Exploring Depleted Oil and Gas Fields for CCS in Compressional Settings: Lessons from Eastern Carpathians

Summary Climate change is undoubtedly recognized as a global 21st-century threat with environmental, socio-political, and socio-economic impacts. Anthropogenic greenhouse gas emissions, including carbon dioxide (CO2) are considered the dominant driver of such change. To reduce the CO2 emissions and be a key contributor to reaching the EU’s net zero emissions target, carbon capture and storage (CCS) has been employed, among other solutions. Romania has a promising theoretical CO2 storage capacity in different settings, including in depleted oil and gas reservoirs. Among these, the Eastern Carpathians fold and thrust belt is considered the second-largest candidate for CCS in Romania. Although a promising setting, CO2 storage in depleted oil and gas reservoirs, in fold and thrust belts, presents several risks, and the major one represents the leakage of CO2 from the storage sites. Here we outline some of the major uncertainties associated with CO2 storage in fold and thrust belts, by analysing one of the oldest hydrocarbon provinces in the world, the Eastern Carpathians fold and thrust belt.