Computer Modelling of Heat and Mass Flow in Steaming Ground at Karapiti Thermal Area, New Zealand Abstract

Abstract

Heat and mass transfer in steaming ground have been
modeled using the TOUGH2 geothermal simulator
and the results compared with field data collected by
Bromley and Hochstein (2001). They measured
temperatures at several sites over periods of 4 to 7
days at the soil surface, and depths of 0.01 m, 0.05 m,
0.10 m, 0.15 m, and 0.20 m. Soil porosities and
saturations were also measured. These data sets were
processed to extract four key sub-sets of data that
were then used to calibrate a TOUGH2 model for
each site. Two of these data sets are the steady state
temperature and gas saturation versus depth; and the
other two involve parameters of the variation with
depth of the transient, approximately sinusoidal,
diurnal temperature, namely, amplitude decay and
phase shift. Calibration of the TOUGH2 models
provides information about soil properties and heat
and mass flows at each site. Model calibration also
indicates a suitable range of parameters for the van
Genuchten-Mualem relative permeability and van
Genuchten capillary functions (Mualem, 1976; van
Genuchten, 1980).