Novel geothermal gradient map of the Croatian part of the Pannonian Basin System based on data interpretation from 154 deep exploration wells

As part of EU strategy to tackle climate changes, energy transition from fossil fuels to renewable resources is necessary. During the last few years, in the Republic of Croatia there is a strong tailwind towards promoting activities of geothermal energy exploration and exploitation. As geothermal sector was often neglected in a favour of petroleum business in the past, there is still a somewhat knowledge gap in groundwork related to defining geothermal resources potential. Since initial investigation related to defining hot spots in geothermal gradient were conducted more than 40 years ago, there was a need to remodel older imprecise maps with a completely new groundwork research in this area. More than 150 deep oil&gas exploration wells scattered in the Croatian part of the Pannonian Basin were elaborated. From the historical well development records and temperature measurements, obtained with different methods, a novel geothermal gradient map was constructed. Furthermore, to define local potential sites for direct heat utilization and electricity production, temperature maps were designed for a depth of 1000 and 2000 m, respectively.