SUBSURFACE MODELING AND UNCERTAINTY MODELS OF THE NEOGENE-QUATERNARY SEDIMENTS IN THE PART OF SAVA DEPRESSION BASED ON DIGITALIZATION OF LEGACY MAP DATA

Abstract

Aim of the research was the accurate digitalization and subsurface modelling of the legacy data, namely paper-based geological maps. The research area covers approximately 1053 km 2 and is located in Croatian part of Pannonian Basin System, Sava Depression, i.e. in the surrounding of Stružec Oil Field. Data input for the structural analysis were structural maps which were previously made in the 1980. Set included five structural maps based on regional E-log markers and one map of pre-Neogene surface. All were digitalized in program ArcGIS, and later modelled in Petrel. Structural contours and total of 134 faults were exported into Petrel software where they were further processed and regrouped. From such digitalized and processed data the geological model (geomodel) was made using complex fault framework. The study concerned the advantages and errors that occur during creation of such geomodel. It clearly displays relations between major and minor faults and fault slips, geological structures and structural traps in 3D (e.g. anticline of the Stružec Field). Another advantage is multicolored presentation of depths and faults, which enables easier recognition of geological structures and potential traps for hydrocarbons. Errors and issues can occur during digitalization of contour lines, selection of the appropriate algorithm and those ones that arise when model is created. Low error between two approaches indicates accuracy of digitalization of data and subsurface modelling. Uncertainty models (maps of statistical percentage deviation) were made in the Petrel Software for the display of the deviation between handmade maps and Petrel models for each E-log marker and one pre-Neogene top.