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Exploring High Temperature reservoirs: new challenges for geothermal energy - Volterra, Italy, Workshop2
Exploring High Temperature reservoirs: new challenges for geothermal energy - Volterra, Italy, Workshop2
1-4 April 2007 Volterra, Tuscany, Italy
email support
Magmas are multiphase multicomponent fluids which undergo chemical evolution and
phase changes during their sub-surface history, implying large variations in fluid
flow properties and a richness and variety of fluid dynamic behaviours. The formation
of gas bubbles upon exsolution from the liquid of magmatic volatiles, mainly water
and carbon dioxide, represents the major factors inducing density differences and
convection in magmatic bodies. This results in complex patterns of fluid flow which
occasionally generate conditions for rock fracturing, magma ascent, and eruption.
In order to simulate the fluid dynamics of magma in magma chambers and
conduit/fissures, we have developed a C++ numerical code which solves the transient,
2D mass, momentum and energy transport equations for a homogeneous multiphase
multicomponent magma with liquid-gas non-ideal equilibrium and locally defined
P-T-composition-dependent physical/chemical properties. The numerical algorithm is
based on a finite element formulation and space-time discretization with Galerkin
least-squares and discontinuity capturing terms, which allow high numerical stability
and robust and accurate solutions over a wide range of flow regimes from compressible
to incompressible. The multicomponent formulation makes the code particularly
suitable for the investigation of several relevant aspects of magma dynamics
involving density changes, mixing, multiple volatile saturation and phase transitions.
Applications of the code have been done to simulate the dynamics of free and forced
convection in magmatic systems originating from gravitational instabilities, magma
chamber replenishment, and conduit flow and magma ascent towards the Earth surface.
The results highlight several aspects of the complex sub-surface magma dynamics,
among which, the major role of carbon dioxide in inducing efficient magma convection
and mixing dynamics, the possible occurrence of magma re-circulation from shallow
reservoirs into deeper feeding conduits, the effect of convection of compressible
magma in causing overpressure and enhancing stress on the confining rocks, and the
generation of pressure fluctuations over a large range of frequencies encompassing
those typical of quasi-static and dynamic rock deformation commonly registered in
volcanic areas. The future research needs to improve the modelling and simulation of
deep magmatic properties, specifically by coupling the dynamics of the fluid magma
and the rock structure, are briefly outlined.
Id: 32
Place: Volterra, Tuscany, Italy
Campus SIAF, SP del Monte Volterrano
Localita' Il Cipresso
Volterra, Italy
Starting date:
03-Apr-2007   08:30
Duration: 30'
Primary Authors: Dr. PAPALE, Paolo (Istituto Nazionale di Geofisica e Vulcanologia - Pisa)
Co-Authors: Dr. LONGO, Antonella (Istituto Nazionale di Geofisica e Vulcanologia - Pisa)
Dr. VASSALLI, Melissa (Istituto Nazionale di Geofisica e Vulcanologia - Pisa)
Dr. BARBATO, David (Istituto Nazionale di Geofisica e Vulcanologia - Pisa)
Dr. SACCOROTTI, Gilberto (Istituto Nazionale di Geofisica e Vulcanologia - Napoli and Pisa)
Dr. BARSANTI, Michele ( Matematica Applicata, Pisa, and INGV Pisa)
Presenters: Dr. PAPALE, Paolo
Material: slides Slides

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