Numerically Simulating the Carbonate Mineralization of Basalt with the Injection of Supercritical Carbon Dioxide in Deep Saline Aquifers

The principal mechanisms for the geologic sequestration of carbon dioxide in deep saline formations include geological structural trapping, hydrological entrapment of nonwetting fluids, aqueous phase dissolution and ionization, and geochemical sorption and mineralization. In sedimentary saline formations the dominant mechanisms are structural and dissolution trapping, with moderate to weak contributions from hydrological and geochemical trapping; where, hydrological trapping occurs during the imbibition of aqueous solution into pore spaces occupied by gaseous carbon dioxide, and geochemical trapping is controlled by generally slow reaction kinetics. In addition to being globally abundant and vast, deep basaltic lava formations offer mineralization kinetics that make geochemical trapping a dominate mechanism for trapping carbon dioxide in these formations. For several decades the United States Department of Energy has been investigating Columbia River basalt in the Pacific Northwest as part of its environmental programs and options for natural gas storage. Recently this nonpotable and extensively characterized basalt formation is being reconsidered as a potential reservoir for geologic sequestration of carbon dioxide. The reservoir has an estimated storage capacity of 100 giga tonnes of carbon dioxide and comprises layered basalt flows with sublayering that generally alternates between low permeability massive and high permeability breccia. Chemical analysis of themore » formation shows 10 wt% Fe, primarily in the +2 valence. The mineralization reaction that makes basalt formations attractive for carbon dioxide sequestration is that of calcium, magnesium, and iron silicates reacting with dissolved carbon dioxide, producing carbonate minerals and amorphous quartz. Preliminary estimates of the kinetics of the silicate-to-carbonate reactions have been determined experimentally and this research is continuing to determine effects of temperature, pressure, rock composition and mineral assemblages on the reaction rates. This study numerically investigates the injection, migration and sequestration of supercritical carbon dioxide in deep Columbia River basalt formations using the multifluid subsurface flow and reactive transport simulator STOMP-CO2 with its ECKEChem module. Simulations are executed on high resolution multiple stochastic realizations of the layered basalt systems and demonstrate the migration behavior through layered basalt formations and the mineralization of dissolved carbon dioxide. Reported results include images of the migration behavior, distribution of carbonate formation, quantities of injected and sequestered carbon dioxide, and percentages of the carbon dioxide sequestered by different mechanisms over time.« less

Geological sequestration of carbon dioxide in deep saline aquifers: coupled flow-mechanical considerations

Water and carbon dioxide in basaltic magmas

Chemical Controls on the Dissolution Kinetics of Calcite in Seawater

Storage of carbon dioxide (CO2) by precipitation of carbon-bearing minerals in geological formations is, on the long run, more stable and therefore much safer than direct storage or solution trapping. Among available options for CO2 sequestration that are particularly attractive are those that offer additional economic benefits apart from the primary positive effect for the atmosphere (e.g., enhanced gas or oil recovery), such as the novel approach of storing dissolved CO2 as calcite in managed geothermal aquifers. Hydrogeothermal energy in Germany is mainly provided from deep sandstone aquifers by a so-called doublet installation consisting of one well for hot water production and one well for injection of the cooled water. When cold brines are enriched with CO2 and injected into an anhydrite-bearing reservoir, this mineral dissolves. As a result, the water becomes enriched in calcium ions. Numerical simulations demonstrate that dissolved Ca and CO2 react to form and precipitate calcium carbonate provided that alkaline buffering capacity is supplied from plagioclase in the reservoir rock or by surface water treatment with fly ashes. We show that anhydrite dissolution with the concurrent pore-space increase is important to balance pore-space reduction by precipitation of calcite and secondary silicates. Laboratory experiments prove the feasibility of transforming anhydrite into calcite and provide necessary kinetic input data for the modeling. Suitable geothermal reservoirs exist, which contain sufficient anhydrite as matrix mineral and plagioclase for supplying alkalinity. Mass balance calculations performed with respect to the anhydrite and feldspar content show that, for an assumed operation time of 30 yr, the theoretical storage capacity is significant: millions of tons of CO2 can be trapped as calcite in geological formations used by geothermal heating plants.

