The Horizontal Directional Drilling Process 2023

A drilling process that avoids damaging the surrounding environment

Horizontal Directional Drilling Machine

A trenchless method for constructing underground cables and pipes is called horizontal directional drilling (HDD). It entails precisely drilling along the selected bore path and back reaming the necessary pipe using a directional drilling machine and related equipment.

These three steps make up the directional drilling process:

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 operator and locator will make adjustments to keep the pilot hole on the planned bore path. Depending on the soil’s current state and the amount of steering needed, the pilot hole’s pace will change. When you get to the exit location, you separate the beacon housing and bit and put a reamer in its place.

Pre-reaming

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.

A clean and stable hole will be created using bentonite and other additives. During pre-reaming, bentonite is used to make a “cake layer” around the outside of the hole. This will aid in preventing fluid loss or infiltration and stabilising the borehole. Clay soils are made easier to break up by the use of additives like polymers. Any clogs inside the borehole will be avoided by a drilling fluid that is more evenly mixed.

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.