ALBERT

Description: Since 2000 a joint project between the Department of Earth Science of Florence and the Unit of Environment and Health of the Municipality of Arezzo has allowed to geochemically characterise the superficial and ground waters of the municipal territory of Arezzo in order to establish the water quality and to investigate the main natural and anthropic processes responsible of their composition. The available geochemical data-base consists of more than 500 samples sites (90% of which are private wells and 7 and 3% are springs and running waters, respectively) on which physical parameters (temperature and electrical conductivity) and major, minor and trace dissolved species (pH, Ca, Mg, Na, K, NH4, HCO3, SO4, NO3, NO2, Cl, Br, F, heavy metals) have been performed by using the same sampling procedure and analytical methodology in order to have a consistent set of data. Fifteen selected sites have been analysed twice per year to evidence possible seasonal effects. No significant differences have been recorded. The Arezzo Basin, formed since Upper Pliocene, is a structural depression limited to the North and to the East by the Pratomagno and Chianti belts, respectively, and to the South and to the East by two tectonic lineaments (Val d’Arbia-Val Marecchia transversal and Chitignano normal faults). Along these tectonic discontinuities CO2-rich manifestations either seep out or exploited by private companies. Hydrogeologically, three main aquifers are recognised: i) a relatively deep aquifer hosted in Tertiary sandstone formations; ii) an intermediate aquifer hosted in Quaternary fluvio-lacustrine sediments and iii) a shallow aquifer in recent alluvional sediments. The content in Total Dissolved Solids (TDS) allows to classify the Arezzo waters in: oligomineral (69%), medium-mineral (30%) and mineral (1%) and they can be regarded as Ca(Mg)-HCO3 (87 %), Na(K)-HCO3 (7%), Ca(Mg)-SO4 (5%) and Na(K)-Cl (1%). It is noteworthy to point of that the Na(K)-HCO3 waters are aligned along the above mentioned tectonic systems. The quality of Arezzo waters has been referred to the Italian legislation that is addressed to the definition of the Maximum Admissible Concentration (MAC, DPR 236/88, Dlgs 31/01) and the Reference Value (RV, DPR 236/88) in terms of waters for the human consumption. Waters from the northern area of Arezzo overcome MAC for chlorides, sulphates and sodium; if we consider nitrogen species (NH4, NO2, NO3) the values overcome CMA for those waters collected into the city, its peripheral areas and in the south-western suburbs. Thematic maps has been produced, on the basis of the principles of linear Geostatistics, in order to analyse the spatial behaviour of the analysed variables. The aim was to find correlations with lithology, use of the soils, drainage density, pressure of antrophic activities and so on, and to identify sensible areas to monitor in their time evolution. The investigation has been developed starting from a detailed variographic analysis by means of the geochemical behaviour of each variable has been analysed in the different directions of the space while the estimation procedure to obtain the maps has been based on the application of sequential Gaussian simulation procedures.

