carbonate.
Deep saline aquifer
A deep underground rock formation composed of permeable
materials and containing highly saline fluids.
Deep sea
The sea below 1000m depth.
Default emissions factor
An approximate emission factor that may be used in the
absence of precise or measured values of an Emissions Factor.
Demonstration phase
Demonstration phase means that the technology is
implemented in a pilot project or on a small scale, but not yet
economically feasible at full scale.
Dense phase
A gas compressed to a density approaching that of the liquid.
Dense fluid
A gas compressed to a density approaching that of the liquid.
Depleted
Of a reservoir: one where production is significantly reduced.
Diagenesis
Processes that cause changes in sediment after it has been
deposited and buried under another layer.
DIC
Dissolved Inorganic Carbon.
Dip
In geology, the angle below the horizontal taken by rock strata.
Discharge
The amount of water issuing from a spring or in a stream that
passes a specific point in a given period of time.
Discordant sequence
In geology, sequence of rock strata that is markedly different
from strata above or below.
Dolomite
A magnesium-rich carbonate sedimentary rock. Also, a
magnesium-rich carbonate mineral (CaMgCO3).
Double-grip packer
A device used to seal a drill string equipped with two gripping
mechanisms.
Down-hole log
Record of conditions in a borehole.
Drill cuttings
The solid particles recovered during the drilling of a well.
Drill string
The assembly of drilling rods that leads from the surface to the
drilling tool.
Drive
Fluid flow created in formations by pressure differences
arising from borehole operations.
Dry ice
Solid carbon dioxide
Dynamic miscibility
The attainment of mixing following the prolonged injection of
gas into an oilfield.
Annex II: Glossary, acronyms and abbreviations 405
ECBM
Enhanced coal bed methane recovery; the use of CO2 to
enhance the recovery of the methane present in unminable
coal beds through the preferential adsorption of CO2 on coal.
Economic potential
The amount of greenhouse gas emissions reductions from
a specific option that could be achieved cost-effectively,
given prevailing circumstances (i.e. a market value of CO2
reductions and costs of other options).
Economically feasible under specific conditions
A technology that is well understood and used in selected
commercial applications, such as in a favourable tax regime or
a niche market, processing at least 0.1 MtCO2/yr, with a few
(less than 5) replications of the technology.
EGR
Enhanced gas recovery: the recovery of gas additional to that
produced naturally by fluid injection or other means.
Emission factor
A normalized measure of GHG emissions in terms of activity,
e.g., tonnes of GHG emitted per tonne of fuel consumed.
Emissions credit
A commodity giving its holder the right to emit a certain
quantity of GHGs (q.v.).
Emissions trading
A trading scheme that allows permits for the release of a
specified number of tonnes of a pollutant to be sold and
bought.
Endothermic
Concerning a chemical reaction that absorbs heat, or requires
heat to drive it.
Enhanced gas recovery
See EGR.
Enhanced oil recovery
See EOR
Entrained flow
Flow in which a solid or liquid, in the form of fine particles, is
transported in diluted form by high velocity gas.
Entrainment gas
The gas employed in entrained flow (q.v.).
EOR
Enhanced oil recovery: the recovery of oil additional to that
produced naturally by fluid injection or other means.
Euphotic zone
The zone of the ocean reached by sunlight.
Evaporite
A rock formed by evaporation.
Exothermic
Concerning a chemical reaction that releases heat, such as
combustion.
Ex-situ mineralization
A process where minerals are mined, transferred to an
industrial facility, reacted with carbon dioxide and processed.
Exsolution
The formation of different phases during the cooling of a
homogeneous fluid.
Extended reach well
Borehole that is diverted into a more horizontal direction to
extend its reach.
Extremophile
Microbe living in environments where life was previously
considered impossible.
Far field
A region remote from a signal source.
Fault
In geology, a surface at which strata are no longer continuous,
but displaced.
Fault reactivation
The tendency for a fault to become active, i.e. for movement
to occur.
Fault slip
The extent to which a fault has slipped in past times.
FBC
Fluidized bed combustion: – combustion in a fluidized bed
(q.v.).
Feldspar
A group of alumino-silicate minerals that makes up much of
the Earth’s crust.
Feedstock
The material that is fed to a process
FGD
Flue gas desulphurization.
