Physical property measurement of surfactant coupled with nanoparticles for enhanced oil recovery

Abstract

The residual oil remained in the reservoir after the primary recovery and water flooding can either be produced by increasing the mobility of the oil or by altering the reservoir rock wetting behavior and diminishing the oil water interfacial tension. The surfactant flooding is one of the chemical enhanced oil recovery methods. At the optimal concentration, the surfactant flooding can provide the low interfacial tension favoring to the enhanced oil recovery. In contrast, the loss of the surfactant at the solid-liquid interface due to an adsorption lessens the amount of the surfactant required for oil displacement during the flooding. Therefore, the silica nanoparticles are used to enhance the surfactant EOR process in minimizing the surfactant adsorption which also results in the wettability alteration. In this study, the behavior of the interfacial tension between oil and different interfaces at the reservoir conditions are observed. From the results, IFT is greatly affected by the surfactant concentration, the presence of the nanoparticles in the surfactant solution, temperature and salinity. At the end, the desired low interfacial tension is achieved when 750 ppm by weight of nanoparticles are used with 2000 ppm concentration of the surfactant in the low salinity of 750 ppm brine solution.

In addition, the physical properties such as densities of each combination of chemicals and viscosities of oil samples acquired from northern Thailand oilfield are measured with and without the surfactant solutions and the silica nanoparticles assisted the surfactant solutions at the different concentration. From the experiments, the anionic surfactants, sodium dodecyl sulfate (SDS)and sodium dodecylbenzene sulfonate (SDBS) are used according to the lower adsorption in the sandstones compared to the cationic surfactants. From the results, the static adsorption behavior of the surfactant at the interface with the reservoir rock from the northern Thailand oilfield is studied and the nano silica can indeed reduce the adsorption of the surfactant by being adsorbed at the rock surface itself and the wettability is also changed consecutively. However, the sacrificial adsorption of the nanoparticles become effective when the surfactant concentration beyond the critical micelle concentration is used. In comparison of two anionic surfactant, SDBS shows the higher adsorption on the rock sample rather than that of SDS.

In conclusion, from the study of the physical property measurement, adding the nano silica to the surfactant solutions enhances the important parameters of EOR. The IFT can be reduced. Also, the surfactant adsorption can be lowered if concentration above CMC is used. Also, the nano silica can provide the effective contact angle reduction and support the oil recovery for the surfactant flooding.