87,012 research outputs found
SANS/VSANS investigation of the porosity microstructure in rocks from a natural CO2 reservoir
No full textSequestration of CO2 in deep geological reservoirs represents one of the potential methods to reduce anthropogenic emissions into the atmosphere. In the long term the injected CO2 dissolves into the local formation of rocks and, when present, in saline deep aquifers, participating to a variety of geochemical reactions. The overall impact of these processes produces changes in mineralogy, texture, permeability and porous structure of the rocks, to a level which depends on the different lithologies present in the rocks.
Mineralogical changes can be investigated by considering what occurs in rocks and minerals with natural CO2 accumulations, as analogues for geological sequestration. Also computer simulations, based on thermodynamics, kinetics and geochemical modeling [1, 2], can be beneficial. On the other hand, reliable data concerning the porous structure, which is so important to trap CO2, can be hardly extracted from computer simulations.
In this context a valuable help can be provided by Small and Very Small Angle Neutron Scattering techniques (SANS and VSANS, respectively): they have been indeed demonstrated to be powerful tools for the determination of the microstructure and porosity of rocks from Ångstrom to millimeter sizes [3], proofing also the existence of fractal dimensions for the volume and surfaces interfaces between pores and rocks.
Here we present the preliminary results of a SANS/VSANS investigation on rocks pertaining to a geological context (located in Eastern Tuscany, Central Italy) featured by a deep geological gas reservoir. The former reservoir was intercepted by a bore-well drilled in ’80 by ENI and is presently hosting 700 bar of supercritical CO2. Texture and mineralogy of volcanic rocks samples, from drill cores corresponding to the top of the reservoir, were found to be heavily modified by the interaction with CO2-rich fluids.
The combined neutron experiments, performed using the PAXE and G5bis diffractometers at LLB (Saclay, F), allowed to approximately investigate pore sizes ranging from ∼ 60 nm to ∼ 6 μm. Samples of host rocks (from drill core) and a selection of possible analogues of the same volcanic rocks, unaffected by CO2 presence, were chosen for the experiments together with samples of rocks, from outcrops, corresponding to the geological layers the characteristics of geological layers overlying the reservoir. Globally these rocks are representative of a wide spectrum of different lithologies (as limestones, marls, evaporitic deposits bearing gypsum and volcanic rocks with intermediate-acid composition).
The information provided by these experiments must still be fully analyzed and integrated with other data (e.g. chemical composition of rocks and fluids [4]) in order to get a better understanding of: i) the role and the possible effects of CO2 in determining the micro-porosity of these host rocks, and ii) the sealing effect of the sedimentary rocks overlying the reservoir which act as a barrier with respect to the CO2-rich gases.
References
[1] Zhu C. and Anderson G., 2002 Environmental Applications of Geochemical Modeling, Cambridge University Press, Cambridge, UK, 284 pp.
[2] Cantucci B, Montegrossi G., Vaselli O., Tassi F., Quattrocchi F., and Perkins E.H., 2009 Geochemical modelling of CO2 storage in deep reservoirs: The Weyburn Project (Canada) case study. Chemical Geology, 265 (1), 181-197.
[3] A.P. Radlinski, 2006 and reference therein, in Neutron Scattering in Earth Sciences, Reviews in Mineralogy & Geochemistry, 63, pp. 363-397.