Fischer-Tropsch
A process that transforms a gas mixture of CO and H2 into
liquid hydrocarbons and water.
406 IPCC Special Report on Carbon dioxide Capture and Storage
Fixation
The immobilization of CO2 by its reaction with another
material to produce a stable compound
Fixed bed
A gas-solid contactor or reactor formed by a bed of stationary
solid particles that allows the passage of gas between the
particles.
Flood
The injection of a fluid into an underground reservoir.
Flue gas
Gases produced by combustion of a fuel that are normally
emitted to the atmosphere.
Fluidized bed
A gas-solid contactor or reactor comprising a bed of fine
solid particles suspended by passing a gas through the bed at
sufficiently high velocity.
Folding
In geology, the bending of rock strata from the plane in which
they were formed.
Formation
A body of rock of considerable extent with distinctive
characteristics that allow geologists to map, describe, and
name it.
Formation water
Water that occurs naturally within the pores of rock
formations.
Fouling
Deposition of a solid on the surface of heat or mass transfer
equipment that has the effect of reducing the heat or mass
transfer.
Fracture
Any break in rock along which no significant movement has
occurred.
Fuel cell
Electrochemical device in which a fuel is oxidized in a
controlled manner to produce an electric current and heat
directly.
Fugitive emission
Any releases of gases or vapours from anthropogenic activities
such as the processing or transportation of gas or petroleum.
FutureGen Project
US Government initiative for a new power station with low
CO2 emissions.
Gas turbine
A machine in which a fuel is burned with compressed air or
oxygen and mechanical work is recovered by the expansion of
the hot products.
Gasification
Process by which a carbon-containing solid fuel is transformed
into a carbon- and hydrogen-containing gaseous fuel by
reaction with air or oxygen and steam.
Geochemical trapping
The retention of injected CO2 by geochemical reactions.
Geological setting
The geological environment of various locations.
Geological time
The time over which geological processes have taken place.
Geomechanics
The science of the movement of the Earth’s crust.
Geosphere
The earth, its rocks and minerals, and its waters.
Geothermal
Concerning heat flowing from deep in the earth.
GHG
Greenhouse gases: carbon dioxide (CO2), methane
(CH4), nitrous oxide (N2O), hydroflurocarbons (HFCs),
perfluorocarbons (PFCs), and sulphur hexafluoride (SF6).
Hazardous and non-hazardous waste
Potentially harmful and non-harmful substances that have
been released or discarded into the environment.
Hazardous waste directive
European directive in force to regulate definitions of waste
classes and to regulate the handling of the waste classes.
HAZOP
HAZard and OPerability, a process used to assess the risks of
operating potentially hazardous equipment.
Helsinki Convention
International legal convention protecting the Baltic water
against pollution.
Henry’s Law
States that the solubility of a gas in a liquid is proportional to
the partial pressure of the gas in contact with the liquid.
HHV
Higher heating value: the energy released from the combustion
of a fuel that includes the latent heat of water.
Annex II: Glossary, acronyms and abbreviations 407
Host rock
In geology, the rock formation that contains a foreign material.
Hybrid vehicle
Vehicle that combines a fossil fuel internal combustion engine
and an alternative energy source, typically batteries.
Hydrate
An ice-like compound formed by the reaction of water and
CO2, CH4 or similar gases.
Hydrodynamic trap
A geological structure in which fluids are retained by low
levels of porosity in the surrounding rocks.
Hydrogeological
Concerning water in the geological environment.
Hydrostatic
Pertaining to the properties of a stationary body of water.
Hypercapnia
Excessively high CO2 levels in the blood.
Hypoxia
Having low rates of oxygen transfer in living tissue.
Hysteresis
The phenomenon of a lagging recovery from deformation or
other disturbance.
IEA GHG
International Energy Agency – Greenhouse Gas R&D
Programme.
IGCC
Integrated gasification combined cycle: power generation in
which hydrocarbons or coal are gasified (q.v.) and the gas is
used as a fuel to drive both a gas and a steam turbine.
Igneous
Rock formed when molten rock (magma) has cooled and
solidified (crystallized).
Immature basin
A basin in which the processes leading to oil or gas formation
have started but are incomplete.
Infrared spectroscopy
Chemical analysis using infrared spectroscope method.
Injection
The process of using pressure to force fluids down wells.
Injection well
A well in which fluids are injected rather than produced.
