CO2 Flooding and Geological Storage Potential Evaluation Method for Low Permeability Reservoirs in Dagang Oilfield

Permanently sequestering carbon dioxide during carbon dioxide flooding is the most realistic way to meet carbon dioxide emission reduction obligations in developing countries. In order to effectively evaluate the potential of carbon dioxide flooding and geological storage of low permeability reservoirs in Dagang Oilfield, it is necessary to establish a reliable CO2 flooding and geological storage potential evaluation method. Based on the characteristics of low permeability reservoirs in Dagang Oilfield, this paper establishes a CO2 enhanced oil recovery (EOR) and geological storage potential evaluation method based on fractional flow theory. Through theoretical analysis and numerical simulation method, the carbon dioxide storage coefficient, carbon dioxide storage and CO2 flooding efficiency of low permeability reservoirs in Dagang Oilfield under carbon dioxide miscible and immiscible flooding conditions were determined, and these values were analyzed and evaluated. The results show that the CO2 flooding efficiency and storage coefficient of miscible flooding are significantly higher than that of immiscible flooding. In addition, as the amount of carbon dioxide injected increases, the carbon dioxide flooding oil increase and the amount of storage increase. Through the evaluation of 272 oil layers in the low-permeability oil area of Dagang Oilfield, the enhanced oil recovery and geological storage potential of CO2 in this area were analyzed. It can be seen from the analysis and evaluation results that CO2 miscible flooding is an effective displacement and storage method. The conclusions drawn can provide technical reference for the implementation of CO2 flooding and storage in low permeability reservoirs in Dagang Oilfield.