Sedimentary Formations Research Articles

Chemometric Analysis Combined with GC × GC-FID and ESI HR-MS to Evaluate Ultralow-Sulfur Diesel Stability.

Diesel has been the most employed fuel in highway and nonhighway transportation systems. Many studies over the past years have attempted to classify diesel as a stable or unstable composition since this fuel can still degrade during storage or thermal oxidative processes. Products generated because of such degradation are the reason for the formation of soluble gums and insoluble organic particulates, which in turn cause a negative influence on engine performance. This work reports a detailed composition of nonpolar and polar compounds in many ultralow-sulfur diesel (ULSD) samples by comprehensive two-dimensional gas chromatography with a flame ionization detector (GC × GC-FID) and electrospray ionization high-resolution mass spectrometry (ESI HR-MS). In addition, chemometric approaches were applied for ULSD storage stability investigation. GC × GC-FID experiments achieved the nonpolar chemical characterization for the ULSD samples, including all main hydrocarbon classes: paraffins, mono- and dinaphthenics and olefins, and aromatics. The GC × GC-FID data combined with principal component analysis (PCA) described that the separation of the samples' concerning storage stability was mainly due to the contents of mono- and diaromatic compounds in the unstable ULSD samples. Moreover, PCA was also applied to the ESI (±) data set, and the results highlight the presence of compounds belonging to O class (natural antioxidants), which decrease the rate of oxygen consumption in the fuel, characterizing it as stable composition. The basic nitrogen compounds are mostly present in the stable ULSD samples indicating that they did not affect the stability of the fuel. On the other hand, the HC classes presented pronounced abundance among unstable ULSD samples suggesting that the fuel degradation may go through the oxidation of hydrocarbons and the formation of Ox compounds as byproducts. Furthermore, MS/MS experiments point to the formation of CcHhNnOo-like precursor species, which can react with each other and lead to the formation of gums and insoluble sediments in the fuel. In summary, the results express the potential of using the GC × GC-FID and ESI (±) Orbitrap MS techniques as valuable tools for diesel stability evaluations.

Sedimentary characteristics, formation conditions, and distribution mechanisms of beach bar sand bodies of Chang 82 submember, southwest Ordos Basin

AbstractBeach bar sand bodies are a relatively new type of reservoir in oil exploration where they can be found in the proximity of the source rock. In this study, the genetic type of sand bodies in the Upper Triassic Yanchang Formation in the southwest Ordos Basin is systematically studied through the observation of outcrops, core description, microscopic inspection of thin sections, along with petrophysical properties, mineralogy, and geochemical analysis of trace elements. The results showed that a new sedimentary type of beach bar sand bodies are developed in the Chang 82 submember of the Yanchang Formation, that are generally characterized with a flat bottom and convex top, where the contact interface between the bottom of the single sand body and mudstone is flat, and the bottom lacks erosion and filling structure. Moreover, a variety of wave‐induced sedimentary structures are developed, showing a reverse sedimentary sequence from fine to coarse grains. The structural and compositional maturity of the beach bar sand bodies are higher than that of the river channel sand body. Moreover, reservoir pore type is mainly comprised of intergranular pores, and the porosity and permeability of the samples retrieved from the sand body are much higher than that of the river channel sand body. Finally, the main controlling factors of the formation and preservation of beach bar sands are found to be the lake basin bottom topography, the base level cycle, and the stable paleo‐lake shoreline. During the Chang 82 submember depositional period, a large area where the beach bar sand bodies were deposited parallel to the lake shoreline in the southwest of the basin was created. Such depositional environments had suitable conditions to host large‐scale oil‐bearing reservoirs, as major exploration and development targets in the Ordos Basin in the future.

Composition, age, and sedimentation environment of the ore-hosting Eravna series of the Udino-Vitim zone (Western Transbaikalia, Russia)

Data on the composition, age and formation conditions of the Ulzutui and Kydzhimit strata, which are combined as part of the Eravna Series of the Eravna Subzone of the Udino-Vitim Zone, are considered. The Eravna series, at least 2400 m thick, is composed of tephroturbidites with a significant amount of lavas and tuffs of felsic and intermediate compositions, with which tectonic-gravitational mixtites are spatially and genetically related. The features of the structure and composition of the Eravna series indicate the formation of sediments in an open deepening marine basin adjacent to the zone of active volcanism. For the first time, according to the Miospores, the time of formation of the Ulzutui sequence is limited to the Late Devonian – Early Carboniferous (Late Famennian – Early Tournaisian), the Kyjimite strata is limited to the Early Carboniferous (Visean) ages. At this time, the Kyjimit volcanic zone was formed. The suprasubduction nature of the zone is evidenced by the features of volcanites (predominance of acidic varieties, belonging of basalts to the tholeiitic, and dacites and rhyodacites to the calcareous-alkaline series, the presence of high-potassium rock varieties, their belonging to the K-Na type of alkalinity, very low MgO values, low and moderate TiO2 contents, high Al2O3 and K2O, enrichment of volcanogenic rocks in large-ionic lithophilic elements relatively to highly charged elements, minimum in Nb and negative values of εNd), their spatial association with monzonites (have suprasubduction features) and tephroturbidites, as well as metallogenic specialization (Cu and Zn) of the Eravna series. We believe that the ore-hosting strata for both pyrite-polymetallic Ulzutui and Ozernoe deposits is the Upper Devonian–Lower Carboniferous Eravna series.

