(759a) Silica Nanoparticles as Wettability Modifier and Mobility Control Agent in Enhanced Oil Recovery

Oil is recovered from a reservoir in three different stages. In the primary stage, oil is recovered due to natural pressure of the reservoir. Only a small fraction (5-10%) of total oil in place is recovered in the primary stage. In secondary stage, reservoir pressure is maintained by injection of external fluids such as water. Only 15% to 25% of original oil in place in an oil reservoir can be recovered after successive use of primary recovery and secondary recovery methods. To recover the remaining oil, tertiary oil recovery or enhanced oil recovery (EOR) methods are used. Chemical EOR is one of the most important techniques in which oil recovery is enhanced by certain chemicals such as surfactants, polymers and/or alkalis by improving the fluid properties. Water soluble polymers improve the oil/water mobility by enhancing the viscosity of displacement fluid (water). Surfactants are injected to change the wettability of rock and to lower the interfacial tension between water and oil. Recently, nanoparticles have also attracted the attention due to their ability to change the wettability of rock, to lower the interfacial tension and to improve the rheological properties of water soluble polymers.

The effect of silica nanoparticles on carbonate rock wettability, interfacial tension and on rheological properties of partially hydrolyzed polyacrylamide was investigated. Rheological properties were assessed using Discovery hybrid rheometer while interfacial tension and the contact angle were measured using a tensiometer. The addition of silica nanoparticles significantly improves the rheological properties of polyacrylamide. However, the improvement in rheological properties is concentration dependent and an optimum concentration is required. Detail results will be discussed in the presentation.