Insights into silicate carbonation processes in water-bearing supercritical CO2 fluids (original) (raw)
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Greenhouse Gases: Science and Technology, 2014
Field tests have clearly demonstrated that injecting CO 2 in geological storage sites results in the release of heavy metals and organic species to groundwater, implying that CO 2 injection may have potentially dramatic consequences for the environment. Numerous laboratory experiments using rock and cement samples from different geological formations typical of injection sites show that rocks reacting with synthetic or natural fl uids and supercritical CO 2 at their respective temperature and pressure conditions generate fl uids with As, Cr, Cu, Cd, Pb, Fe, and Mn concentrations above Environmental Protection Agency drinking water standards. The solubility of a compound in supercritical-CO 2 (sc-CO 2 ), expressed in terms of the compound's activity or fugacity, also depends on the composition of the phases present at the pressure and temperature of the storage site. In a brine sc-CO 2 system, estimating the activity of an inorganic compound or the fugacity of an organic compound is a prerequisite to predicting the solubility of a compound in sc-CO 2 phases. Available models (e.g. Pitzer equations) require the use of binary salt concentrations and are best applicable to polar ionic compounds; but the effect of brines on larger hydrocarbons has not yet been explored. New experimental data will be needed to determine the magnitude of pH effects on the partitioning behavior of organic acids and trace metal complexes from brine to sc-CO 2 .
Energy Conversion and Management, 2013
Carbon dioxide injection in porous reservoirs is the basis for carbon capture and storage, enhanced oil and gas recovery. Injected carbon dioxide is stored at multiple scales in porous media, from the pore-level as a residual phase to large scales as macroscopic accumulations by the injection site, under the caprock and at reservoir internal capillary pressure barriers. These carbon dioxide saturation zones create regions across which the full spectrum of mutual CO 2-H 2 O solubility may occur. Most studies assume that geochemical reaction is restricted to rocks and carbon dioxide-saturated formation waters, but this paradigm ignores injection of anhydrous carbon dioxide against brine and water-alternating-gas flooding for enhanced oil recovery. A series of laboratory experiments was performed to evaluate the reactivity of the common reservoir mineral dolomite with water-saturated supercritical carbon dioxide. Experiments were conducted at reservoir conditions (55 and 110°C, 25 MPa) and elevated temperature (220°C, 25 MPa) for approximately 96 and 164 h (4 and 7 days). Dolomite dissolves and new carbonate mineral precipitates by reaction with water-saturated supercritical carbon dioxide. Dolomite does not react with anhydrous supercritical carbon dioxide. Temperature and reaction time control the composition, morphology, and extent of formation of new carbonate minerals. Mineral dissolution and re-precipitation due to reaction with water-saturated carbon dioxide may affect the contact line between phases, the carbon dioxide contact angle, and the relative permeability and permeability distribution of the reservoir. These changes influence fundamental properties of hysteresis of drainage and imbibition cycles, rock wettability, and capillary pressure. The efficacy of physical carbon dioxide trapping mechanisms, integrity of caprock, and injectivity of a carbon dioxide storage reservoir as well as the injectivity and production rate of an enhanced oil recovery operation may be affected.
Geological Storage of Carbon Dioxide
Environmental and Engineering Geoscience, 2009
Carbon dioxide is the main compound identified as affecting the stability of the Earth's climate. A significant reduction in the volume of greenhouse gas emissions to the atmosphere is a key mechanism for mitigating against climate change. Geological storage of CO 2, or the injection and stabilization of large volumes of CO 2 in the subsurface in saline aquifers, existing hydrocarbon reservoirs or unmineable coal-seams, is one of the more technologically advanced options available. A number of studies have been carried out aimed at understanding the behaviour and long term fate of CO 2 when stored in geological formations.
Carbonate geochemistry and its role in geologic carbon storage
2021
Massive quantities of CO 2 need to be captured and stored to address the potential consequences of global warming. Geologic storage of CO 2 may be the only realistic option available to store the bulk of this CO 2 due to the required storage volumes. Geologic storage involves the injection of CO 2 into the subsurface. This injection will lead to the acidification of the formation fluids and provoke a large number of fluid-mineral reactions in the subsurface. Of these reactions, those among CO 2-rich fluids and carbonate minerals may be the most significant as these reactions are relatively rapid and have the potential to alter the integrity of caprocks and well bore cements. This review provides a detailed summary of field, laboratory and modeling results illuminating the potential impacts of the injection of large quantities of CO 2 into the subsurface as part of geologic storage efforts
Geological Storage of CO2: a State-Of-The-Art of Injection Processes and Technologies
Oil & Gas Science and Technology, 2005
-Stockage géologique du CO 2 : état de l'art des technologies d'injection-Dans cet article, les technologies de puits nécessaires à l'injection de CO 2 sont présentées ainsi que les mécanismes physico-chimiques provoqués par l'injection autour du puits :-Les matériaux utilisés pour le puits et les procédures d'abandon de puits doivent être choisis de façon à éviter toute fuite de CO 2 le long du puits et d'assurer la sécurité à long terme du stockage.-La zone autour du puits subit des mécanismes de dissolution/reprécipitation causés par l'injection de CO 2 , qui peuvent influer sur l'injectivité. Ces phénomènes dépendent fortement des caractéristiques du réservoir et requièrent aujourd'hui une étude théorique et expérimentale approfondie afin de contrôler l'injectivité des puits d'injection de CO 2 , élément clé car de grandes quantités de CO 2 devront être injectées.