Radiogenic heat of Zechstein and Carboniferous rocks calculated using well-logging data from the Brońsko Reef area

Rocks characterized by an increased kerogene transformation ratio, which is an important indicator of hydrocarbon generation in petroleum exploration, generate more radiogenic heat as well. The goal of this paper was to evaluate radiogenic heat (A) in several boreholes drilled through Zechstein and Carboniferous deposits of the Brońsko Reef. Based on spectral gamma ray and Litho-Density Logs measurements, the quantitative concentration of radioactive elements including uranium, thorium and radioactive isotope of potassium (40K) was evaluated. These data along with bulk density were subsequently used to calculate the radioactive heat. The calculations were performed for boreholes B-2, B-3, B-4 and B-8, located in central part of the reef. Increased values of A appeared characteristic for the Main Dolomite, Zechstein limestone and Carboniferous deposits with high share of shales