Categories of rivers that formed vendian and lower cambrian sedimentary sequences, western part of east european platform (according to lithogeochemistry data)

Based on lithogeochemical data for fine-grained clastic rocks of the Volyn, Valdai and Baltic series of the west of the East European Platform (Belarus and Volyn, partly Lithuania), categories of rivers that transported fine-grained aluminosiliciclastics to the sinks were reconstructed. It is concluded that the formation of Vendian and Lower Cambrian sedimentary sequences developed in this area was controlled mainly by river systems similar to modern large rivers (rivers with a catchment area 100000 km2) and rivers draining sedimentary formations (rivers with a catchment area 100000 km2). The fine-grained aluminosiliciclastics transported by them came mainly from areas composed of rocks of the crystalline basement of the platform and, in part, sedimentary formations. The distribution of data points of Vendian and Lower Cambrian clay rocks on the diagrams (La/Yb)N–Eu/Eu* and (La/Yb)N–Th with fields of composition of pelitic and silty-pelitic sediments in the estuarine parts of modern rivers of different categories shows that mafic rocks of the Volyn-Brest large igneous province, apparently, were not suppliers of fine-grained aluminosiliciclastics in the indicated time intervals.

Early-middle permian terrigenous deposits of South-Western Primorye: material composition, source areas and formation settings

The study presents the results of studying the material composition of terrigenous rocks from the Early – Middle Permian deposits of the Reshetnikovka formation of the Laoeling-Grodekovo terrane of South-Western Primorye. Studies were carried out in order to reconstruct paleogeodynamic environments for the accumulation of studied deposits, as well as to determine the tectonic type and composition of source rocks of sources areas. It has been established that in terms of mineral and geochemical parameters, the sandstones of the formation are petrogenic or “first cycle” rocks, correspond to arcoses and, only partially, subarcoses and lithite arenites, are characterized by a fairly high degree of maturity of clastic material, and their formation was due to the destruction of largely weathered parent rocks of sources areas. Paleogeodynamic interpretation of the obtained data indicates that in the Early and Middle Permian sedimentation occurred in the basins of the passive continental margin, which are intra-and intercontinental rifts and aulacogens. The main influence on sedimentation processes was exerted by continental sources areas: cratons and uplifted basement blocks, which were projections of the crystalline basement framed by rift zones. Mainly acidic igneous and metamorphic rocks were eroded with the participation of ancient sedimentary formations. U–Pb isotopic dating of detrital zircons made it possible to establish the age and possible location of magmatic complexes, due to the destruction of which formation deposits were formed.

Impacts of Terrain Conductivity Survey for Groundwater Investigation in a Typical Sedimentary Formation; A Case Study of Itori, South-West Nigeria

A geophysical investigation for groundwater development involving conductivity measurement using Electromagnetic profiling was conducted to locate fractured and fissured zones and associated groundwater containing media at Itori communities, Southwestern Nigeria. The area is underlain by the typical sedimentary rocks of South-West, Nigeria with the local geology predominantly clay, shale, clay sand, limestone and Sandstone. Measurements of the ground conductivity were carried out with Geonics EM 34-3 along 5 traverses whose profile lengths varied between 160 and 200 m. Intensive geophysical fieldworks were performed utilizing Frequency Domain Electromagnetic Method (FDEM) using Geonics-EM-34 to determine the vertical and lateral variations of subsurface conductivity probing depths of 20 m, 40 m and 60 m. The EM data were acquired at 500 m intervals along 10 profiles. The Vertical Dipole Moment in the first layer exhibited the highest true conductivity and lowest true conductivity of 42.65 mS/m and 29.1 mS/m for EMITO1 and EMITO2 respectively and the corresponding Horizontal Dipole Moment exhibited the highest true conductivity of 36.0 mS/m and 25.41 mS/m for EMITO1 alongside EMITO2 and EMITO8 respectively while the Vertical Dipole Moment in the second layer exhibited the highest true conductivity of 45.62 mS/m and lowest true conductivity of 34.76 mS/m for EMITO1 and EMITO8 respectively and the corresponding Horizontal Dipole Moment exhibited the highest true conductivity of 44.0 mS/m and lowest true conductivity of 36.3 mS/m for EMITO3 and EMITO8 respectively. The qualitative interpretation of EM results identified areas of hydrogeologic importance and forms a predictive and suggestive basis for Vertical Electrical Sounding (VES) investigation; points of positive EM anomalies were considered as priority area for electrical resistivity sounding and prospective groundwater development, since they suggest lithological variations within the unconsolidated overburden and/or water–filled fissures in the bedrock. The identified major geological interfaces were suspected to be of weathered zones

