The current situation in the mining and geological industry requires acceleration and reduction of the cost of exploration works. Ground-based contactless methods as well as methods using unmanned aerial vehicles have significant prospects for geophysical exploration optimization in difficult-to-access areas with faltering galvanic grounding. The purpose of the study is to present the results of both the use of contactless electrical exploration (electric field contactless measurement), which is commonly used in engineering surveys, and magnetic exploration performed with the use of unmanned aerial vehicles. The complex is aimed at searching for primary gold in the Bodaibo district of the Irkutsk region. The paper provides a brief description of the geological (geophysical) situation and justifies a rational measurement method. Geophysical works have been carried out on a scale of 1:10000. Also, the obtained data have been compared with the application field of the contactless technology of the resistivity method. As a result, additional and necessary theses have been proposed for the long-held measurement technique. It has been determined that the proposed complex allows confident mapping of the main geological structures promising for gold mineralization in a shorter period of field work.

The seismoelectric effect and the effect of induced polarization of the electro-osmotic type belong to the category of electrokinetic phenomena. The theoretical foundations of both effects are based on the Helmholtz – Smoluchowski equations applied to streaming potentials and electro-osmosis. However, electrokinetic phenomena of significant amplitude do not occur in every type of rocks. Using the mathematical concepts of M. Biot who regarded the fluid motion relative to a solid matrix for slow seismic waves in the wave equation and R.N. Chandler’s problem on transient pressure inside a pore, the amplitude of seismoelectric effect in porous rocks has been calculated. The purpose of the study is to present the analysis results of the amplitudes of electrokinetic effects that occur either when a pressure gradient is imposed on the rock or when there is a potential difference, based on F. Gassman’s classification of the relationship between the components of distinguishing rocks with perfect, imperfect and absent connections between the phases. It has been shown that seismoelectric effect does not occur in rocks with no bonding between the components, where the pore filler freely circulates in the pore space and pores are well connected to each other. The rocks with perfect connection also feature no motion of pore moisture as a result electrokinetic phenomena in these rocks are suppressed. The seismoelectric effect and electroosmotic phenomena occur only in the rocks with imperfect bonding between the components (rocks with low, medium and partially high permeability (except clays)) with the pore radius of 1·10^-6–n·10^-4 m. The effects of induced polarization distort TEM signals and can be detected only at the values of the induced polarization decay constant of ~ 1 μs – n ms.

The purpose of the research is to give a detailed description of hydrogeological conditions of the Irkutsk artesian basin, which is a large hydrogeological structure of the second order. The method of morphostructural analysis has been used to distinguish the territories with different formation conditions of fresh groundwater deposits as well as to identify the boundaries of large lowlands and uplands in comparison with the geological structure. To make a generalization, the author uses the data on 45 deposits of fresh drinking groundwater explored on the territory of the Irkutsk artesian basin of the second order with the operational reserves of more than 500 m³/day. Deposits of fresh groundwater in Jurassic terrigenous rocks are confined to large relief elevations within tectonic depressions while the deposits in both Cambrian carbonate and Jurassic-Ordovician terrigenous sediments are confined to tectonic uplifts.The deposits are replenished by natural resources. The production horizons of large deposits in Cambrian and Ordovician rocks are fed by attracted resources. In the lowlands the deposits of fresh groundwater are formed only in Quaternary alluvial deposits, due to infiltration from rivers (attracted resources). Neotectonic movements are the ones that had a dominant influence on the formation of natural resources and dynamic reserves as well as on underground flow localization as they ensured the distribution and localization of surface and underground flow. It is also noted that when identifying promising areas for searching for fresh underground water, it is advisable to rely on the distribution patterns of fresh underground water reserves of already explored deposits within the identified morphostructures.

The purpose of the study is to compare and adjust the results of stability forecast for Irokinda gold deposit underground mine workings using various estimation methods of rock mass state based on the analysis of structural parameters only, multiparameter classification of structural parameters and engineering-geological indicators according to Z. Bieniawski as well as mass fracturing distribution. Engineering and geological conditions of deposit deep horizons have been estimated using the data obtained under geomechanical description of the core when drilling exploratory and hydrogeological boreholes and description of the walls of underground mine workings. All these made it possible to estimate the rock mass fragmentation degree, which affects the stability of underground mine workings. A full range of physical, mechanical and deformation property definition was performed using rock samples taken from the core of exploratory boreholes and mine workings. A total of 184 samples have been taken and analyzed during the field season with distinguishing of 10 rock varieties characterized by different strength and stability degree. The comparative analysis conducted on the example of the Irokinda field implies the need of the integrated use of these methods, which will enable increasing of result reliability and most accurate determination of the stability class of the rock mass for its further mining. The results obtained by various methods should be considered as a set of signals for making design decisions on strengthening mine workings.

