Interpretation and modelling of the temperature distribution at Laugavatn in Thelamörk, N-Iceland

Abstract

In this work several possibilities as to the flowpaths of hot water were examined in a small low temperature geothermal field, Laugaland in Thelamörk, N-Iceland, after taking into consideration all available geological, geophysical and temperature data. Four possibilities were tested by calculating the temperature distribution created by a near vertical fracture on profiles perpendicular to its strike, and comparing it to measured temperatures in the wells. First, the calculations in the modelling process were made using a programme called VARMI, which numerically solves the Laplace equation in two dimensions, with no time dependency. The assumption of steady state conditions, as well as the influence of recent horizontal flow (the last 30 years) through thin horizontal layers, were then checked with a numerical simulator PT that solves both mass and energy transport equations in time; here, only the part that solves the energy transport equation was used. The possibilities that remained valid after the modelling were even more restricted after taking into consideration temperature data from well LL9, which was drilled during the completion of the report. These data made it possible to construct temperature maps at different depths, which helped to clarify some of the ambiguities that still remained.