Horizontal directional drilling (HDD) refers to an extremely versatile technique related to trenchless technologies for drilling.
Professionals use it in order to install everything ranging from buildings or residences, cables or pipes below the rivers and the roadways, to service connections. This technique is optimally suited for installing condiments and pressure pipes in cases where precise grade requirements are absent.
So, what are the main components of HDD? They are as follows:
- Rig sized directional drills for at hand projects
- Linked drill rods forming drill strings
- Receiver/transmitter for recording, tracking product & drill location
- Tank for holding & mixing drilling fluid
- Palm for drilling fluid circulation
Drill strings help to drive the drill bits, or to pullback products and reamers. Additionally, other components associated with HDD involve pulling heads, bits, swivels, and reamers.
In larger projects, there is a need for recycling of drilling fluids and this occurs through a combination of hydro cyclones, screens, and centrifugal pumps for removal of cutting from the fluid. In cases where drill head tracking via walkovers system seems impossible due to surface conditions or depth, professionals utilize wire lines in order to track the progress.
Operationally, HDD projects come with launch sites with positioning and setup of rigs for drilling a pilot bore along a planned pathway. This pathway leads to an exit pit having a product, reamer, or product pipe attachment.
Attachment of pipe reamer occurs and it is pulled back via the borehole. For product in small diameter pipes, this can be a simple enough procedure covering short distances, but quite complex in cases where large products over long distances are present.
Securing of rig occurs through power rotating on-board augurs that are positioned at some distance behind the entry points. This allows drill entry through planned locations.
Drill string entry angle remains typically at 8 to 60 degrees. Aside from this, professionals use pits for capturing drilling fluids that return at both entry points as well as planned exit points.
Drill strings generally comprise of drill rod series with advancements through thrust and rotation combinations, which the rigs supply.
Advancement of the string initially occurs through thrust as well as rotational torque until the drill strings attain optimal down-hole stability, allowing the operator to make directional changes.
Through such motions, the string advances further through the planned bore pathways. Many types of bit designs may be present, which helps in navigation via various soil types ranging from clay, sand, to rocky layers.
Many of the drill bits come with a slanting face and the orientation of this face will determine the bit advancement’s direction. In order to move in straight lines, rig operators will both push and rotate the drill strings.
Pathways change their direction depending on where the slant face of the bit is pointed at.
The presence of on-board controls allows operators to effectively monitor the bit orientation as well as to determine changes related to the bore’s general direction.
The presence of tracking walkovers systems offers ideal help in the monitoring or tracking of bore locations. This kind of system will comprise of a receiver and transmitter with the sonde or transmitter being located within housing units nearby drill string, front area.
The transmitter of the system emits magnetic signals continuously and handheld portable receivers will be able to pick it up with accuracy. Data transmission to the receiver allows tracking hands to determine their position accurately along with the drill bit clock face’s positions.
Such information will allow operators to track locations across planned bore pathways successfully ensuring timely changes for optimal results. Pumped down drilling fluids through drill hollow rods and drill bit holes have a crucial role to play in keeping the electronic transmitter cool.
Aside from this, the drilling fluids also play a role in extracting returns from the bore hole as well as hole-stabilization.
The mixing of the drilling fluids is for addressing solid conditions anticipated along a planned pathway.
Testing of returns related to installation confirms whether an accurate water additive mixture is in use. Once the pilot bore has reached the exit area, product pipe installation and reaming phase will then begin.
Reaming of the hole occurs in one or more passes until it is enlarged to the required diameter. Once the bore is large enough to accommodate the product, the product is then attached to the drill strings with head swivel and pulled back to rig.