This report compiles and reviews published guidelines on the selection and management of a geological CO2Carbon dioxide storage(CO2) A process for retaining captured CO2, so that it does not reach the atmosphere site as constrained by the existing regulatory environments.
Storage(CO2) A process for retaining captured CO2, so that it does not reach the atmosphere site selection is the first step for CCSCarbon dioxide Capture and Storage to proceed to a full-chain technology solution to greenhouse gasGas in the atmosphere that absorbs and emits infrared radiation emitted by the Earth’s surface, the atmosphere, and clouds; thus, trapping heat within the surface-troposphere system. e.g. water vapour (H2O), carbon dioxide (CO2), nitrous oxide (N2O), methane (CH4), ozone (O3), sulfur hexafluoride (SF6), hydrofluorocarbons (HFCs), and perfluorocarbons (PFCs) emissions reductionThe gain of one or more electrons by an atom, molecule, or ion. Detailed characterisation and monitoringMeasurement and surveillance activities necessary for ensuring safe and reliable operation of a CGS project (storage integrity), and for estimating emission reductions of the site is required for ensuring and demonstrating safety and integrity of the storage(CO2) A process for retaining captured CO2, so that it does not reach the atmosphere project. In essence, a site selection process should demonstrate that the site has: sufficient capacity to accept the expected CO2Carbon dioxide volume, sufficient injectivityA measure of the rate at which a quantity of fluid can be injected into a well for the expected rate of CO2Carbon dioxide captureThe separation of carbon dioxide from other gases before it is emitted to the atmosphere and supply; and sufficient containmentRestriction of the movement of a fluid to a designated volume (e.g. reservoir) to store the injected CO2Carbon dioxide for the period of time required by the regulatory authority, so as not to pose unacceptable risks to the environment, human health or other uses of the subsurface.
This report considers a stepwise progression of studies through geological characterisation to flow and geomechanical modelling, and also includes environmental riskConcept that denotes the product of the probability of a hazard and the subsequent consequence of the associated event and economic assessments. Bibliographic coverage is also provided for the area of public awareness and acceptance.
Geological characterization of the site
Geological characterization requires a progressive approach from regional screening to successive refinement through data acquisition and modelling to produce capacity assessment and ranking, leading to selection of the optimal storage(CO2) A process for retaining captured CO2, so that it does not reach the atmosphere site for a CCSCarbon dioxide Capture and Storage project. The process must take account of legal and regulatory regimes, environmental constraints, and economic aspects pertaining to the site.
The biggest knowledge gaps and uncertainties generally exist for storage(CO2) A process for retaining captured CO2, so that it does not reach the atmosphere in saline aquifers, where often few data are available to evaluate the sites against principal screening criteria and drilling new, exploratory wells and acquiring new seismic and other geophysical surveys will be required. For depleted(hydrocarbon reservoir) one where production is significantly reduced hydrocarbon fields, many exploration and production data will be available to assist with an accurate storage(CO2) A process for retaining captured CO2, so that it does not reach the atmosphere assessment.
Conflicts of the use of subsurface must also be managed. There may be competing interests in natural gasGas stored underground; It consists largely of methane, but can also contain other hydrocarbons, water, hydrogen sulphide and carbon dioxide, these other substances are separated before the methane is put into a pipeline or tanker storage(CO2) A process for retaining captured CO2, so that it does not reach the atmosphere, geothermalConcerning heat flowing from deep in the earth energy or other uses of the same reservoirA subsurface body of rock with sufficient porosity and permeability to store and transmit fluids system.
Flow modelling
During site assessment and the pre-operational phase, simulation models are used to predict CO2 plumeDispersing volume of CO2-rich phase contained in target formation migrationThe movement of fluids in reservoir rocks and the effectiveness of solubility, residual gas (capillary) and mineral trapping(CO2) Containment or immobilisation of CO2, there are four main trapping mechanisms: structural or stratigraphic trapping; residual CO2 trapping (capillary trapping) by capillary forces; solubility trapping by dissolution of CO2 in resident formation fluids forming a non-buoyant fluid; and mineral trapping where CO2 is absorbed by solid minerals present in the storage volume. During operations, comparison between simulated and monitored plume migrationThe movement of fluids in reservoir rocks is used to refine and calibrate the model and update forecasts of plume migrationThe movement of fluids in reservoir rocks. This iterative approach is required to develop confidence in the prediction of plume behaviour. During the post-operational phase, a similar iterative approach is used to predict post-injectionThe process of using pressure to force fluids down wells plume behaviour - with a primary focus on quantifying the secondary trapping(CO2) Containment or immobilisation of CO2, there are four main trapping mechanisms: structural or stratigraphic trapping; residual CO2 trapping (capillary trapping) by capillary forces; solubility trapping by dissolution of CO2 in resident formation fluids forming a non-buoyant fluid; and mineral trapping where CO2 is absorbed by solid minerals present in the storage volume mechanisms that will eventually immobilise the CO2Carbon dioxide.
