ROTATIONAL DRILLING (EN: rotary drilling; DE: Drehbohren, Rotarybohren; FR: forage rotatif, forage par rotation; ES: sondeo por rotacion; RU: вращательное бурение) is the method for the construction of the boreholes, using the destruction of the rock on the account of the rotation of the rock-breaking tool (drilling bit, drilling crown), which is pressed into the bottomhole.
The major varieties of the rotational drilling, which are used for the construction of the research and operational boreholes, are the rotary drilling (the rotation is transmitted to the tool through the drill string from the rotor, which is installed within the drilling derrick), the turbine drilling (the rotation of the tool is performed using the turbodrill engine immediately within the bottomhole), the rotary-turbine drilling (the rotation of the tool is performed using the turbodrill, which is installed within the bottomhole aggregate, which is rotated using the rotor through the drill string), the reactive-turbine drilling (the rotation of the tool is performed using the turbodrill, the bottomhole aggregate is rotated because of the reactive moments of the force), the electric drilling (the rotation of the tool is performed using the electric motor immediately within the bottomhole), and the drilling using the volumetric motor (the rotation of the tool is performed using the helical hydraulic motor within the bottomhole).
The rotational drilling of the shallow (mainly blasting) boreholes is performed using the transmission of the torque from the drilling installation through the rod to the rock-breaking tool, which is either of the roller-cone type (see the "Roller-cone drilling" article), or of the vane type, with the removal of the rocks along the twisted rods, namely, along the auger conveyors (see the "Auger conveyor drilling" article); the principle of the rotational drilling is also used for the drilling using the drill bits. They use the rotation of the drilling tool in combination with the blow, for example, during the rotational-percussive drilling, and during the percussive-rotational drilling. Depending on the depth of the drilling, the power of the drilling installations, which are used for the rotational drilling, amounts to from several tens kilowatts to several thousands kilowatts. During the rotational drilling, the rocks are destructed within the entire bottomhole, or within the annulus with the extraction of the core (the core drilling). Depending on the mining-technical conditions, in case of the rotational drilling, they construct the vertical, horizontal, inclined, branched, and grouped boreholes.
The rotational drilling has replaced the percussive drilling during the 2nd half of the 19th century, and since the start of the 20th century, the rotational drilling is the major method for the construction of the boreholes (see the "Drilling" article). Within the USSR, there has obtained the greatest usage (for example, for the drilling of the boreholes for the petroleum and gas reservoirs) the turbine drilling (approximately 80% of the rotational drilling), and there is expected to increase the quantities of the rotary drilling, and of the drilling using the helical bottomhole motors; within the USA, the major method for the rotational drilling is rotary, and there is expanding the quantity of the drilling using the bottomhole motors.
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