Experimental Microfluidic Strategies for Enhanced Recovery with Ferrofluid

Abstract The objective of this microfluidic investigation is to identify and test two novel applications for magnetic fluids in porous media for subsurface oil field applications. In particular, the study assesses the possibility of utilizing water-based or oil-based ferrofluids as agents in enhanced oil recovery and temporary in-situ valves to divert multiphase fluid flow. Ferrofluid is a liquid dispersion of nanoscale ferromagnetic particles that exhibits dynamic response to changes in magnetic fields. Three forms of external magnetic fields were tested, a stationary magnetic field from a permanent magnet, an oscillating magnetic field from an electromagnet, and a rotating magnetic field from a magnetic stirrer. The micromodel porous medium consisted of two types that are simple trapping mechanism designs (converging-diverging channel and pore doublet) and sample rock-like designs (sandstone and fractured sandstone). The experimental results confirmed that ferrofluid is an effective enhanced oil recovery agent for both the wetting and nonwetting phases and showed five different mechanisms by which ferrofluids could improve recovery at the microscale that are (i) direct displacement by the magnetic body force (ii) pore-scale agitation (iii) mobility ratio reduction by viscosity alteration (iv) interfacial tension reduction, and (v) magnetic nanoparticle chaining.