Summary Twenty-one national geological surveys contributed to the European wide project ‘EU Unconventional Oil and Gas Assessment’ (EUOGA). The goal of EUOGA was to assess all potentially prospective shale formations from the main onshore basins in Europe and included contributions of twenty-one European geological surveys. Each participating geological survey characterized their domestic shale plays using thirty systematic parameters such as areal distribution, structural setting, average net to gross ratio of the shale reservoir, average Total Organic Carboncontent (TOC) and average mineralogical composition. The assessment covers 82 geological formations from 38 basins. Subsequently a stochastic volumetric probability assessment was performed on 49 of these formations which met the prerequisites for assessment. Importantly, this study for the first time used a unified methodology for assessing resources across European borders. Paleozoic plays in Poland, the United Kingdom, Denmark and Ukraine hold the largest potential gas resources. Most shale oil potential is observed in Bulgaria, the United Kingdom and Ukraine. The total resource potential for the geological formations that were evaluated in the project is 89.2 trillion cubic meter of gas initially in place (GIIP P50) and 31.4 billion bbl of oil initially in place (OIIP P50). The outcome of this project represents the most complete and accurate determination of shale hydrocarbon resources in Europe to date. Introduction Europe may hold significant volumes of unconventional hydrocarbons as has been showed by both national and international agencies (e.g., EIA 2011, 2013, van Bergen 2013, Andrews 2013, 2014, BGR 2012, Ladage 2016, PGI-NRI 2012). Interpretation and comparability of these studies is problematic, primarily due to difference in assessment methodology and both the quality and quantity of geological data that was available for the different plays. As a consequence the total European shale resource potential remains uncertain making long term planning, both political and economic, difficult. To overcome this problem a uniform assessment of European shale resources was required tailored to the specific challenges of the European situation.

Summary Characterizing and mapping the regional extent of the Lower Paleozoic shales in Poland has, in the past, been challenging. However, the integration of newly-acquired broadband seismic data, designed to image deeper within the basins and with greater resolution, and key well data has more clearly defined the tectonic structure and regional depositional architecture of the Upper Ordovician-Silurian succession. Geological Background The Lower Paleozoic basin in Poland is located above the southwest edge of the East European Craton, northwest from the Teisseyre - Tornquist Zone which is separating the cratonic plate from the West European Platform (Fig. 1; Ziegler, 1992; Doornenbal & Stevenson, 2010). Later Late Paleozoic tectonic movements resulted in compartmentalization of the Lower Paleozoic basin into three sub-basins: Baltic Basin, Podlasie Basin and Lublin Basin (Fig. 2). During the Precambrian/Cambrian, the cratonic edge underwent extension and rifting of the Rodinia supercontinent, while Cambrian - Middle Ordovician subsidence was driven by a post-rift lithospheric thermal cooling (Poprawa et al., 1999; Poprawa, 2006a). In the Late Ordovician - Silurian, the cratonic edge was under the strong influence of the Caledonide thrust belt, and was incorporated into its flexural foredeep basin (Poprawa et al., 1999; Nawrocki & Poprawa, 2006). Deposition was dominated by fine-grained organic rich shales, generally derived from the eroded orogenic wedge and deposited in the distal foredeep basin (Poprawa et al., 1999; Poprawa, 2006b). The Silurian Caledonian foredeep basin encompassed vast areas stretching from the present-day Sweden across Estonia, Latvian, Lithuania, Russia (i.e. Kaliningrad District), Poland, Belarus, Ukraine and farther to the southeast (Poprawa et al., 1999; Skompski et al., 2008; Zdanaviciute and Lazauskiene, 2007). Presently available information regarding the Caledonian orogenic wedge is very limited and mostly indirect, based on e.g. provenance studies of the foredeep infill, as it was destroyed and deeply buried during the later tectonic phases (Poprawa, 2006b). URTeC 1578800

Abstract In unconventional shale plays both sides of the hydrocarbon systems - source and reservoir - are joined together in one shale unit. Many workflows established in exploration of conventional hydrocarbon systems, are focused on one side only, reservoir or source rock units. Therefore new workflows are needed for the comprehensive assessment of shale systems - as source, trap and seal altogether - for a better understanding and enhanced evaluation of unconventional shale plays. OPTICAL KEROGEN ANALYSIS is a new workflow, focused on the needs of unconventional shale play analysis, based on optical methods to analyse both sides of the system: the source rock potential by high resolution studies of kerogen composition and maturation and the reservoir potential by the analysis of kerogen microporosity estimated from kerogen preservation, indicating the gas storage capacity of the shales. Beside the optical analysis some basic chemical analysis is included in this workflow: TOC and optional CNS analysis. Kerogen composition quantifies the components of the total kerogen according to schemes developed for palynofacies analysis. The palynologically defined organic matter groups get transfered to standard kerogen types, leading to the detailed quantification of each kerogen type seperately. This enhances significantly the resolution and reliability of kerogen analysis, compared to bulk-rock geochemical methods like Rock Eval pyrolysis. Kerogen preservation indicates the level of generated hydrocarbons due to the increasing degradation of organic matter during hydrocarbon generation. On the other hand, of particular interest for unconventional shale plays, preservation is a key parameter for the estimation of kerogen microporosity and therefore for the storage capacity of shale plays, because most of the secondary generated gas is trapped there. Optical analysis of maturation is based on vitrinite reflectance and palynomorph colour indices. For vitrinite reflectance a new digital analysis workflow is used based on high resolution digital images of vitrinite. This strongly enhances both, resolution and reliabiltiy of VR analysis, especially for fine-grained rocks with dispersed organic matter like shales. Cross-calibration of both methods improves the confidence level of maturation data, leading to enhanced palaeothermal models of basin and hydrocarbon system development. Data from OPTICAL KEROGEN ANALYSIS can get implemented directly into organofacies based hydrocarbom system modeling. OPTICAL KEROGEN ANALYSIS is tested at organic rich shales from potential unconventional shale plays in different geological settings and stratigraphical ages: from the Carboniferous in Germany, the lower Palaeozoic of northern and eastern Europe and the lower Jurassic of southern Germany. URTeC 1581418