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Relevance. All technological processes occurring in the reservoir, wellbore and in the system for collecting and preparing oil, gas and gas condensate require knowledge of the physicochemical properties of the well production. These parameters are associated with hydrocarbon reserves, changes in composition of the reservoir mixture, the rate of water intrusion into the reservoir, partial pressure of individual components, well construction, hydraulic losses, selection of the optimal operation mode, etc. All technological processes of extraction, collection, preparation and transportation are accompanied by continuous changes in pressure and temperature, which directly affect the properties of products, «PVT-properties». The lack of ideas about the physicochemical properties and phase transformations occurring when the temperature and pressure conditions change in multicomponent systems leads to adoption of incorrect technological decisions, occurrence of complications during the well operation and, consequently, decrease in the efficiency of field development. Therefore, it is important to be able to predict the change in pressure and temperature and calculate the PVT-properties along the fluid flow path. The aim of this work is to calculate and analyze changes in the PVT-properties of the produced products and the temperature along the well length. Methods. The Standing method, developed in the USA as a result of numerous studies of oil and gas samples, was used to calculate oil density and viscosity, oil volume factor, solubility, and supercompressibility factor; the Alves method was used to calculate the temperature change curve over the well depth. Findings. The solubility of gas increases linearly with increasing pressure, which also leads to increase in gas content and, accordingly, the volume factor. The increase in oil gas content results in its turn in density gradual decrease. Temperature increase along the wellbore leads to decrease of oil viscosity. The development of analytical methods for predicting temperature in a well over depth is complicated by the need to take into account the thermophysical properties of rocks, reservoir fluids, which have to be neglected, as is the case with the Alves method. This inevitably results in discrepancies between actual and theoretical temperature values.