The high performance of modern drilling rigs allows the development of wells with large diameters and depths. If we are talking about small operating parameters, then the very approach to the technical implementation of the problem may be different. For example, core drilling makes it possible to cost-effectively drill narrow holes while maintaining high precision and accuracy when cutting rock.
Technology Features
The core method has been used in industry and surveying for over 150 years. Its special place in the general range of geological development technologies is due to the fact that after the 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 - depending 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. In this case, the movement of the crown also occurs strictly along the edges, which allows you to save the rock. Along with this, the shafts are filled with working equipment, which is represented by core drilling rigs - bits, augers and core receivers. This technology also has a number of limitations, since as the depth increases, the pressure on the cutting elements increases. For this reason, the maximum depth of core holes is only 150-160 mm, depending on the type of soil and the characteristics of the equipment.
Scope of the method
The use of core drills pays off when mining hard rocks. This mainly concerns mountain deposits that are explored for scientific or design purposes. For example, in engineering surveys, a solid soil sample 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 industry. In the mining industry, before installing hydromechanics and multi-screw excavators, core drilling is performed directly at the development site, the results of which are a project for a future well.
Used equipment
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 integrated into the chassis of KAMAZ, MAZ, Ural, etc. vehicles in a mobile way. Tracked vehicles are used to perform work in difficult conditions.
Design of the installation of a columndrilling is formed by a supporting frame, an engine, a hydraulic system for controlling the position of working bodies, a hose for flushing the well and equipment surfaces, as well as a mechanism for attaching nozzles of the SDS type. 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, the means of independent fuel supply are the main source of energy for such equipment.
Drilling accessories and consumables
Different-sized crowns and auxiliary tools can be used in the development of rocks. For high-strength hard formations, diamond and shot segments are used. In terms of strength, medium rock is cut with wolframite pobedit and crowns, and low-strength soil is treated with steel elements. In each case, the use of tools for servicing the face is mandatory.
Pipes, augers, core rods and flush glands can be used to supply water or extract cores. In difficult areas, when organizing a multi-stage drilling configuration, special adapters with mounting fittings, rotators and butt joints are also involved.
Workflow
At the first stage, the target area is cleared of debris, turf and foreign objects. A pit is formed a few meters from the drilling point for the future drain of the flushing solution. Its depth depends onplanned scope of work. Then, a hole is created by a hole to accommodate the drill itself, after which the bit is integrated into the gripping mechanism. At this stage, the core drilling machine is built up by the outreach of the working equipment by means of pipes and adapters. Next, the rotation of the pipe begins with the cutters along the edges.
After each pass with filling the nozzle with a core, the structure rises. With the manual maintenance method, workers extract the rock with hammer blows. In mechanized installations, this operation is performed automatically using a special pusher. Then flushing is performed, and the drill plunges into the well again until the desired depth is reached. For rocks with a fragile unstable structure, as the depth of the passage increases, reinforcing casing pipes are used. They prevent the walls from collapsing and disturbing the drilling parameters.
Advantages of Technology
From the point of view of the possibility of obtaining an accurate core, this is the best way to drill. As an alternative, the use of a rotary chisel can be recommended, but even in this case it is impossible to achieve the same exact cut geometry. It also maintains high performance. Powerful installations allow serial 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.
With this method, you canstably pass and high-strength rocks, including granite and bas alt. The wells themselves can be multilateral, raised and deviated - the equipment allows you to create different development models, varying the speed and size parameters.
Flaws of technology
Among the main disadvantages of core drilling technique are the need to use flushing solutions, restrictions on the depth of passage and stringent requirements for tool maintenance. The most sensitive factor in the course of work will be the wear factor of the pipes. 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 mud. In general, with regard to flushing, without it it is impossible to obtain a high-quality cut in a core circle while maintaining the functionality of the functional equipment. Many organizations practice the dry drilling technique, but in the end it is more expensive in terms of both financial and technical resources.
Conclusion
Optimization of technological approaches to the implementation of wells in different directions is reduced to automating the process and reducing the number of units and assemblies used. The focus is on versatility and practicality, which is achieved, among other things, by improving the working qualities of the crowns used. In the case of core drilling, it is worth emphasizing the optimization in the scheme itself.well development. For all its shortcomings, this is the best solution for providing a shallow sample of the breed. Moreover, this technology can theoretically be used in domestic conditions, using small-format equipment and manual power equipment.
