Remedial Measures to Tame the Frost Heaves at Gas Distribution Stations in West-East Gas Pipeline

The first West-East Gas Pipeline, running from the Tarim Basin gas fields in Xinjiang to the Yangtze River Delta area in China, is an 1016-mm-dia, 3900-km-long pipeline, the design capacity and pressure of which are 12 billion cubic meters annually and 10 MPa respectively. The whole pipeline was put into commercial operation on Oct. 2004, and the distribution stations suffered from frost heaves due to subfreezing gas temperatures, with obvious uplifts of valves from the bases, upheavals of the ground, and cracks of the paved surfaces and fence walls, and deformations of gas pipelines. From the commission on, the demand on gas in the downstream market was booming, and the company strove to upgrade the throughput to 17 billion cubic meters annually by building new gas compressor stations, so the more serious frost heaves are expected at the regulator stations. As we know, gas-fueled heaters can effectively tackle the frost heaves, but the difficulty of land acquisition, and more expensive CAPEX and OPEX limit the installation of the gas-fueled heaters. In this paper, various types of measures to cope with the frost heaves are compared and analyzed. Based on the geotechnical survey of field soils, theoretical calculations and actual data, soil replacement schemes with a water migration control technique are developed and successfully applied at different gas distribution stations with different water tables. The schemes are simple to use, and are cost-effective. When the remedial actions with this scheme are conducted, no interruptions of service are required. Furthermore, a large sum of expense is saved in comparison with the gas-fueled heaters.