The article discusses the method of hurricane sample replacement taking into account the spatial relationship of other routine samples. This sample is presented as the result of selecting sampling parameters with the mineral content above average values determined using the proposed methodology. The approach is based on geostatistical findings regarding the spatial dependence of sampled subsurface areas within a single geological block. The feature of the proposed methodology is the calculation of the studied indicator taking into account all samples for the evaluated block including the hurricane one. The approach is based on the method for determining weighting coefficients from the inverse distance weighted method. The method has been tested using the exploration data from a placer gold deposit. All key parameters of the proposed method, such as the radius and number of additional points created, as well as the power coefficient of the weighting function are analyzed. Several indicators are identified that will influence the results of mineral reserves calculations taking into account a hurricane sample and when it is replaced by the values calculated using the proposed methodology. The article analyses a situation in which the study object is selected incorrectly. It is demonstrated how the replacement of an outlier value can affect the assessment results for a given geological block. Examples of replacing similar samples are provided along with the assessment of the impact on the change in estimated reserves for a placer gold deposit. A conclusion is drawn regarding the error in determining the hurricane sample with the comparison of the impact on the exploration results and geological block assessment. The article is based on the study of a geological block tested by vertical boreholes, in which the gold content was determined. The results were obtained by modeling the process of determining the values to be used to replace the selected sample. The conducted analysis shows the effect of volume changes for various parameter variants of the proposed method. The article is illustrated with grade-interpolated plots and graphs showing curves for various parameters of calculated indicators.

A seismic attribute can be defined as any parameter or observation retrieved from available seismic data that directly or indirectly enhances and deepens understanding of data processing and interpretation in hydrocarbon exploration. Indeed, seismic attributes contribute to better understanding of geological structures, petrophysical properties, fluid content and their differentiation in a simplified but more detailed form that enables the determination of their presence in reservoirs as well as the spatiotemporal distribution of subsurface geological elements. This work studies the application of various seismic attributes to identify and describe the oil and gas potential of the license area. This site is characterized as a deepwater alluvial fan on the end-slope fan on the Turonian stage based on regional seismic data, whereas the 3D seismic data clearly determining the boundaries of the stratigraphic trap indicate the likelihood of hydrocarbon saturation. Analysis of dynamic characteristics of seismic waves confirmed the presence of oil and gas-bearing indicators that imply the high potential of the reservoir. The study showed how seismic attributes retrieved from 3D seismic data can qualitatively provide valuable information about subsurface geological features. This, research is highly promising for hydrocarbon exploration based on the results of the combined seismic attribute analysis. However, even if this study is deemed sufficient for drilling an exploratory well, it may be useful to propose other geophysical methods to be integrated into this study that could improve the assessment. For example, electrical methods are known for their effectiveness in direct detecting of fluids in reservoirs and have proven their efficiency in Western Siberia, Russia.

The article deals with the features of mineral composition of gold-bearing waste from the gold concentration plant. The tailings material consists primarily of a finely dispersed, silty fraction. The structure of the accumulated tailings resembles a layered pie: three horizons of different compositions are distinguished. They were formed during the processing of mixed, and primary (sulfide) ores oxidized in different years. The most common ore minerals in the tailings dump deposits are pyrrhotite, arsenopyrite, pyrite, stibnite, magnetite, and iron hydroxides. In addition, native bismuth, native gold, bismuth and tellurium sulfides, scheelite, and secondary antimony and arsenic minerals (valentinite, tripugiite, and scorodite) are also noted.The composition of the tailings dump’s recirculating water and sludge was studied. Vertical variability in the chemical composition of the tailings storage facility’s recycled waters was established. Sharp variability in water composition is observed at depths of 6–8 meters. To study the direction and rate of dissolution and precipitation of substances in the liquid phase of the tailings dump field experiments were conducted. During the experiments, samples of minerals and man-made materials including rubber, sulfur, mercury amalgam on copper, copper, steel, graphite, native gold in quartz, pyrite and pyrrhotite, arsenopyrite were placed in recycled sludge water at various depths to be extracted in batches with the exposure times of 1, 2, and 3 months. The experiment revealed the etching traces of native gold and a diverse range of newly formed mineral phases including gypsum, iron hydroxides, scorodite, iron and manganese cyanides, copper sulfates and thiocyanates, and others. The Selector-Windows software package was selected for physicochemical modeling of the hypergene processes occurring in the tailings sludge waters. The Selector-Windows software package features a system of built-in thermodynamic databases and a module for generating models of varying complexity and architecture. Performed thermodynamic modeling using the software package allowed the authors to calculate the parameters and direction of technogenic processes occurring in the concentration tailings, determine the elemental and ionic composition, Еh-pH parameters of forming solutions, crystallizing minerals, and their associations as well as to propose a mechanism for secondary gold concentrations in the silt fraction of tailings.

One of the fundamental problems of prospecting, exploration and exploitation of oil and gas fields is the co–occurrence, temporal and spatial relationships of oil and gas-bearing and salt-bearing strata of various scales: from productive oil and gas horizons of individual fields to oil and gas complexes. Almost all productive oil and gas horizons of hydrocarbon fields of the Siberian platform including the widespread Yaraktinsky horizon are subject to intensive salinization processes of various scales and for various reasons. Based on genetic features and the sequence of occurrence salinizations could be classified into primary salinization – syngenetic occurring simultaneously with sedimentation, and secondary one – postgenetic caused by a number of diverse natural and man-made factors. The paper considers the main factors of salinization, which with a certain degree of conventionality can be differentiated as follows: by scale – global (historical and geological) and regional (trap magmatism); by causes – tectonic and magmatic; by occurrence time – primary (syngenetic) and secondary (epigenetic); by nature – natural and man-made (occurring during operation). Downhole equipment is subject to intense man-made salinization in the near-wellbore zone of the productive formation in the interwellbore space, which ultimately complicates drilling processes, leads to accidents, and significantly increases the cost of equipment during operation.

