Tectono-thermal Evolution of the Lower Paleozoic Petroleum Source Rocks in the Southern Lublin Trough: Implications for Shale Gas Exploration from Maturity Modelling

Abstract

The Lower Paleozoic basins of eastern Poland have recently been the focus of intensive exploration for shale gas. In the Lublin Basin potential unconventional play is related to Lower Silurian source rocks. In order to assess petroleum charge history of these shale gas reservoirs, 1-D maturity modeling has been performed. In the Łopiennik IG-1 well, which is the only well that penetrated Lower Paleozoic strata in the study area, the uniform vitrinite reflectance values within the Paleozoic section are interpreted as being mainly the result of higher heat flow in the Late Carboniferous to Early Permian times and ~3500 m thick overburden eroded due to the Variscan inversion. Moreover, our model has been supported by zircon helium and apatite fission track dating. The Lower Paleozoic strata in the study area reached maximum temperature in the Late Carboniferous time. Accomplished tectono-thermal model allowed establishing that petroleum generation in the Lower Silurian source rocks developed mainly in the Devonian – Carboniferous period. Whereas, during Mesozoic burial, hydrocarbon generation processes did not develop again. This has negative influence on potential durability of shale gas reservoirs.

Reply on RC1

“…11c). Both estimates are similar to that from maturity modelling based on the VR and porosity data (Botor, 2018;Botor et al, 2019a…”

“…Maturity modelling, based on downhole VR profiles (Fig. 5), showed that the thermal evolution in the Lublin Basin was related to burial in Devonian-Carboniferous times with the most prominent temperature increase in the late Carboniferous (Botor et al, 2002;Karnkowski, 2003;Kosakowski et al, 2013;Botor, 2018;Botor et al, 2019a,b). A fluid flow influence on thermal maturity in this area was suggested by Poprawa andŻywiecki (2005) based on combined analysis of fluid inclusions and modelling of organic maturation.…”

Thermal history of the East European Platform margin in Poland based on apatite and zircon low-temperature thermochronology

“…The locations of PolandSPAN™ seismic profiles (PL1-5100, 5300, 5400) used in Fig. 2 al., 2018;Mazur et al, 2018b). The initially uniform early Paleozoic basin was subsequently separated by differential exhumation in three distinct parts: the Baltic, Podlasie, and Lublin basins, straddling the SW slope of the EEP from the NW to SE (Fig.…”

“…Permian and Mesozoic rocks in the Baltic Basin show much lower thermal maturity compared to the lower Paleozoic sediments, usually below 0.6 % VR (Grotek, 1999(Grotek, , 2006Poprawa et al, 2010). Further SE, thermal maturity is variable in the Carboniferous and Devonian-Carboniferous strata of the Podlasie and Lublin basins, respectively (Poprawa and Pacześnia, 2002;Grotek, 2005;Botor et al, 2002Botor et al, , 2019a. However, the Permian-Mesozoic sediments consistently show low thermal maturity below 0.5 % VR in these basins (Grotek, 2005(Grotek, , 2006(Grotek, , 2016.…”

“…Although quantitative estimates of exhumation have been previously performed based on thermal maturity of organic matter, they provided divergent results due to the absence of thermochronological data (e.g. Botor et al, 2002;Poprawa et al, 2010). However, in the Scandinavian part of the EEP, the discordant zircon U-Pb ages, onlap of Paleozoic sediments, geomorphological analyses, and low-temperature thermochronology indicate that the Precambrian basement was buried beneath extensive Paleozoic and Mesozoic sedimentary successions (Lidmar-Bergström, 1993, 1996Hansen, 1995;Larson and Tullborg, 1998;Larson et al, 1999;Hendriks and Redfield, 2005;Söderlund et al, 2005;Green and Duddy, 2006;Larson et al, 2006;Hendriks et al, 2007;Japsen et al, 2016Japsen et al, , 2018Guenthner et al, 2017).…”