Rotary drilling: technology, principle of operation and features

One of the most widely used methods of creating operational and exploration wells for water is rotary drilling. It ensures transfer of rotational motion from the surface of the rotor on the column-Bur.

Rotary drilling is characterized in that it has no axial force generated by the actuator. In the process of cleaning production (slaughter) from the waste rock with water and special solutions. Consider the method in more detail.

Historical background

Rotary drilling has been used for more than one hundred forty years. The technology of this method of penetration of wells was first used in the United States of America in the early eighties of the nineteenth century. Since that time it has remained virtually unchanged except for minor innovations, which led to greater efficiency. The changes affected the rock-destructive tools – they were improved, created a new liquid medium for flushing boreholes, increased strength of parts of the mechanism.

Rotary drilling of wells – is one type of drilling method of rotation. The principle is that the tool for destruction of rocks, lying inside the well, powered by the efforts transmitted to it by the motor or gas turbine equipment. This method is simple and effective. With it, operational and drilled oil exploration wells. Compact dimensions allow to use the private land for the creation of water wells.

Drilling Methods

Currently, drilling for water is partiesreceive methods with the use of special mechanisms. Feeding ground up can be done in two ways:

• Using the mechanisms-dry method.
• Water Jet under high pressure or by gravity-hydraulic.

In the General case, a mechanical drilling is performed in one of three ways:

• Rotary rotary drilling – the soil is drilled with rotary movements.
• Shock & ndash; ground is broken by blows of the drill string.
• Vibration – ground is broken by fluctuations of high frequencies.

The First method is the most used because of its simplicity, low cost and at the same time performance.

When using method

The rotary Drilling method is used when the development of half rock and rock soils for the device wells to a depth of one hundred and fifty meters. For the successful drilling of rocks you need to choose the right drilling tools – drill bit and drill pipe. According to experts, for the effective operation of rotary drilling should be used if in compliance with the following conditions:

• The Study of the hydrogeological section of the site carried out in detail.
• It is Known that the soil consists of rock.
• There is data on the level of occurrence of water-bearing veins.
• Have good pressure groundwater.
• There is a possibility of constant delivery of wash liquid.

In addition, it should be noted that the conditions of the southern regions enable you to drill year-round, and in the Northern areas of work limited to the thermal performance of the environment in which freezes the liquid for flushing.

Equipment for drilling wells

The Technology of rotary drilling requires the use of special installations – mounted on the basis of self-propelled vehicles or stationary. And those and others should have the following components:

• The Engine.
• Tower.
• Drive.
• Swivel – a system supplying fluid to the slaughter.
• The Drill column.
• Rotor.
• Piston pump.
• Linkage, which includes the unit and cronobloc.
• Discharge line.
• The recovery System and the cleaning liquid containing hydro-cyclones, hopper and vibrating screen.

Advantages and disadvantages

The Rotary method of drilling has several advantages over other methods. Among them, the following should be noted:

• Performance exceeds the others: five times – drums and ten – vibration method.
• Has a high rate of performance.
• Through the use of various detachable bits can be used on soils of different complexity.
• The Installation has a compact size, so can function in a confined space.
• Due to the possibility of the location on the platform the unit is completely mobile.
• Enables the drilling of deep wells and extract water from the fractured limestone.
• The Method has good qualities opening of the water-carrier.
• Allows you to set wells up to two hundred centimetersin diameter.

Along with these advantages of a rotary-driven drilling has the following disadvantages:

• It is Necessary to consider the type of soil to find the right bit.
• The Presence of hard particles of rocks on the road can be a barrier, requiring a more destructive mechanisms.
• Interference can be a clay soil.
• A Serious obstacle to drilling works – the frozen earth.
• Power is highly dependent on the moment of the rotor.
• The Need for continuous availability of large amounts of fluid for flushing.

Despite some cons, the pros this method is much more.

The Principle of action of rotary units

Rotary drilling is performed with a special installation-frame or lattice tower mounted on the platform. To it are attached all the other systems, allowing you to raise and lower the drill string shaped forms. This column is going to of several pipes connected dismountable couplings.

Driving force is a motor car or a separate generator which via a drive shaft and a gear transmission transmits the rotation of the column rotor. Rotating the rotor operates the bit which the working edges in the hole destroys the soil layer. The range of turns can be adjusted. Edge of the bit may be diamond, or carbide composite. Their form may vary.

Developed layer of soil direct or reverse flushing is displaced from the mine by gravity or under pressure with the application of pumping systems. After washing the wells it installed casing. By means of a swivel and hollow pipes of the drill string to the bit is supplied the liquid for washing, eroding the soil beneath the chisel. Through the gap between the tubes and the stem the fluid makes the ground outside. On the surface through special filters, the liquid is collected and purified to be again put in use the piston pumps.

The technology features of rotary drilling

The drilling Process is organized so that due to erosion of soil from the mine drillstring with every movement deepens and lower. Periodically it is necessary to build up adding the other pipes.

The drilling Process step is performed:

• After the first loose layers of soil, the column rise, and the shaft down the well casing.
• A Gap in a circle filled with cement mortar.
• After hardening of the cement in the shaft serves a bit with a smaller diameter, and work continues.

Such steps may occur more, and then the shaft drops perforated on the end of the operational pipe. Depending on the quality of soil layer and depth choose the number and weight of pipes, type of bit, speed of rotation and material edges, the pressure of the flushing liquid. Specificity is as follows:

• Easy rock formations are conducted with maximum speed and maximum flushing.
• Rocky soils require reduced frequency and a reduced fluid pressure.

Stop can ground solids – boulders – in the way of a rotor that may be stuck, or soil, actively absorbing washing. Also slows down the process of water scarcity in the place of work and the presence of a large clay layer. Clay mixes with water, clog the water channel and requires extra careful cleaning.

The Casing

After drilling the well it is important to strengthen its walls. The ground is uneven and can be displaced, which negatively affect the bottom.

To the earth breed has not collapsed, set the casing. It helps to prevent osypanie of the soil and prevent water percolation. The first column is called “conductor”. It is mounted to overlap the unstable rocks. The installation is at a distance sooner at 30 meters and not later than 600 meters. For oil wells, the column is placed at a distance as close as possible to the surface.

As rotary drilling is used for almost all types of soil, the installation process work focused on geological conditions. Sometimes you have to use some casing to reinforce the bottom.

The Smallest diameter of them drops deeper than the rest and is called – operational. Perforation is made from below, through these holes the mass of gas, water or oil in her to do that.

The value of the washing liquid in drilling operations

Correct method of washing in the rotary drilling of a borehole can significantlyto increase the efficiency of the process. In works of this type are used:

• Polymer solutions.
• Oil emulsion.
• Aerated solutions.
• Water.

Also widespread use of the method of air purge. If work is carried out in areas with low formation pressure, the workers used special gas. Rinsing helps to get rid of excess impurities and objects, falling rocks, which is inevitable in the process of drilling. The liquid caught on the bit, cools it. That extends the life of the tool.

Rotary drilling of wells occurs in three stages:

1. The Destruction of the earth's subsurface with the use of chisels.
2. Run water for the removal of the destroyed rock. The process can be made both reverse and direct the washing, it all depends on hole depth, volume of water used and the soil type. In private households is popular method of direct leaching.
3. Strengthen the walls of new wells with casing pipes.

The Drilling of wells by the rotary method is a time consuming process, which must take into account many factors. Despite this, he is considered to be quite effective and is used in various conditions.