Geophysical investigations in the Gañuelas-Mazarrón Tertiary basin (SE Spain): A natural analogue of a geological CO 2 storage affected by anthropogenic leakages (original) (raw)
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Effects on the shallow aquifers by CO2 leakages in a tertiary basin (province of Murcia, Spain)
2011
Geological storage of CO 2 is nowadays internationally considered as the most effective method for greenhouse gas emission mitigation, in order to minimize its effects on the global climatology. One of the main options is to store CO 2 in deep saline aquifers at more than 800m depth, because it reaches its supercritical state. Study of the CO 2 natural accumulations as natural analogues of an artificial CO 2 storage is very useful in order to understand the CO 2 long term behaviour and thus to predict its possible impact on the surficial environment and life. Therefore the main objective of this work is to detect the affection of the CO 2 leakages from a deep saline aquifer on the shallow aquifers, all of them located in the Gañuelas-Mazarrón Tertiary basin (Province of Murcia, Spain). This CO 2 storage and leakage natural system can be analogous to an artificial CO 2 storage with leakage phenomena. In order to reach these objectives, groundwaters from different aquifers in the site have been sampled and analysed for major elements, free and dissolved gases and stable isotopes, particularly ∂ 13 C and 3 He/ 4 He. The results obtained allow to conclude that this natural system is an interesting example of natural analogue for an artificial CO 2 storage affected by leakage processes because the shallow fresh aquifers in the site are polluted by CO 2 from the deep saline aquifer as a consequence of an intensive over-exploitation of these freshwater aquifers.
Journal of Applied Geophysics, 2014
The Lusitanian sedimentary basin, in Portugal, has a complex tectonic history and a seismic activity determined by its proximity to the Eurasian-Nubian tectonic plate boundary. Seismic activity and geological structure impose serious constraints to the selection of CO 2 storage sites. This article focuses on the constraints imposed by active seismicity, geological structure and, as a direct consequence of the latter, by the hydrogeology and geothermal framework on the identification of onshore CO 2 storage sites in deep saline aquifers of the Lusitanian basin (central and north sectors). Several active faults and areas of higher seismic hazard have been defined, favouring the selection of storage sites in the northern part of the basin. The halokinetic tectonics, responsible for emplacement of salt domes, constrains the regional groundwater flow system, and suggests that it is unreasonable to consider post-salt reservoirs. In most of the Lusitanian basin the pre-salt Silves Formation is the only reservoir worth considering. Four areas have been selected where the reservoir is at adequate depth, but given the other criteria for site selection, the area designated as S. Mamede is the most interesting one for CO 2 injection.
Hydrogeology Journal
The mineral water of Vilajuïga village in Alt Empordà (NE Catalonia, Spain) owes its uniqueness to an emanation of geogenic CO2 that modifies groundwater hydrochemistry to produce a differentiated HCO3–Na- and CO2-rich groundwater among the usual Ca–HCO3 type found in this region. A hydrogeological conceptual model attributes its occurrence to the intersection of two faults: La Valleta and Garriguella-Roses. The former provides a thrust of metamorphic over igneous rocks, formed during the Paleozoic, over a layer of ampelitic shale that, from a hydrogeological perspective, acts as a confining layer. The Garriguella-Roses normal fault, which originated during the Neogene, permits the degassing of geogenic CO2 that is attributed to volcanic activity occurring in the Neogene. Groundwater mixing from the metamorphic and igneous rock units plus the local occurrence of CO2 creates a HCO3–Na water that still holds free-CO2 in solution. Interaction with the gas phase is restricted at the int...
International Journal of Greenhouse Gas Control, 2014
The magnetotelluric (MT) method was used to characterise the underground research laboratory (URL) for CO 2 storage in a deep saline aquifer at Hontomín (Spain). A total grid of 109 closely-spaced broadband MT sites was acquired in the study area covering an areal extent of 3 × 5 km 2. Different three-dimensional (3D) inversion codes were employed to invert the MT data in the period range of 0.001-10 s (frequency range 1000-0.1 Hz), with all of them giving similar results. The final preferred 3D model validates a previously published two-dimensional (2D) MT study and is supported by a variety of multidisciplinary data (e.g., well log, 3D seismic and hydrogeochemistry data). The 3D model constitutes the baseline electrical resistivity model of the site that will be used for the future time-lapse electromagnetic (EM) monitoring experiments of the URL. The 3D resistivity distribution shows the dome-like structure of the saline aquifer and images fracture regions, thus identifying the most likely leakage pathways and consequently, the monitoring requirements of the Hontomín site.
Deep Geological Conditions and Constrains for CO 2 Storage in the Setúbal Peninsula, Portugal
This paper describes the research conducted in order to identify potential CO 2 storage reservoirs in the Setúbal Peninsula, Portugal. The studied area is located in the southern sector of the Lusitanian Basin, the largest Portuguese Mesozoic sedimentary basin. Data from deep geological conditions was collected from oil and gas exploration wells and structural maps of the target geological horizons were processed from seismic reflection profiles. A potential reservoir for CO 2 storage in the Lower Cretaceous was identified and its volume was calculated based on kriging interpolation methods. Net-to-gross ratio and porosities were determined from geological logs. A total CO 2 storage capacity of 42 Mt was estimated. However, the lack of data about the lateral continuity of the seal, the presence of the most important Portuguese groundwater resources at shallower depths and the relatively high earthquake hazard, hinders the studied reservoir from offering the necessary geological cond...
