NUMERICAL STUDY OF STORAGE CAPACITY AND POTENTIAL GROUND UPLIFT DUE TO CO2 INJECTION INTO KUTAI BASIN BY USING COUPLING HYDROMECHANICAL SIMULATOR

摘要

Carbon capture and geological storage (CCGS) is one of the most feasible options in mitigating global warming. CCGS can be applied in capturing CO2 emission produced by large stationary sources, transporting to a site and then injecting it into a deep sedimentary basin. Kutai Basin in East Kalimantan is potential basin for CO2 geological storage. However, this requires a detail and comprehensive information about storage capacity of the basin, and it senvironmental impact associated with CO2 leakage to groundwater and geomechanical deformation due to the injection of CO2 into the basin. This paper presents numerical study of the injection of CO2 into Kutai Basin and potential geomechanical deformation as a consequence of the change of stress and hydraulic pressure due to the injection. Numerical simulations were undertaken by modeling 3-dimensional Kutai Basin with a injection well at 800 meters. The injection was specified at 3024 ton/day within one year period. To simulate the process of CO2 migration in the basin including its geomechanical efffect, a coupling hydromechanical simulator of TOUGH2-FLAC3D was utilized. It was found that CO2 injection is able to increase hydraulic pressure in rock formation of the basin as CO2 plume migrates, escaping the injection point. As a result, the hydraulic pressure rises from its natural pressure 9 MPa to 13 MPa and the total volume of CO2 injected becomes 1.1 million tons. The injection also generates a ground uplift, accounted for about 304 mm. The results suggested that the basin has large storage capacity for CO2, however its severe ground uplift needs to be carefully examined prior to commercial CO2 injection in a field scale.