The investigation was devoted to the effect of electromagnetic field on crystallization of calcium carbonate, structure of CaCO3 crystals generated from oversaturated aqueous solutions, and water-in-oil emulsion (crude oil) properties. XRD demonstrated that electromagnetic field caused a decrease in mean size of CaCO3 particles by 30 μm and prevalent aragonite formation. We detected that electromagnetic field application leads to decreased apparent viscosity of water-in-oil emulsion and inhibits influence of a non-ionogenic surfactant on stability and viscosity properties of crude oil. As a matter of practice, the method demonstrated its efficiency to prevent scale deposits in oil production wells.