Modeling of CO2 Injection in North Stavropol Underground Gas Storage Reservoir (Russia)

Abstract

North Stavropol Underground Gas Storage (UGS) has been established on the basis of sufficiently large depleted gas field (33 x 18 km), intra-structural Pelagiada rise (16 x 11 km) is considered as a reservoir of ÑÎ2 injection. The production horizon is represented by Paleogene sediments of the lower Oligocene with total thickness of 80-95 m. After the establishment of the UGS, the pressure in the horizon stands at 3 MPa. TOUGH2-TMVOC modeling of ÑÎ2 injection in 16 wells was assigned with rates from 16 to 160 kg/s. The modeling results show that no more than 8% - 10% of the injected CO2 is dissolved in the liquid phase, of which not more than 1.4% is dissolved in the marginal waters. With a maximum rate of injection, the pressure in Pelagiada reservoir remains below the critical value. Modeling proved potential of CO2 sequestration during 30 years was estimated 0.005 gigaton.