Several numerical modelling packages are available for flow modelling in CO2Carbon dioxide storage(CO2) A process for retaining captured CO2, so that it does not reach the atmosphere. The accuracy of flow models depends on the quality of the input parameters and their capability in handling the various flow and transport processes that control the spread of CO2Carbon dioxide in the storage(CO2) A process for retaining captured CO2, so that it does not reach the atmosphere medium: fluid flow in response to natural hydraulic gradients or pressure gradients created by the injectionThe process of using pressure to force fluids down wells process; buoyancyTendency of a fluid or solid to rise through a fluid of higher density; diffusion; and the various trapping(CO2) Containment or immobilisation of CO2, there are four main trapping mechanisms: structural or stratigraphic trapping; residual CO2 trapping (capillary trapping) by capillary forces; solubility trapping by dissolution of CO2 in resident formation fluids forming a non-buoyant fluid; and mineral trapping where CO2 is absorbed by solid minerals present in the storage volume mechanisms.
The results of flow modelling versus monitored plume migrationThe movement of fluids in reservoir rocks in several CO2Carbon dioxide storage(CO2) A process for retaining captured CO2, so that it does not reach the atmosphere projects and injectionThe process of using pressure to force fluids down wells pilot studies have been reviewed.
Reactive flow modelling
Reactive flow modelling combines hydrodynamic modelling and geochemical modelling to provide a complete calculation over time of the amount of CO2Carbon dioxide trapped through a combination of structural, dissolution or mineral trapping(CO2) Containment or immobilisation of CO2, there are four main trapping mechanisms: structural or stratigraphic trapping; residual CO2 trapping (capillary trapping) by capillary forces; solubility trapping by dissolution of CO2 in resident formation fluids forming a non-buoyant fluid; and mineral trapping where CO2 is absorbed by solid minerals present in the storage volume. The storage(CO2) A process for retaining captured CO2, so that it does not reach the atmosphere site can be modelled through its different operational phases: pre-injectionThe process of using pressure to force fluids down wells, injectionThe process of using pressure to force fluids down wells and post-injectionThe process of using pressure to force fluids down wells, to assess the geochemical impact of CO2Carbon dioxide on injectivityA measure of the rate at which a quantity of fluid can be injected into a well and long-term integrity of the site. The uncertainties affecting the modelled results are strongly influenced by the chemical parameters such as the mineral phases, their kinetics and the reactive surface area. One should, therefore, carefully select the codes for modelling with reference to the specific conditions in the selected site (see, for example, results from the Sleipner site as discussed by Gaus et al., 20082008 - I. Gaus, P. Audigane, L. André, J. Lions, N. Jacquemet, P. Durst, I. Czernichowski-Lauriol and M. AzaroualGeochemical and solute transport modelling for CO2 storage, what to expect from it?see more).
Coupled geomechanical and flow modelling
InjectionThe process of using pressure to force fluids down wells of a large volume of fluid in the subsurface over a period of time can have geomechanical effects. Changes in pore pressure during injectionThe process of using pressure to force fluids down wells will change the effective stress and cause rock to deform. If the injectionThe process of using pressure to force fluids down wells-induced pressure increase is too large, shear slip or tensile opening of pre-existing faults in the storage(CO2) A process for retaining captured CO2, so that it does not reach the atmosphere reservoirA subsurface body of rock with sufficient porosity and permeability to store and transmit fluids/caprockRock of very low permeability that acts as an upper seal to prevent fluid flow out of a reservoir may occur, and a previously sealing fault(geology) A surface at which strata are no longer continuous, but are found displaced may become conductive, leading to leakage(in CO2 storage) The escape of injected fluid from the storage formation to the atmosphere or water column. Induced shear-stress changes may also induce micro-seismicityThe episodic occurrence of natural or man-induced earthquakes and even earthquakes of moderate local magnitudes. Different situations will pertain to injectionThe process of using pressure to force fluids down wells into a depleted(hydrocarbon reservoir) one where production is significantly reduced, underpressured hydrocarbon reservoirA subsurface body of rock with sufficient porosity and permeability to store and transmit fluids and a previously undisturbed saline aquiferAn underground layer of fluid-bearing permeable rock or unconsolidated materials (gravel, sand, or silt) with significant permeability to allow flow.
