Improving the Crude Oil Metering Accuracy

Crude oil fiscal metering is a complex metrological procedure, as the main metering means – SIKNS (crude oil quantity and quality parameters measuring systems) are affected by many interfering external factors. Among other things, paraffin deposits on the inner surface of the SIKNS measuring lines (MLs), in which flow meters are installed have a significant effect. Direct measuring the paraffin layer thickness in the time of the SIKNS operation is impossible, however, there is a relationship between the ML flow and the line pressure and temperature, which depends on the presence of paraffin deposits.Studies conducted based on the mathematical model of the SIKN measuring line section developed in the Aspen HYSYS software environment have shown that regression equations, which relate the ML flow to the line pressure and temperature depending on the paraffin layer thickness can be obtained. To increase the model adequacy, the errors of specific measuring instruments involved in the metering process (pressure and temperature transmitters) have been considered. Assessment of the adequacy of the regression equations obtained has shown that the relationship and the equation coefficients are only significant for pressure, so the ML temperature cannot be used to analyze the amount of paraffin deposits in it. In general, the measures proposed in the article allow developing a high-quality procedure for evaluating the paraffin contamination of MLs to ensure their timely shutdown for washing that will improve the crude oil metering accuracy.