At 10am past 40, 21st Feb. 2014, the Jinzhou-Shishou natural gas pipeline directional drilling crossing engineering of Yangtze River which was built by Huayuan Corporation has completed back dragging successfully. After the finish of Huang-Da line Yangtze River crossing engineering of directional drilling on 6th April 2012, Huayuan Corporation successfully crossed the Yangtze River again.
The Jinzhou-Shishou natural gas pipeline directional drilling crossing engineering of Yangtze River is located in Jinzhou city, Hubei province. The whole length is 1837.44m, and the pipeline diameter is φ406.4×10.3mm. The penetrating angle and the unearthed angle is respectively 20°and 19°. The maximum depth of crossing curve relative penetration point is about 120mm. Because there are deep gravel layer at the two ends of the crossing curve whose length is about 300m (curve length), and thickness is about 100m, this made the construction face with great challenges. In order to reduce the length of crossing gravel layer, the corporation researched and determined to increase the penetration angle of guide hole, and used the way of 2 drilling machines working in synchronization to drill into the guide hole at the two ends of the crossing curve with the penetration angle of 20°and 19°respectively. They also used the butt guide positioning system which was independently developed by the corporation to make accurate positioning. After the drilling of no longer than a month, the two drilling machines finished the directional drilling work with a length of 1837.44m successfully, and achieved the docking of the drill crown.
In the period of guide hole expansion, through improving the slurry, Huayuan Corporation successfully solve the problem of the guide hole in gravel layer’s been easy to collapse, and finish the construction of guide hole expansion. In the aspect of piping fabrication, because of the limitation of space, the main welding pipe need be fabricated in 2 pieces, and be connected into one piece while the process of back dragging. This added the risk of back dragging to a certain extent. At the same time, because of the large penetration angle, the front 160m of the pipe need be dangling in the air while back dragging, and the maximum height was about 10.4m. And at the same time, the first pipe whose length is 176m had 90m located on arc segment. This made it very difficult for the back dragging, and break the record of Huayuan Corporation’s dangling height while back dragging pipeline and at the same time dangling at the arc segment in history.