The process was developed starting from vertical drilling, used, especially, in the oil industry. This technology allows overcoming the engineering problems associated with digging ditches, reduces social costs and participates in the restoration of contaminated sites [M. Stéphan Montambeault, Director of Drilling Directors C.D.G. Inc.].
Depending on the situation in the field, different construction works can be adopted, achievable through horizontal directed drilling. Directional drilling can be used for underpasses or for the installation just below the road (at distances of about 50 m, between the manholes) of small cables and pipes. Also, the method can be used to consolidate by injection the unstable lands and affected by landslides and torrential erosions in the area of transport roads and bridges. By performing drains and injections of material at the base of the slopes that present a risk of loss of stability. But with the horizontal drilling method, the geotechnical problems of stability and consolidation can be solved very easily. The process can also be used to eliminate any pollution situations, being applicable to the recovery of any type of pollutant of economic interest (gas, oil, etc.) by drilling holes that can reach directly into the center of the contaminated area.
Directed horizontal drilling technology is a rotary, hydrodynamic drilling system, directed and focused on three basic technological principles:
- use of a rotary digging tool (working organ), having the shape of a spear with a beveled tip;
- advancing horizontally in a rotating system and by displacing the ground based on the injection under high pressure of a special jet of drilling fluid, which also fulfills the function of a greasing agent;
- Directed piloting of the rods and the drilling device from the surface, by remote control, with the help of an electromagnetic wave emitter and a parameter computer (inclination angle, speed and direction of drilling), which allows to avoid obstacles and exit with precision at the desired location of underground drilling.
It is necessary to provide a work surface both at the entrance and at the exit of the drilling. The horizontal directional drilling method, the most modern method of laying pipes underground, sums up the following technological steps:
- The initial stage of pilot drilling consists of drilling an opening in a wet system, using a bentonite-based drilling fluid. The drilling fluid (mud), transported through a system of rods to a drilling head, presses the encountered material and mixes with it forming a crust around the drilled opening.
- The intermediate stage, of the widening drilling, consists in the withdrawal of the rod system – drilling head, the replacement of the drilling head with a widening head and the execution of the drilling again, at higher levels. The stage is repeated until the projected quotas are reached;
The final stage, of pulling the pipe, consists in detaching the widening head at the opposite end of the place where the drilling started and replacing it with a pulling head to which the pipe to be laid is attached. The rods together with the firing head and the pipe are retracted towards the installation, the pipe remaining laid underground.
- Eliminates transport and storage of material;
- Keeps the soil structure intact;
- It is possible regardless of the degree of soil saturation;
- It is possible in situations where the open ditch is not feasible;
- Allows depollution and recovery of any pollutant of economic interest (gas, oil, etc.);
- It is almost independent of climate. >
- It is profitable due to reasonable prices and high working speed;
- Eliminates expenses with breaking, transporting land and repairing road surfaces;
- Ensures the activity and in during the cold and rainy season.
- Does not affect the fauna and flora in the work area;
- Does not mechanically, chemically and acoustically pollute the environment;
- Allows soil decontamination;
- Avoid dislocation of contaminated soils.