Rapid permafrost thaw induced by heat loss from a buried warm-oil pipeline and a new mitigation measure combining seasonal air-cooled embankment and pipe insulation

In permafrost regions, the pipelines buried under the ground are widely used for long-distance transportation of fossil fuel, which contributed to research focusing on the interaction between such pipelines and surrounding permafrost. In this study, field observations were conducted since 2011 to investigate the thermal interaction between the China-Russia Crude Oil Pipeline and the surrounding permafrost. Air and oil temperatures at the study site were collected, and the ground temperatures on and off the right-of-way of the pipeline were observed. The observations showed that the large heat loss from the buried pipeline made a rapid increase in the ground temperatures and thawing of underlying permafrost. To slow down the rapid permafrost thawing, a new design was proposed by combining a seasonal air-cooled embankment and pipe insulation. A coupled model was developed to describe the complicated heat transfer process among the ambient air, embankment, warm-oil pipe and permafrost. The numerical simulations showed the design could effectively transfer the heat from the pipeline to the environments in the cold season and reduce the heat intake of the permafrost subgrade in the warm season. The design can be effectively used to control the ground thermal regimes of pipeline systems built in cold regions.