Methodology and results of digital mapping and 3D modelling of the Lower Palaeozoic strata on the East European Craton, Poland
Annales Societatis Geologorum Poloniae
One of the main goals of the GAZGEOLMOD Project was the construction of a complete set of 3D structural models and 2D grid-based structural and thickness maps of the Lower Palaeozoic complexes Papiernik, 2017a, b) . The methodology selected to obtain these objectives comprised a multistage set of procedures, based on the direct efforts of a team with approximately 10 members and indirect collaboration with practically all scientific participants of the project, in fact with dozens of
... ozens of scientists. The main phases of the procedure included the completion of an exhaustive database project in Petrel TM , completion of several generations of intermediate structural and thickness maps and composed of them 3D structural models, separately for the Baltic Basin, the Podlasie Basin and the Lublin Basin, then the integration of partial maps into the digital maps (2D grids) and 3D models for the onshore part of the East European Craton (EEC), and finally the construction of parametric models of selected basic components of the Silurian-Ordovician petroleum system , such as total organic carbon content (TOC), vitrinite reflectance (Ro) and porosity. Preliminary, regional models of velocity for the Lublin Basin, Abstract: The paper presents a multi-phase and multi-stage methodology of 3D structural-parametric modelling and mapping that has been applied during implementation of the GAZGEOLMOD project. The core of the applied processing workflows is a 3D geological model constructed in Petrel, which functions as a spatial database for all kinds of geological models. The first phase of the workflow comprised an extended process of database project building that was very intensive at the beginning of the project and continued to its end. The second phase of processing consisted of a complex process of mapping and structural modelling that is performed in 8 stages, allowing for iterative improvements of model resolution. During the realization of stages 1 to 7, processing was run independently for the Baltic (BB), Podlasie (PB) and Lublin Basins (LB). The workflow included the following stages: (1) unification and digitization of published and on file analogue and digital, structural maps; (2) preliminary reinterpretation, including adjustment to stratigraphy data acquired from archives; (3) adjusting the maps to the primary results of seismic interpretation, mainly from archival data; (4) digitization and gridding of pre-existing palaeothickness maps and updates of them with data from boreholes completed after 2009; the reinterpretation of the palaeothickness maps into contemporary thickness maps; (5) elaboration of the primary structural 3D models for the three basins; (6) increasing of the stratigraphic resolution of models up to the rank of the geological epoch for Ordovician-Silurian strata; (7) conversion of basin-scale structural models into a 2D grid, and their merging into platform-scale surfaces, resulting in 45 structural and thickness maps; finally, they were adjusted to the results of seismic interpretation and sedimentological studies, obtained in the project; and (8) completion of the resulting structural models for each of the basins and for the entire Polish part of the East European Craton in several different versions. In the third phase of processing, parametric models of vitrinite reflectance (R o ) and Total Organic Carbon (TOC) were estimated.