Economic analysis of use of the early application CO2 and CO2/N2-EOR technology in Poland

Enhanced oil recovery methods are applied more frequently nowadays, mainly because of economic reasons. The classic waterflooding methods that aim to maintain the reservoir pressure are substituted or updated by the Water Alternating Gas technology (WAG). It involves alternating injection of water and gas, or simultaneous injection of water into the bottom of reservoir and gas into the cap of it. The new intelligent methods (which use synergy of gathering and processing reservoir data, special injection systems and modification of viscosity if injection fluids) are very promising in new EOR. The application of high-nitrogen content gas, residue gases after methane-nitrogen separation processes, carbon dioxide or solutions containing carbon dioxide and nitrogen are considered in terms of the oil recovery efficiency, defined as obtaining of a maximal depletion during twenty years of exploitation. For the selected small oil reservoir in the Polish Lowland, it was performed model research with usage of a pseudo-compositional simulator. Various aspects of gas injection concerning increasing of the reservoir pressure and increase of recovery has been analyzed. Presented results show possibility to increase of recovery factor from 11% and 36% up to 53/56% in case of CO2/N-2 and CO2 EOR. The presented results are promising and show potential possibilities of rising oil recovery up to 60% for average oil price higher than 40 $ per bbl.