Spectral measurements of dielectric characteristics of petroleum and petroleum oils in the millimeter wave range

We obtain experimental data on the complex refractive index N = n+ik of petroleum, five petroleum oils, and water-petroleum emulsion in the frequency range f = 75–120 GHz. Measurements were performed in a quasioptical equipment with a backward-wave oscillator generating the radiation and an OAP-7 optical-acoustic receivers for a temperature of 27°C of studied liquids. The refractive indices n of petroleum and oil have a weak negative dispersion (dn/df < 0) and close values. At a frequency of 100 GHz, they lie in the range n = 1.477–1.495. The absorption indices k have different frequency dependences such that k increases for four oils, while it decreases for petroleum and SM-4.5 oil with increasing f. At the frequency f = 100 GHz, the values of k vary in a wide range from 2.4 · 10−4 to 1.7 · 10−3. The measurement results for petroleum and oils are compared with experimental results obtained by other authors. The frequency dependences of n and k of water-petroleum emulsion for water concentrations 0.11% and 0.58% are compared with the data calculated using various analytical models of dielectric mixtures. The dependences n(f) and k(f) calculated by the Kubo-Nakamura formula are the closest to the experimental data.