Horizontal drilling: execution technology
Horizontal directional drilling (GNB) Is a way of laying pipes, as well as cables without digging trenches, performed, usually, under automobiles and railways. To implement this method, special equipment is used, which includes directional drilling rigs. With the help of such installations the work is carried out on 90% underground.
The method of horizontal drilling is a modern way of laying pipelines for various purposes
Purpose and main advantages of the GNB method
The method of horizontal directional drilling is currently considered very popular. This is primarily due to the fact, that the use of such a method reduces the financial costs of laying the pipeline in 2,5-3 times.
Consider the main tasks, which are performed using this method:
- pipe laying, which will act as a protective case (casing) for various power cables;
- GNB technology allows to carry out trenchless installation of pipelines, which transport drinking water or sewage.
Importantly! A puncture under the railway or a carriageway is the only option of installation of communication without digging of a traditional trench.
GNB puncture under the road or other engineering structure allows you to preserve the natural landscape, which is also an important advantage. Consider other benefits of GNB:
- in addition to financial costs, labor costs are also reduced, as the main work is performed by special equipment;
- by means of GNB of a puncture it is possible to lay the pipeline or the cable channel not only under transport ways, but also under reservoirs.
- such work does not require a large number of people. Usually, fairly small crew, consisting of 3-5 man.
Such work does not require much space, and the surrounding landscape will NOT be spoiled
Drilling horizontal wells can rightly be considered a unique way, whose technology eliminates damage to the environment and reduces labor costs, as well as monetary costs.
Necessary equipment
All equipment, which is operated for drilling by the GNB method, is divided into several main varieties:
- machine for horizontal directional drilling GNB;
- location system for drilling;
- secondary components (brackets, clamps, etc.. d.).
A location system for drilling horizontal wells is needed to control drilling. It is very important, since the drill is in the ground during operation, that is, outside the visible zone. This system protects the storm from collision with various obstacles, which can damage drilling equipment.
Geolocation system for workflow control is equipped with a mini-probe, which is needed to track geolocation indicators during drilling. The mini-probe is mounted on the drill head and on the device. Data, transmitted by the probe, come to the operator, which makes adjustments to the workflow.
It should be noted, that the equipment for GNB is rather expensive and belongs to professional equipment. Horizontal drilling rig (UGB) may have a different configuration, however, all such machines consist of the following structural elements:
- body;
- engine;
- chassis.
The equipment for GNB is professional and has high cost
The functional part of the UGNB consists of three main components:
- drilling element;
- hose, which supplies water to the drilling element (it is necessary to cool the drill);
- control panel.
All UGNBs are classified according to one main indicator - the ultimate tensile force. Other characteristics of these machines include:
- channel cross-section indicators, which can perform such a machine;
- maximum channel length;
- concrete consumption rate (l / min);
- the use of the horizontal drilling method also takes into account the maximum possible bending radius of the drill rods. This indicator is considered very important, as it affects the mobility of the drilling rig and its ability to bypass various obstacles.
The following devices belong to the secondary equipment:
- fixing elements;
- adapters;
- expanders;
- pumping equipment;
- generators, operating on electricity;
- lighting device.
The horizontal drilling rig must be selected correctly, in accordance with all factors, listed above.
Preparatory work for the GNB
Horizontal drilling involves puncture, which is carried out by professional equipment. However, before you start drilling under the road, it is necessary to perform preparatory work.
Horizontal drilling requires preparatory work
First of all, you need to prepare a flat site for the rig. For this purpose it is necessary to level a platform, which should have an approximate size of 10x15 m. exept this, in some specific situations, it is necessary to prepare a bypass for the drilling complex.
Importantly! Prepared ??the site must be fenced with a warning tape. This is necessary for that, to prevent the intrusion of strangers into the territory. This tape is installed at a height of approximately 80 see above the ground.
The site for drilling equipment is being prepared in that place, where the well will be laid. After preparation of a platform it is necessary to carry out installation of the drilling equipment and to place it in the necessary position for implementation of a puncture..
exept this, it is necessary to anchor a basic plate for the equipment. This measure is carried out with the help of augers. Further, it is necessary to adjust the angle of entry of the drill into the ground.
