Investigation of Fracture Characterization Through the Transport Behavior of Magnetic Nanoemulsions

Abstract

Abstract Hydraulic fracturing is a promising way to increase oil recovery in tight reservoirs. The accurate assessment of the expansion of fracture networks within the reservoir is a prominent challenge encountered in hydraulic fracturing operations. To overcome this obstacle, the incorporation of tracer injection along with the fracturing fluids and flowback analysis provides fundamental knowledge for reservoir characterization. Herein, a magnetic Pickering nanoemulsion is introduced as a potential tracer for hydraulic fracturing applications. In this regard, the transportation behavior of this particular Pickering nanoemulsion is a crucial factor for designing and optimizing its implementation in energy, sustainability, and environmental areas. In this study, a polymer-coated iron oxide (Fe3O4) nanoparticle (NP) was synthesized and utilized as a stabilizer to form stable oil-in-water (O/W) nanoemulsions. Two different types of nanoemulsions (with the highest and the lowest stability) were then fabricated with various ratios of polymer shell to Fe3O4 nanoparticle core (3:1 and 0.5:1). Core flooding experiments were then performed in a sandpack to evaluate the stability and retention behavior of the synthesized nanoemulsions in porous media. The nanoemulsion flow profiles were quantitatively monitored by X-ray CT scanning and sandpack magnetic susceptibility experiments. In addition, the density of the nanoemulsion effluents and pressure drop during the whole flooding process were measured to evaluate the most effective nanoemulsion formulation with the lowest retention in the porous media. According to the obtained results, the most stable nanoemulsion formulation with the highest polymer-to-nanoparticle coating ratio (3:1) was transported through the sandpack effortlessly with the lowest retention. The pressure-drop results also showed a gradual increase of pressure during nanoemulsion flooding due to the drag force and higher viscosity of the nanoemulsions compared to water. However, throughout the chase water flooding, the nanoemulsion with the highest stability was displaced piston-like along the sandpack with lower pressure drop, implying lower retention of the nanoemulsion at the higher ratio of polymer to nanoparticle coating.