When classifying the process of oil dehydration for preliminary assessments of the technological parameters of its treatment at various stages of the design and development of oil fields, it is necessary to take into account regional differences, starting with the geographical and geological location of oil deposits and the conditions of their occurrence, ending with the features of the physicochemical properties of reservoir fluids extracted to the surface. On the example of a number of fields in the Samara region, the dependence of the change in viscosity when changing from reservoir conditions to surface conditions is built, a comparative grouping of oil by viscosity in reservoir and surface conditions is considered, consistent with the classification of oil to assess the parameters of its preparation simultaneously in terms of density and viscosity in surface conditions. A conditional comparison of the classification parameters and the required temperature of the emulsion during oil dehydration to a residual water content of 10 wt% (preliminary dehydration) and 0.5-1 wt% (deep dehydration) was carried out according to various literature sources. It is proposed for the range of Paleozoic production of oil wells in the Volga-Ural oil and gas province, in addition to assessing the generally accepted characteristics of oil density and the content of paraffin in it, to select technological parameters for oil treatment, additionally use the relative indicators, taking into account the unique properties of highly mineralized reservoir waters and the heterogeneous hydrocarbon composition of the oil itself. On the basis of the introduced characteristics, the classification of oil dehydration of a number of fields in the Orenburg, Samara regions and Siberia is considered. A comparative assessment of the quality of wastewater treatment was carried out taking into account two calculation methods based on the properties of the separated phases, taking into account the mentioned characteristics, as well as the oil density and the specific load on the interface of the apparatuses for the combined preparation of oil and water.
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