Description: Published

Description: Spoleto, Italy

Description: 2.4. TTC - Laboratori di geochimica dei fluidi

Description: open

Description: EnCana’s CO2 injection EOR project at Weyburn (Saskatchewan, Canada) is the focal point of a multi-faceted research program, sponsored by IEA GHG R&D and numerous international industrial and government partners including the European Community (BGS, BRGM, INGV and GEUS research providers), to find co-optimization of “CO2-EOR Production” and “CO2 -Geological Storage”, addressed to environmental purposes, in the frame of the Kyoto Agreement Policies. The Weyburn oil-pull is recovered from Midale Beds (at the depth of 1300-1500 m). This formation consists of Mississipian shallow marine carbonate-evaporites that can be subdivided into two units: i) the dolomitic “Marly” and ii) the underlying calcitic “Vuggy”, sealed by an anhydrite cap. Presently, around 3 billions mc of supercritical CO2 have been injected into the “Phase A1”injection area that includes around 90 oil producers, 30 water injectors and 30 CO2 injection wells, build up since September 2000. INGV has carried out a geochemical monitoring programme -approximately thrice yearly from pre-injection (“Baseline” trip, August 2000) to September 2004- performing trace element and dissolved gas analysis along with fluids sampling surveys, the latter being performed by the Canadian partners. The experimental data are the base of a geochemical modelling, i.e. the main goal of the present study. In the past, assumptions and gap-acceptance have been made in the literature in the frame of the geochemical modelling of CO2 geological storage, in order to reconstruct the reservoir conditions (pressure, pH and boundary conditions). As these parameters of deep fluids cannot be measured in-situ, all this information must be computed by a a posteriori procedure involving the analytical data. In this work we applied a geochemical model to: i) reconstruct the in-situ reservoir chemical composition (including pH) and ii) evaluate the boundary conditions (pCO2, pH2S), necessary to implement the reaction path modelling. This is the starting point to assess the geochemical impact of CO2 into the oil reservoir and, as main target, to quantify water-gas-rock reactions. Our geochemical modelling procedure is based on the available data such as: a) bulk mineralogy of the Marly and Vuggy zones; b) gas-cap composition and c) pre-and post-CO2 injection selected water samples from Midale Beds. The PRHEEQC (V2.11) Software Package was used to reconstruct the in-situ reservoir composition by calculating the chemical equilibrium among the various phases at reservoir temperature (60°C) and pressure (150 bars) conditions by suitable thermodynamic corrections to code database. Then, we identified possible compositions of the initially reservoir liquid phases, always taking into account the case histories of the Marly and Vuggy units. Finally, we modelled the geochemical impact of CO2 injection on Weyburn reservoir subjected to both local equilibrium and kinetically controlled reactions. The inverse modelling simulation (IMS) was then performed in order to calculate the amounts of mass transfer of liquid, gas and solid phases that accounted for changes in the water chemistry between the 2000 and 2003 data-sets. IMS calculations suggest that the reservoir underwent mineralogical changes, such as precipitation of chalcedony, gypsum and kaolinite and dissolution of anhydrite and k-feldspar. Calcite dissolution is predicted, but the precipitation of others carbonates (dolomite, dawsonite and siderite) can also occur. All experimental data and geochemical modelling confirm that “solubility trapping” is prevailing in this early stage of CO2 injection. Further and detailed studies are necessary until all the kinetic parameters will fully be identified. Thermo-kinetic modeling of the evolution of the CO2-rich Weyburn brine interacting with host rock minerals over 1000 years is one of main aims of this study in the framework of a PhD programme between the INGV of Rome and the Department of Earth Sciences of Florence.

Description: Published

Description: Spoleto, Italy

Description: 2.4. TTC - Laboratori di geochimica dei fluidi

Description: open

Description: In this paper thematic maps produced on the basis of the principles of linear geostatistics are described in order to characterise the superficial and ground waters of the municipal territory of Arezzo. The aim is to assess the correlation with lithology, use of soil, drainage density and anthropogenic pressure and identify sensible areas to be periodically monitored in time. This study has used an original geochemical data-base consisting of about 500 water samples. A statistical approach has been used for the identification of anomalous values and homogenous populations. This step was followed by a detailed variographic study in order to analyse the spatial behaviour of the variables. Subsequently, an estimation procedure based on the application of ordinary kriging algorithm and sequential Gaussian simulation methods was applied to obtain the maps.

