Adsorption polymer on reservoir rock and role of the nanoparticles, clay and SiO2

Abstract

Nanotechnology has been used in many appli- cations and new possibilities are discovered constantly. Recently, a renewed interest has risen in the application of nanotechnology for the upstream petroleum industry, such as exploration, drilling, production and distribution. In particular, adding nanoparticles to fluids may significantly benefit enhanced oil recovery and improve well drilling, such as changing the properties of the fluid, wettability alternation of rocks, advanced drag reduction, strengthen- ing sand consolidation, reducing the interfacial tension and increasing the mobility of the capillary-trapped oil. In this study, we focus on the roles of clay and silica nanoparticles in adsorption process on reservoir rocks. Polymer-flooding schemes for recovering residual oil have been in general less satisfactory due to loss of chemicals by adsorption on reservoir rocks, precipitation, and resultant changes in rheological properties. Adsorption and rheological property changes are mainly determined by the chemical structure of the polymers, surface properties of the rock, composition of the oil and reservoir fluids, the nature of the polymers added and solution conditions such as salinity, pH and temperature. Because this method relies on the adsorption of a polymer layer onto the rock surface, a deeper under- standing of the relevant polymer–rock interactions is of primary importance to develop reliable chemical selection rules for field applications. In this paper, the role of nanoparticles in the adsorption of water-soluble polymers onto solid surfaces of carbonate and sandstone is studied. The results obtained by means of static adsorption tests show that the adsorption is dominated by the nanoclay and nanosilica between the polymer molecules and the solid surface. These results also show that lithology, brine con- centration and polymer viscosity are critical parameters influencing the adsorption behavior at a rock interface. On the other hand, in this study, the focus is on viscosity, temperature and salinity of solutions of polyacrylamide polymers with different nanoparticle degrees and molecu- lar weight. The adsorption of nanopolymer solution is always higher in carbonated stones than in sandstones, and polymer solutions containing silica nanoparticles have less adsorption based on weight percent than similar samples containing clay. Based on the area of contact for stone, this behavior is the same regarding adsorption.