Vol 41 Iss. 2

The current state of exploration drilling technology and the emerging trends in its development indicate that in the coming years, existing mechanical methods of rock breaking will predominate, with rotary drilling foremost among them. The highest priority tasks are the mechanization of all labor-intensive operations and the transition to automation of drilling processes. It is necessary to accelerate the mechanization of shallow well drilling, because up to 1 million meters of shallow wells are drilled by hand every year. The situation is particularly unsatisfactory in engineering geological surveys. These operations require highly portable rigs, since wells are often drilled along railway track beds with heavy train traffic. Vibratory drilling and auger drilling should become more widespread in the near future.

Quantitative determination of the free fall velocity of a body in a liquid or gaseous medium is of paramount importance in the theory of hydraulic and pneumatic transport, gravitational methods of enrichment, for the calculation of a number of apparatuses, machines, technological processes and, in particular, is the basis for calculating the required flow rate of liquid or gaseous flushing agent for the removal of cuttings when drilling wells. At free fall in the medium, the body reaches a terminal velocity when the resistance force of the medium becomes equal to the driving force of the weight of the body in the medium.

The spatial position of a deviated borehole is determined from measurement data. At a number of points Mᵢ (i = 1, 2, …, n) taken along the borehole length, measurements provide values of inclination angles θᵢ and azimuth φᵢ. From these data and the distances sᵢ of points Mᵢ from the wellhead, the position of points Mᵢ and of the entire borehole is determined. This determination can be made by various methods, each of which yields an approximate borehole position. The question arises of evaluating the possible deviation of the obtained borehole position from the actual one, and of how the accuracy of determining the borehole's spatial position depends on the accuracy of the angle measurements and on the number of points at which such measurements are made.

The complex geological structure of the Bakal area causes intensive zenith and azimuthal deflections of core drilling boreholes, which reduces the quality of geological documentation, worsens drilling conditions and increases the cost of drilling operations. From the analysis and generalization of data on deflection of a large number of core drilling boreholes some regularities of their natural deflection are established. Using the established regularities, it is possible to carry out more accurate and directed drilling of core boreholes. The geological structure of the area includes rocks of the Bakalskaya, Zigalginskaya and Zigazino-Komarovskaya formations. Stratigraphic and lithological characteristics of the main rocks of these formations are as follows (section from top to bottom).

Borehole curvature, i.e. deviation of the borehole axis from its design profile, is a highly undesirable phenomenon that often leads to failure of the drilled borehole to fulfill its geological tasks and brings great losses to the national economy. Therefore, the identification and study of all factors affecting the curvature of core boreholes is an urgent and important issue.

In many studies of rock fracture in rotary drilling, the following view of the sequence of phenomena occurring during the interaction of the cutter with the rock has been established. Under the action of the axial force C, the cutter penetrates the rock to a certain depth ...

The percussive-rotary method of drilling has found in recent years increasingly widespread use both in the USSR and abroad. When sinking explosive wells, pneumatic percussion drilling units confidently displace low-productive cable percussion drills. Percussive-rotary machines for borehole drilling in underground workings have appeared. A number of research organizations of our country are working on the creation of hydraulic percussion machines for sinking exploration and production wells. However, the theoretical basis of percussive-rotary drilling is very poorly studied, despite more than half a century of research history of this undoubtedly progressive method of rock destruction. If now it is possible to point out certain successes in the field of design and study of different kinds of percussive-rotary machines, at the same time it is impossible not to note the almost complete absence of works devoted to the study of the physical essence of the process of interaction of the tool with the rock. The progress in this field has now become an absolutely necessary condition for further improvement of the theory and practice of percussive-rotary drilling.

Currently, hard rocks account for about 25-30% of the total volume of exploration core drilling. Drilling is carried out by shot drilling. By the end of the seven-year plan (1959-1965) about 50% of shot drilling will be replaced by fine-diamond drilling. Thus, the improvement of shot drilling technology still plays a major role in accelerating the exploration of mineral deposits. One of the ways to improve the technology of shot drilling is flushing the bottom hole with compressed air instead of flushing with water. Air, as a flushing agent, is not able to keep the walls of the well from collapse, but this is not required in shot drilling in strong rocks, as a rule. Compressed air successfully fulfills the other requirements to the flushing agent.

When exploring mineral deposits, drilling with a solid bottom hole, i.e. without coring, is being used more and more widely. Coreless drilling makes it possible to increase productivity by increasing the mechanical speed of drilling, reducing the time for trip operations, eliminating the time spent on core jamming, simplifying drilling technology and, accordingly, reduces the cost per linear meter of drilling.

In the practice of prospecting and exploration work, shallow wells in soft sedimentary deposits are drilled mainly by rotary core drilling method or by using extremely backward manual percussive-rotary drilling. Not to mention the latter, core drilling also cannot fully meet the modern requirements of exploration work both in terms of labor productivity and the quantity and quality of samples taken. This is explained, first of all, by the necessity to drastically reduce the drilling parameters (in terms of the rotation speed of the drilling tool and the amount of fluid fed into the well), based on the mandatory conditions of core preservation. Taking into account that the method of “dry drilling” used in practice in order to increase the core yield takes 30% of clean drilling time in each trip (1.2-2 m long), it becomes obvious that this method is unacceptable for drilling in soft sedimentary deposits.

One of the methods of mechanization of shallow well drilling in soft rocks, as it is known, is vibratory drilling. In recent years, it has become relatively widespread. However, the vibratory method of drilling, unlike the vibromethod in construction, is not sufficiently covered in the literature. This article is devoted to the development of the main rock-destroying drilling tools, as well as some operating parameters of vibro drills.

Drilling of wells is accompanied by expenditure of a certain amount of energy, which is spent to overcome friction in the ground equipment, to rotate the drill string, the destruction of rock at the bottom hole and the friction of the drill tip on the rock. The article analyzes the power formulas and gives the results of experimental studies of two components of power: 1) on the destruction of rock and friction of the drill tip; 2) on the rotation of the drill string.

When selecting the engine power for the machine drive, the determining factors are the power consumption for drilling process and production of hoisting operations. The latter are of great importance when working at great depths, where the rock strength increases significantly and the time of the drill bit stay at the bottomhole decreases. Below we propose a method of determining the required engine power for hoisting operations.