The aim of the study is to clarify the mineral composition and determine the conditions of the formation of the quartz-hubnerite veins of the Inkur stockwork tungsten deposit (the Dzhidinsky ore field, South-Western Transbaikalia). The research methods include a mineralogical and petrographic description of the ore quartz-hubnerite veins; an electron microprobe analysis of the mineral associations; thermometry, cryometry, and Raman spectroscopy of the individual fluid inclusions in quartz, fluorite, hubnerite, and muscovite. The mineralogical and petrographic studies has made it possible to clarify the mineral composition of the Inkur deposit ores and determine the mineral paragenesis formation sequence. The fluid inclusion studies have established that the ore deposition was occurring in the relatively low-salinity (~5.7–14.6 wt. % eq. NaCl) homogeneous solutions due to a decrease of the temperature. The study of the salt composition of the solutions has identified Ca chloride as a prevailing component, with NaCl, KCl, and MgCl as admixtures. CO₂ and N₂ have been identified in the gas phase of inclusions. Two stages of mineral formation have been defined: high-temperature (≥300 °С) and low-temperature (≥2.00–300 °С). The conducted studies allow qualitative estimation of the chemical composition of the ore-forming solutions. It has been established that one of the main factors of the hubnerite deposition is a temperature factor.

Opening-closing tectonics is a new idea for exploring the global tectonics, which holds that every tectonic movement of all materials and geological bodies on earth is characterized by opening and closing. The opening-closing tectonic view can be used to explain some geological phenomena developing in continents which cannot be reasonably explained by the theory of plate tectonics. Based on the available basic geological data and combining with the opening-closing view, we analyzed the divisions and characteristics of tectonic units in South Tibet, and propose that Tibet can be divided into gravitational detachment and detachment fault zones, which are superimposed thrust fault zones and reconstructed normal fault zones, respectively. Although the mainstream opinion believed that the Tibetan Plateau is formed by collision-compression orogenesis, field investigation revealed the existence of the Rongbu Temple normal fault in the 1970s. We consider that the Rongbu Temple normal fault and the Main Central Thrust were formed earlier than the South Tibet detachment fault, and the former two faults constitute the two boundaries of the southern Tibet extrusion structure. The South Tibet detachment fault partially superimposes on the Main Central Thrust and manifests a relatively high angle in following the Rongbu Temple normal fault north of the Chomolangma. We suggest that the three fault systems are the products of different periods and tectonic backgrounds. The tectonic units, such as klippes and windows identified by previous researchers in southern Tibet, belong to thrust fault system but usually have no obvious extrusion or thrust characteristics; however, they are characterized by missing strata columns as younger strata overlapping the older ones. These klippes and windows should be the results of later gravitational decollement and must be characterized as extensions and slips, respectively. Based on opening-closing theory, we suggest that since the Cenozoic the study area had undergone multistage development, which can be divided into the oceanic crust expansion (opening) and subduction (closing) and the continental collision (closing) and intracontinental extension (opening) stages. Geothermal energy from the deep earth, gravitational potential energy from the earth’s interior, and additional stress energy from tectonic movements, all played a key role in the multistage tectonic evolutionary process.

The purpose of the study is to show the effect of the probe dimensions on the display of the low-frequency dispersion of the geological formations’ electromagnetic properties in transient measurements by electric lines in the axial area of the source for the water areas up to 100 m deep. The study analyzes the change in the transient signal, the finite difference, and the transform (the ratio of the above two) as a function of the length of the source (a horizontal grounded electric line (AB) 50 to 2,000 m), the receiver (a three-electrode electric line (MON) 50 to 2,000 m), and the distance between their centers (spacing) 100 to 4,000 m. The values obtained from the conductive and conductive polarizing models are compared for the identical probes installed at the same depth. The grounded electric line is located within the conducting medium with a conductive polarizable base. The conducting medium is associated with the seawater thickness in the marine shelves up to 100 m deep. The conductive polarizable base is a geological environment (earth) covered with a layer of water. The polarizability of the base is registered by introducing frequency-dependent electrical resistivity by the Cole-Cole formula. The calculations show the display of different transient components associated with the transient buildup and the earth’s low-dispersion properties caused by both galvanic and eddy currents. These components manifest themselves differently for the probes with different dimensions of the source line, receiving line, and spacing. Based on the calculations, it can be argued that in the time range from 1 ms to 16 s, at the probes that have different dimensions and are immersed in the water layer up to 100 m thick, the signal changes depending on the immersion depth for “small” installations (AB of 50 and 100 m), while there is no such dependence for the rest of the probes used in the calculations (AB of 250, 500, 1,000, and 2,000 m).

