Influence of Warm Oil Pipeline on Underlying Permafrost and Cooling Effect of Thermosyphon Based on Field Observations

Ground temperatures under a buried warm China-Russia oil pipeline were monitored to evaluate permafrost thawing and cooling performance of thermosyphons installed near the pipe in sporadic permafrost regions. Field observations demonstrated that warm oil thawed the underlying permafrost and increased the active layer thickness. Thermosyphons can cool the soils surrounding the pipe and effectively mitigate the permafrost thawing depending on their number and working duration. But now the heat dissipated from the warm pipeline and construction disturbance were not completely removed by two pairs of thermosyphons after two winters of operation. There was still a thawed layer beneath the thermosyphons even in winter. Further long-term monitoring of the cooling performance of thermosyphons is needed. This study provided basic data and analytic references for other similar cold region pipelines.