Abstract

Results of laboratory experiments and well logging processing and interpretation are described to show the investigation trial realized on the Polish Silurian and Ordovician shale gas deposits in the Baltic Basin, north Poland. Standard and sophisticated laboratory methods of density, porosity, permeability, mineral composition and geochemical parameters measurements on rock samples were performed. Statistical methods were applied to standard, dipole sonic and geochemical well logs to limit the processed data without loss of useful petrophysical information, avoiding redundancy and doing the primary classification. The goal of this specific trial was to build petrophysical model of shale gas rocks taking into account low porosity, very low permeability, TOC equal at least 2 wt.% and organic matter as a kerogen and bitumen, free gas gathered in the rock matrix effective porosity and in secondary porosity. The unique model for the Polish shale gas formations is explained by age, depth of occurrence and mineral composition of the Silurian and Ordovician shales, different from those described in the literature.

Keywords: Silurian and Ordovician shale gas formation; Baltic basin; Poland