PROCESS OF DRILLING

     

1. DEVISION OF THE PROJECT

Division means the preparation of the drilling and the land-survey of the drilling area. For the preparation of the drilling the object needs to be well examined, for the land-survey, the existing public utility networks and the safety distances need to be well determined, also a preparation and analysis of soil conditions by expert needs to be done – depending on the length of drilling but at least 2, or one at 50-100m. Comparison of the given plans and documentation.

   

2. PREPARATION OF THE LEAD THROUGH LAYOUT 

There is a differentiation between the permission layout and the drilling lead through layout. The permission layout is done by the path designer, the drilling lead through layout is done by the horizontal directional drilling company based on the permission plan.

During the preparation of the drilling layout we have to take into consideration the

technical parameters of the product pipe, such as length, and diameter, the depth of the object, the soil combination.

During the preparation of the layout the bend radius of the product pipe is taken into account. In case of steel pipes the bend radius of the product pipe determines the minimal drilling bend radius. But when the product pipe is HDPE plastic pipe, than the maximal bend radius of the drilling rods determines the drilling path.

At the preparation process the safety distance of all the existing public utility networks has to be taken into account. A drilling data table belongs to the drilling layour, which shows the bend radius of each drilling rod to keep the planned curve. The possible accuracy on land is 0-30cm in vertical direction, 0-40cm in horizontal direction, while on water it is 0-50 in vertical, and 0-80cm in horizontal direction.

  

3. PREPARATION OF OPERATION AREA, STARTING AND TAKING SITE, SET UP SLURRY PIT

After the lead through layout is done the exact site of the horizontal drilling machine, the bentonite pit, the water pump and the drilling rod depot is located. In case of larger horizontal drillings an organizational plan is prepared. The size of the start and end pit depends on the diameter of the product pipe.

 

4. PREPARATION OF THE PRODUCT PIPE

The steel or the HDPE plastic pipe is welded together at the predefined ending point, where the pressure test is done as well.

 

5. CARRYING OUT THE PILOT BORE

The directional drilling is carried out by the DigiTrak SST computed based directional system. The directional system is in continuous connection with the computer located in the drilling machine sending the data such as the depth, the angle, and the horizontal direction of the bore head.

  

  

  

The bore head is chosen according to the soil composition. In case of limestone or sandstone mud motorized bore head is used. During the drilling, bentonite is pumped continuously through the drill rods, with 30-50 bar pressure.

  

 

6. PREPARATION OF THE ENLARGEMENTS

After the successful pulling through, the suitable reamer is set up based on the soil conditions.

During the enlargements a certain amount of bentonite is injected in the bore.

All the materials used by us is environmentalfriendly, it does not cause any environmental harm.

The bentonite slurry used during the enlargements is complex:

- it supports the bore

- it carries out the soil from the bore

- it closes down the pores of the soil, so the ground water can not dilute the slurry, and the bentonite in the bore does not leak.

The flowing bentonite from the bore is continuously cleaned, and reused.

  

7. PULLING THE PRODUCT PIPE

The welded product pipes are controlled based on the specifications. The pulling of the product pipes are only started when the hole is stable enough.

The pulling head is set up after the reamer with installation of the swivel and than the product pipe can be pulled through. The pull through of the product pipe starts with continuous control.

  

 

8. COMING DOWN, ENVIRONMENTAL RECONSTRUCTION

After the product pipe is pulled, laid down, the drilling equipments are transported

away in the reverse order than setting up the site.

The used drilling mud is taken to the dumping area, and the reconstruction of the drilling area is done after the pipe system is connected together.

  

9. DOCUMENTATION OF THE FINISHED PROJECT

As a result of accurate set up and computer based data recording, the documentation of the drilling is done by counting out the data in the computer and its processing. These data are forwarded in digital form for further procession of the surveyor.