Injectivity
A measure of the rate at which a quantity of fluid can be
injected into a well.
In-situ mineralization
A process where minerals are not mined: carbon dioxide
is injected in the silicate formation where it reacts with the
minerals, forming carbonates and silica.
International Seabed Authority
An organization established under the 1982 UN Convention
on the Law of the Sea, headquartered in Kingston, Jamaica.
Ion
An atom or molecule that has acquired a charge by either
gaining or losing electrons.
IPCC
Intergovernmental Panel on Climate Change
JI
Joint Implementation: under the Kyoto Protocol, it allows a
Party with a GHG emission target to receive credits from other
Annex 1 Parties.
Kyoto Protocol
Protocol to the United Nations Framework Convention on
Climate Change, which was adopted at Kyoto on 11 December
1997.
Leach
To dissolve a substance from a solid.
Leakage
In respect of carbon trading, the change of anthropogenic
emissions by sources or removals by sinks which occurs
outside the project boundary.
Leakage
In respect of carbon storage, the escape of injected fluid from
storage.
Levellized cost
The future values of an input or product that would make the
NPV (q.v.) of a project equal to zero.
LHV
Lower heating value: energy released from the combustion of
a fuel that excludes the latent heat of water.
Lignite/sub-bituminous coal
Relatively young coal of low rank with a relatively high
hydrogen and oxygen content.
408 IPCC Special Report on Carbon dioxide Capture and Storage
Limestone
A sedimentary rock made mostly of the mineral calcite
(calcium carbonate), usually formed from shells of dead
organisms.
LNG
Liquefied natural gas
Lithology
Science of the nature and composition of rocks
Lithosphere
The outer layer of the Earth, made of solid rock, which
includes the crust and uppermost mantle up to 100 km thick.
Log
Records taken during or after the drilling of a well.
London Convention
On the Prevention of Marine Pollution by Dumping of Wastes
and Other Matter, which was adopted at London, Mexico City,
Moscow and Washington on 29 December 1972.
London Protocol
Protocol to the Convention adopted in London on 2 November
1996 but which had not entered into force at the time of
writing.
Low-carbon energy carrier
Fuel that provides low fuel-cycle-wide emissions of CO2, such
as methanol.
Macro-invertebrate
Small creature living in the seabed and subsoil, like
earthworms, snails and beetles.
Madrid Protocol
A protocol to the 11th Antarctic Treaty to provide for
Antarctica’s environmental protection.
Mafic
Term used for silicate minerals, magmas, and rocks, which are
relatively high in the heavier elements.
Magmatic activity
The flow of magma (lava).
Marginal cost
Additional cost that arises from the expansion of activity. For
example, emission reduction by one additional unit.
Maturation
The geological process of changing with time. For example,
the alteration of peat into lignite, then into sub-bituminous and
bituminous coal, and then into anthracite.
Mature sedimentary basins
Geological provinces formed by the deposition of particulate
matter under water when the deposits have matured into
hydrocarbon reserves.
MEA
Mono-ethanolamine
Medium-gravity oil
Oil with a density of between about 850 and 925kg/m3
(between 20 and 30 API).
Membrane
A sheet or block of material that selectively separates the
components of a fluid mixture.
Metamorphic
Of rocks that have been altered by heat or pressure.
Mica
Class of silicate minerals with internal plate structure.
Microseismicity
Small-scale seismic tremors.
Migration
The movement of fluids in reservoir rocks.
Mineral trap
A geological structure in which fluids are retained by the
reaction of the fluid to form a stable mineral.
Miscible displacement
Injection process that introduces miscible gases into the
reservoir, thereby maintaining reservoir pressure and
improving oil displacement.
Mitigation
The process of reducing the impact of any failure.
Monitoring
The process of measuring the quantity of carbon dioxide
stored and its location.
Monte Carlo
A modelling technique in which the statistical properties of
outcomes are tested by random inputs.
Mudstone
A very fine-grained sedimentary rock formed from mud.
MWh
Megawatt-hour
Annex II: Glossary, acronyms and abbreviations 409
National Greenhouse Gas Inventory
An inventory of anthropogenic emissions by sources and
removals by sinks of greenhouse gases prepared by Parties to
the UNFCCC.
Natural analogue
A natural occurrence that mirrors in most essential elements an
intended or actual human activity.