Geomechanical data, such as the elastic properties of the storage(CO2) A process for retaining captured CO2, so that it does not reach the atmosphere formationA body of rock of considerable extent with distinctive characteristics that allow geologists to map, describe, and name it and caprockRock of very low permeability that acts as an upper seal to prevent fluid flow out of a reservoir, pre-existing fault(geology) A surface at which strata are no longer continuous, but are found displaced strength properties, and in situ stress state need to be included in coupled geomechanical-fluid flow numerical models for rigorous CO2Carbon dioxide storage(CO2) A process for retaining captured CO2, so that it does not reach the atmosphere evaluation and riskConcept that denotes the product of the probability of a hazard and the subsequent consequence of the associated event during site characterisation. The interplay of geochemical and geomechanical processes within the reservoirA subsurface body of rock with sufficient porosity and permeability to store and transmit fluids and the caprockRock of very low permeability that acts as an upper seal to prevent fluid flow out of a reservoir can strongly influence storage(CO2) A process for retaining captured CO2, so that it does not reach the atmosphere containmentRestriction of the movement of a fluid to a designated volume (e.g. reservoir), capacity and the CO2 plumeDispersing volume of CO2-rich phase contained in target formation distribution. The coupling of geomechanical codes with flow-transport codes for numerical modelling remains a challenge fully; coupled thermal-hydraulic-chemical-mechanical codes are still in the development stage. Examples of coupled simulations using different codes and their results at specific sites are reviewed in Chapter 5.
Environmental impact and riskConcept that denotes the product of the probability of a hazard and the subsequent consequence of the associated event
It may be stated that the overriding global riskConcept that denotes the product of the probability of a hazard and the subsequent consequence of the associated event is that without geological storage(CO2) A process for retaining captured CO2, so that it does not reach the atmosphere of CO2Carbon dioxide, emissions will continue to reach the atmosphereThe layer of gases surrounding the earth; the gases are mainly nitrogen (78%) and oxygen (around 21%) and contribute significantly to climate change.
Risks from geological storage(CO2) A process for retaining captured CO2, so that it does not reach the atmosphere of CO2Carbon dioxide primarily result from the consequences of unintended leakage(in CO2 storage) The escape of injected fluid from the storage formation to the atmosphere or water column from the storage(CO2) A process for retaining captured CO2, so that it does not reach the atmosphere formationA body of rock of considerable extent with distinctive characteristics that allow geologists to map, describe, and name it. Leakage(in CO2 storage) The escape of injected fluid from the storage formation to the atmosphere or water column can range between short-term potentially large leakages (injectionThe process of using pressure to force fluids down wells wellManmade hole drilled into the earth to produce liquids or gases, or to allow the injection of fluids failures or leakage(in CO2 storage) The escape of injected fluid from the storage formation to the atmosphere or water column up abandoned wells) and long-term, more diffuse leakages through undetected faults, fractures or through leaking wells. Potential risks can also be distinguished between onshore and offshore storage(CO2) A process for retaining captured CO2, so that it does not reach the atmosphere settings. Hazards to humans, ecosystems and groundwater include: elevated gas-phase CO2Carbon dioxide concentrations in the shallow subsurface and near-surface environment effecting humans and other living organisms; acidification of soils and displacement of oxygen in soils; undetected accumulations of CO2Carbon dioxide-supersaturated water or gaseous CO2Carbon dioxide in shallow traps that might be a riskConcept that denotes the product of the probability of a hazard and the subsequent consequence of the associated event for future drilling; possible groundwater contamination both from CO2Carbon dioxide leaking directly into an aquiferAn underground layer of fluid-bearing permeable rock or unconsolidated materials (gravel, sand, or silt) with significant permeability to allow flow or displaced brines entering the aquiferAn underground layer of fluid-bearing permeable rock or unconsolidated materials (gravel, sand, or silt) with significant permeability to allow flow during the injectionThe process of using pressure to force fluids down wells process.
