| Abstract [eng] |
As long as alternative energy sources for our society such as wave or tidal, wind and solar power cannot play a significant role in the energy supply human kind will remain dependent on hydrocarbons and other fossil fuels such as coal. it is crucial to further develop existing oil and gas resources and find new techniques to extend their economic life. the study is focused on the Minija regional stage, which belongs to the lower pridolian series of the silurian. The Minija regional stage carbonate facies in the silurian Baltic basin ranges from shallow in the east to deep marine in the western part. based on the study, a depositional and diagenetic model for the silurian carbonate system was built and was in particular focused on interpreting the Minija regional stage in central Lithuania. This augments the undertanding carbonate depositional systems in general and the development of petrophysical properties, mainly porosity and permeability. the central stromatoporoidal facies belt most probably were mainly stromatoporoidal biostromes instead of classic reefs. these were continuously reworked by storm induced currents into widespread proximal skeletal rudstones to more distal packstones. The entire carbonate system is more likely to be a ramp instead of a platform, because the biostromes had little or no relief because of continuous reworking. The reservoir quality of the limestones in the studied area is not good, with low porosity and low permeability. This is because of the intense diagenesis including early marine cementation of part of the coarser grained limestones, mechanical compaction, chemical compaction and almost complete cementation by calcite during burial. The best reservoir properties are found in the dolostones in the eastern shallow parts of the basin. |
