Wiercenia na obszarze struktury Mogilna

Józef Stemulak, Julian Sokołowski

Abstract


DRILLINGS IN THE REGION OF THE MOGILNO-STRUCTURE

During 1955-57, the oil industry has been undertaking exploration work in.· the region of Mogilno 20 seismic profiles were carried out, and on their basis the first structural maps have been plotted.

Simultaneously with this seismic research, cartographical test holes were sunk to depths of 500 to 800 m.

The results of these studies yielded the cognizance of the geological structure of this region. We have to do here with an elevated structure of anticlinal type, genetically associated with the tectonics of the salt dome. This anticline has developed in the regional unit known as the Łódź - Szczecin basin.

The north-western part of this structure, beyond the fault (Fig. 2), and the south-western part, within the range of dipping, disclose a relatively gentle anticlinal form while the central part is strongly elevated. In this part, the core of the structure consists of saline Zechstein sediments and Keuper clays, enveloped by Jurassic and Cretaceous deposits.

The seismic picture of the central part of this structure (Fig. 6) indicated a possibility of a salt dome appearing there; this conjecture was upheld by the -test drillings Mogilno Geo 10 and Mogilno 1.

As to the investigation for. oil, the hopes as to the Cretaceous have failed; in this region oil had been expected to be found in the Cretaceous formations. There arises, however, the possibility of reaching bitumina in the Dogger and Lias; furthermore a new problem arose - namely of the Zechstein. It seems possible to reach the main dolomites at a depth of maximum 3000 m.

An important matter, as far as industrial utilization is concerned, is the discovery of ore-bearing horizons in the Lower Cretaceous; this refers not only to the discussed area, but likewise to the adjacent Gopło structure.

For those interested in seams of brown coal it should be mentioned that - at an average depth of 100 m. - in all boreholes the occurrence of a seam of brown coal in the Miocene has been ascertained, of a thickness of 10 to. 20 m.

The above presented information is to be considered a temporary report; detailed data shall be published after termination of drillings in this region.


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