Microfluidic methods for studying oil recovery by aqueous floods at different wettability, temperature and pressure conditions
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To keep up with the energy consumption in the world and recover sustainably from the currently developed oil fields, enhanced oil recovery (EOR) methods have been proven important. To be able to test the processes and new methods as well as to screen chemicals for the processes, core flooding has been traditionally used. However, to complement core flooding or compensate for the shortcomings of the method, microfluidics has proven advantageous. The benefits this novel method can offer for studying oil recovery has made it an attractive subject among researchers in recent years. As it is not yet widely utilized, the microfluidic setup and method had to be developed first. After the custom setup for ambient condition tests was developed, different parameters were tested. The parameters range from operational factors such as flood volume and injection rate to reservoir representing parameters such as initial water saturation, aging and oil types to flood properties such as surfactant type, salinity, and brine composition. The effect of the parameters on recovery factor and displacement patterns were reported. Consequently, a low salinity water EOR test was conducted using the method developed from the results of all previous preliminary tests. In order to understand the effect of surface wettability, the wettability of the micromodels was altered. Different parameters including salinity, oil type, brine composition, surfactant type, and network design were tested. The different displacement patterns and recovery outcomes were then compared based on the wettability of the surfaces. Finally, low salinity surfactant floods as the EOR method proved more effective in recovering additional oil in water-wet networks. Moreover, to elevate the test conditions to more reservoir-relevant values, a new setup and method was developed to accommodate higher temperatures and pressures. The effect of pressure and temperature on oil displacement were tested using the setup. The use of low salinity surfactant as an EOR flood at ambient conditions, elevated pressure and elevated pressure and temperature was also studied. Although the elevated pressure did not significantly affect the recovery, higher temperature strongly influenced both the recovery factor and displacement patterns.