Possibilities for Well Log Correlation using Standard Deviation Trends in Neogene-Quaternary Sediments, Sava Depression, Pannonian Basin

The regular working method for well log correlation in the Neogene-Quaternary infill of the Croatian Pannonian Basin is based on visual identification of specific motifs that can be observed regionally through the sub-basins or depressions. This method is proven successful through exploration for petroleum accumulations in the aforementioned area but its application is limited outside of the interval of the Upper Miocene sediments and has proven to be subjective. Standard deviation values of well log data from conventional well logs (spontaneous potential, shallow and deep resistivity) were calculated and observed over the entire Neogene-Quaternary well interval for defining new correlation markers which correspond to the old well log marker horizons. Traditionally determined marker horizons did not coincide with those defined by the standard deviation technique. However, new regional horizons were established in the youngest part of the infill, which made more detailed correlation now possible.