Proposal of a New Method for Controlling the Thaw of Permafrost around the China–Russia Crude Oil Pipeline and a Preliminary Study of Its Ventilation Capacity

Yapeng Cao,Hailiang Jia,Kai Gao,Liyun Tang,Gang Wu,Dun Chen,Guoyu Li,Fuqiang Che

doi:10.3390/w13202908

Abstract

The China–Russia crude oil pipeline (CRCOP) has been in operation for over ten years. Field observation results have shown that a thaw bulb has developed around the CRCOP which expands at a rate of more than 0.8 m∙a−1 in depth. In view of the deficits of existing measures in mitigating permafrost thaw, a new control method is proposed based on active cooling. According to the relationship between total pressure loss and the driving force of natural ventilation, the wind speed in a U-shaped air-ventilation pipe around the CRCOP is calculated. By analyzing the theoretical calculation and numerical analysis results, it is found that the influence of thermal pressure difference on the natural ventilation of the structure can be negligible, and the influences of resistance loss along the pipe and local resistance loss in the pipe are similarly negligible. Exhaust elbows greatly improve the ventilation performance of the U-shaped air-ventilated pipe. This study developed a novel structure around warm-oil pipelines in permafrost for mitigating thaw settlement along the CRCOP and other similar projects across the world.

Highlights

With the further development and utilization of global oil and gas resources, the number of pipelines has increased at an unprecedented rate
For the Norman Wells oil pipeline, thaw settlement induced by pipeline construction, water ponding on the right of way (ROW), and high oil temperatures have threatened its operation. [6,7]
A new structure for pipeline thaw settlement prevention is proposed from the perspective of active cooling, which can be used for ground cooling around the pipeline but can function as an underground support part for the pipeline

Summary

Introduction

With the further development and utilization of global oil and gas resources, the number of pipelines has increased at an unprecedented rate. When crossing permafrost regions, heat from a warm-oil pipeline is able to thaw permafrost around a pipeline [1]. For the Norman Wells oil pipeline, thaw settlement induced by pipeline construction, water ponding on the right of way (ROW), and high oil temperatures have threatened its operation. The off-ground laying structure of the Trans-Alaska Pipeline System, as mentioned. The off-ground laying structure of the Trans-Alaska Pipeline System, as mentioned above, is costly and unable to prevent forest fires.

Proposal of a New Control Method to Determine the Ground Thermal Regime

Calculation of Structure Driving Force for Natural Ventilation

Thermal-Pressure Difference Calculation

Wind-Pressure Difference Calculation

Calculation of the Wind Speed in the Pipe

Conclusions