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This article discusses the issue of assessment of the quality of petroleum pipeline preparation for light oil product transportation. The need to implement appropriate measures is conditioned by the requirement to maintain the quality of oil products during their transportation. We identified vulnerable indicators, which are most prone to change if oil products contact with asphaltene-resin-paraffin deposits remaining in the pipeline, as well as estimated probability of failures and emergencies if off-spec oil products are used in automotive and aviation equipment. The scope of the article includes considering variants of technical solutions for the cleanup of the line part of petroleum pipelines and process pipelines of oil pumping stations from asphaltene-resin-paraffin deposits using specially selected chemical reagents and the methodology for assessing the quality of their preparation for oil product transportation. We considered the order of estimation of the possible volume of off-spec oil products formed as a result of the oil product’s contact with residues of the cleanup products and chemical reagents located in the cavity of the pipeline and provided the results of the implementation of technical solutions to ensure the quality of petroleum pipeline cleanup at the facilities of PJSC Transneft repurposed for oil product transportation in 2014–2017.

The results of investigations of the main causes and the most significant factors of intensification of paraffin deposition in main oil pipelines are presented. A comprehensive analysis of the composition and properties of commercial oils and their sediments was carried out, according to which phase diagrams of equilibrium of oil dispersed systems were obtained using the example of commercial oils from Bashkir fields. Based on the phase diagrams, a curve of wax oil saturation was constructed, the analysis of which confirms that the existing thermobaric conditions during the operation of main oil pipelines do not allow transporting oil without the risk of waxing. It was noted a special influence of the value of the temperature gradient in the near-wall zone and the imbalance of the ratio of high-molecular oil components in commercial batches formed in the process of joint pumping on the intensity of waxing of sections of oil pipelines complicated by deposits, which was confirmed by statistical data on the frequency of pigging. The regularities obtained in this way are proposed to be used as an express method for predicting complications associated with intensive waxing of main oil pipelines. In order to quickly assess the risks of waxing of sections of main oil pipelines, an indicator is introduced that characterizes the ratio of the content of solid paraffins to the total content of resins and asphaltenes of oil, called the criterion of instability of a commercial oil batch.