Temperature Prediction Oil Pipeline in Frost Areas

Abstract

Pipeline operation in frost areas is essential thing in the present days. Changes of low-temperature profile of frozen soil along the length of a pipeline lead to changing conditions of the pipeline. That’s why it is vital to properly forecast and model thermo-hydraulics regimes and evaluate pipeline conditions to sustain correct positioning of the pipeline and to prevent incidents. That’s why this paper describes a simple forecasting method. It is based on heat balance equation, where coefficient k describing heat transfer from a pipeline to the environment considers that soil gets to technogenic state. Actual efficiency and temperature data from an active non-isothermal pipeline over 2 years period after its commissioning are used to derive actual value of the coefficient k. Pipeline type – underground, insulated, initial petrol temperature is up to 45 °С. Using Shukhov’s formula it is possible to calculate average value of the coefficient k. Based on this coefficient we can then derive forecasted values and get the following data: temperature profile, temperature value at specific points and cross sections of a pipeline, thawing area, critical locations of a pipeline. This method allows to timely evaluate conditions of a pipeline in permanent frost soil. Results can be used to forecast and predict thermo-hydraulics regimes not only for a specific pipeline but also for other Northern ones. It also allows to evaluate conditions of critical parts of a pipeline when taking in account actual size of thawing areas.