Example 3
The ratio of the nanoparticles to the surface-active agent is an important factor as it controls the zeta potential of the nanoparticles and the time scale of the aggregation process. For zeta potential higher than ±30, the aggregation time scale is extremely long and may be infinite. As the zeta potential get s closer to the zero, the time scale of aggregations decreased significantly and optimally instantaneous at the zero.
This wide range of gelation times may be made use of in different applications when these materials are emplaced in a porous medium, particularly when used in subterranean formations to assist in hydrocarbon recovery techniques. For example, materials with relatively long gelation times may be used post-CHOPS reservoirs to plug the wormholes. While materials with relatively short gelation times may be used for near-wellbore applications, such as water shutoff or acid diversion.