The article presents the results of the selection of the grouting mortar made out of the cement that does not comply with the state standard (GOST) for cementing the upper part of the column during the construction of an oil well. The object of study was the cement grade PСT III-ob 5-50 GOST 1581-96. The study used the additives that, according to the literary sources, are able to enhance the cement technological parameters. The additives were calcium chloride (CaСl₂), sodium chloride, magnesium chloride (MgCl₂), gypsum (CaSO₄·2H₂O), marble chips (MK-100), silica fume (МК-65, МК-85), caustic soda (NaOH) and calcined soda (Na₂CO₃), as well as high and low viscosity polyanionic cellulose. The following technological parameters were determined: the mortar density, the mortar paste spreadability, water separation, the thickening of the mortar, the ultimate bending and ultimate compression strength of the cement stone. The study was conducted taking into account the domestic and international standards. The test results show that the use of the agents such as NaCl, MgCl₂, CaСl₂, Easy SET, МК-100, and CaSO₄·2H₂O enhances the water separation of the mortar and the strength properties of the cement stone. However, the agents used to improve water separation (low viscosity polyanionic cellulose, high viscosity polyanionic cellulose, Na₂CO₃, МК-65, and МК-85) significantly reduce the strength properties of the cement stone. The columns can be fixed with the above mentioned cement using agents such as CaCl₂ (2 % of the cement mass), NaCl (1.2 %), MgCl₂ (1 %), and the hardening agent Easy SET (1 % of the cement mass).

The study aims to analyze the relationship between the redetermination of the complexity of the geological structure of the Verkhnechonsky oil and gas condensate field and the schedule adjustment of the field development plans. The paper uses the data on the exploration and production wells obtained from the pilot operation of JSC Verkhnechonskneftegaz, the geophysical work results, and the research materials publicly available in the press. The geological structure of the Verhnechonskoye oil and gas condensate field is unique in its complexity. This is due to the following factors: a combination of tectonic disturbances accompanied by the intrusion of traps; high mineralization of the reservoir water; sharp variability of the filtration and reservoir properties of the producing horizons by area and section due to the unevenness of the lithological composition of the reservoirs, their salinization and complete pinch-out. The development system of any field should take into account the peculiarities of the field’s tectonic and lithological-facies structure, and meet specific technical and economic requirements for drilling and operating wells. The complexity of the field structure requires a thorough selection of a development system that inevitably changes as the features of the field structure are studied, e.g. vertical drilling suggested at the initial stage of the filed development was shortly after replaced with inclined-horizontal drilling with the calculation of two options. Within the pilot operation project of the Verkhnechonsky field, JSC Verkhnechonskneftegaz has developed two variants of uniform grids of directional and horizontal wells with pattern flooding for the most explored deposits of the Verkhnechonsky horizon of blocks I and II. Because of the intensive processes of the reservoirs’ secondary salinization, the flooding method required a study of the reservoir water composition. However, the proposed drilling plan using a downhole engine and gamma-ray logging could not ensure the wellbores ducting through the most productive sections of the horizon, therefore, the flow rates of some directional and horizontal wells were not high enough. To increase the drilling efficiency, the specialists of the Drilling Department (JSC Verhnechonskneftegaz), together with the Department of Geology and Field Development (Schlumberger Ltd.), proposed a new methodology that increases the drilling efficiency by using a rotary-controlled system, logging-while-drilling, and geosteering. Thus, the development system of the Verkhnechonsky oils and gas condensate field was changing in the process of specifying the field’s geological structure, anisotropy reservoir properties, and the thickness of the producing horizons in size and cut, their salinization and pinch-out, and the composition of the reservoir waters.