The main purpose of the work was to analyze the current state of pollutant distribution in the area of the Babkhinsky sludge storage landfill of the Baikal Pulp and Paper Mill. To solve the set problem the long-term data reflecting the chemical composition of natural and above-sludge waters during various periods of plant operation and after its closure were analyzed, followed by modeling and evaluation of the geological, structural and hydrogeological conditions of the area, technological features of engineering structures and wastewater composition, which together influenced the nature and extent of pollutants in the coastal area of Lake Baikal. As a result of the conducted analysis, it was concluded that the highest concentrations are demonstrated by the following indicators: lead, iron, arsenic, increased turbidity and color of water. The maximum pollution is concentrated within the area of map No. 14, as well as on the border area between the areas of maps No. 14 and 13 located located approximately 1.5 km from the water’s edge of Lake Baikal. This situation is due to the fact that during the closure of the Baikal Pulp and Paper Mill, in addition to Class IV and V hazard waste disposed of in the plant’s ash disposal site, highly toxic green liquor was discharged into the area shown on map no. 14. Since this area is dominated by low-permeability rocks, the groundwater composition stabilized and its recovery is extremely slow. To eliminate accumulated environmental damage and prevent further groundwater pollution, it is necessary to restore routine monitoring of changes in the chemical composition of groundwater, intensify the ongoing multi-stage treatment of above-sludge waters, and subsequently reclaim the area, including the use of impermeable materials to line the bottom and sides of ash and sludge disposal sites and the construction of flood and mudflow control structures.

The purpose of this article is to summarize the data of engineering and geological surveys conducted in the 1970–1990s in the town of Neryungri in Southern Yakutia. According to the surveys, the foundation of engineering structures is composed of an unfrozen-frozen layer of coal-bearing sedimentary rocks, whose main lithotype is sandstones, which are also the object of study. The subject of the study is laboratory values of the uniaxial compressive strength of sandstone samples in the air-dry and water-saturated states. Variability of sandstone sample strength in the annual heat cycle layer was studied using probability theory and mathematical statistics. Using laboratory data, the strength of a sandstone massif at the depths of 2–11 m was estimated with 90 % reliability. The strength of the fractured part of sandstones was studied sporadically at depths of up to 22.5 m. The unbalanced probability distribution of strength near the mean values was interpreted as a natural defect of sandstones associated with their decompression by tectonic and exogenous-cryogenic processes. The defect is correctly approximated by the Weibull law.The strength of the sandstone massif in air-dry and water-saturated conditions varies from very low to very high. The proportion of rocky sandstones with the strength above 120 MPa is 78.9 %. The proportion of semi-rocky sandstones with the strength below 15 MPa is 12.1%. The background strengths of air-dry and water-saturated rocky sandstones range from 54.49 to 171.42 MPa and from 32.14 to 135.78 MPa, respectively. In the same conditions, the background strength values of semi-rocky sandstones are lower and range from 1.65 to 27.2 MPa and from 0.67 to 10.12 MPa. When the material is saturated with water, the variability of its strength decreases by a factor of 4. This pattern is explained by the loss of structural-petrographic, cryogenic-thermal, and temperature-moisture diversity in sandstones when they are soaked in water. The conducted studies led to the following conclusion: predicted based on laboratory data strength of the sandstone massif with the approximate reliability of 80 %, is sufficient for the safe operation of engineering structures in Neryungri.

The majority of the world and Russian Federation oil deposits are confined to complex carbonate reservoirs. Most carbonate reservoirs feature a complex geological and geophysical structure, the presence of high-capacity caverns, cracks, and pores, high-viscosity oils, as well as hard-to-recover reserves. To control development parameters in such challenging conditions and fulfill oil and gas production targets it is required to use modern enhanced oil recovery technologies. One of the most widely used methods is well acidizing to restore formation permeability. Today, global oil production employs various methods of acid treatment, which differ in their production technology, dependence on the lithological and mineralogical composition of the reservoir, duration, their effect, etc. Each of the methods used has both advantages and disadvantages, which sometimes makes it difficult for oil specialists to choose the right technology for treating the bottomhole formation zone. The present work discusses domestic and international experience in acid treatment of carbonate reservoir wells, in order to identify the advantages and disadvantages of the methods used.

This article discusses a new, simple, and inexpensive method for determining high concentrations of watersoluble forms of heavy metals using a non-destructive chemical analytical method – an X-ray fluorescence analysis. Unlike standard approaches, which employ labor-intensive and expensive acid digestion techniques (inductively coupled plasma atomic emission spectrograhy, inductively coupled plasma mass spectrometry, and atomic absorption spectroscopy) to measure pollutant concentrations in solution (requiring analysis of aqueous extracts), this method studies changes in concentrations in the solid residue of samples on filters at specific time intervals that enables the use of a more cost-effective X-ray fluorescence analysis method. The effectiveness of this method is demonstrated on example of the study of copper and lead migration in man-made waste generated by the combined effects of the mining and metallurgical industries at one of the facilities in the Irkutsk region. The concentrations determined using X-ray fluorescence analysis and inductively coupled plasma atomic emission spectrograhy are compared. The study results are shown to be completely comparable, while the labor intensity and cost of the proposed approach, as well as the qualification requirements for the personnel performing sample preparation and analysis, are significantly lower. The proposed method allows to assess the potential for toxic agent migration under various conditions – from short-term exposure to precipitation to prolonged exposure to water. The visualization results presented enable rapid categorization of samples based on the leaching behavior of water-soluble forms.