CO2 storage characteristics and migration patterns under different abandoned oil and gas well types

In oil and gas fields, there are numerous abandoned wells that are distributed in a network pattern. The reuse of abandoned wells for CO2 storage can reduce storage costs and pollution. Previous studies have been limited to single-well researches, neglecting the effect of CO2 injection on different abandoned wells. This paper develops a numerical model with dual-well coupling the thermal-flow-multiphase field, simulating mechanisms of CO2 storage and migration under the dual-well and comparing effects of injection parameters and heterogeneous reservoir parameters on CO2 storage effect. The results indicate that the dual-well can alleviate the increase in reservoir pressure. The injection rate and injection time should be large to ensure desirable storage efficiency and migration range. Compared to the minimum well spacing, the maximum well spacing increases the storage capacity by 2.41 × 109 kg and extends the migration distance by approximately 800 m. The migration distance of the upper-injection and down-production mode is about 300 m less than that of the other two modes. Heterogeneity in reservoirs benefits storage and impedes migration. By selecting proper well positions, negative impacts of heterogeneity on CO2 migration can be reduced. This work assists in providing supports for the CO2 storage with abandoned wells.