The Caspe geological structure was formed by the convergence of the Iberian Range and the Catalonian Coastal Range, during the Tertiary compression. Traditionally, the Caspe structure has been interpreted from seismic profiles without considering surface structural data. The aim of this study is to build a 3D geological model taking into account the structural data from the geological map, stress fields and lineaments, and evaluate its possibility as potential CO 2 storage site. Four surfaces have been modelled: Buntsandstein Top, Muschelkalk-I Top, Muschelkalk-II Top and Cenozoic Bottom. Considering the geometry and depth for storage the target reservoir was considered to be the Buntsandstein facies. The available seismic data indicate that the Buntsandstein facies top is at approximately 500 m depth and hosts a deep saline aquifer. The target reservoir series include the conglomerate and sandstone of the Hoz del Gallo and Cañizar Fms (Buntsandstein Facies) with an average thickness of 500 m and 21% porosity. The seal comprises the shales and silts of the Röt Fm with an average thickness of 100-150 m. The structure volume was calculated based on the-500 mbsl for the Buntsandstein top deepest closed contour lines. The estimated volume is 5,800 Mm 3 with most of CO 2 in gaseous state.
Hydrogeology Journal
The mineral water of Vilajuïga village in Alt Empordà (NE Catalonia, Spain) owes its uniqueness to an emanation of geogenic CO2 that modifies groundwater hydrochemistry to produce a differentiated HCO3–Na- and CO2-rich groundwater among the usual Ca–HCO3 type found in this region. A hydrogeological conceptual model attributes its occurrence to the intersection of two faults: La Valleta and Garriguella-Roses. The former provides a thrust of metamorphic over igneous rocks, formed during the Paleozoic, over a layer of ampelitic shale that, from a hydrogeological perspective, acts as a confining layer. The Garriguella-Roses normal fault, which originated during the Neogene, permits the degassing of geogenic CO2 that is attributed to volcanic activity occurring in the Neogene. Groundwater mixing from the metamorphic and igneous rock units plus the local occurrence of CO2 creates a HCO3–Na water that still holds free-CO2 in solution. Interaction with the gas phase is restricted at the int...
Hydrogeochemical modeling of a thermal system and lessons learned for CO 2 geologic storage
Chemical Geology, 2009
Geological storage of carbon dioxide is presently considered to be one of the main strategies to mitigate the impact of the emissions of this gas on global warming. Among the various alternatives considered for CO 2 geological storage, one of the main geological candidates for hosting injected CO 2 in the long term are deep porous reservoir rock formations saturated with brackish or saline solutions. Although valuable information on the expected hydrogeochemical processes involved in the CO 2 storage in such deep saline aquifers can be obtained in laboratory or modeling studies, the only direct source of information about the long-term behavior of geological storages for CO 2 in deep aquifers is natural analogues. In this work, a classical and simple geochemical methodology is successfully applied to the study of the features and hydrogeochemical processes determining the evolution of a Spanish thermal system (the Alhama-Jaraba complex), which can be considered as a natural analogue for deep geological CO 2 storage in carbonate rocks. The geology, structure, depth and hydrogeochemistry of the Alhama-Jaraba thermal system are very similar to the expected features of a potential CO 2 reservoir in carbonate materials. The processes determining the hydrogeochemical evolution in the Alhama-Jaraba thermal system have been successfully identified and quantified with the assistance of ion-ion plots, speciation-solubility calculations and mass-balance calculations. Furthermore, the feasibility of the proposed conceptual hydrogeochemical model for this system has been verified by using reaction-path calculations. Mass-balance calculation results have indicated that the observed hydrogeochemical evolution between springs is mainly due to halite dissolution and dedolomitization triggered by gypsum or anhydrite dissolution. CO 2 (g) mass transfer has been estimated to be negligible, which suggests that the main processes responsible for the variation in the TIC and the CO 2 (g) pressure during deep circulation are dissolution and precipitation reactions for carbonate minerals. All the processes identified in the Alhama-Jaraba thermal system are relevant for the long-term evolution of a deep CO 2 storage site hosted by carbonate rocks. As shown in this study, the application of classical geochemical tools provides an excellent starting point for understanding the behavior of prospective storage systems. Moreover, the existence of dedolomitization is very relevant for the hydraulic properties of carbonate aquifers potentially used for CO 2 geological storage because of the effects on porosity and, therefore, permeability during the long-term evolution of such systems. Furthermore, dedolomitization may represent a mechanism of mineral trapping for CO 2 sequestration under certain conditions.
Deep geological conditions and constraints for CO2 storage in the Setúbal Península, Portugal
2011
This paper describes the research conducted in order to identify potential CO 2 storage reservoirs in the Setúbal Peninsula, Portugal. The studied area is located in the southern sector of the Lusitanian Basin, the largest Portuguese Mesozoic sedimentary basin. Data from deep geological conditions was collected from oil and gas exploration wells and structural maps of the target geological horizons were processed from seismic reflection profiles. A potential reservoir for CO 2 storage in the Lower Cretaceous was identified and its volume was calculated based on kriging interpolation methods. Net-to-gross ratio and porosities were determined from geological logs. A total CO 2 storage capacity of 42 Mt was estimated. However, the lack of data about the lateral continuity of the seal, the presence of the most important Portuguese groundwater resources at shallower depths and the relatively high earthquake hazard, hinders the studied reservoir from offering the necessary geological conditions for a safe CO 2 storage in the studied area.