Natural underground trap
A geological structure in which fluids are retained by natural
processes.
Navier-Stokes equations
The general equations describing the flow of fluids.
Near-field
The region close to a signal source.
NGCC
Natural gas combined cycle: natural-gas-fired power plant
with gas and steam turbines.
Non-hazardous waste
Non-harmful substances that have been released or discarded
into the environment.
NPV
Net present value: the value of future cash flows discounted to
the present at a defined rate of interest.
Numerical approximation
Representation of physico-mathematical laws through linear
approximations.
Observation well
A well installed to permit the observation of subsurface
conditions.
OECD
Organization for Economic Co-operation and Development
OSPAR
Convention for the Protection of the Marine Environment of
the North-East Atlantic, which was adopted at Paris on 22
September 1992.
Outcrop
The point at which a particular stratum reaches the earth’s
surface.
Overburden
Rocks and sediments above any particular stratum.
Overpressure
Pressure created in a reservoir that exceeds the pressure
inherent at the reservoir’s depth.
Oxidation
The loss of one or more electrons by an atom, molecule, or
ion.
Oxyfuel combustion
Combustion of a fuel with pure oxygen or a mixture of
oxygen, water and carbon dioxide.
Packer
A device for sealing off a section of a borehole or part of a
borehole.
Partial oxidation
The oxidation of a carbon-containing fuel under conditions
that produce a large fraction of CO and hydrogen.
Partial pressure
The pressure that would be exerted by a particular gas in a
mixture of gases if the other gases were not present.
pCO2 The partial pressure (q.v.) of CO2.
PC
Pulverized coal: usually used in connection with boilers fed
with finely ground coal.
Pejus level
The level in the ocean below which the functioning of animals
deteriorates significantly.
Pelagic
Relating to, or occurring, or living in, or frequenting, the open
ocean.
Perfluorocarbon
Synthetically produced halocarbons containing only carbon
and fluorine atoms. They are characterized by extreme
stability, non-flammability, low toxicity and high global
warming potential.
Permeability
Ability to flow or transmit fluids through a porous solid such
as rock.
Permian
A geological age between 290 and 248 million years ago.
Phytotoxic
Poisonous to plants.
Piezo-electric transducer
Crystals or films that are able to convert mechanical energy in
electrical energy or vice-versa.
410 IPCC Special Report on Carbon dioxide Capture and Storage
Pig
A device that is driven down pipelines to inspect and/or clean
them.
Point source
An emission source that is confined to a single small location
Polygeneration
Production of more than one form of energy, for example
synthetic liquid fuels plus electricity.
Pore space
Space between rock or sediment grains that can contain fluids.
Poroelastic
Elastic behaviour of porous media.
Porosity
Measure for the amount of pore space in a rock.
Post-combustion capture
The capture of carbon dioxide after combustion.
POX
Partial oxidation (q.v.)
Pre-combustion capture
The capture of carbon dioxide following the processing of the
fuel before combustion.
Primary legal source
Legal source not depending on authority given by others.
Probability density function
Function that describes the probability for a series of
parameter values.
Prospectivity
A qualitative assessment of the likelihood that a suitable
storage location is present in a given area based on the
available information
Proven reserve
For oil declared by operator to be economical; for gas about
which a decision has been taken to proceed with development
and production; see Resource.
Province
An area with separate but similar geological formations.
PSA
Pressure swing adsorption: a method of separating gases
using the physical adsorption of one gas at high pressure and
releasing it at low pressure.
Rank
Quality criterion for coal.
Reduction
The gain of one or more electrons by an atom, molecule, or
ion
Reduction commitment
A commitment by a Party to the Kyoto Protocol to meet its
quantified emission limit.
Reforestation
Planting of forests on lands that have previously contained
forests but that have been converted to some other use.
Regional scale
A geological feature that crosses an entire basin.
Remediation
The process of correcting any source of failure.
Renewables
Energy sources that are inherently renewable such as solar
energy, hydropower, wind, and biomass.
Rep. Value
Representative value
Reproductive dysfunction
Inability to reproduce.
Reserve
A resource (q.v.) from which it is generally economic to
produce valuable minerals or hydrocarbons.
Reservoir
A subsurface body of rock with sufficient porosity and
permeability to store and transmit fluids.
