horizontal directional drilling specifications

When drilling through harder ground formations and in rock a mud motor is used to drive the drilling bit independently of drill rod rotation. The image above shows a sonde and battery fitted inside a slant face drilling head. The drilling mud lubricates and cools the drilling tools, as well as providing support to the periphery of the bore.ĭrill bit location for smaller and shallow installations is typically transmitted by a battery powered sonde, located just behind the bit, the signals being picked up by a receiver operated at the surface. The drilling fluid is typically a suspension of a bentonite clay and polymers. This is achieved by pumping drilling fluid (‘mud’) down the inside of the drill rods, which flushes the drilled material back out of the bore. This picture shows a small barrel reamer attached to the new pipe ready to be pulled in.įor larger diameters, and in rock, the drilled material must be removed from the bored hole as drilling and reaming progresses. A bore diameter of 1.2 to 1.5 times the PE100 pipe OD is normally required. Successive reamers of increasing diameter are used until the bore is of sufficient size to accept the PE100 pipe. Pilot holes are enlarged in pre-reaming stages using a reamer (soft soils) or a hole opener (rock).

Fluid can be pumped through the drill rods and out through jets in the bit to assist the operation This picture shows a slant face drilling bit, also fitted with carbide tipped teeth that enable it to penetrate hard ground. Whilst the rods are simultaneously rotated and pushed, the bore will, provided it is not deflected by some obstruction, proceed in a straight line, but if it is simply pushed without rotation it will deflect in the opposite direction to the slant face on the drilling head. The pilot bore is created using a drilling head, which in it’s simplest form has a slanted face, and this is pushed and rotated by long high tensile flexible drill rods. This technique involves drilling a pilot bore, generally along a closely defined shallow arc, and then, if necessary, enlarging the bore using a reamer or hole opener to create a bore large enough to accept the new PE100 pipe, which is generally pulled in behind a reamer. HORIZONTAL DIRECTIONAL DRILLING- INSTALLATION PROCEDURE HORIZONTAL DIRECTIONAL DRILLING - PE100 APPLICATIONS This is not a technique to which the ‘lowest price wins the contract’ principle should be applied. This is a highly specialised technique, and needs an experienced and highly trained operating team, an essential member of which is the drilling mud technician, particularly on the larger diameters. For the larger diameters, the equipment is large, and requires support equipment such as generators and hydraulic power units. Where large parts of the route of the main are not accessible, such as for river crossings, horizontal directional drilling is a much less costly technique than tunnelling, and can be used for large diameters, such as trunk mains. This method is regularly used on distribution systems, which typically use small diameter mains, and on rural distribution systems it often enables mains to be installed alongside the carriageway without impeding traffic flow, as the drilling equipment is compact and self contained. This method has a very small potential damage footprint provided that adjacent buried infrastructure can be accurately located.

When new pipe is to be installed or it is not possible to rehabilitate a pipe, so that it needs to be replaced but is in a congested area of buried infrastructure so that conventional methods such as bursting cannot be used safely, then a new or replacement PE100 pipe can often be installed by horizontal directional drilling. HORIZONTAL DIRECTIONAL DRILLING - TECHNIQUE

Horizontal directional drilling specifications