Description: Published

Description: San Giovanni valdarno (AR), Italy

Description: 2.4. TTC - Laboratori di geochimica dei fluidi

Description: open

Description: EnCana’s CO2 injection EOR project at Weyburn (Saskatchewan, Canada) is the focal point of a multi-faceted research program, sponsored by IEA GHG R&D and numerous international industrial and government partners including the European Community (BGS, BRGM, INGV and GEUS research providers), to find co-optimization of “CO2-EOR Production” and “CO2 -Geological Storage”, addressed to environmental purposes, in the frame of the Kyoto Agreement Policies. The Weyburn oil-pull is recovered from Midale Beds (at the depth of 1300-1500 m). This formation consists of Mississipian shallow marine carbonate-evaporites that can be subdivided into two units: i) the dolomitic “Marly” and ii) the underlying calcitic “Vuggy”, sealed by an anhydrite cap. Presently, around 3 billions mc of supercritical CO2 have been injected into the “Phase A1”injection area that includes around 90 oil producers, 30 water injectors and 30 CO2 injection wells, build up since September 2000. INGV has carried out a geochemical monitoring programme -approximately thrice yearly from pre-injection (“Baseline” trip, August 2000) to September 2004- performing trace element and dissolved gas analysis along with fluids sampling surveys, the latter being performed by the Canadian partners. The experimental data are the base of a geochemical modelling, i.e. the main goal of the present study. In the past, assumptions and gap-acceptance have been made in the literature in the frame of the geochemical modelling of CO2 geological storage, in order to reconstruct the reservoir conditions (pressure, pH and boundary conditions). As these parameters of deep fluids cannot be measured in-situ, all this information must be computed by a a posteriori procedure involving the analytical data. In this work we proposed an approach to geochemical modeling in order to:: i) reconstruct the in-situ reservoir chemical composition (including pH) and ii) evaluate the boundary conditions (e.g. pCO2, pH2S), necessary to implement the reaction path modelling. This is the starting point to assess the geochemical impact of CO2 into the oil reservoir and, as main target, to quantify water-gas-rock reactions. Our geochemical modelling procedure is based on the available data such as: a) bulk mineralogy of the Marly and Vuggy zones; b) average gas-cap composition and c) pre-and post-CO2 injection selected water samples from Midale Beds. The PRHEEQC (V2.11) Software Package was used to reconstruct the in-situ reservoir composition by calculating the chemical equilibrium among the various phases at reservoir temperature (60°C) and pressure (150 bars) conditions by suitable thermodynamic corrections to code database. Then, we identified possible compositions of the initially reservoir liquid phases, always taking into account the case histories of the Marly and Vuggy units. The inverse modelling simulation (IMS) was then performed in order to calculate the amounts of mass transfer of liquid, gas and solid phases that accounted for changes in the water chemistry between the 2000 and 2003 data-sets. IMS calculations suggest that the reservoir underwent mineralogical changes, such as precipitation of chalcedony, gypsum and kaolinite and dissolution of anhydrite and k-feldspar. Calcite dissolution is predicted, but the precipitation of others carbonates (dolomite, dawsonite and siderite) can also occur. Finally, we modelled the geochemical impact of CO2 injection on Weyburn reservoir subjected to both local equilibrium and kinetically controlled reactions. All experimental data and thermo-kinetic modeling of the evolution of the CO2-rich Weyburn brine interacting with host rock minerals performed over 100 years after injection confirm that “solubility trapping” is prevailing in this early stage of CO2 injection. Further and detailed studies on the evolution of the CO2-rich Weyburn brine is one of main aims of this study in the framework of a PhD programme between the INGV of Rome and the Department of Earth Sciences of Florence.

Description: Published

Description: Berkeley, California (USA)

