Drilling is the process of using mechanical equipment to drill a certain number of boreholes in the ground. It can be subdivided into tonnage drilling technology and rotary drilling technology according to the way of rock crushing and the type of drilling tools.

In geological exploration and geological engineering, the drilling equipment is used to drill holes into the ground, and for smaller diameter and deeper columnar round holes, they are called boreholes. Depending on the drilling application, different borehole diameters and depths are designed. For example, boreholes for drilling oil, natural gas, and groundwater are larger in diameter. Boreholes for geophysical logging and coring are generally small.

The main functions of drilling:
1. To obtain underground physical information, cores, rock chips, oil, water, natural gas, etc. from the bottom of the well.
2、As a geophysical logging channel, to obtain information of various geophysical fields in rock formations, such as for underground arms testing.
3、As an artificial channel to observe the mineral, hydrology and geological structure in the stratum, etc.
4、Comprehensive application, exploration and acquisition of phase junction, and development of underground resources.
According to the use division, the drilling is generally divided into geological census drilling, geological exploration drilling, water well, engineering geological drilling, geothermal drilling, oil drilling, etc.

The drill bit is generally sent to the bottom of the well by a steel wire rope and driven by a power-driven traveler mechanism, which makes the traveler move up and down and drives the wire rope and the drill bit to produce up and down impact. The drill bit is driven up and down by the power-driven traveler mechanism. However, the drilling speed is slow, the efficiency is low, the hole is shallow, and it cannot adapt to the requirements of complex formations and deep wells. It is gradually replaced by rotary drilling.

Rotary drill is beneficial to the cutting or grinding action generated when the drill bit rotates to break the rock. It is currently the most common drilling technology. It is faster than the stop drilling speed, and is easy to deal with complex situations such as well collapse and blowout.

According to the power transmission method, rotary drilling can be divided into two types: national rotary drilling and downhole power drilling.

The turntable is a drilling platform with a square hole in the center of the turntable. The upper end of the drill column has a square drill pipe through the square hole, and the lower end is connected to the drill pipe and the drill bit. This technology has an obvious disadvantage, that is, the deeper you drill, the more drill pipe you use, the more weight the turntable drives, and the wear and tear of the drill pipe increases exponentially, and the energy consumption gradually increases until the power machine is overloaded.

Downhole power drilling is beneficial to downhole power drilling tools, which drive the drill bit to break the rock, and the drill bit does not rotate when drilling, which reduces the wear of the drill pipe, increases the life of the drill pipe, reduces energy consumption, and is suitable for drilling deeper wells. However, this technology is also relatively complex, and the drilling equipment is divided into rotary system, lifting system, mud circulation system, etc. by function, and the technical difficulty of equipment manufacturing and application is high, which is not suitable for the use of small drilling enterprises.