Supercritical CO2-philic nanoparticles suitable for determining the viability of carbon sequestration in shale

Abstract

A fracture spacing less than a decimeter is probably required for the successful sequestration of CO₂ in shale. Tracer experiments using inert nanoparticles could determine if a fracturing this intense has been achieved. Here we describe the synthesis of supercritical CO₂-philic nanoparticles suitable for this application. The nanoparticles are ~50 nm in diameter and consist of iron oxide (Fe₃O₄) and silica (SiO₂) cores functionalized with a fluorescent polymeric corona. The nanoparticles stably disperse in supercritical carbon dioxide (scCO₂) and are detectable to concentrations of 10 ppm.