Numerical Study on the Optimal Thermally Affected Region of a Buried Oil Pipeline

Crude oil pipeline transportation is usually a closedprocess undera certain depth of burial, and the condition of oil in the pipelinechanges with the continuous decline of temperature during the transportationprocess. The safety and energy consumption of pipeline transportationare closely related to the accurate prediction of oil temperature.It is a popular technique to use the thermally affected region toovercome the problem of an unclosed calculation domain caused by thesemi-infinite soil around the pipeline. However, there is no clearand unified guidance on the thermally affected region at present,and improper region size may lead to a loss of the accuracy of thepipeline system. Therefore, our study answers two questions aboutthe optimal form of the thermally affected region and its economicscope of application. The coupled solution of heat transfer and flowin a tridimensional numerical model is carried out, and the thermodynamicinfluences of the geometric shape and range of the thermally affectedregion on the buried pipeline system are investigated. The resultsshow that the rectangular region is more suitable for the modelingof buried oil pipelines, and a region with 16 m width and 9 m heightis recommended for the conventional case.