GNGTS 2021 - Atti del 39° Convegno Nazionale

GNGTS 2021 S essione 1.2 110 temperature variations along the conduit and/or in the surface area occur if the unrest phase is accompanied by a restriction of the conduit and of the inlet and an increase in its permeability (Fig. 3a, b), so as to simulate the rise of the flow along a narrow highly fractured zone. The permeability configuration and the size of the conduit also affect pressure changes and the geophysical obser- vables. In a more permeable configuration the pressure variations are smaller compared to a less permeable configuration, but affect a wider area (Fig. 3c, d), causing larger ground deformation. Under the same configuration, a narrower conduit is accompanied by higher pressure variations but affects a smaller area of ​the volcanic system (Fig. 2d-f) contributing to a lesser extent to surface deformations (Fig. 2o-q). Changes in gravity also decrease as the conduit is narrowed (Fig. 2r-t). The results obtained from these parametric simulations, which highlight the important role played by the permeability of the conduit and by its size, were applied to simulate the surface temperatures recorded in the F5AT fumaroles of the La Fossa cone over the period 2001-2005, in which a peak of temperature, accompanied by an increase in the CO 2 content (Diliberto, 2011; Granieri et al., 2006; Selva et al., 2020), was observed in January 2005. The geophysical observables were also evaluated. References Afanasyev, A. (2012). Simulation of the Properties of a Binary Carbon Dioxide-Water Mixture under Sub- and Supercritical Conditions. High Temperature 50:340-347. doi:10.1134/S0018151X12030017 Afanasyev, A. (2013a). Application of the Reservoir Simulator MUFITS for 3D Modelling of CO 2 Storage in Geological Formations. Energy Procedia 40:365-374 . doi:org/10.1016/j.egypro.2013.08.042 Afanasyev, A.A. (2013b). Multiphase compositional modelling of CO 2 injection under subcritical conditions: the impact of dissolution and phase transitions between liquid and gaseous CO2on reservoir tempera- ture. Int. J. Greenh. Gas Control 19, 731-732 . https://doi.org/10.1016/j.ijggc.2013.01.042 Fig. 3 - Changes in temperature (∆T) and in pressure (∆P) and gas saturation distribution (S g ) during an unrest phase, induced by the injection of a mixture of H 2 O and of CO 2 at a temperature of 600 °C. The unrest phase was simulated after narrowing the conduit and increasing its permeability by two orders of magnitude for two different permeability configurations: HP (left panels) and LP (right panels). The LP configuration is an order of magnitude less permeable than the HP configuration.