Costs for carbon dioxide sequestration into deep saline aquifers can be transformed into a benefit when combined with ecologically desirable geothermal heat or power production. The produced energy can be used and marketed. Aim is a scientifically and technically feasible new technology to achieve a safe and economically attractive long-term storage of CO2 trapped in minerals. We develop, study, and evaluate a novel approach not only to sequester CO2 by physical trapping within a reservoir, but to convert dissolved CO2 into the geochemically more stable form of calcite. Due to the geological situation exploitation of geothermal energy in Germany is mainly provided from deep aquifers. The common arrangement of bore holes is the well doublet, consisting of one well for hot water production and one well for cooled water re-injection. The cooled water is loaded with dissolved CO2, and after re-injection into the reservoir this cold water becomes enriched in calcium e.g. due to dissolution of anhydrite (CaSO4). Subsequently CO2 precipitates as calcium carbonate (CaCO3), provided that alkalinity is present either by the dissolution of feldspars in the aquifer or by surface water treatment with fly ashes. Processes are studied both in laboratory and by numerical simulations. The latter are essential to quantify the entire process of CO2 storage and to deepen the understanding of the detailed chemical processes. Reaction modelling and reactive transport simulations are done on multiple scales since the combination of all scales is not feasible in numerical models up to now. The relevant scales studying CO2 storage in combination with geothermal energy production reach down from the reservoir scale (ca. 10 km) to the micro scale (ca. 1 cm). Results from larger scale models provide constraints for smaller scale scenarios. For processes which cannot be resolved on the larger scale, due to restrictions of discretization of the applied numerical mesh, functionalities are derived from the smaller scale. To be predictive and capable of quantifying amounts of storable CO2 numerical investigations on the reservoir scale are vital. Simulations on the borehole scale are necessary, because the near vicinity of wells is vulnerable to permeability decrease as a result of mineral reactions. Laboratory experiments are used to calibrate the numerical tools and simulations on the micro scale allow further investigation of the overall process of mineral dissolution and precipitation. Simulation results as well as laboratory experiments prove that anhydrite can be successfully transferred into calcite and thus are evidence for the feasibility of the new technology.

The geologic formations, which can be utilized for CO 2 storage include: deep saline aquifers, oil and gas reservoirs and coal bed reservoirs. The fluids in the subsurface fill the porous rock as occurs with water, oil, natural gas, carbon dioxide, among others. In these formations, carbon dioxide is stored by different trapping mechanisms; the exact mechanism depends on the type of rock. The main mechanisms are: hydrodynamic trapping, solubility trapping and mineral trapping. Among the geologic formations, oil reservoirs are strong candidates to be used in the reduction of carbon dioxide in the atmosphere due to the technological knowledge acquired by the oil industry. These reservoirs are proved geologic traps with capacity to retain fluids and gases for long term. The CO 2 injection technique for enhanced recovery is a common practice in the oil industry and it can be used in carbon sequestration. The storage of some part of the injected gas in reservoirs submitted to Enhanced Oil Recovery operations is a direct consequence of CO 2 utilization since the gas produced with the oil be captured and re-injected in the reservoir. This work presents a global dynamic model of the carbon sequestration process in enhanced oil recovery operations in a typical mature oil reservoir aiming to quantify the real contribution of the stored gas.

Study of reservoir rock and caprock integrity in geo-sequestration of carbon dioxide

This paper summarizes the results of an investigation on carbon dioxide (CO2) sequestration in concrete. Carbon dioxide (CO 2 ) is the predominant greenhouse gas resulting from human industrial Activities. A significant fraction of CO 2 discharged into the atmosphere comes from Industry point sources. Cement production alone contributes approximately 5% of global CO 2 emissions. This emitted carbon dioxide, however, can be partially recycled into concretes through early age curing to form thermodynamically stable calcium carbonates. The carbonation reaction between carbon dioxide and appropriate calcium Compounds results in permanent fixation of the carbon dioxide in a thermodynamically stable calcium carbonate. Carbon dioxide and water can be found in almost every environment and thus all concretes will be subjected to carbonation. This paper summarizes a recent study on optimization of concrete and the flue gas carbon dioxide collected from cement kiln can be beneficially utilized in concrete production to reduce carbon emission, accelerate early strength, and improve durability of the products. Cement industry contributes to 5% of global CO2 emissions. To mitigate pollution, there is a need of CO2 sequestration into stable forms. Present research focusses on CO2 being channelized towards an important construction practice. This paper summarizes the potential of CO2 absorption in concrete. In reference to cement content, carbon uptake in 4-hour carbonation reaches 28 days strength achieved by conventional curing method.