Other risks arise from CO2Carbon dioxide injectionThe process of using pressure to force fluids down wells into the deep subsurface, including fault(geology) A surface at which strata are no longer continuous, but are found displaced activation and induced microseismicitySmall-scale seismic tremors, changes in the geomechanical stress field and vertical uplift above large reservoirs, and surface geotechnical effects caused by unexpected migrationThe movement of fluids in reservoir rocks of CO2Carbon dioxide or water through faults and fractures.
RiskConcept that denotes the product of the probability of a hazard and the subsequent consequence of the associated event for CO2Carbon dioxide storage(CO2Carbon dioxide) A process for retaining captured CO2Carbon dioxide, so that it does not reach the atmosphereThe layer of gases surrounding the earth; the gases are mainly nitrogen (78%) and oxygen (around 21%) is the process that examines and evaluates the potential for adverse health, safety and environmental effects on human health, the environment, and potentially other receptors resulting from CO2Carbon dioxide exposure and leakage(in CO2Carbon dioxide storage) The escape of injected fluid from the storage formationA body of rock of considerable extent with distinctive characteristics that allow geologists to map, describe, and name it to the atmosphereThe layer of gases surrounding the earth; the gases are mainly nitrogen (78%) and oxygen (around 21%) or water column of injected or displaced fluids via wells, faults, fractures, and seismic events. The identification of potential leakage(in CO2 storage) The escape of injected fluid from the storage formation to the atmosphere or water column pathways is integrated with a MMV (Measurement, MonitoringMeasurement and surveillance activities necessary for ensuring safe and reliable operation of a CGS project (storage integrity), and for estimating emission reductions and Verification(CO2 storage) The proof, to a standard still to be decided, of the CO2 storage using monitoring results; (in the context of CDM) The independent review by a designated operational entity of monitored reductions in anthropogenic emissions) plan. RiskConcept that denotes the product of the probability of a hazard and the subsequent consequence of the associated event is used to ensure the safety and acceptability of geological storage(CO2) A process for retaining captured CO2, so that it does not reach the atmosphere and it involves determining both the consequences and likelihood of an event. RiskConcept that denotes the product of the probability of a hazard and the subsequent consequence of the associated event mitigationThe process of reducing the impact of any failure is the planning for and implementationof contingency plans, should the need arise, to remediate adverseimpacts. A good monitoringMeasurement and surveillance activities necessary for ensuring safe and reliable operation of a CGS project (storage integrity), and for estimating emission reductions and mitigationThe process of reducing the impact of any failure plan will decrease the riskConcept that denotes the product of the probability of a hazard and the subsequent consequence of the associated event and uncertainty associated with many potential consequences.
Many of the ongoing riskConcept that denotes the product of the probability of a hazard and the subsequent consequence of the associated event efforts are cooperating to identify, classify and screen all factors that may influence the safety of storage(CO2) A process for retaining captured CO2, so that it does not reach the atmosphere facilities, using the Features, Events and Processes (FEP) methodology. Because the future evolution of a geologic system cannot be precisely determined, various possible scenarios for possible evolutions of the system and situations of particular interest are developed. Most riskConcept that denotes the product of the probability of a hazard and the subsequent consequence of the associated event assessments involve the use of scenarios that describe possible future states of the storage(CO2Carbon dioxide) A process for retaining captured CO2Carbon dioxide, so that it does not reach the atmosphereThe layer of gases surrounding the earth; the gases are mainly nitrogen (78%) and oxygen (around 21%) facility and events that result in leakage(in CO2Carbon dioxide storage) The escape of injected fluid from the storage formationA body of rock of considerable extent with distinctive characteristics that allow geologists to map, describe, and name it to the atmosphereThe layer of gases surrounding the earth; the gases are mainly nitrogen (78%) and oxygen (around 21%) or water column of CO2Carbon dioxide or other risks. The FEP assessment methodology is useful but still has gaps in knowledge and there is some discussion as to whether a 'bottom-up' (identifying every conceivable FEP and then building scenarios from these) or 'top-down' (identifying a limited number of key riskConcept that denotes the product of the probability of a hazard and the subsequent consequence of the associated event Scenarios and developing a limited FEP listing from these) approach is best.
