Silica nanoparticles modified with a variety of chemical surface functionalities are interesting additives, which can bring enhanced properties such as increased sustainability, ductility and flexibility to polymer materials. These functional nanoparticles have already shown promising applications in paints, lacquers and coatings. By elaborating an appropriate surface functionalisation, silica nanoparticles can be adapted to the conditions in oil reservoirs, modify polymer transport, adjust their gelation behaviour and thus show a great potential for oil recovery processes.

The objectives of the present work are to investigate transport properties of functionalised silica nanoparticles and polymer in porous media by characterizing their stability, retention and other physical properties.

Transport properties of functionalised hybrid silica nanoparticles and polymer have been investigated through flooding experiments in two types of sandstones, high permeability Bentheimer and lower permeability Berea. The experiments were conducted at room temperature by use of 500 - 2000 ppm solutions of polymer and nanoparticles. Each experiment consisted of four stages; the active materials were injected at stages 1 and 3 whereas only brine was injected in stages 2 and 4. The polymer and the nanoparticles were quantified at the core outlet by inline viscosity measurements and by use of inline measurements of UV absorption or refractive index. The history of effluent concentrations was compared with un-retained flow by use of a conductivity contrast as tracer.

Mechanical entrapment, adsorption and inaccessible pore volume were estimated through analyses of component profiles and mass balance calculations. These quantities were generally found to be higher in Berea compared to Bentheimer, both for polymer and nanoparticles. Unlike polymer, nanoparticles appear to be transported through the entire pore space with low and partly reversible retention.

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