Improved Understanding of CO2/Foam EOR Techniques by Aid of Tracer Technology

摘要

low due to the combination of high mobility ratio, gravity segregation and heterogeneity. By decreasing the mobility of CO2 th macroscopic sweep efficiency can be improved. In the present work the surfactant, alpha olefin sulphonate (AOS), has been use as CO2 foaming agent. Dynamic flooding experiments have been carried out at realistic reservoir conditions to study the relativ transport of water, CO2 and surfactant when foam is generated in the porous network. The surfactant has been labeled with th radioactive sulfur isotope ~(35)S. The water has been labeled with the radioactive hydrogen isotope tritium (~3H) and the CO2 has bee labeled with the ~(14) C isotope. It is shown that the flow of the individual phases in a CO2-foam flooding can be monitored by using of tracer technolog Variations in the flow rates of surfactant solution and CO2 can be clearly detected, and the accessible pore volume can also b determined. AOS products contain different chemical structures. In the study, the main AOS components have been chemical separated prior to injection on the porous column. The transport of the individual components was shown to be different. In th reservoir, chromatographic separation of the AOS components may change the efficiency of the foam process. The study has shown that use of tracer technology can be a powerful tool in study of transport mechanisms in CO2-foam flooding