Quantitative and qualitative petrophysical characteristics of main dolomite subfacies in pleogeographical zones

This work focuses on analysis and characterization of petrophysical properties of the Main Dolomite strata in the study area, against the background of its paleogeographic and facial development. The microfacial analysis, together with detailed sedimentological analysis, made it possible to distinguish the depositional environments of the Main Dolomite succession in the study area. The Main Dolomite is characterized by diversity in thickness, lithology, and facial development of the following zones: foot of the carbonate platform, barrier, and platform plain. Three principal sub-facies were distinguished there grainstones, mudstones, and boundstones (the microbial sub-facies). These sub-facies reveal diversified petrophysical parameters. The analysis is based on the results of porosimetric measurements which enable assessment and qualification of this horizon from the point of view of its hydrocarbon reservoir capacity and pore space character. Principles of porous rock qualification in terms of hydrocarbon reservoirs include mainly assessment of effective and dynamic porosities for oil and gas, bulk and framework densities, and pore space geometry (distribution of predominating pore diameters and specific surface of the pore space). This assessment refers to the pore space in which processes of migration and accumulation of reservoir fluids occur. Statistical analysis of the petrophysical parameters revealed their relationships within the distinguished lithofacial zones, which also represent an important solution.