Influence of Individual Ions on Silica Nanoparticles Interaction with Berea Sandstone Minerals.

Nanofluids are prepared by dispersing silica nanoparticles in aqueous media (brines). The purpose of this work is to address brine/rock interactions in presence of nanoparticles. Our previous studies have shown that silica nanofluids are effective in reducing formation damage in sandstone reservoirs. This study addresses effect of individual ions on dispersed silica nanoparticles' interaction with Berea Sandstone minerals. The selected ions are Mg(2+), SO(4)(2-) and Na(+), in MgCl(2), Na(2)SO(4) and NaCl, which are the major constituents of seawater. Three flooding stages for Berea Sandstone cores were followed. The first flooding stage was without nanoparticles, the second one was a slug of the nanoparticles with tracer and the third stage was a post-flushing of the core with the respective ion. The effluent tracer concentration, nanoparticle content, ion concentrations and pH reflect the effect of individual ions on nanoparticle/mineral interaction which were used for suggesting possible interaction mechanisms. Presence of Mg(2+) and SO(4)(2-) ions improved the adsorption of nanoparticles on minerals, however the effect of Na(+) was lesser. In general, in all the cases nanoparticles reduced the mineral dissolution and associated fine migration/possible formation damage.