The purpose of the study is to extend the use of nuclear magnetic resonance relaxometry and dielectric spectrometry methods. This is realized through a complex interpretation of the data by the above methods to timely provide additional petrophysical information about the drill cuttings pore space properties and structure. The relevance of the study is that the data on the drill cuttings obtained by the NMR method can be used as prior information in the logging data interpretation before a detailed petrophysical study of the core sample or in case of the core absence in the sampling interval. The objects of study are the drill cuttings samples from the fields of the West Siberian oil-and-gas province. The samples are saturated with different fluids, and their reservoir properties are determined by the nuclear magnetic resonance and dielectric spectrometry methods. As part of the experimental research, nuclear magnetic resonance investigations of the core samples of different discretization degrees have been carried out to determine the reservoir properties of the samples depending on the degree of their particle size reduction. It has been shown that the obtained results do not depend on the particle size of the measured sample and are consistent with the results of the standard petrophysical studies. The relationship between the porosity and the saturating fluid type has been established. Based on the data obtained by the dielectric spectroscopy method, the study has determined the value of the complex dielectric constant that shows how the degree of saturation changes depending on the fluid, and what happens in the pore space. The complex interpretation of the results obtained by the two methods provides additional information on the drill cuttings reservoir properties that can be used as a priori information on the formation properties.

The Earth’s surface is a complex system involving mutual interactions of its many components, including mountains, rivers, forests, farmlands, lakes and grasses. The interaction and mutual feedback of chemical elements in Earth's surface layer can drive changes in chemical elemental distribution patterns. In this study, we evaluated the mechanisms and interactions driving the distribution patterns of macroelements, probiotics, halogens and heavy metals in soils in Southwest China, based on a systematic geochemical land-quality survey at a scale of 1:250000. The results showed that the parent material determines the natural state of chemical elements in land resources. Epigenetic geochemical dynamics reshapes the distribution patterns of chemical elements in top soil; biogeochemical processes drive the evolutionary trends of land quality; and human activities, such as mining, disrupt the natural evolution of chemical elemental distribution patterns. The establishment of an epigenetic geochemical dynamics theory allows the construction of a framework for understanding the Earth's surface layer and promoting technological innovations for the comprehensive geochemical investigation of land resources.

The article presents the structure and results of the students’ field study program (Institute of Subsoil Use, Irkutsk National Research Technical University, Russia) that took place at Nanjing University (China) in the period September 6–21, 2019. The purpose of the work was to describe the investigations conducted under Professor Yongzhan Zhang in the area of Nanjing, Eastern China. The focus of the field routes was on the study of the geological-structural and geographical features of the South China block as well as on learning the major endo- and exogenous processes in the area. The analysis of the archive and literary sources and the compilation of the filed observation material has provided data on the tectonics and magmatism of the study area, the conditions of the formation of the Tangshan underground hydrothermal sources, the causes of the volcanism and other geodynamic processes, and the peculiarities of the hydrological regime of the Fuchunjiang River.

Olkhon region in East Siberia has abundant and unique vegetation and animal resource for its peculiar geographic location, including ants. Ant, recognized as ecosystem engineers, has an important role in ecosystem. In order to investigate the ecological role of mound-building ants in this region, we focused our attention on the correlation between the distribution of ant mounds and plant species. Five quadrats (5 m × 5 m) were set up in this region, each of which was then divided into twenty-five quadrats (1 m × 1 m). We collected the location of every Black Bog Ant (Formica candida) mound, the number and biomass of various plants in every small quadrat. Using matrices, we tested the distribution pattern of ant mound randomly. The correlation between plants and ant mound pattern was tested by correlation analysis and regression analysis. The result showed that the spatial distribution of ant mound was random. We also found that Artemisia frigida, Carexduriuscula and Oxytropis sylvesfris had a significant linear relationship with the spatial distribution of ant mound (P < 0.05), suggesting that the spatial distribution of ant mound was dependent on the spatial distribution of some plants. The underlying mechanism was further studied. We attributed this correlation to the feeding habits and foraging strategies of Black Bog Ant and tissue structure of these three plants. Our study figured out the interaction between Black Bog Ant and plant resource in Olkhon region, laying down the foundation for future study on the co-evolution of plant and animal resource in this unique ecosystem.