Horizontal Directional Drilling is a construction methodology used to install a product/application below the grounds surface on a horizontal plan without disturbing the surface or above ground activities.
Horizontal drilling allows a passage, pipeline, wire etc to be installed where other techniques such as open trenching would become perilous, sloppy, time consuming and on occasions impossible to construct.
The Horizontal Directional Drilling process consist of three major objectives:
- The Pilot Bore
- Reaming Process
- Product Installation
The Pilot Bore
Through the utilization of a drillhead, which penetrates into the ground formation, a bore hole is produced under the surface in accordance with the chosen bore path. The drillhead location is monitored at all points by the use of a transmitter located in the drillhead sending info to a receiver on the surface. This info tells the operator the drillheads lateral position, depth and pitch as well as drillhead temperature The bore path may need the drillhead to led around existing services or below a structure such as a road, buildings, train line or perhaps waterway. In the complete process, drilling fluid is pumped thru the drill rods and out thru the drillhead. This specialized drilling fluid mixers with the cuttings to form a drill slurry which helps stabilize the hole, suspend cutting & prevent frac-outs. Once the drillhead enters the exit pit, which has been constructed at the other end of the bore trail, the pilot bore has been completed.
Reaming Process
Once the pilot hole is complete, the drillhead is removed and a back reamer attached to the drill string. The reamer is then slowly pulled back through the hole whilst being revolved. As the reamer enlarges the hole, the cutting again mix with the drilling fluid being pumped through the drill rods to help stabilise the hole and ensure flow continues to the exit pit. Several different size reamers maybe required to bring the hole to its elected size.
Product Installation
Once the bore hole has been enlarged to its correct size and the hole is cleaned out, the product is connected to the reamer via a pipe puller, a few metres of chain and swivel. As the product is being pulled back thru the bore hole, drill slurry is forced into any voids which will a have been produced round the product. Here is where the correct drilling additions used are so vital. Once the product has entered the entry pit is it disconnected from the drill string, HDD machine is removed, site returned to its original condition and all open pits made safe including fencing.
The advantages for using Trenchless technology are numerous and sundry but each job site should be evaluated on its own separate form as some advantages might not be as equally crucial as others.
- Only minimum disruption is caused to all surface movements and structures when using Trenchless technology.
- No necessity to excavate hard surfaces such as roads. Reducing interruption to traffic flow.
- Constructs a bore hole under the roots of trees and plants thus causing nominal turmoil to vegetation.
- Preferred methodology for installing products under rivers and waterways thus minimising bridge modification and development of overhead wires.
- Safer to the general public as no long trenchers are required.
- Multiple products can be installed in a single bore hole.
- Trenchless equipment includes both pit and surfaced launched machines minimizing set-up time and cost.
- Minimum visual effect to residence while construction process is taking place.
- Time on the work site can be shortened.
- Can be led horizontally and vertically en-ambling the bore hole to navigate through existing structures and services.
About the Author:
Trackson Driller's articles and books are all around the planet,. Read more drilling companies or horizontal drilling
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