The Jiangyin Yangtze River Crossing Project sets up a record with the length of horizontal directional drilling (HDD) of 3300?m in the world. Inevitably, many technical difficulties might exist in pilot hole docking, reaming torque, property requirement and recovery of drilling fluids, and pullback resistance. Accordingly, some innovative measures were taken in each stage. At the pilot hole drilling stage, a reasonable drill tool assembly was chosen, namely, a new type of ? 193.7?mm (S-135) drill pipe with high-strength was applied along with the fully guided cable and rotating magnate docking technologies. At the reaming stage, an innovative ? 168.3?mm (V-150) drill pipe was adopted along with the optimized reamers and the improved hydraulic parameters to successfully reduce the reaming torque and significantly improve the reaming efficiency. At the pullback stage, a specific ground anchor was designed for large-tonnage pullback resistance, and drift pipe, super lubricants and novel glass fiber reinforced plastics were combined for protecting the pipeline coating. Finally, the drilling fluid formula was optimally selected to ensure the hole stability and flowback of drilling cuttings, and a centrifugal was used to recycle the drilling mud to ensure its necessary performance. All these measures not only ensured the success of this HDD project, but also broke many records in this respect.
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