Description: 2.4. TTC - Laboratori di geochimica dei fluidi

Description: open

Description: CO2 Capture & Storage (CCS) is presently one of the most promising technologies for reducing anthropogenic emissions of CO2. The numerical modeling procedures of geochemical processes are one of the few approaches for investigating the short-long-term consequences of CO2 storage into a deep reservoir. We present the results of a new approach for the reconstruction of thermo-physical properties of an off-shore deep well (situated in the medium Tyrrhenian Sea, only 5 miles from the coast, in the frame of a distensive and relatively high heat flux regime as a whole,with good outcrops, on-shore, of its stratigraphy includes six Late Triassic-Early Jurassic carbonatic formations at the depth of 2500-3700 m b.s.l). We used the well-log coupled with temperature profile and new mineralogical analyses of the outcrops geological formations, being the original core data lacking. This kind of procedure is new as a whole, and it is useful to create background petro-physical data, for reservoir engineering numerical simulations both of mass-transport and geochemical as well as geo-mechanical, in order to asses its general properties, without re-opening the well itself for industrial use, such as CO2 geological storage. The profile of thermal capacity and conductivity, as well as porosity and permeability resulted very well constrained and detailed for further numerical simulation uses. Porosity is a very important parameter for reservoir engineering, mainly for numerical simulations including geochemical modelling, being strongly necessary for CO2 geological storage feasibility studies, because it allows to compute: i) the reservoir storage capacity for each trapping mechanisms (some algorithms are discussed in the presentation) and ii) the water/rock ratio (one of the input parameter requested by the geochemical software codes). A common problem, working with closed wells with, available the well-log report only, is to obtain data on the thermo-physical properties of the rock. Usually the available well-log report the temperature profile measured during drilling, the mud-loss and some other information on water and gas phase presence. In this work we present a procedure that allow to estimate porosity and permeability of the rock formation from the well-log data joint with a rough mineralogical analyses of the corresponding geological formations outcrop with the use of a boundary condition such as shallow heat flow measurements; a similar approach were presented from some authors that dealt with similar problems e.g. Singh V.K., (2007). The analyses of the rock samples proceed by using i) petro-graphical analyses; ii) calcimetry with Dietrich-Fruhling apparatus in order to analyse the carbonate content of each sample; iii) XRD Rietveld analyses in order to quantify the major mineralogy of each sample and to apply the dolomite correction to the results of calcimetry determination. Rietveld quantification procedure were performed by using Maud v 2.2.; iv) SEM analyses have been accomplished later in details. Successively, hints about the subsequent geochemical modelling approach are presented. Chemical composition of the aquifer pore water has been has been inferred by batch modeling assuming thermodynamic equilibrium between minerals and a NaCl equivalent brine at reservoir conditions (up to 70 °C and 200 bar). Numerical simulations has been carried out by the PRHEEQC (V2.11) Software Package via corrections to the code default thermodynamic to obtain a more realistic modeling.

Description: Published

Description: La Habana, Cuba

Description: 2.4. TTC - Laboratori di geochimica dei fluidi

Description: open

Description: In this study numerical simulations of reactive transport in an off-shore deep saline aquifer for the geological sequestration of carbon dioxide are presented and discussed. The main goals are to assess: i) the CO2 injection impact in the reservoir and ii) the cap-rock stability, both being strategic requisites for feasibility studies that are about to be started in Italy. The stratigraphic succession is characterized by a sedimentary succession: from Triassic anhydrites to Jurassic Tuscan calcareous units, up to Cretaceous calcarenites, belonging to the Liguride units, and Quaternary shallow marine sediments. Stratigraphic data from a deep well indicate that below an 1,800 m thick cap-rock, constituted by allochtonous marly calcarenites and clay marls, a regional deep saline aquifer is present. This aquifer, hosted in six Late Triassic to Early Jurassic formations, belonging to the Tuscan Nappe units, consists of porous limestone (mainly calcite) and marly limestone deposits at 1900-3100 m b.s.l. A common problem working with off-shore closed wells, where only the well-log information are available, is that to obtain reliable physico-chemical parameters (e.g. petrophysical and mineralogical) to be used for numerical simulations. Available site-specific data include only basic physical parameters such as temperature, pressure, and salinity of the formation waters. Bulk and modal mineralogical composition were obtained after sampling each formation in contiguous on-shore zones. Mineralogy was determined by X-Ray diffraction analysis coupled with Rietfield refinement. The latter was performed using Maud v2.2. The surface reactive area of minerals was assumed as geometric area of a truncated sphere calculated on the basis of Scanning Electronic Microscopy analysis. Porosity and permeability were inferred by the well-log data along with the use of boundary conditions such as surficial measurements and temperature profiles. The chemical composition of the aquifer pore water is unknown. As a consequence, this was calculated by batch modeling, assuming thermodynamic equilibrium between minerals and a NaCl (0.45 M) equivalent brine at reservoir conditions (up to 118 °C and 300 bars). The reconstructed dataset represented the base of numerical simulations to evaluate the potential geochemical impact of CO2 storage and to quantify water-gas-rock reactions. Three dimensional simulations were performed by the TOUGHREACT code via the implementation to the source code and the correction of the chemical parameters at the theoretical CO2 injection pressure. A re-interpretation of the available seismic reflection data was carried out to: i) define the 3D geometry, and ii) evaluate the volume of the geological structure potentially suitable for CO2 storage. In particular the main surfaces where physicochemical modeling was applied, i.e. the top and the bottom of the cap-rock units and the spill point surface, to better define the 3D geometry of the potential injection reservoir, were reconstructed. Reactive transport simulations were conducted under multiphase advection, aqueous diffusion, gas phase participation in multiphase fluid flow and geochemical reaction in non-isothermal conditions. Feedbacks between flow and geochemical processes were taken into account to evaluate changes in porosity and permeability as kinetic reactions were proceeding. Twenty years of CO2 injection at the rate of 1.5 Mt/year were simulated, whereas water-gas-rock interactions between CO2-rich brines and minerals over a period of 100 years were performed. Preliminary results suggest that injected CO2 can safely be retained in the reservoir by mineral trapping and that the cap-rock can be considered as efficient barrier.

