The Hole Opener used in Horizontal Directional Drilling (HDD) does not “drill a new hole from scratch”. Instead, it follows a three-step process: first drilling a small pilot hole, then using the hole opener to gradually expand the hole to the designed diameter, and finally pulling back the pipeline. This non-excavation technology is widely used in pipeline laying projects, effectively avoiding damage to the ground surface, roads, and buildings.
1. Drill the Pilot Hole First
① The drilling rig drills a small-diameter pilot hole (φ80–200mm) at the entry point according to the designed trajectory. ② The drill bit, probe, and bend sub (1°–2°) are used for orientation, rotating and advancing while drilling. Mud is used for cooling, cuttings carrying, and hole wall protection. ③ Drill until reaching the exit point to complete the penetration of the pilot hole.
2. Replace with Hole Opener for Pullback Reaming
Remove the pilot drill bit at the exit end and connect it to the HDD Hole Opener, then perform step-by-step pullback reaming. ① Structure: It consists of a central body, replaceable blades/roller cones, and nozzles. It is divided into three types: scraper type (for soft soil), roller cone type (for rock), and combined type (for complex formations). ② Working Principle (Core): The drilling rig rotates and pulls back, the blades/roller cones cut, squeeze, and crush the hole wall, expanding the φ200mm pilot hole to φ600–1500mm. High-pressure mud jetting cools the cutting tools, carries cuttings back, and protects the hole wall to prevent collapse. ③ Multi-stage Reaming: For example, φ200→φ400→φ600→φ800. Each pullback expands one level to avoid hole collapse.
3. Hole Formation and Pipeline Pullback
① The final hole diameter is ≥1.5 times the pipe diameter (e.g., φ610mm pipe → ≥φ915mm hole). ② After hole cleaning, connect the swivel joint and the pipe to be laid behind the hole opener, then pull back the pipe into the hole to complete the laying.
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Post time: May-06-2026