Distributed parameter models : The Glerardalur geothermal field, N-Iceland : the Podhale geothermal field, Poland

Abstract

The report describes distributed parameter models of two geothermal reservoirs. The basic equations of the problem are derived and the reservoir behaviour of two different geothermal fields is analyzed. The first field is the Glerardalur geothermal field in N-Iceland. In this case the calibration of the model was made on the basis of 10 years of observations of the reservoir response to production. A good fit was achieved with the model for drawdown. The obtained reservoir parameters were used for future prediction of the pressure response of the field for different constant production rates. The present trend of stabilized drawdown can be maintained only for an annual average production rate not larger than 15 l/s. The calculations showed no cooling during the production period as well as for the future prediction period. The second field is the Podhale geothermal field in S-Poland. Because of insufficient amount of data from existing wells, only the theoretical model of the field was tested. The reservoir parameters chosen are believed to be close to real values. A stationary flow problem was solved for various constant production rates, as well as the transient heat transport problem, in order to determine the break-through time for the cold front. Two cases were examined: one consisting of one geothermal doublet (one production well and one injection well) and the other of five doublets in operation. The model shows that there is almost no difference in drawdown in both cases. Assuming production does not exceed the present artesian outflow of 20 l/s, the predicted temperature decline in production wells after 50 years of operation is less than 2 C. For the smallest distance between the wells, 710 m, the expected breakthrough time is 400 years.