|Directional Drilling Installations|
|Residential & commercial projects|
The directional drilling control is brought about by a small angle on the drill the cutting head.
The pilot drill string is not rotated except to orient the bend.
If the bend is oriented to the right, the directional drilling path then proceeds in a smooth radius bend to the right. The directional drilling path is monitored by an electronic package housed in the pilot drill string near the cutting head. The electronic package detects the relation of the drill string to the earth's magnetic field and its inclination. This data is transmitted back to the surface where calculations are made as to the location of the cutting head. Surface location of the drill head also can be used where there is reasonable access.
Once the pilot hole is complete, the hole must be enlarged to a suitable diameter for the product pipeline. For instance, if the pipeline to be installed is 4 in. diameter, the hole may be enlarged to 6 in. diameter or larger. This is accomplished by "prereaming" the hole to successively larger diameters. Generally, the reamer is attached to the directional drilling string on the bank opposite the drilling rig and pulled back into the pilot hole. Joints of drill pipe are added as the reamer makes its way back to the drilling rig. Large quantities of slurry are pumped into the hole to maintain the integrity of the hole and to flush out cuttings.
Once the drilled hole is enlarged, the product pipeline can be pulled through it. The pipeline is prefabricated on the bank opposite the directional drilling rig. A reamer is attached to the drill string, and then connected to the pipeline pullhead via a swivel. The swivel prevents any translation of the reamer's rotation into the pipeline string allowing for a smooth pull into the drilled hole. The directional drilling rig then begins the pullback operation, rotating and pulling on the drill string and once again circulating high volumes of drilling slurry. The pullback continues until the reamer and pipeline break ground at the directional drilling rig.