Paleozoic Near Salt Dome Formations – A New Target For Egs In Poland

In recent years, a significant increase in interest in the use of geothermal energy in Poland has been observed. The cumulative number of approved geological work aim at drilling exploration boreholes has increased to over 100 by the end of 2021. Almost all geothermal projects, excluding the Sudetes region, completed up to now have been focused on hydrogeothermal reserves related to Mesozoic formations. In particular, five out of six geothermal heating plants in Poland are located in the Polish Lowlands and are limited to the exploitation of waters from the Lower Jurassic and Lower Cretaceous aquifers. The geothermal potential of Paleozoic formations remains largely untapped. This is mainly due to the relatively poor hydrogeological recognition of the deep geological profile and relatively worse petrophysical parameters of Paleozoic rocks, resulting with low hydrogeothermal potential and significant high geological risk. Joint research conducted so far by the AGH University of Science and Technology and Polish Oil and Gas Company - PGNiG SA show that high geothermal potential of deep Paleozoic structures can be released while conducting oil exploration, especially in the area of confirmed high regional geothermal potential including anomaly high geothermal gradient and Earth's heat flux area. Thereby, the article focuses on concepts related to the adaptation of negative exploration or depleted hydrocarbon boreholes located in the vicinity of salt structures and accompanying thermal anomalies in order to exploit petrothermal energy resources using EGS systems in Poland. In our study, the site favorable for EGS system related to the Rotliegend tight sandstones complex found in the borehole K-1 drilled in 2019, located north-east of Poznań, have been investigated. The results indicate the importance of local structural and geothermal anomalies related to halo-tectonic structures and shows that the investigated target Kłecko Anticline structure, with the expected temperature in the most prospective Eolian complex reaches 160°C, meets all the requirements for setting up the first EGS system in Poland.