Key words: reservoir, permeability and porosity, void space configuration, secondary porosity, vugs, fractures, dolomites, limestones, capillary and subcapillary pores.
The paper presents the results of core, thin section and log data analysis for the Lower Devonian Ovinparma Formation and Upper Silurian Greben Formation on R. Trebs oil field. The reservoir rocks are Devonian and Upper Silurian carbonates. Based on core and thin section description they are highly heterogeneous both in their lithology as well as in the configuration of their void space. The productive formations consist of dolomites, muddy dolomites, limestones and mudstones. The change from dolomites to calcareous dolomites and dolomitic limestones is accompanied by decrease in porosity and permeability of the reservoir. The void space is characterized by the presence of vugs and fractures. The pores are capillary and subcapillary. The comparison of reservoir properties and its structural arrangement from core data to the data evaluated from certain well-logging techniques allowed the identification of flow intervals within these complex reservoirs.
