Adsorption of nanoparticles on glass bead surface for enhancing proppant performance: A systematic experimental study

Effective coating of nanoparticles on the proppant pack has been regarded as a promising technique for enhancing proppant functions to achieve multiple objectives. In this work, a dynamic soaking technique which we refer as “pseudo-continuous fixed bed (PCFB)” adsorption has been employed for the first time for coating of four bare NPs (Al₂O₃, SiO₂, MgO, ZrO₂) with divergent physical and chemical properties, onto a fixed adsorbent glass bead proppant pack. A systematic study of the formulated nanofluid (brine+NPs) adsorption onto the proppant pack was conducted vis-à-vis salinity (0 to 10.5 wt% NaCl), temperature (298.15 to 348.15 K), NPs loading (0.01 to 0.2 wt%), and injection rates (1 to 50 mL.min⁻¹). Nanofluid stability was measured via zeta-potential measurements, where NP adsorption was verified through optical microscopy and atomic force microscopy. Results show that PCFB adsorption of NPs with higher specific surface area resulted in faster adsorption (adsorbed in ~25 mins) with >99% immobilisation of NPs on the proppant pack. Adsorption kinetics showed reasonable conformity with the pseudo-first-order model, where isothermal adsorption followed a Sips model. The adsorption capacity of MgO NPs (specific surface area 50–80 m².g⁻¹, 7.0 wt% NaCl) at 298.15 K was found to be the highest when compared with silica NPs. Accordingly, this method can be used for onsite treatment of proppants with nanoparticles, which can then be injected into a fractured formation to achieve multiple objectives.