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Hidden Drilling Method

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Horizontal directional drilling (Hidden drilling method) is a way to lay various underground communications by trenchless technology. Using this method, the surface of the landscape remains intact, including beautification features, roadway, building, and constructions. Currently, several proven techniques of horizontal directional drilling are developed and frequently used to reduce the costs of communications laying and preservation of the objects above the ground...

Horizontal directional drilling

When using the Hidden drilling method, the cost of similar works can be reduced by 2-3 times. If it is not possible to lay communications on the landscape in the traditional way, the soil puncturing method is applied.

The method of horizontal directional drilling is used for various purposes:

  • Laying of pipelines, gas lines, electric cables, and other communication lines for buildings.
  • Formation of wells for oil and minerals extraction.
  • Replacement of old communications and equipment.
  • Arrangement of underground highways.

Besides the demand for technology, Hidden drilling provides certain advantages:

  • Destructions on the surface are minimized (it is needed to dig only 2 basins).
  • It is required a small team of 3-5 people to carry out the work.
  • The equipment for drilling is mobile, it is easily delivered and installed at the worksite.

HDD method allows to equip communications more quickly and cheaper so that the technology has gained huge popularity everywhere.

General description of the technology

Horizontal Directional Drilling is based on using the drilling equipment. The general technology of puncturing comes to the following manipulations:

  1. Project documentation with calculations is prepared for accurate horizontal drilling in the soil.
  2. The projects are compliant with local authority and landowners.
  3. Two basins are digged out at the site of works start and communications exit in the location, where the drilling will take place.
  4. Laying of necessary pipelines are carried out with the help of drilling tools.
  5. Completion of work, removal of basins, restoration of sites at their location if necessary.

The above description is brief, currently several types of Hidden drilling have been developed. The application of a certain type of horizontal drilling is carried out depending on the soil type, laying communication lines and other factors.

Drilling equipment

Various drilling tools are used in drilling technology:

  1. Drilling machine. It is industrial equipment run on diesel fuel. Operation and movement are carried out by the operator. Drilling is based on functional components of such machines as carriage, hydraulic power station, control panels.
  2. Accessory tools. Various tools are used for the soil puncturing and punching as hoses, reamers, pumps, screw elements with thread, and so on. Based on the type and stages of the works carried out, the team set a different tool on the drilling rig.
  3. Navigation system. It is important to observe the trajectory of transmitter housing (drill head) passing, the accuracy of the outlet (output) at the second basin during HDD works. In order to do that, a probe is mounted into the transmitter housing, and the workers follow the movement of the tool with the help of a locator.

Each part of industrial equipment for Hidden drilling takes on an important role, requires professional handling and routine maintenance.

Advantages and disadvantages of Hidden drilling technology

Horizontal directional drilling was invented in 1960. From then on, the Hidden drilling has been actively used all over the world. Like any other technologies, the Hidden drilling has its advantages and disadvantages


  • Less waste of resources, finance, labor and time
  • Costs for laying communications are reduced due to the lack of the need to restore the environment;
  • You can work in any areas, including historical places, high-voltage stations, unfavorable climatic conditions;
  • The soil structure is preserved; the fertile soil layers are not disturbed;
  • The usual urban rhythm is also not disturbed, there is no need to stop the road traffic.


  • If it is necessary to lay a pipeline of high length or at great depth, the trenchless method is more expensive.

Labor Protection and Safety Department while working with Hidden drilling rigs

Site preparation, as-built documentation maintenance rules

Pumping mixing unit operator training

HDD operator training

Location system operator training

Calculation of the pilot drilling route, problem solving

Drilling tool, regulations on its use

Drilling mud, its features and regulations on the use

As client wishes, we can provide instruction in any city with visit of our

Stages of Hidden drilling works

Drilling process demands an attentive attitude, control and adherence to technological characteristics at every step.

Preparatory works

Before underground communications laying, the landscape and equipment must be prepared:

  1. 1-Site development for the drilling machine is of universal size, 10х15m.
  2. If necessary, provide a detour road for the machine.
  3. Set down the drilling equipment in appropriate place of the pilot boring launch.
  4. Fix all necessary systems before the operation.
  5. Adjust all necessary drilling tools.
  6. Adjust the radio communication between team members.
  7. If it’s necessary, built an additional lead for bentonite liquid and groundwater.

At the preparation stage, in order to bring any harm to the existing pipelines it is important to calculate the location of them. It is also necessary to have the 10 m distance between the main machine and mud mixing system.

It is also very important to explore the soil of project and choose the appropriate drill bits and reamers before pilot drilling. The whole drilling object must be protected with a yellow warning tape.

Drilling process

After finishing the preparatory work, the next stage is drilling process:

Pilot boring requirements:

  • The diameter of pilot boring is 10 cm.
  • Adjusting drill bit by 10 – 20 ° relative to the horizon line;
  • Pilot boring path is checking every 3 meters’ length.

Backreaming process requirements:

  • Expansion of the pilot hole: the drill bit is removed and replaced by an appropriate reamer;
  • Full extension of the reamer through the formed channel with constant correction of movement.

It is necessary to use a drilling mud during whole drilling process. The drilling mud must have sufficient gel strength to keep cuttings suspended for transport, to form a filter cake on the borehole wall that contains the water within the drilling fluid, and to provide lubrication between the pipe and the borehole on pullback.

It is important to consider the possibility of soil caving. In order to exclude the violation of the technology, it is necessary to connect all parts of the pipes with each other reliably.

Construction of underground communications using the technology of horizontal directional drilling is carried out in three stages:

  1. Drilling a pilot hole.
  2. Back reaming drilling.
  3. Pulling the pipe.

1-Hidden Drilling Method

2-Hidden Drilling Method

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