The Horizontal Directional Drilling Process 2023

A drilling process that avoids damaging the surrounding environment

Horizontal Directional Drilling Machine

Pilot Hole

Drilling a pilot hole with a small diameter is the first step. High-pressure jets and the drill bit will grind the soils ahead of the drill stem as drilling fluid is fed through the drill pipe to the drill bit. The drilling fluid will also transport the drilling waste back to the drill rig’s entrance pit. Depending on the size and complexity of the shot, there are various methods for tracking the pilot hole. A walkover guidance system is used for smaller pictures while a wireline magnetics type system is used for larger, more intricate shots. In all cases, the drill stem’s precise coordinates are communicated to the location engineer via a transmitter or steering tool that is placed close to the drill head. Continuous readings are taken to monitor the drill head’s depth, alignment, and percentage slope.


The pilot hole must then be pre-reamed and enlarged to a size that will allow the product lines to be installed safely. In order to cut and remove particles and widen the hole, a reamer is pulled back and rotated as drilling fluid is pumped. The number of cuttings removed from the hole and the current soil conditions will both influence the pre-reaming speed.

Pipe Pullback

The retraction of the pipe inside the previously reamed hole is the last phase. To prevent any torsional stress from the rotating drill string being transferred to the product pipe, the drill rod and reamer will be coupled to a swivel, which is used between the product line and the reamer. Drilling fluid is poured deep into the earth to lubricate the product pipe as it is drawn into the drill hole.



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