Huayuan Corporation successfully completed pullback of Boai--Zhengzhou—Xuedian natural gas pipeline Zhengzhou Yellow River directional drilling crossing project at eleven p.m. on June 10th, 2014. This is the eighth crossing that Huayuan Corporation crossed Yellow River.
Zhengzhou Yellow River directional drilling crossing project, the length of crossing pipeline is 2,621.76m, pipeline diameter is 610m and wall thickness is 12.5mm; the stratum which is passed through is mainly medium sand layer. Entry point is located in east of Lupo, Wangcun Town, Xingyang, Henan and exit point is located in Wen County, Jiaozuo, Henan, contiguous to Chenjiagou, the birthplace of Chinese Wushu - Chenstyle tai chi chuan.
For the problems like torque of drilling machine is insufficient, severity of drill pipe is inadequate and drill’s positioning is difficult caused by the long crossing distance, Huayuan abandoned traditional construction method of single-ended drilling of the pilot hole and the craft that using two drilling machines to separately drill simultaneously from entry point and exit point and directional butt in the middle part. Huayuan adopted self-developed DX-I type guide system and pilot hole directional butt technology, equipped with self-developed magnetic target positioning measuring instrument, to overcome the influence of factors such as long crossing distance and flowing river water on positioning of drill; Finally, according to designed crossing curve, drill butt and drilling of pilot hole can be successfully completed——. In the phase of reaming, using the craft of simultaneously reaming by two drilling machines will resolve problems caused by insufficient torque of drilling machine and insufficient severity of drill pipe.
The stratum passing through is mainly the sand layer which has shrinkage defects and the crossing distance is long thus making pullback increment be enhanced and easily occur bearing pipe. If adopting the traditional pullback method that using one drilling machine to pull back forcibly, the drill pipe is likely to be pulled cut thus leading to the failure of pullback. On account of this, when the drill machine is dragging pipes, Huayuan Corporation adopted self-developed 500-ton pipe pusher to assist in the push. Finally, under the tension force of drilling machine and pushing force of pipe pusher, pullback construction will be completed successfully.