Size Dependence of Nano-/Microparticles Flowing Through Fracture Structures

Abstract

Nano- and microparticle tracers are expected to be useful for evaluating structures in geological developments, however their transport behavior is not well characterized. This study investigated nano-/microparticle transport in a fractured medium using a microscope. A single fracture and rock matrix (grain and pore space) were fabricated on a silicon wafer, which is called a micromodel. Water and nano-/microparticles were injected into the micromodel, and the temporal change of particle concentration was measured by Tunable Resistive Pulse Sensing (TRPS). The larger particles were observed only at early time, while the smaller particles were detected over a wider range of time. This indicates that particles with different sizes transport through fractured media differently depending on the fracture structures and that the tracer response may be useful to evaluate the flow properties for each flow path.