Integrated Approach to CO2 EOR and Storage Potential Evaluation in an Abandoned Oil Field in Czech Republic

The paper presents the results of the experimental and simulation activities of the Czech-Norwegian CO2 Pilot Preparation project (REPP-CO2) carried out under Norway Grants. A relatively small hydrocarbon field located in Vienna basin was selected as a candidate for the CO2-EOR and storage (CCUS) pilot. The field produced in 1950-1970’s, the available reservoir data is somewhat limited and uncertain as typical for old abandoned fields. Nevertheless, based on available geological knowledge, core material and fluid samples (sometimes from the neighboring analog fields) a geological model was build and an integrated approach to evaluation of CO2-EOR and storage (CCUS) potential was suggested. As a first approximation to the CCUS potential, a material balance model was established to evaluate aquifer size and connectivity, as well as potential CO2 storage capacity. The material balance study was based on available production history. Laboratory investigations of available core material and fluid samples allowed to identify and reduce the uncertainties related to fluid properties, geochemistry and geomechanics. An approach was suggested to link core scale geomechanical experiments to the field scale, while addressing the uncertainty in geomechanical parameters in a systematic way. Material balance studies, geological modelling and interpretation of experimental data enabled us to create a simulation model matched to available production and pressure data, therefore laying out a good basis for evaluation of CO2-EOR and storage (CCUS) potential. Simulations taking into account advantages in drilling, monitoring and reservoir technology over four decades since the field abandonment indicated a potential to recover approximately as much oil as was produced from the virgin reservoir. The CO2-EOR is also believed to create a business case suitable for paving the way for the storage project where estimated capacity is up to 1 million tons depending on technical and economic conditions.