Huayuan News
The Qianyu Pipeline starts in Guiyang to the north and ends in Chongqing to the south, spanning two provinces and three cities, with a total length of 491 kilometers. Along this route, Huayuan undertook 12 horizontal directional drilling (HDD) crossing projects, several of which were considered key control projects due to their high level of difficulty. By the end of 2013, 11 of the 12 crossings had been completed, with only the Yudong Gorge HDD crossing still in progress.
Located on the Yunnan–Guizhou Plateau, the Qianyu region is characterized by mountainous terrain, deep valleys, and typical karst landscapes, which posed significant challenges for Huayuan’s HDD construction teams. The main difficulties included:
Complex Karst Geology – Uneven hardness of strata, numerous underground caves, fractures, and groundwater led to frequent problems such as drilling fluid loss and misalignment during reaming, making pullback operations extremely challenging.
Mountainous Crossings with Steep Angles – Both entry and exit angles could be very large, up to 25°. The elevation difference between the highest and lowest points was also considerable: nearly 200 meters for the Qijiang mountain crossing and over 150 meters for the Yudong Gorge crossing.
Limited Work Space in Mountainous Areas – Restricted space made pipeline prefabrication difficult, requiring the use of multi-section welding during pullback. Each additional weld increased time consumption, and when combined with the complex geological conditions of the Qianyu region, the pullback process became even more difficult.