Description: Published

Description: Rimini (Italy)

Description: 2.4. TTC - Laboratori di geochimica dei fluidi

Description: open

Description: New high-resolution bathymetric and magnetic data from the western Aeolian sector, southern Tyrrhenian Sea, provide insights into structural and volcanic development of the area, suggesting a strong interaction between volcanism and tectonics. The analysis of these data combined with relocated earthquake distribution, focal plane solutions and strain rate evaluation indicates that the dextral strike-slip Sisifo-Alicudi shear zone is a complex and wide area of active deformation, representing the superficial expression of the deep seated lithospheric tear fault separating the subduction slab below Sicily and Calabria. Most of the observed volcanic features are aligned along a NW–SE trend, such as the Filicudi island-Alicudi North Seamount and Eolo-Enarete alignments, and are dissected by hundred-metre-high scarps along conjugate NNE–SSW trending fault systems. The magnetic field pattern matches the main trends of volcanic features. Spectral analysis and Euler deconvolution of magnetic anomalies show the existence of both deep and shallow sources. High-amplitude, high-frequency anomalies due to shallow sources are dominant close to the volcanic edifices of Alicudi and Filicudi, while the main contribution on the surrounding Eolo, Enarete, Alicudi North and Filicudi North seamounts is given by low-amplitude anomalies and/or deeper magnetic sources. This is probably related to different ages of the volcanic rocks, although hydrothermal processes may have played an important role in blanketing magnetic anomalies, in particular at Enarete and Eolo seamounts. Relative chronology of the eruptive centres and the inferred deformation pattern outline the Quaternary evolution of the western Aeolian Arc: Sisifo, Alicudi North and Filicudi North seamounts might have developed in an early stage, following the Late Pliocene–Early Pleistocene SE-ward migration of arc-related volcanism due to the Ionian subduction hinge retreat; Eolo, Enarete and Filicudi represent later manifestations that led volcanoes to develop duringMid-Late Pleistocene, when the stress regime in the area changed, due to the SSE-ward propagation of the subduction slab tear fault and the consequent reorientation and decrease of trench migration velocity. Finally, volcanic activity occurred in a very short time span at Alicudi, where an almost conical volcanic edifice emerged, suggesting negligible interactions with regional fault systems.

Description: Published

Description: 64-78

Description: 2.6. TTC - Laboratorio di gravimetria, magnetismo ed elettromagnetismo in aree attive

Description: 3.3. Geodinamica e struttura dell'interno della Terra

Description: 3.4. Geomagnetismo

Description: JCR Journal

Description: restricted

Description: A systematic analysis is made of static Coulomb stress changes and earthquake occurrence in the area of the North Aegean Sea, Greece, in order to assess the prospect of using static stress changes to construct a regional earthquake likelihood model.

