MODELING INTERFACIAL TENSION IN RESERVOIR FLUIDS AND SIMULATION OF THEIR EFFECTS ON ADVANCED OIL RECOVERY VIA CARBON DIOXIDE INJECTION.
Pre-salt, CO2, enhanced oil recovery, interfacial tension, reservoir numerical
simulation
CO2 Enhanced Oil Recovery methods have been widely applied worldwide due to their great capability to increase the oil recovery factor. Regarding the Brazilian Pre-Salt reservoirs, CO2 Enhanced Oil Recovery techniques are especially indicated due to the high-CO2 content of the produced associated gas, which makes CO2 injection more operationally and economically feasible. Also, CO2 injection aiming to enhance oil recovery is related to carbon
geological storage to mitigate greenhouse gas emissions. The interfacial tension is a key property for CO2 Enhance Oil Recovery processes’ performance, once it affects many of the major reservoir properties as wettability, capillary pressure, and relative permeabilities, governing fluid distribution and displacement inside the reservoir. Therefore, the modeling of the interfacial tension and the assessment of its behavior in reservoir conditions are greatly important in CO2 Enhanced Oil Recovery processes. Aiming to fill some gaps identified in the literature, the major objectives of this dissertation are to study and model the CO2-aqueous phase interfacial tension using empirical and semiempirical equations through novel approaches over reservoir conditions. To reach this goal, an assessment of the CO2-oil interfacial tension behavior in CO2 injection processes was performed using reservoir numerical simulation to evaluate the behavior of the main reservoir properties through the CO2-oil
interfacial tension standpoint. It is also aimed to establish a qualitative relationship between the CO2-oil interfacial tension and the oil recovery factor behaviors. Results indicated a great accuracy of the CO2-aqueous phase interfacial tension modeling approaches, with highlights given to their mathematical simplicity, which makes it feasible for reservoir numerical simulation purposes. CO2 injection simulation results demonstrated that it is possible to assess the most relevant properties for oil recovery through evaluating the CO2-oil interfacial tension
behavior because it suitably describes the general performance of the recovery process, which performs better when the CO2-oil interfacial tension is decreased.