Hydrothermal fluids are a fundamental resource for understanding and monitoring volcanic and non-volcanic systems. This thesis is focused on the study of hydrothermal system through numerical modeling with the geothermal simulator TOUGH2. Several simulations are presented, and geophysical and geochemical observables, arising from fluids circulation, are analyzed in detail throughout the thesis. In a volcanic setting, fluids feeding fumaroles and hot spring may play a key role in the hazard evaluation. The evolution of the fluids circulation is caused by a strong interaction between magmatic and hydrothermal systems. A simultaneous analysis of different geophysical and geochemical observables is a sound approach for interpreting monitored data and to infer a consistent conceptual model. Analyzed observables are ground displacement, gravity changes, electrical conductivity, amount, composition and temperature of the emitted gases at surface, and extent of degassing area. Results highlight the different temporal response of the considered observables, as well as the different radial pattern of variation. However, magnitude, temporal response and radial pattern of these signals depend not only on the evolution of fluid circulation, but a main role is played by the considered rock properties. Numerical simulations highlight differences that arise from the assumption of different permeabilities, for both homogeneous and heterogeneous systems. Rock properties affect hydrothermal fluid circulation, controlling both the range of variation and the temporal evolution of the observable signals. Low temperature fumaroles and low discharge rate may be affected by atmospheric conditions. Detailed parametric simulations were performed, aimed to understand the effects of system properties, such as permeability and gas reservoir overpressure, on diffuse degassing when air temperature and barometric pressure changes are applied to the ground surface. Hydrothermal circulation, however, is not only a characteristic of volcanic system. Hot fluids may be involved in several mankind problems, such as studies on geothermal engineering, nuclear waste propagation in porous medium, and Geological Carbon Sequestration (GCS). The current concept for large-scale GCS is the direct injection of supercritical carbon dioxide into deep geological formations which typically contain brine. Upward displacement of such brine from deep reservoirs driven by pressure increases resulting from carbon dioxide injection may occur through abandoned wells, permeable faults or permeable channels. Brine intrusion into aquifers may degrade groundwater resources. Numerical results show that pressure rise drives dense water up to the conduits, and does not necessarily result in continuous flow. Rather, overpressure leads to new hydrostatic equilibrium if fluids are initially density stratified. If warm and salty fluid does not cool passing through the conduit, an oscillatory solution is then possible. Parameter studies delineate steady-state (static) and oscillatory solutions.

Inorganic carbon dynamics in coastal marine systems

In Victoria, brown coal combustion is the single largest source for energy, meeting greater than 85% of the electricity needs. However this produces approximately 1.3 million tonnes of fly ash annually, which is predominantly dumped into ash ponds. The brown coal fly ash is rich in alkali and alkaline earth metals and transition metals with little aluminium and silicon. Industrial wastes such as fly ash are being considered for CO₂ mineralisation as part of the strategy for carbon dioxide capture, storage and utilisation (CCSU). This process also converts the valueless wastes, into value-added products such as magnesium carbonate and calcium carbonate to replace dolomite in industrial applications. A cost-effective carbon capture process is fundamental for the sustainability of brown coal in the carbon-constrained future. With the continuous increase in the amount of fly ash generated, there is an increasing demand in the use of vast land for landfill, which simultaneously contaminates soil, ground and water. To date, the majority of studies on fly ash utilisation have focused on direct route (single stage leaching and carbonation in the same reactor) under high CO₂ partial pressure with a long reaction time. However, there are a limited number of studies on utilisation of brown coal fly ash through the indirect mineral carbonation route, i.e. using separate leaching and carbonation steps. The scope of this thesis includes, firstly establishing a closed-loop multi-step leaching-carbonation process using regenerative ammonium chloride as the leaching reagent. This process allows efficient extraction of magnesium and calcium from Victorian brown coal fly ash under relatively mild operating condition (

The work described in this Thesis has been carried out within the Erasmus Mundus framework for Sustainable Industrial Chemistry (SINCHEM). The work concentrates on the possible utilisation of carbon dioxide as a solvent and as a starting material. Chapter 1 introduces carbon dioxide and its utilisation. In addition, the 12 Principles of CO2 Chemistry are presented, as well as continuous flow chemistry and self-optimising reactors. The relevant aspects of these reactors are discussed further in Chapter 2. The results of the research are presented in Chapters 3-6. A self-optimising reactor with FT-IR analysis was employed for the methylation of alcohols as explained in Chapter 3. Chapters 4-6 concentrate on N-alkylation reactions. In Chapter 4, the reactivity between aniline, tetrahydrofuran and dimethyl carbonate in supercritical carbon dioxide is discussed. This research led to the discovery of novel transformations. In Chapters 5 and 6, methanol was employed to methylate amines. A ruthenium triphosphate catalyst, which can produce methanol from carbon dioxide and hydrogen, was used to catalyse the reactions between methanol and aliphatic amines, as described in Chapter 5. Also the cyclisation and subsequent methylation of amino alcohols was studied. This reactivity is also the topic of Chapter 6, where γ-alumina was used as catalyst and supercritical carbon dioxide as solvent. Finally, Chapter 7 summarises the work described in this Thesis and evaluates the progress made towards achieving the aims that are introduced at the end of Chapter 1. One of these aims is to evaluate the work carried out in this Thesis according to the 12 principles of CO2 Chemistry. This evaluation is shown in Chapter 7.

