Abstract: Apparatus and methods for determining the fluid conductivity of a fluid network. The method includes injecting a nanoemulsion into the formation, the nanoemulsion including a carrier liquid and nanodroplets. The nanodroplets are stabilized within the carrier liquid by polymer-coated iron oxide nanoparticles. After extracting fluid from the formation, a parameter of the extracted nanodroplets is determined. Based on the determined parameter, the fluid conductivity of the fluid network is determined.