(126e) Polyelectrolyte Nanoparticles for Enhanced Oil Recovery

Nanoparticles consisting of self-assembling complexes of polyanions and polycations are able to entrap a variety of charged species, including many oil and gas chemicals. Entrapment in these polyelectrolye complexes (PEC) is through a combination of electrostatic and steric interactions. Entrapped material is protected from the hostile subterranean environment, and its release delayed while it is transported to target locations underground. The size and surface charge of the nanoparticles can be tuned to favor propagation or retention in porous media. This is a flexible technology with great promise for the upstream oil and gas industry. We review our work on applying it to two aspects of flow assurance: (i) delayed gelation of polymers used in water shut-off and conformance control by entrapping crosslinking agents such as Cr(III), and (ii) hydraulic fracturing fluid cleanup using PEC-entrapped enzymes.