The high performance of modern drilling rigs allows you to develop wells with a large diameter and depth. If we are talking about small operating parameters, then the approach to the technical implementation of the task itself may be different. For example, core drilling allows you to perform narrow wells at minimal cost, while maintaining high accuracy and accuracy when cutting rock.
Technology features
The column method has been used in industry and geodetic surveys for more than 150 years. Its special place in the general number of geological development technologies is due to the fact that after completion of the work a solid core remains. This is a cylindrical column with material from the well, which can be discarded or stored for further study of the rock - depends on the tasks. In other words, cutting and development is carried out not over the entire area of the drill, but along the edges of the well. The movement of the crown also occurs strictly along the edges, which allows you to save the breed. Along with this, the trunks are filled with working equipment, which is represented by core drilling rigs - crowns, augers and core receivers. This technology has a number of limitations, as the pressure on the cutting elements increases as they deepen. For this reason, the maximum depth of core wells reaches only 150-160 mm, depending on the type of soil and the characteristics of the equipment.
Method application areas
The use of core drills justifies itself in the development of strong rocks. This mainly concerns mining deposits that are being studied for scientific or design purposes. For example, in engineering and geodetic studies, a sample of whole soil with a depth of more than 1 m may be required. Accordingly, the method is used in reconnaissance surveys, and not only in the construction sector. In the mining industry, before the installation of hydromechanics and multi-screw excavators, core drilling is carried out directly at the development site, according to the results of which a future well is designed.
Equipment used
The main functional unit is a core drilling rig. It can be delivered to the workplace and subsequently used on a special support platform, or it can be integrated in a mobile way into the chassis of KAMAZ, MAZ, Ural and others. To carry out work in difficult conditions, tracked vehicles are used.
The design of the core drilling installation is formed by a supporting frame, an engine, a hydraulic system for controlling the position of the working bodies, a hose for flushing the well and equipment surfaces, as well as an attachment mechanism for SDS nozzles. Modular control points and generators can be used for control and power supply. Since the work in most cases is carried out away from the central communications, autonomous fuel supply is the main source of energy for such equipment.
Accessories and consumables for drilling
Different-format crowns and an auxiliary tool may be involved in the development of breeds. For high-strength hard formations, diamond and shot segments are used. From the point of view of strength, middle breed is cut with tungsten victorious and crowns, and soil of small strength is treated with steel elements. In each case, the use of tools for servicing the face is mandatory.
Pipes, augers, rods for increasing the depth of core drilling and flushing glands can be used to supply water or to extract core samples. In complex areas, when organizing a multi-stage drilling configuration, special adapters with mounting fittings, rotators and butt joints are also involved.
The working process
At the first stage, the target site is cleaned of debris, turf and foreign objects. A few meters from the drilling point, a pit forms for the future discharge of the wash solution. Its depth depends on the planned volume of work. Then, a hole is created to accommodate the drill itself, after which the crown is integrated into the gripping mechanism. At this stage, the core drilling machine grows at the departure of the working equipment through pipes and adapters. Then begins the rotation of the pipe with cutters along the edges.
After each pass with core filling, the structure rises. In the manual maintenance method, workers remove the rock with hammer blows. In mechanized installations, this operation is performed automatically using a special pusher. Then flushing is performed, and the drill is again immersed in the well until the desired depth is reached. For rocks with a brittle unstable structure, reinforcing casing pipes are used as the depth of the passage increases. They prevent the walls from collapsing and disrupt the drilling parameters.
Technology benefits
From the point of view of the possibility of obtaining a neat core, this is the best way to drill. Alternatively, the use of a rotary bit can be recommended, but even in this case it is impossible to achieve the same precise geometry of the cut. High performance is also maintained. Powerful installations allow batch processing of the target area at several positions in a short period of time. Therefore, with an integrated approach to the survey, core drilling technology makes it possible to study the underground structure of soils.
Using this method, it is possible to stably pass high-strength rocks, including granite and basalt. Wells themselves can be multilateral, rising and inclined - the equipment allows you to create different development models, varying the speed and size parameters.
Technology disadvantages
Among the main disadvantages of the core drilling technique are the need for flushing solutions, restrictions on the depth of the passage and strict requirements for tool maintenance. The most sensitive during operation will be the factor of pipe wear. The cutting edges wear out quickly, after which it is necessary to sharpen or completely update the working segments. Therefore, even when developing rocks of medium strength, it is recommended to use diamond core drilling with abundant use of clay mud. In general, with regard to flushing, without it it is impossible to obtain a high-quality cut in a circle of the core while maintaining the functionality of the functional equipment. Many organizations practice dry drilling techniques, but in the end it costs more in terms of both financial and technical resources.
Conclusion
Optimization of technological approaches to the implementation of wells in different directions is reduced to automation of the process and a reduction in the number of nodes and assemblies used. The stake is on multifunctionality and practicality, which is achieved, inter alia, by increasing the working qualities of the used crowns. In the case of core drilling, it is worth emphasizing optimization in the well development scheme itself. For all its drawbacks, this is the best solution for providing shallow sampling of the breed. Moreover, this technology can theoretically be used in domestic conditions, using small-format equipment and manual power equipment.