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EN
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 area
EN
The Pogórska Wola palaeovalley of combined tectonic and erosional origin dissects the Mesozoic floor of the Carpathian Foredeep Basin to a depth exceeding 1200 m. It formed during Paleogene times presumably due to fluvial and submarine erosion, concentrated along a local pre-Late Badenian graben system. All members of the foredeep’s Badenian-Sarmatian sedimentary fill attain distinctly greater values inside the palaeovalley than on top of elevated plateaux on palaeovalley shoulders. The fill comprises the Early to Late Badenian sub-evaporite Skawina Formation, the laterally equivalent Late Badenian evaporite Krzyżanowice and Wieliczka formations and the supra-evaporite Late Badenian to Early Sarmatian Machów Formation. Over the plateaux and in the highest palaeovalley segment, the evaporites are developed in the sulphate facies Krzyżanowice Formation, whereas in the lower palaeovalley segments chloride-sulphate facies evaporites of the Wieliczka Formation occur. The rock salt-bearing rocks are involved in thrusting and folding at the Carpathian orogenic front, which helps to assess the lateral extent of the Wieliczka Formation in seismic records. The deep palaeotopographic position of the evaporites inside the palaeovalley, combined with their lithological and sedimentary features, point to their formation via subaqueous gravity flow-driven redeposition of originally shallow-water evaporites, preferentially halite-bearing, presumably combined with precipitation from sulphate and chloride brines at the palaeovalley floor. Both the redeposited sediments and the brines must have come from the adjacent plateaux and from a thrust-sheet top basin, approaching from the south on top of the Cretaceous-Paleogene Carpathian flysch thrust wedge.
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