Baltic countries are located in the limits of the Baltic sedimentary basin, a 700 km long and 500 km wide synclinal structure. The axis of the syneclise plunges to the southwest. In Poland the Precambrian basement occurs at a depth of 5 km. The Baltic Basin includes the Neoproterozoic Ediacaran (Vendian) at the base and all Phanerozoic systems. Two aquifers, the lower Devonian and Cambrian reservoirs, meet the basic requirements for CO₂ storage. The porosity and permeability of sandstone decrease with depth. The average porosity of Cambrian sandstone at depths of 80–800, 800–1800, and 1800–2300 m is 18.6, 14.2, and 5.5%, respectively. The average permeability is, respectively, 311, 251, and 12 mD. Devonian sandstone has an average porosity of 26% and permeability in the range of 0.5–2 D. Prospective Cambrian structural traps occur only in Latvia. The 16 largest ones have CO₂ storage capacity in the range of 2–74 Mt, with total capacity exceeding 400 Mt. The structural trapping is not an option for Lithuania as the uplifts there are too small. Another option is utilization of CO₂ for enhanced oil recovery (EOR). The estimated total EOR net volume of CO₂ (part of CO₂ remaining in the formation) in Lithuania is 5.6 Mt. Solubility and mineral trapping are a long-term option. The calculated total solubility trapping capacity of the Cambrian reservoir is as high as 11 Gt of CO₂ within the area of the supercritical state of carbon dioxide.

Industrial CO₂ emissions and geological storage opportunities in Estonia, Latvia and Lithuania are studied within the framework of EU GEO­CAPACITY and CO2NET EAST projects supported by European Commission through Framework Programme 6. The structure of the energy sector and socio-economic conditions vary considerably between these three countries. A total of 24 large (emitting more than 0.1 million tonnes (Mt) of CO₂) industrial sources of CO₂ emissions, registered in 2005 in the European Trad­ing Scheme, consists of 11.5 Mt of CO₂  from Estonia, 1.9 Mt from Latvia and 5.6 Mt from Lithuania. The highest amount of CO₂ emission in Estonia is related to the oil shale used as the main fuel for power generation; the two largest Estonian power plants – Estonian and Baltic – produced respectively 7.7 and 2.25 Mt of CO₂ in 2005 and 9.4 and 2.7 Mt of CO₂ in 2007. CO₂ emission from oil shale combustion is significantly higher in comparison with other fossil fuels as energy sources. This is why CO₂ emission per capita in Estonia is about two times higher than the average value in Europe. The three Baltic States are located within the Baltic sedimentary basin, the thickness of which varies from 100 m in Northeast Estonia up to 1900 m in Southwest Latvia and 2300 m in West Lithuania. The most prospective formation for geological storage of CO₂ is the Cambrian reservoir. 15 large structures have been identified in Latvia with a total capacity exceeding 300 Mt of CO₂. The tightness of structures is evidenced by 40 years of success­ful operation of the Inčukalns Underground Gas Storage. Due to shallow setting, geological conditions in Estonia are unfavourable for CO₂ storage. Therefore an option of transporting CO₂ from Estonia via pipelines to one of the Latvian storage structures could be considered. Alternatively, the technology of CO₂ trapping by sorption of oil shale ash is under develop­ment in Estonia. In Lithuania, the capacity of CO₂ storage in Cambrian and Devonian structures as well as in oil fields is negligible, but CO₂ solubility and mineral trapping is a long-term option.

The Early Carboniferous magmatic event in the southern Baltic Sea is manifested by dolerite intrusions. The presumable area in which the dolerite intrusions occur ranges from 30 to 60 km in east–west direction, and is about 100 km in north–south direction. The dolerites were sampled in well D1-1 and investigated by applying chemical analysis and ⁴⁰Ar/³⁹Ar step-heating dating. Dolerites are classified as alkali and sodic, characterized by high TiO₂ (3.92, 3.99 wt%) and P₂O₅ (1.67, 1.77 wt%) and low MgO (4.89, 4.91 wt%) concentrations, enriched in light rare earth elements, originated from an enriched mantle magma source and emplaced in a continental rift tectonic setting. The 351 ± 11 Ma ⁴⁰Ar/³⁹Ar plateau age for groundmass plagioclase indicates a considerable age gap with the 310–250 Ma magmatism in southern Scandinavia and northern Germany. The magmatic rocks in the Baltic Sedimentary Basin are coeval with alkaline intrusions of NE Poland. Both magmatic provinces lie in the northwestward prolongation of the Pripyat–Dnieper–Donetsk Rift (370–359 Ma) and may constitute a later phase of magmatic activity of this propagating rift system.

The Baltic sedimentary basin contains numerous hydrocarbon fields in Lithuania. The Lower Silurian shales are considered as potential for shale gas exploration. The thickness of shale units within the oil window ranges from 115 to 180 m in west Lithuania. The average total organic carbon (TOC) content of the Lower Silurian shales is about 1.0–1.2%, with an elevated content averaging 6.7% in the Aeronian black shales. The organic matter (OM) is Type II kerogen. Pyrolysis analysis shows moderate thermal maturity parameters; T_max is from 428 °C in central Lithuania to 455 °C in the west of the country, implying the oil generation stage. It is concluded that the burial conditions were favorable for oil generation, while the gas potential of Silurian shales is rather limited.