Puncture by the method of horizontally directed drilling of GNB is carried out taking into account safety precautions, as well as all necessary building codes. In the process of drilling a special bentonite solution is used. Apparatus, which prepares this solution, must be located on the side of the horizontal directional drilling rig. The distance between the UGNB and the bentonite preparation plant must be at least 10 m. Bentonite solution performs the following functions:
- strengthening the walls of the well channel;
- and this solution helps to remove soil from the canal.
In the places of entrance and exit of the channel it is recommended to install special pits, in which the excess solution will be disposed of. exept this, it is necessary to establish constant radio communication between the drilling manager and the operators.
Consider, what still needs to be done in preparation for horizontal drilling of GNB:
- identify places, where underground communications take place, so as not to touch them when drilling;
- to study the composition of the soil and its features. This is required to select the optimal drilling route.
There should be a small indentation at the puncture site, filled with bentonite mortar
Execution of a pilot well
Once all the preparatory work is done, it is possible to start laying pipes directly by the method of horizontal directional drilling. For this purpose the drilling rig is located in the necessary place. Further, you need to perform a check (pilot well). The cross-sectional characteristics of such a well should be approximately 100 mm.
When organizing a pilot well under the railway tracks or expensive, the movement of the drilling element should be regulated by the geolocation system. It is forbidden to perform trenchless work without such a system or in case of its malfunction.
The initial position of the drill head, usually, is 10-20 ° in relation to the horizon. This angle must constantly decrease depending on the depth of immersion. Once the required depth is reached for laying the pipeline by the GNB method, drilling is carried out in the horizontal plane. During drilling it is allowed to make adjustments to the movement of the drill bit. Correction of drill motion is carried out in that case, if it deviates from the specified trajectory. Determination of deviation from the desired trajectory is performed using a positioning system.
The puncture method involves checking the state of the drill using geolocation systems through each 3 m. After passing a certain point, the drill head begins to move up, allowing you to reach the exit point. Exit from the ground (as well as the entrance) must be calculated in advance and performed at a strictly defined angle.
The pilot well needs to be expanded, this is done using a special device - Rimmer
expansion
At the next stage of laying pipes under the road it is necessary to expand the pilot channel. To do this, dismantle the drill head, and in its place install a special device - Rimmer. Rimmer is a constructive element, which is used when laying pipes by the method of GNB, which performs the function of expanding the pilot channel. It is worth noting, that Rimmer is a feedback extender (it extends from the exit of the channel to its entrance).
Taking into account the technology of drilling GNB, to achieve the required diameter, expansion is performed from one to several times. The number of extensions depends on that, what diameter should the future well have.
Horizontal drilling can be performed in difficult conditions (bad soil, a large number of obstacles in the way of the storm, etc.. D.). In this case, the work of expanding the well is performed before, as the necessary communications will be laid in the channel. exept this, it is worth noting, that all work must be performed using coolant. It has to do with that, that geolocation equipment is very sensitive to elevated temperatures. Road puncture is a serious event, which must be thought out from beginning to end.
There is another important factor, which should be provided - soil shedding. Puncture under the road by the method of GNB must also take into account that, that before drawing plastic or metal pipes into the well, they must be connected. The structure must be securely connected, otherwise problems may occur. Then, when the drilling equipment is switched off, the annular expander is joined to the rods. Then through a rotating swivel the necessary communication is joined. A special transition element or other possible device will be required for docking.
Useful Information! The GNB method takes into account the selection of the expansion part by this calculation: channel must be on 25% more extensible pipeline. If the communication is laid with insulation, then the channel should be more on 50%.
The finished channel should be about a quarter wider than the pipe
If the pressure inside the channel is high, then the bentonite solution evenly fills the space between the outer wall of the pipe and the inner wall of the well. After the bentonite solution hardens, soil subsidence is excluded.
pipeline laying
Puncture under the railway or roadway is performed in the first place. Further, the well is expanded to the desired diameter. At the third stage the pipe laying is performed according to the GNB method.
This is done quite simply: the pipeline is tightened together with the last Rimmer expansion. Fastening of communication to the expander is carried out by means of special connecting brackets or swivels.
Preliminarily, the conductor is pulled through the finished channel. This is necessary when organizing cable wiring in communications. In this case, the pipeline structure will serve as a protective cover, which protects the wiring in the soil from damage.
This technology allows you to quickly, to reliably and economically extend the pipeline through the ground without the organization of trenches, which, usually, performed manually. After laying the GNB pipeline can be considered complete. Finally, drilling and other equipment must be evacuated from the work site.