Residual saturation
The fraction of the injected CO2 that is trapped in pores by
capillary forces.
Resource
A body of a potentially valuable mineral or hydrocarbon.
Retrofit
A modification of the existing equipment to upgrade and
incorporate changes after installation.
Risk assessment
Part of a risk-management system.
Root anoxia
Lack, or deficiency, of oxygen in root zone.
Root zone
Part of the soil in which plants have their roots.
Annex II: Glossary, acronyms and abbreviations 411
Safe Drinking Water Act
An Act of the US Congress originally passed in 1974. It
regulates, among other things, the possible contamination of
underground water.
Saline formation
Sediment or rock body containing brackish water or brine.
Saline groundwater
Groundwater in which salts are dissolved.
Sandstone
Sand that has turned into a rock due to geological processes.
Saturated zone
Part of the subsurface that is totally saturated with
groundwater.
Scenario
A plausible description of the future based on an internally
consistent set of assumptions about key relationships and
driving forces. Note that scenarios are neither predictions nor
forecasts.
SCR
Selective catalytic reduction
Scrubber
A gas-liquid contacting device for the purification of gases or
capture of a gaseous component.
Seabed
Borderline between the free water and the top of the bottom
sediment.
Seal
An impermeable rock that forms a barrier above and around a
reservoir such that fluids are held in the reservoir.
Secondary recovery
Recovery of oil by artificial means, after natural production
mechanisms like overpressure have ceased.
Sedimentary basin
Natural large-scale depression in the earth’s surface that is
filled with sediments.
Seismic profile
A two-dimensional seismic image of the subsurface.
Seismic technique
Measurement of the properties of rocks by the speed of sound
waves generated artificially or naturally.
Seismicity
The episodic occurrence of natural or man-induced
earthquakes.
Selexol
A commercial physical absorption process to remove CO2
using glycol dimethylethers.
Shale
Clay that has changed into a rock due to geological processes.
Shift convertor
A reactor in which the water-gas shift reaction, CO + H2O =
CO2 + H2, takes place.
Simplex orifice fitting
An apparatus for measuring the flow rate of gases or liquids.
Sink
The natural uptake of CO2 from the atmosphere, typically in
soils, forests or the oceans.
SMR
Steam methane reforming: a catalytic process in which
methane reacts with steam to produce a mixture of H2, CO and
CO2.
SNG
Synthetic natural gas: fuel gas with a high concentration of
methane produced from coal or heavy hydrocarbons.
SOFC
Solid oxide fuel cell: a fuel cell (q.v.) in which the electrolyte
is a solid ceramic composed of calcium- or yttrium-stabilized
zirconium oxides.
Soil gas
Gas contained in the space between soil grains
Solubility trapping
A process in which fluids are retained by dissolution in liquids
naturally present.
Sour gas
Natural gas containing significant quantities of acid gases like
H2S and CO2.
Source
Any process, activity or mechanism that releases a greenhouse
gas, an aerosol, or a precursor thereof into the atmosphere.
Speciation
The determination of the number of species into which a
single species will divide over time.
Spill point
The structurally lowest point in a structural trap (q.v.) that can
retain fluids lighter than background
fluids.
412 IPCC Special Report on Carbon dioxide Capture and Storage
Spoil pile
Heap of waste material derived from mining or processing
operations.
SRES
Special Report on Emissions Scenarios; used as a basis for the
climate projections in the TAR (q.v.).
Stabilization
Relating to the stabilization atmospheric concentrations of
greenhouse gases.
Stable geological formation
A formation (q.v.) that has not recently been disturbed by
tectonic movement.
Steam reforming
A catalytic process in which a hydrocarbon is reacted with
steam to produce a mixture of H2, CO and CO2.
Storage
A process for retaining captured CO2 so that it does not reach
the atmosphere.
Strain gauge
Gauge to determine the deformation of an object subjected to
stress.
Stratigraphic
The order and relative position of strata.
Stratigraphic column
A column showing the sequence of different strata.
Stratigraphic trap
A sealed geological container capable of retaining fluids,
formed by changes in rock type, structure or facies.
Stimulation
The enhancement of the ability to inject fluids into, or recover
fluids from, a well.
Stripper
A gas-liquid contacting device, in which a component is
transferred from liquid phase to the gas phase.
Structural trap
Geological structure capable of retaining hydrocarbons, sealed
structurally by a fault or fold.
