Reactive chemical transport in a two-phase porous media.
by
Stephen White
Industrial Research Ltd
Coauthors: Bruce Christenson (IGNS)

In this work, we have applied the reactive transport simulator CHEM-TOUGH2 to a problem that is highly relevant to evolutionary development of Taupo Volcanic Zone (TVZ) geothermal systems, that of simulating fluid flow adjacent to a shallowly-seated, degassing magmatic intrusion. Model parameters for this work have been derived in part from the paleo-magmatic heat-source environment in the Ngatamariki system. The work is an extension of our previously published study of a single phase reservoir above a degassing intrusion and allows for two-phase reservoir conditions with transport in the gas phase of several volcanic gases. There are several significant differences from the results presented in the single phase case. We consider the effect of a pulse of magmatic vapor into the base of the reservoir and calculate the changed chemical and physical conditions as the reservoir is allowed to evolve for a further 20,000 years. The chemistry in the reservoir is described by eleven component species, H2O, H+, Cl-, SO4=, HCO3-, HS-, SiO2, Al+++, Ca++, K+ and Na+. Associated with these components are 32 secondary species, nine minerals and four gases.

Date received: June 28, 1999