Case studies on the CO2 storage and EOR in heterogeneous, highly water-saturated, and extra-low permeability Chinese reservoirs

• Three typical reservoirs were presented to study the CO2 EOR potential and CO2 storage capacity of these types of reservoirs.
• The reservoir simulation method was utilized to analyze the CO2 injection process and storage.
• The low permeability reservoir exhibited the highest EOR potential and CO2 storage capacity than the other two reservoirs.
• Nonetheless, injecting CO2 into reservoirs to decrease atmospheric greenhouse gas emissions while enhancing oil recovery.

The CO2 storage and CO2 enhanced oil recovery (EOR) in reservoirs often face challenges due to a high heterogeneity, high levels of water saturation, or low permeability. Based on the evaluation method of the CO2 storage capacity and EOR, three typical reservoirs representing these challenges are introduced to study their effect on the CO2 EOR potentials and CO2 storage capacities. The properties of these reservoirs were analyzed in detail, and geological models were built. The reservoir simulation method is adopted to analyze and validate the CO2 injection process and the storage effect for different types of reservoirs. From the examples in this paper, the low permeability reservoirs appear to have a higher EOR potential and CO2 storage capacity than highly heterogeneous reservoirs. These results support the premise of injecting CO2 into reservoirs to decrease atmospheric greenhouse gas emissions while enhancing oil recovery.