Combined effect of silica nanofluid and wettability on enhanced oil recovery process

Abstract

The objectives of this study are to characterize the properties of water-SiO2 nanofluid and quantify its flooding efficiency in an initially oil-filled micro-porous medium of two different surface wettability conditions, i.e. water-wet and neutral-wet. The average nanoparticle size (as a result of aggregation) in water-SiO2 nanofluid is characterized using dynamic light scattering method. Viscosity and surface tension of water-SiO2 nanofluid are measured respectively by vibration string and drop volume methods. For the flooding experiments, a transparent PDMS microchannel with internal square obstacles mimicking a porous medium is designed and fabricated. The wettability of PDMS over time, as a result of aging, is investigated. The effect of SiO2 nanoparticles on 3-phases contact angle (nanofluid, crude oil and PDMS) is reported. The flooding efficiency of water-SiO2 nanofluid is then quantified. The results reveal that the best oil recovery process occur when the water-SiO2 nanofluid flooding is used in a neutral-wet surface condition. As the injection rate increases, the oil displacement efficiency decreases. This oil recovery behavior implies the dominant nature of viscous forces at low flow rate. At high flow rate, the effect of viscous force is not obvious.