In the evaluation of consequences versus environmental criteria, the criteria must correspond to amounts or concentrations that are measurable and acceptable levels and limit values must therefore be determined.
Economic analysis
According to the ZEPEuropean Technology Platform for Zero Emission Fossil Fuel Power Plants report "The Costs of CO2Carbon dioxide CaptureThe separation of carbon dioxide from other gases before it is emitted to the atmosphereThe layer of gases surrounding the earth; the gases are mainly nitrogen (78%) and oxygen (around 21%), Transport and Storage(CO2Carbon dioxide) A process for retaining captured CO2Carbon dioxide, so that it does not reach the atmosphereThe layer of gases surrounding the earth; the gases are mainly nitrogen (78%) and oxygen (around 21%): Post-demonstration CCSCarbon dioxide CaptureThe separation of carbon dioxide from other gases before it is emitted to the atmosphereThe layer of gases surrounding the earth; the gases are mainly nitrogen (78%) and oxygen (around 21%) and Storage in the EUEuropean Union", the cost of CO2Carbon dioxide storage(CO2) A process for retaining captured CO2, so that it does not reach the atmosphere will range from €1 to €7 per tonne CO2Carbon dioxide stored for a depleted(hydrocarbon reservoir) one where production is significantly reduced oil or gas field with re-usable wells to €6 to €20 per tonne CO2Carbon dioxide stored for offshore saline aquifers. Uncertainty ranges within each case are due to the natural variability of the storage(CO2) A process for retaining captured CO2, so that it does not reach the atmosphere-limiting parameters, reservoirA subsurface body of rock with sufficient porosity and permeability to store and transmit fluids capacity and injectivityA measure of the rate at which a quantity of fluid can be injected into a well, and structural factors such as site location, level of existing data and availability of re-usable infrastructure and wells. Costs will be higher for smaller and poorer quality reservoirs, for offshore sites, and where significant data collection or infrastructural development is required. The effect of the learning rate was found to be negligible (implying that existing knowledge can anticipate the technological issues involved).
Cost sensitivity analysis reveals that the top two factors for all cases are storage capacityThe accumulated mass of CO2 that can be stored environmentally safely, i.e., without causing leakage of CO2 or native reservoir fluids or triggering geologic activity that has a negative impact on human health or the environment and injectivityA measure of the rate at which a quantity of fluid can be injected into a well. Therefore, exploration and reservoirA subsurface body of rock with sufficient porosity and permeability to store and transmit fluids characterisationare vital activities for CO2Carbon dioxide storage(CO2) A process for retaining captured CO2, so that it does not reach the atmosphere as they allow selection of a storage(CO2) A process for retaining captured CO2, so that it does not reach the atmosphere reservoirA subsurface body of rock with sufficient porosity and permeability to store and transmit fluids with lowest storage(CO2) A process for retaining captured CO2, so that it does not reach the atmosphere costs. Capacity is of particular importance in the case of offshore saline aquifers, where the use of larger reservoirs results in considerably lower costs than for smaller ones (economy of scale benefit). WellManmade hole drilled into the earth to produce liquids or gases, or to allow the injection of fluids capacity is the top second contributor to variations of cost for onshore cases and thus the design and placement of wells is a basic activity for such cases. WellManmade hole drilled into the earth to produce liquids or gases, or to allow the injection of fluids completion(well) Refers to the cementing and perforating of casing and stimulation to connect a well bore to reservoir costs are the succeeding most important factor for offshore cases, highlighting the specificities of that offshore environment. The assumed cost of liability is equal for all cases when reported per tonne of CO2Carbon dioxide stored. Therefore its relative weight is the largest for cases where the total cost of storage(CO2) A process for retaining captured CO2, so that it does not reach the atmosphere per CO2Carbon dioxide tonne stored is the smallest (probably onshore).
Regarding demonstration projects, the ZEPEuropean Technology Platform for Zero Emission Fossil Fuel Power Plants study concludes that it is very likely that the costs per tonne of CO2Carbon dioxide stored will be significantly higher than those of projects in the early commercial phase.This should be taken into account when financing demonstration projects and when comparing the actual costs of demonstration projects with those of early commercial projects.