Vol 66 Iss. 1

In recent years, the work of the department has been characterized by a move away from multi-theme research. This is explained by the establishment of more stable relations with large customers and the extension of contract periods. The total amount of contracts concluded annually is about 140 thousand rubles. All this has had a favorable effect on the department's performance.

The rate of penetration in hard rock drilling depends on the geometric shape of the cutters. The bottom-hole process in drilling hard rocks with a cylindrical bit with sharpened plate-type cutters was first considered by E. F. Epshtein.

The paper considers the main solution of the penetration rate problem based on the theoretical principles stated earlier. The solution is based on the constancy of the cutter contact area during drilling and on the division of the penetration depth of the contact area into two parts — upper and lower.

The first solutions to the problem of drilling with simultaneous freezing of the rocks being penetrated, which reduces to finding the relationship between the depth of the freezing front and the mechanical rate of drilling, are approximate and contain parameters determined from experiment or arbitrarily.

The regularities of the temperature regime of boreholes and mine workings, especially under conditions of changes in the phase state of the surrounding rocks, are described by extremely complex analytical expressions. The concepts of the coefficient of unsteady heat exchange kτ and the coefficient of heat exchange intensification during phase transition kagr significantly simplify the solution of this range of problems.

When drilling through perennially frozen rocks, the same flushing fluids can be used as are usually used in rocks with positive temperatures. All requirements for flushing agents in these conditions apply to media designed for operation at negative temperatures.

At the Department of Well Drilling Technology and Techniques of the Leningrad Mining Institute, studies of mixtures of surface-active agents (surfactants) have been carried out. The purpose of the experiments is to obtain surfactant additives that are more effective than the single surfactants currently used.

One of the first priorities in Antarctica is to study the ice covering the continent. This article provides some thoughts on the possibility of using transportable equipment requiring relatively low energy costs for core drilling in Antarctica. Mechanical destruction of ice is supposed to be carried out with a special design bit reinforced with pointed cutters made of hard alloy. The cuttings formed during ice destruction will be carried out from under the face of the bit by the flow of circulating agent, which can be air, kerosene or paraffinic diesel fuel.

Prospective reserves of coquina phosphorite deposits in Estonia and the Leningrad Region are estimated at 2–3 billion tons. Genetically, they are associated with a thickness of quartz–obolus sandy sediments of the Pakerort horizon of the Early Ordovician, distributed over almost the entire territory of Estonia and stretching 320 km to the east into the Leningrad Region. The thickness of the productive strata varies from 1 to 6 m, with an average thickness of 4 m. Phosphorite-bearing sandy sediments with erosion lie on sandstones, siltstones or clays of the Cambrian.

Modern scientific and technological progress requires increasingly complete utilization of natural resources. Along with the use of other types of energy and fuel, geothermal resources, i.e. the heat content of the Earth's crust, represent an important energy reserve. The necessary prerequisites for the wide practical development of these resources are created by the development of techniques and technology of drilling wells, contributing to the study of ever deeper horizons of the Earth's crust and the accumulation of actual material on geothermy.

The main factors determining the peculiarities of drilling technology for high-temperature waters are the increased values of reservoir pressure, gas saturation and water temperature. Depending on the magnitude of the geothermal gradient and the depth of drilling, the temperature in the well can vary widely and reach 200°C or more.

Exploration of the Tyrnyauz deposit, carried out on the flanks mainly by means of mining and drilling operations, is complicated not only by specific features of the highlands, but mainly by thick (from 50 to 180 m) deluvial-moraine deposits. These sediments are represented by unconsolidated fragments of altered rocks of different hardness and abrasiveness: mudstones, siltstones, tuff-sandstones, granite-gneisses and hornfels of various compositions. In addition, on the northern slopes of the ridge there are widespread areas of permafrost, which makes the specifics of drilling operations close to the conditions of the Far North.

In the existing standard (normal) of the tubular assortment of exploration drilling equipment, coring and casing pipes have dimensions that differ significantly from those of drill pipes. Recently, in connection with the transition to drilling exploration wells with removable core barrels, drill pipes in outer diameter are approaching core pipes.

The main task of exploration of offshore deposits, as well as deposits occurring on land, is to determine the quantity, quality and conditions of occurrence of the mineral. The specificity due to the location of the mineral deposit under the water column at different depths, in different climatic zones, makes it necessary to search for new ways and technical means of exploration.

Standard tungsten-cobalt carbide bonds, depending on their hardness and purpose, are produced by cold (No. 3, 20–25 HRC, and No. 4, 30–35 HRC) and hot (No. 5, 50–55 HRC) pressing. Sintering temperatures of bond matrices vary from 1150 (No. 3) to 1350°C (No. 5) and in a reducing medium do not lead to the appearance of noticeable traces of graphitization or loss of mechanical strength in perfect single crystals of natural diamond.

In the process of drilling, heat is generated in the bottom-hole zone due to mechanical work of the rock-destroying tool. As a result, the natural temperature and phase state of frozen rock cores is disturbed. Studying the mechanism of frozen rock core thawing during drilling, elucidating the regularities of the thawing process for deliberate regulation and normalization of its temperature regime are of practical importance.