Prospective zones for unconventional hydrocarbon resources in Cambrian, Ordovician, Silurian and Carboniferous rocks of Poland : integration of the research results

The paper presents the characteristics of prospective zones identified for the first time within the lower Palaeozoic shale formations occurring in the Baltic-Podlasie-Lublin Basin and within the Carboniferous shale, sandstone, and mixed shale-sandstone complexes (the so-called hybrid complexes) in the basin of south-western Poland. The lateral and vertical ranges of these zones are determined based on specific criteria using the results of various research methods and analyses, i.e.: stratigraphic, sedimentological, mineralogical, petrological and geochemical of organic matter, petrographic and petrophysical, including interpretation of well logs. Archived geological materials and those coming from the boreholes drilled recently in the concession areas were also used. Four prospective zones have been distinguished in the lower Palaeozoic of the so-called shale belt: SP1, SP2, SP3 and SP4. The most prospective area for the occurrence of unconventional hydrocarbon deposits in shale formations is the Baltic region – the Łeba Elevation, where there are all four perspective zones, only partially covering the range of potentially prospective formations. In each of these zones, both liquid and gas hydrocarbons can be expected in this area. Due to the low percentage of organic matter, the lowest hydrocarbon generation potential is attributed to the Lublin region. However, the low values of this parameter are compensated by other parameters, i.e. the considerable thickness and lateral extent of zone SP4 corresponding partly to the Pelplin Formation. In the Carboniferous rocks of south-western Poland, seven prospective zones have been distinguished in four borehole sections. Four of them are “tight” zones in compact sandstones, while the other three zones represent a hybrid type in complexes with mixed lithology. No prospective zones have been defined in complexes with homogeneous shale lithologies. Determination of lateral extents of the identified zones has not been possible due to the scarcity of data on the geological structure and stratigraphy of the Carboniferous succession in the study are