This work investigates the removal of non-aqueous phase liquids (NAPLs) from groundwater resources using nanotechnology. We present results of a series of multiphase fluid displacement experiments conducted in a naturally occurring sandstone rock. These experiments involve injection of an aqueous suspension of silica nanoparticles to remove a trapped NAPL phase. Specifically, the effect of nanoparticle concentration on the efficiency of the NAPL removal is studied. Our results show that silica nanoparticles successfully remobilised the trapped NAPL phase and resulted in 13% increase in its removal efficiency. The optimal concentration for NAPL removal efficiency is found to be 0.3 wt%.