Description: A systematic analysis is made of static Coulomb stress changes and earthquake occurrence in the area of the North Aegean Sea, Greece, in order to assess the prospect of using static stress changes to construct a regional earthquake likelihood model. The earthquake data set comprises all events of magnitude M ≥ 5.2 which have occurred since 1964. This is compared to the evolving stress field due to constant tectonic loading and perturbations due to coseismic slip associated with major earthquakes (M ≥ 6.4) over the same period. The stress was resolved for sixteen fault orientation classes, covering the observed focal mechanisms of all earthquakes in the region. Analysis using error diagrams shows that earthquake occurrence is better correlated with the constant tectonic loading component of the stress field than with the total stress field changes since 1964, and that little, if any, information on earthquake occurrence is lost if only the maximum of the tectonic loading over the fault orientation classes is considered. Moreover, the information on earthquake occurrence is actually increased by taking the maximum of the evolving stress field since 1964, and of its coseismic–slip component, over the fault orientation classes. The maximum, over fault orientation classes, of linear combinations of the tectonic loading and the evolving stress field is insignificantly better correlated with earthquake occurrence than the maximum of the tectonic loading by itself. A composite stress–change variable is constructed from ordering of the maximum tectonic loading component and the maximum coseismic–slip component, in order to optimize the correlation with earthquake occurrence. The results indicate that it would be difficult to construct a time–varying earthquake likelihood model from the evolving stress field that is more informative than a time–invariant model based on the constant tectonic loading.

Description: This research was supported by the Foundation for Research, Science and Technology under contract CO5X0402. Geophysics Department, AUTH, contribution number 741.

Description: Published

Description: 1049–1066

Description: 6T. Studi di pericolosità sismica e da maremoto

Description: JCR Journal

Description: open

Description: CO2 Capture & Storage (CCS) in saline aquifer is one of the most promising technologies for reducing anthropogenic emission of CO2. Feasibility studies for CO2 geo-sequestration in Italy have increased in the last few years. Before planning a CCS plant an appropriate precision and accuracy in the prediction of the reservoir evolution during injection, in terms of both geochemical calculation and fluid flow properties, is demanded. In this work a geochemical model will be presented for an offshore well in the Tyrrhenian Sea where the injection of 1.5 million ton/year of CO2 is planned. The dimension of the trapping structure requires to study an area of about 100 km2 and 4 km deep. Consequently, three different simulations were performed by means of TOUGHREACT code with Equation Of State module ECO2N. The first simulation is a stratigraphic column with a size of 110*110*4,000 meters and a metric resolution in the injection/cap-rock area (total of 8,470 elements), performed in order to asses the geochemical evolution of the cap-rock and to ensure the sealing of the system. The second simulation is at large scale in order to assess the CO2 path from the injection towards the spill point (total of about 154,000 elements). During this simulation, the effect of the full coupling of chemistry with fluid flow and a relevant effect in the expected CO2 diffusion velocity was recognized. Owing to the effect of chemical reaction and coupling terms (porosity/permeability variation with mineral dissolution/precipitation), the diffusion velocity results to be 20% slower than in a pure fluid flow simulation. In order to give a better picture of this 'barrier' effect, where the diffusion of the CO2-rich acidic water into the carbonate reservoir originates a complex precipitation/dissolution area, a small volume simulation with a 0.1 m grid was elapsed. This effect may potentially i) have a big impact on CO2 sequestration due to the reduction of available storage volume reached by the CO2 plume in 20 years and/or the enhanced injection pressure and ii) outline the relevance of a full geochemical simulation in an accurate prediction of the reservoir properties.

Description: Published

Description: Lawrence Berkeley National Laboratory, Berkeley, California

Description: 2.4. TTC - Laboratori di geochimica dei fluidi

Description: open

Description: We presents the results of a new approach for the reconstruction of thermo-physical properties of deep well from the well log and mineralogical analisys of the outcrops formation. This kind of procedure are generally new, and they are useful for creating the background data for reservoir engeneers and geochemist for modelling a well in order to asses its properties prior of re-opening the well itself for industrial use, such as CO2 sequestration. We used the temperature profile obtained from the well log and the bulk mineralogy analysed from the corresponding formation outcrops. The profile of thermal capacity and conductivity, and porosity and permeability as well, result well constrained and detaile for further use.

Description: Published

Description: Firenze, Italy

Description: 2.4. TTC - Laboratori di geochimica dei fluidi

Description: open