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Papiernik Bartosz, AGH University of Science and Technology (Poland)
Paweł Kosakowski, AGH University of Science and Technology (Poland)
Grzegorz Machowski, AGH University of Science and Technology (Poland)
Roman Semyrka, AGH University of Science and Technology (Poland)
Kazimierz Słupczyński, AGH University of Science and Technology (Poland)
Adam Kowalski, AGH University of Science and Technology (Poland)
Marek Capik, AGH University of Science and Technology (Poland)
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The Grotów Peninsula area (W Poland) is an excellent illustration of hydrocarbon generation conditions as well as lithofacial, paleogeographical, petrophysical and structural variability of the most prospective zone of the Zechstein Main Dolomite (Ca2) Petroleum System in the Fore-Sudetic Monocline. It comprises separate depositional systems of the basin flat, slope of the carbonate platform and the carbonate platform itself. In such places, potentially source and reservoir rocks were deposited close to each other. Carbonates deposited on platform flats and within oolite barriers most frequently are sands textured as grainstones and packstones. Locally in low energy zones of the platform flats mudstones occur mudstone admixtures. Over the whole platform area, intercalations of microbial boundstones are present. On the platform slope and at the toe of the slope grainstones, mudstones and boundstones are represented in variable proportions. Towards the basin floor carbonates are more homogeneous and they become dominated by mudstones.
Geochemical characteristics of the organic matter - amounts, depositional environment and genetic types, and transformation degree in carbonates of the Grotów Peninsula was based on the analytical results of 436 core samples collected from 13 wells. The samples represent carbonate platform, oolite reef barrier and slope of carbonate platform. The content of organic carbon in the Main Dolomite carbonates in the study area vary widely from 0.01 to 4.3 wt.%, with average of 0.42 wt.%. The highest concentration of TOC was measured in the northern part of the carbonate platform in intercalations of mudstones and boundstones. In the Main Dolomite carbonates, oil-prone type II kerogen dominates with occasional amounts of type III or type I kerogens. The thermal maturation of organic matter corresponds to the "oil window" (0.5 � 1.3 %Ro) and partially in the eastern part, to the "gas window" (>1.3 %Ro).
Structural, lithological as well as reservoir variability and saturation of the Main Dolomite were reconstructed in a form of 3D grid in the western part of the Grotów Peninsula. It was based on 3D seismic interpretation, petrophysical and petrographical data from cores, and well logging data from 13 wells. Modeling allowed to establish the shape of OWC according to logs interpretation and GOC according to saturation pressure and PVT measurements. Spatial modeling results let to demonstrate that the best reservoir are textured as grainstones and packstones (total effective porosity up to 33%, av.∼11%). Mudstones are generally poorer reservoirs, displaying porosity up to 22% (av.∼5%). Porosity of boundstones is not higher than 11% (av. 5%). Modeling results show clearly that the zones where reservoirs are relatively better (comprising permeability up to 40mD) occur within grainstones dominated oolite barriers as well as on slopes and at the toe of the slope where interfingering of grainstones and mudstones took place.
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