The oil pipeline transportation of highly waxy oils when it is cold is accompanied by the deposition of paraffins in the inner surface of the pipeline. This study of the initial properties of the oil; the composition, structure, and nature of the components of normal alkanes in oil; and their influence on the aggregative stability of the resulting system makes it possible to find the best solutions to optimize the conditions of oil transportation with the lowest energy costs. This study shows that, according to the content of solid paraffin (14.0–16.2%), the oils of the Kumkol group of fields in Kazakhstan are highly waxy. They are characterized by high yield loss temperature values (+9–+12 °C), which also correlate with the values of the rheological parameters (τ₀ 1.389 Pa, 3.564 Pa). The influence of the temperature and shear rate on the shear stress and effective viscosity of the initial oils was studied. At temperatures below 20 °C, depending on the shear rate, there is an increase in the effective viscosity values (0.020 Pa∙s, 0.351 Pa∙s). The influence of the nature of solid hydrocarbons on the parameters of the paraffinization process and of the intensity of the paraffinization of the metal surfaces was studied. Our study shows that the main share of n-alkanes in the Kumkol and Akshabulak oils falls on paraffins of the C15–C44 group. The greater the temperature difference between the oil and the cold steel surface (≤40 °C), the lesser the amount of asphalt–resin–paraffin deposits (ARPDs) that fall out on the surface of the rod, although the content of long-chain paraffins prevails in these ARPDs. At the same time, the consistency of the released asphalt–resin–paraffin deposits (ARPDs) becomes denser, which makes their mechanical removal more difficult. Furthermore, the results of this study of the cooling rate shows that the rapid cooling of oils leads to the formation of a large number of crystallization centers, which leads to an increase in the values of the yield loss temperature and kinematic viscosity of the oils.

The possibility of improving the rheological characteristics of waxy oils by using low-viscosity oil as a diluent to optimize oil transportation has been studied. We have previously demonstrated the processes of paraffin deposition in the highly paraffinic oil of the Kumkol oilfields group. In this study, we examine the physicochemical properties and rheological parameters of highly paraffinic West Kazakhstan oil and light Aktobe oil (with different compositions of Aktobe oil—1 to 50%). Our data show that the Aktobe oils are characterized by a low paraffin content (5.6%), a low temperature of yield loss (−30 °C), and low density (820.2 kg/m³) compared with the West Kazakhstan oil mixture (17.3%; +15 °C; 880.2 kg/m³). The effective viscosity of the Aktobe oils at −5 °C was 0.021 Pa·s, while for the West Kazakhstan oil, it was 5.459 Pa·s at +5 °C. The addition of the low-viscosity Aktobe oil as a diluent led to a decrease in the temperature of loss of fluidity (+9 °C) of the highly solidified non-Newtonian West Kazakhstan oil, as well as a decrease in the viscosity (0.367 Pa·s). Accordingly, with the addition of Aktobe oils to the composite oil, the content of naphtheno-aromatic hydrocarbons increased, which led to an improvement in the aggregative stability of the oil dispersion and enhanced the viscosity properties of the oil.

The article presents the results of the study of the influence of the composition and temperature of heating on the flow of the mixture of oil of West Kazakhstan/Mangyshlak/Aktobe fields (transported through the main pipeline «Kenkiyak-Kumkol») and oil fields of Kumkol group (treated with depressant); degree of rheological reduction depends on heating temperature, wax and asphalt-resin content and cooling conditions, and paraffin oils have an optimal heating temperature, where the heat treatment effect is greatest. This temperature is always higher than the melting point of the paraffins in the oil. At the same time, the most favorable conditions are created for dendritic crystallization of paraffin with the formation of the least stable structure. When heating high-frozen oil below the melting point of paraffins, there may be a sharp deterioration of the rheological parameters of the oil due to the formation of a solid fine-crystalline structure; the results of the physical-crystalline research are obtainedthe chemical and rheological properties of the oil mixture of ZKNS-Kumkol formulations 30-70 and 40-60% have shown that the negative effect from heating to 35 and 45 ^oC must be taken into account when deciding on the use of oil heating technology to improve transmission modes, because this will lead to deterioration of rheological properties of oil and will reduce the effectiveness of the depressant additive (which is used to process the Kumkol component of the oil mixture). In order to improve the flow of the oil mixture ZKNS-Kumkolskaya can consider the possibility of heating the oil up to 55 ^oC, or increasing the share of the West Kazakhstan component along with the absence of heating of the oil mixture (mixing of components at actual temperatures).