As already mentioned, in the processes of extraction, storage and transportation of oils, they mix with each other or with water, which leads to changes in their rheological and physicochemical properties.
The oils entering the refining and transportation stages are subject to strict requirements in terms of the amount of water, sulfur, chlorine salts and mechanical impurities in a number of indicators that determine their quality characteristics. Different types of oils have different qualities depending on the density and percentage of sulfur. It is these indicators that greatly affect the quality of oil and its selling price. High-viscosity oils with high density are usually not supplied to terminals and general purpose pipelines. To transport such oils, better quality, lighter oil or gas condensate is added to them. Oils with a high percentage of sulfur should also be refined or mixed with light oil or condensate. Mixing of different quality commercial oils can occur both in terminals and in transportation systems. The analysis shows that the quality of the mixture obtained is very different from the quality of the mixed oils.
Given very little study of how the mixing of different types of liquefied oils affects their rheological, physicochemical properties and quality indicators, rotoviscosimetric rheological studies and physicochemical analyzes were performed in the laboratory for different mixtures of rheological complex oils and wetting rates. Mixing of different types of oil usually occurs when there are not enough tanks in the fields where acceptance operations take place. Sometimes different oils are injected into the same jaw in sequence and separately, without accounting. In such cases, the measurements made on the oil at the receiving points are different from the calculated price.
Information on quality indicators of crude oils and their mixtures produced in mines (density, viscosity, freezing point, mechanical mixtures, chlorine salts, asphaltene, paraffin, amount of resins, etc.) It is also important for forecasting the operating modes of stations. In the existing normative documents and literature, as a rule, the definition of the main quality indicators of oils and their mixtures is based on established rules and dependencies. The study of the effect of mixing of different types of heterogeneous oils of Azerbaijan on their rheological and physical-chemical properties shows that the additive rule can lead to serious errors in the process of determining the predicted parameters, as many properties of complex oil mixtures are taken from calculations for ideal mixtures.
Laboratory studies were conducted for individual oil samples, their different mixtures and degree of dehydration, oil and condensate, as well as mixtures of various types of light petroleum products, and the experimental results were analyzed.
In the laboratory, the effect of the degree of dehydration of high-viscosity heavy oils taken from wells 43 (0%), 28 (15%), 37 (40%) and the storage tank of the "Jafarli" field of the "Muradkhanli" IPC on their rheological properties was studied. has been. All of the studied oils are high-viscosity, heavy oils and differ in the amount of water, mechanical impurities and chlorine salts they contain. Thus, the oil of well No. 43 was without water, and the oil of wells No. 28 and 37 had a water content of 15 and 40%, respectively. Most mechanical impurities (2.1%) were in well oil No 28, and most chlorine salts were in well oil No 37. Irrigation of the considered oil samples was artificially increased and their rheological parameters (γ ̇ and τ) were determined in the “Reotest-2” viscometer under different conditions at different irrigation levels.
The increase in viscosity at small values of the velocity gradient at a certain degree of dehydration of wetting has led to a rapid decrease in the shear stress at large values. It was determined that the maximum value of the degree of dispersion of oils in water or the degree of saturation, indicating the saturation limit, was 70-80%, 40%, and 80% for mixed oil, respectively, for samples taken from wells 28, 37 and 43.
Keywords: oil, mixed oil, mechanical mixture, degree of dehydration, rheological parameters.
