Thermal Characteristics of Oil and Permafrost along the Proposed China-Russia Crude Oil Pipeline

Abstract

The proposed China-Russia Crude Oil Pipeline (CRCOP) faces significant challenges due to differential frost heaving and thaw settlement resulting from significant variations of oil temperatures along the pipeline. It is thus important to investigate the oil temperature distribution along the pipeline during the long-term operation period, the development of the frozen and thawed cylinders around the pipeline, and the variation of maximum freezing-thawing depths beneath the pipeline in the permafrost regions. The investigation is of help for selecting route, assessing and predicting the differential frost heave and thaw settlement of the Soils Surrounding Pipeline (SSP), analyzing pipeline strain/stress, designing foundation, optimizing the wall-thickness of the pipe and taking mitigative measures against the potential adverse impacts from the freezing-thawing of the SSP. In this study, a quasi three-dimensional computational model was developed to investigate the above issues considering the latest conditions. The results indicated that: 1) the compressor station and frictional heat have the significant warming impacts on the oil temperatures along the CRCOP; 2) the variation of the oil temperatures is mainly controlled by the thermal regime of the SSP, the inlet oil temperatures, the warming effects of the compressor stations and factional heat as well as global climate warming, and the volume of the pipeline's throughput; 3) the variations of the frozen and thawed cylinders and freezing-thawing depths at the typical locations along the CRCOP have been remarkably influenced by the oil temperatures, climate change, and the water (ice) content; 4) the warming effects of climate change, compressor stations and factional heat are adverse factors against abating thaw settlement in permafrost area, but they are advantageous for mitigating frost heave in the seasonally frozen ground area or taliks.