Komputerowa analiza potencjalnych możliwości akumulacji gazu ziemnego w utworach czerwonego spągowca w polskim basenie permskim

Paweł Henryk Karnkowski

Abstrakt


COMPUTER-AIDED ANALYSIS OF GAS ACCUMULATION POTENTIAL WITHIN THE ROTLIEGEND DEPOSITS IN THE POLISH PERMIAN BASIN

Summary
Polish Permian Basin is the eastern part of the great Southern Permian Basin which extended from England, through the Netherlands, North Sea, Germany, Denmark, up to Poland. The current investigations indicate further possibilities of oil and gas exploration in this basin. The former geosynopsis elaborations for this basin were done without workstations. Now, we have PetroMode (IES) application and from this moment the geological, geophysical and geochemical data are analysed together. This analysis becomes a base for simulation programme of hydrocarbon's generation, expulsion and migration resulted from the geological evolution of basin. The fourteen geological cross-sections, from 100 to 400 km long, cutting perpendicularly the Polish Rotliegend Basin, were a basis of analysis (Figs 1-3). The cross-sections were prepared with complementary usage of seismic, gravimetric and well data. The Carboniferous rocks, underlying the Rotliegend deposits, were taken under simulation as source rocks. The Zechstein evaporites, overlying Rotliegend Group, were regarded as seal rocks. For the Rotliegend deposits differentiated lithology was assumed: claystone and siltstone mainly in the basin centre, but sands tones and conglomerates in the transitional and marginal zones (Figs 1, 4). Maximum value of erosion during the late Jurassic and early Tertiary is assumed to attain 2-3 km in the zones with highest degradation (Mid Polish Anticlinorium, Fore-Sudetic Monocline). The paleobathymetriccorrection also was considered. The value of heat flow for modelling of 60 W\m2 was assumed. Since the Carboniferous rocks are almost in the gas phase, it should be thought that a heat flow value used for simulation is sufficient. The simulation results are fourteen cross-sections showing quantity and quality total petroleum volume for each geological region (Fig. 5). Obtained results were visualized on the map (Fig. 6) and compared to actual gas fields distribution. In the zones ofhydrocarbons accumulation the value of total petroleum volumeeverywhere is high. On the other hand the map indicatesthe new prospective regions for future studies. There are as follows: 1) Western Pomerania region between Daszewo and Resko, 2) region between Poznań and Czeszewo, 3) region located north-east of Września, 4) region between Sława and Głogów. Regions of high gas accumulation potential mentioned above are partly concordant with the prognostic zones indicated in other projects, but the suggested here are more precisely contoured and limited to individual areas.

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