The purpose of the research is to present the analysis results of construction and operation features of oil and gas wells in permafrost conditions. Considering the materials relevant to this topic, the method of comparative analysis is applied. The object of the research is technologies and equipment used for high-quality and fast construction of deep wells in permafrost conditions. As a result, complications and accidents occur due to the collapse of well walls, occurrence of caverns, stuck pipes, casing deformation and subsidence of wellhead equipment. It is noticed that the most unstable rocks in permafrost sections are located in the range of 0–200 m. The effect of temperature on thermal interaction intensity in the ”flushing agent – wellhead – drill (production) string” system is analyzed. It is found out that maintaining negative temperature of well walls is the main way to prevent complications while drilling in permafrost. The use of thermally insulating casing pipes to form a well conductor string is considered. The rotary method is specified as the main drilling method in the cryolithozone while auger without flushing is relevant for drilling for shaft direction. It is determined that drilling with the use of drilling fluids has to solve the problem of solution freezing prevention when flushing has been stopped continuously. Taking into account that the permafrost zone, as a rule, consists of loose, unstable rocks, the great importance is given to the duration of drilling under the conductor, which should last not more than 3 days. During this time, almost no complications occur when using high-quality clay mud with the temperature in the range from 0.5 to 2.5 °C. The real possibility of using a drilling fluid with a negative temperature as a cleaning agent, as well as the same with a positive temperature, but with the use of additional special technologies, is investigated. The use of drilling fluids with a negative temperature is recornized to be not economical. It is specified that prevention of permafrost rock thawing requires not only pre-cooling of the circulating solution but also selection of increased values of the rotation frequency and axial load on the bottomhole with a simultaneous change in the amount of fluid supplied to the well when designing the drilling mode. Consideration is given to the implementation options of the drilling technology based on increasing mineralization degree of drilling fluids. A conclusion is drawn that “well – rock” system is in isotonic equilibrium if the mineralization degree of drilling fluids and pore water of permafrost rocks is the same.

When conducting remote sensing of the Earth using unmanned aerial vehicles, the problem of connection disruption between the operator’s base station and the unmanned aerial vehicle controller often arises due to natural obstacles to radio signal propagation (relief, vegetation, etc.) as well as a large range of the vehicle. The loss of connection is especially critical when surveying is carried out using a real-time kinematics technology, which ensures the transmission of correction amendments from the base station to the unmanned aerial vehicle controller to ensure high-precision spatial referencing of the obtained data. The objective of the work was to create a signal retransmission system with the possibility to install it on a light-class unmanned aerial vehicle capable of hovering in the air for more than three hours, for transmitting a radio signal from the base to the unmanned aerial vehicle via a third-party device beyond natural terrain obstacles and over long distances. Having compared various methods of signal transmission via a third-party device, the authors determined the most suitable configuration that meets the requirements for signal transmission quality and design simplicity for performing work in hard-to-reach regions. To create the repeater, RFD radio modems of various series were used and various operating frequencies were tested due to their availability and wide customization capabilities. The work resulted in obtaining a repeater pair of radio modems that make it possible to redirect the radio signal from the base station to the unmanned aerial vehicle without any loss of data quality and transfer rate for performing remote sensing of the Earth using the real-time kinematics technology. A secondary feature of the repeater is the possibility to use it as a search system in case of unmanned aerial vehicles emergency landing if the search beacon is unavailable.

The objective of the study is to present the analysis results of the distribution patterns of hydrocarbon accumulations for the case of the Osinsky productive horizon as a regional hydrocarbon reservoir and an independent geofluidodynamic system. The work uses the drilling and geophysical operation data, as well as research materials published in the open press. The Osinsky oil and gas horizon occurring in the lower parts of the Cambrian section is a widespread productive horizon in the area of oil and gas-bearing regions in the south of a number of tectonic structures of the Siberian platform (Angara-Lena bench, Baikit anteclise, southwestern part of the Nepa-Botuoba anteclise, Angara fold zone). The obtained oil exploration results showed that the Osinsky horizon is the only stratigraphic level of the Vendian-Lower Cambrian carbonate complex characterized by regional oil and gas potential. The formation conditions of the fluid dynamic system of the Osinsky mega-reservoir are determined by the nature of the lithological-facies formation environment, which determined its geological heterogeneity, features of its lithological composition, wide areal distribution in the structures of oil and gas bearing regions, possible migration routes of hydrocarbons from generation centres. Each geofluidodynamic system consists of oil and gas generation centres, migration route channels, natural containers of hydrocarbons – reservoirs and traps, reservoir rocks and seal rocks, and is also controlled by a favourable combination of these factors in geological time and space. The ordinary fluid dynamic system is represented by hydrocarbon solutions in the oil and gas generation centres, which are the defluidization places of oil and gas source rocks of the sedimentary oil and gas basin. The Osinsky horizon in the central regions of the Lena-Tunguska oil and gas province is associated with the deposits of various phase composition of hydrocarbons of the Markovskoye, Danilovskoye, Pilyudinskoye, Yaraktinskoye, Chayandinskoye, Srednebotuobinskoye, Talakanskoye, Kovyktinskoye and other fields, where its industrial productivity has been proven. The Sredne-Usolsky Osinsky reservoir is regionally oil and gas bearing in the oil and gas bearing areas of the Baikitskaya and Nepa-Botuoba anteclise as well as the Angara-Lena bench and the zone of the Angara folds. Today, the Osinsky horizon is associated with further growing prospects of hydrocarbon resources in the Vendian-Lower Cambrian carbonate complex.

The purpose of the study is to make an overview of subglacial rock core drilling projects on Arctic and Antarctic islands, which have been carried out by the experts from Russia, the United States of America, Denmark and China. By analyzing the outcomes of Russian and international projects, it was possible to pinpoint the technical and geological aspects of subglacial core drilling, as well as the benefits and drawbacks of the various technologies employed. Additionally, it was possible to identify the best kind of rock-cutting tool and identify a potential direction for further advancement of currently available technologies.The authors propose to consider a method for drilling basal ice and subglacial rocks, which is based on the principle of reciprocating rotary motion of the rock-cutting tool. The first evaluation test of the method under discussion was carried out more than ten years ago at Saint Petersburg Mining University and the results were encouraging. However, the researches dealt mainly with the processes occurring in the electromechanical drive rather than rock drilling modes. The authors of the article intend to carry out a series of studies with the goal of developing a core drilling method based on the reciprocating rotary motion of the rock-cutting tool for wells in subglacial rocks.