Structure
Geological feature produced by the deformation of the Earth’s
crust, such as a fold or a fault; a feature within a rock such as a
fracture; or, more generally, the spatial arrangement of rocks.
Structure contour map
Map showing the contours of geological structures.
Subsoil
Term used in London and OSPAR conventions, meaning the
sediments below the seabed.
Sub-bituminous coal
Coal of a rank between lignite (q.v.) and bituminous (q.v.)
coal.
Sustainable
Of development, that which is sustainable in ecological, social
and economic areas.
Supercritical
At a temperature and pressure above the critical temperature
and pressure of the substance concerned. The critical point
represents the highest temperature and pressure at which the
substance can exist as a vapour and liquid in equilibrium
Syngas
Synthesis gas (q.v.)
Synthesis gas
A gas mixture containing a suitable proportion of CO and H2
for the synthesis of organic compounds or combustion.
Synfuel
Fuel, typically liquid fuel, produced by processing fossil fuel.
Tail gas
Effluent gas at the end of a process.
Tailing
The waste resulting from the extraction of value from ore.
TAR
Third Assessment Report of the Intergovernmental Panel on
Climate Change
TCR
Total capital requirement
Technical Potential
The amount by which it is possible to reduce greenhouse gas
emissions by implementing a technology or practice that has
reached the demonstration phase.
Tectonically active area
Area of the Earth where deformation is presently causing
structural changes.
Tertiary
Geological age about 65 to 2 million years ago.
Tertiary recovery
Oil generated by a third method; the first is by pressure release
or depletion, and the second by oil driven out by the injection
of water.
Annex II: Glossary, acronyms and abbreviations 413
Thermocline
The ocean phenomenon characterized by a sharp change in
temperature with depth.
Thermohaline
The vertical overturning of water masses due to seasonal
heating, evaporation, and cooling.
Top-down model
A model based on applying macro-economic theory and
econometric techniques to historical data about consumption,
prices, etc.
Toxemia
Poisoning, usually of the blood.
Toxicology
Scientific study of poisons and their effects.
Tracer
A chemical compound or isotope added in small quantities to
trace flow patterns.
Transaction cost
The full cost of transferring property or rights between parties.
Trap
A geological structure that physically retains fluids that are
lighter than the background fluids, e.g. an inverted cup.
Ultramafic rocks
An igneous rock consisting almost entirely of iron- and
magnesium-rich minerals with a silica content typically less
than 45%.
UNCLOS
United Nations Convention on the Law of the Sea, which was
adopted at Montego Bay on 10 December 1982.
Unconformity
A geological surface separating older from younger rocks and
representing a gap in the geological record.
Under-saturated
A solution that could contain more solute than is presently
dissolved in it.
UNFCCC
United Nations Framework Convention on Climate Change,
which was adopted at New York on 9 May 1992.
Unminable
Extremely unlikely to be mined under current or foreseeable
economic conditions
Updip
Inclining upwards following a structural contour of strata.
Upper ocean
The ocean above 1000m depth.
Vacuum residue
The heavy hydrocarbon mixture that is produced at the bottom
of vacuum distillation columns in oil refineries.
Vadose zone
Region from the water table to the ground surface, also called
the unsaturated zone because it is partially water-saturated.
Validation
In the context of CDM (q.v.), the process of the independent
evaluation of a project by a designated operational entity on
the basis of set requirements.
Ventilation
The exchange of gases dissolved in sea-water with the
atmosphere, or gas exchange between an animal and the
environment.
Verification
The proving, to a standard still to be decided, of the results
of monitoring (q.v.). In the context of CDM, the independent
review by a designated operational entity of monitored
reductions in anthropogenic emissions.
Viscous fingering
Flow phenomenon arising from the flow of two largely
immiscible fluids through a porous medium.
Well
Manmade hole drilled into the earth to produce liquids or
gases, or to allow the injection of fluids.
Well with multiple completions
Well drilled with multiple branching holes and more than one
hole being made ready for use.
Well-bore annulus
The annulus between the rock and the well casing.
Wellhead pressure
Pressure developed on surface at the top of the well.
Wettability
Surface with properties allowing water to contact the surface
intimately.
Zero-carbon energy carrier
Carbon-free energy carrier, typically electricity or hydrogen.