[4] Bicocchi G., Montegrossi G., Ruggieri G., Buccianti A. and Vaselli O. (2011). Modeling composition of Ca-Fe-Mg carbonates in a natural CO2 reservoir. In: Egozcue, J.J., Tolosana-Delgado, R. and Ortego, M.I. (eds.). Codawork11 Proceedings, 16 p
Il controllo di gestione per favorire l'accesso al credito. Un'applicazione nel settore turistico-ricettivo
No full textTenere l'azienda "sotto controllo" è una condizione imprescindibile per operare in condizioni di funzionalità duratura. Di ciò sono tanto più consapevoli le aziende di piccole-medie dimensioni che, in quanto più bisognose di finanziamenti di terzi, sono sottoposte a stringenti valutazioni di merito creditizio. Questo è il caso della realtà turistico-ricettiva esaminata, la quale è ricorsa ad expertise esterne per attivare quei processi di apprendimento manageriale basati sui principi e strumenti del controllo di gestione che, oltre a supportare un'azione di governo che va oltre la compliance, costituisce un necessario "viatico" per l'accesso al credito
Geochemical monitoring of active volcanoes: organic compounds in low-to-high gas exalations at Vulcano Island (Aeolian Islands; Italy)
No full textControllo e governo sostenibile della «crescita aziendale»: il caso Colmic Spa
No full textIl contributo si focalizza sui processi di crescita aziendale, mettendo non solo in evidenza le sottostanti motivazioni, ma anche alcune delle strategie atte a realizzare tali processi con successo ed in modo duraturo o “sostenibile”. L’articolo evidenzia inoltre il ruolo che può essere svolto da un efficace sistema di controllo di gestione, sia nella fase di progettazione degli interventi volti ad innescare la crescita, sia tramite un controllo ed un reporting in itinere ed ex-post tali da fornire un valido supporto informativo ai decision-makers. Nello specifico, il contributo analizza il caso della Colmic SpA, illustrando il percorso di crescita intrapreso, discutendone le politiche innovative implementate ed evidenziando il ruolo svolto dal sistema di controllo adottato nell’efficiente gestione delle risorse strategiche a disposizione dell’azienda
Geochemical monitoring at the Phlegrean Fields (Naples, Italy): new insights from organic gas compounds
No full textLight hydrocarbons in gas discharges from active volcanoes, geothermal fields and hydrothermal systems: constraints on the chemical-physical conditions of fluid reservoirs
No full textTemporal variability of hydrocarbons composition in the volcanic/hydrothermal system of El Chichon volcano (Chiapas State, Mexico): 8 years of discontinuous geochemical monitoring
No full textScrubbing processes on light hydrocarbons: an example from Ahuachapan and Berlin geothermal fields (Salvador)
No full textNon-methane Volatile Organic Compounds (VOCs) at El Chichón volcano (Chiapas, México):Geochemical features, origin and behavior
No full textSe presenta un estudio de las características geoquímicas de la fracción orgánica en las fumarolas del volcán Chichón (Estado de Chiapas, México) para obtener información sobre el origen de los compuestos orgánicos volátiles exceptuando el metano (VOCs) y los procesos que rigen su comportamiento. Los VOCs en fumarolas y pozas burbujeantes consisten principalmente de alcanos (C2-C5) cuya abundancia total tiene un orden de magnitud menor que el metano, y concentraciones altas de aromáticos (benceno y tolueno) y C2-C3 alquenos (principalmente propano e iso-butano). Se encontraron también concentraciones significativas de compuestos de azufre substituidos que en su mayoría pertenecen al grupo de los heterocíclicos. Esta composición, similar a la de las emisiones gaseosas relacionadas a sistemas geotérmicos, sugiere que la producción de gases orgánicos en el volcán El Chichón es principalmente debida a procesos termogénicos. La abundancia total de VOCs es relativamente baja en comparación con la composición típica de fluidos hidrotermales, lo que podría estar relacionado a una contribución importante de fluidos de origen magmático al reservorio que alimenta las emisiones termales del cráter. Sin embargo, la ausencia de compuestos de O-substituidos parece indicar que la composición de los fluidos hidrotermales no es afectada por el aporte de especies orgánicas producidas en profundidades someras por la descomposición de material vegetal reciente, como aquél sepultado por los productos de la erupción de 1982.
doi: https://doi.org/10.22201/igeof.00167169p.2009.48.1.10
Organics in volcanic gases: patterns of distribution and application to volcanic surveillance
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