2-D modelling of petroleum processes of the lower Paleozoic strata in the Polish part of the Baltic region

2-D modelling of hydrocarbon generation, expulsion, migration and accumulation processes was carried out for the four (Middle Cambrian, Upper Cambrian-Tremadocian, Caradocian and Llandovery) source rock horizons. The petroleum potential of these source rocks is different, the highest being observed in the Upper Cambrian-Tremadocian horizon and the lowest in the Middle Cambrian one. The maturity of organic matter within these source units increases from the north-east to the south-west of the Polish part of Baltic region. The petroleum generation from these source rocks was highest in the Darlowo and Slupsk blocks as well as in the onshore part of the Leba Block. Expulsion took place mainly from the Upper Cambrian-Tremadocian source rocks and these rocks sourced almost all hydrocarbons accumulated within the Middle Cambrian sandstone reservoirs. Migration of hydrocarbons proceeded along fault zones. Almost all petroleum processes in the study area took place between the end of the Pridoli and the end of the Carboniferous. Moreover, during the Permian and the Mesozoic, part of the hydrocarbons remigrated within the reservoir. This process changed the setting and the volume of hydrocarbon accumulations. It was caused by the tectonic rebuilding of the basin and, in most cases, it led to the modification of accumulation range or to the dispersion of hydrocarbons.