Model of Permafrost Thaw Halo Formation Around a Pipeline

Permafrost thawing around buried pipelines transporting warm hydrocarbons can result in dangerous bending of the pipeline and it's possible damage. Prediction of the permafrost-pipeline thermal interactions reflected in the thawing halo dimensions is an important problem both for design and operation of the pipeline. The aim of this work was to develop a predictive model of thawing halo formation with high ratio of the accuracy in estimating thawing halo dimensions to the quality of input data. A theoretical model that considered factors possibly influencing permafrost-pipeline thermal interaction was developed. Oil pipeline field experiments were performed in Eastern Siberia, Russia. Thaw halo extent and other local factors were measured. Then calculated thawing halo dimensions were compared with the measurements obtained in the field experiment. In addition evaluation of the individual influence of each factor considered in the model was performed in numerical studies. The developed and tested predictive model of permafrost thaw halo formation demonstrated a reasonable ratio of accuracy in estimating thawing halo dimensions to the quality of input data. The dimensions of the thawing halo were most sensitive to the temperature of the transported hydrocarbons, thermal conductivity of frozen soil and the initial temperature field of permafrost within the region of the pipeline's thermal influence.