CO2 geo-sequestration (CGS) is considered to be a feasible technology for reducing the amount of CO2 emission into the atmosphere. Selection of an appropriate reservoir is vital and requires appropriate knowledge of the involved phenomena and processes. In a CO2 geo-sequestration process, carbon dioxide goes through mainly four storage (trapping) mechanisms: structural and stratigraphic trapping, residual trapping, solubility trapping and mineral trapping. In this study, focus is placed on modeling the first trapping mechanism, together with corresponding deformation and electrokinetic flow. Multiphase fluid flow due to injection of CO2 in an unsaturated reservoir is accompanied by continuous redistribution of pore pressure and effective stress, causing local and regional deformations and probably major uplifting or subsidence. This flow is also accompanied by electrokinetic flow. In such a system, electrokinetic potentials occur due to the interaction between the formation fluid and the mineral grains. Due to pressure gradients, the flow of the pore fluid produces an advective electric current: such a flow generates an electric field, which produces a counter electric current through the interface, known as the self-potential (SP). Since the electrical conductivity of CO2 is lower than that of the formation brine, it can be detected by measuring the self-potential. Based on this, the SP can be used for monitoring CO2 plume movement, a necessary procedure to ensure that geologic sequestration is both safe and effective. In spite of the versatility of the available numerical tools, attempts to model CO2 geo-sequestration in a region and considering events occurring in local areas lead to enormous demands for computational power. This makes the development of numerical tools for CO2 geo-sequestration not only difficult, but rather expensive. In this study, the governing field equations are derived based on the averaging theory and solved numerically based on a mixed discretization scheme. In this scheme, variables exhibiting different nature are treated using different numerical discretization techniques. Techniques such as the standard Galerkin finite element method (SG), the extended finite element method (XFEM), the level-set method (LS) and the Petrov-Galerkin method (PG) are integrated in a single numerical scheme. SG is utilized to discretize the deformation and the diffusive dominant field equations, and XFEM, together with LS, are utilized to discretize the advective dominant field equations. The level-set method is employed to trace and locate the CO2 plume front, and the XFEM is employed to model the associated high gradient in the saturation field front. The use of XFEM for the advective field leads to a computationally efficient, stable and effectively mesh-independent discretization. However, it gives rise to an extra degree of freedom. The use of SG for the deformation and the diffusive fields requires only standard degrees of freedom, limiting the total number of degrees of freedom and making the scheme computationally efficient. Several verification and numerical examples are presented for both homogenous and fractured reservoirs. The examples demonstrate the capability of the proposed mixed discretization model to simulate challenging, coupled analyses. It has been shown that this model is capable of solving problems, which typically involve several state variables with different transient nature, using relatively coarse meshes.

In 2002, the Japanese Ministry of Economy, Trade, and Industry began a 6-yr project on carbon dioxide (CO2) sequestration in coal seams entitled Japan CO2 Geosequestration in Coal Seams Project (JCOP), a component of the Carbon Dioxide Sequestration and Effective Use Program. The goal of JCOP is to develop a series of processes that can (1) extract the CO2 discharged from thermal power plants and other large-scale emitters, (2) fix it in a stable state within coal seams, and in the process (3) recover methane (CH4) as a clean energy source. The project involves fundamental research into CO2 adsorption on coal, CO2 monitoring methods that ensure the safety of the sequestration process, and micropilot tests. From analyses of JCOP results obtained to date, several outcomes can be highlighted. (1) A total of 461 t of CO2 was injected at an average rate of 3.0 tons/day. (2) Carbon dioxide breakthrough has not yet been observed. (3) An enhanced coalbed methane effect was observed. (4) Coal-seam permeability changed dynamically because of coal-matrix swelling or shrinkage. (5) Nitrogen (N2) injection was effective in recovering the lost injectivity associated with coal swelling. (6) A history-matched model was constructed for the micropilot tests based on coal properties determined in situ or with laboratory measurements. (7) No signs of CO2 leakage have been observed so far.