A comprehensive review on Exploration and Production scenario of Natural Gas Hydrate

Gas hydrates have emerged as a highly focused area of study over the past two decades due to their distinctive advantages and potential applications. Among gas hydrates, methane hydrates stand out for their enormous energy potential, serving as both an energy resource and finding utility in various applications such as gas storage, separation and enrichment. This study discusses the extraction of gas hydrates, which involves employing different methods such as depressurization, thermal stimulation and inhibitor injection to dissociate the compounds. Ensuring the safety and efficiency of gas production requires a comprehensive understanding of the geotechnical properties of hydrate reservoirs. It is essential to maintain flow assurance, sediment formation integrity and wellbore stability for secure and efficient extraction of gas from hydrates in sedimentary deposits. The key factors that influence these aspects, encompass strength and deformation characteristics, fluid migration behaviour and thermal conduction properties.

Formation mechanism of drift-moat contourite systems revealed by in-situ observations in the South China Sea

Contourite drifts are ubiquitous sedimentary features in the world′s oceans, and their formation are usually ascribed to sedimentation from contour currents. However, in-situ observations of contour currents and their associated sedimentary processes were inadequate. Here, we present mooring observation results from a drift-moat contourite system in the South China Sea to gain insight into its sediment dynamics and formation mechanism. We found that quasi-persistent contour currents develop in the moat, on and below the drift, yet subject to diverse physical oceanographic processes. High suspended sediment concentrations observed on the drift mainly occur in winter, induced by high levels of sediments transported by contour currents from Taiwan. In the moat, however, high suspended sediment concentrations are mostly caused by erosion of the moat wall during periods of strong tidal currents and low shear variance. Such results underscore the complexity of current patterns and sedimentary processes across various topographic units in the drift-moat contourite system. A novel formation mechanism of the contourite drift is thereby proposed, wherein sediment transport by contour currents brings materials for constructing the drift, while its formation is driven by near-critical reflection and upslope transport of sediments by tidal currents.

Modeling Sediment Production In Urban Environments: Case Of Russian Cities

The aim of this study is to provide a tool to assess sediment production in an urban area. The urban environment is affected by a variety of anthropogenic and natural factors that, in particular, lead to the sediment production. The storage of sediments in the urban landscape negatively affects the quality of the urban environment. The model was developed on the basis of landscape studies conducted in residential areas of six Russian cities. The model takes into account (1) the influence of precipitation, spring snowmelt, and vehicles, (2) the influence of erosion factors for two seasons: warm (t>5°C) and cold (t<5°C), and (3) the presence of disturbed surfaces. The application of the developed model to Ekaterinburg city conditions returned sediment production equal to 1.2 kg/m2/y. A comparison of seasonal values shows that sediment production in cold season is 2.5 times higher than in the warm season. In the absence of the disturbed surfaces, sediment production decreases to 0.44 kg/m2/y. Modeling showed a correlation between sediment production in Russian cities and duration of the cold season. The efficiency of various urban area maintenance practices and cleaning measures were evaluated in terms of sediment production and storage. The developed model presented in this paper is based on research in Russian cities, but can be applied to assess the formation of sediment and measures to reduce the value of its accumulation in the urban environment in different regions of the world.

Environmental Variability of the Northern Caspian Sea during Khazarian Epoch (Based on Drilling Data)

The objective of our work was to reconstruct transgressive-regressive events in the Northern Caspian Sea during the Khazarian epoch of its Pleistocene history to determine the natural conditions of the development of the basins and to assess their response to climate change. This work is based onstudies of the sedimentary formations of the upper part of the Quaternary sequence in the Northern Caspian Sea. The borehole was drilled in the eastern part of the depression Shirotnaya, the sea depth was 11.9 m, and the depth of drilling was 56.4 m. The core was subjected to lithological, malacological, and palynological analysis. This paper discusses the results related to the interval 56.0–26.6 m. The structure, facies-lithological, and malacological composition of the core capture three transgressive stages of the Caspian, namely the Early Khazarian, Late Khazarian, and Hyrcanian stages, separated by regressive phases. The representative spore-pollen assemblages made it possible to carry out the climatic and stratigraphic subdivision of the studied Khazarian deposits and to suggest a provisional version of the history of climatic and phytocenotic events during the sedimentation period. The results of our studies have introduced new discussion points into the paleogeography of the Northern Caspian Sea.

The Influence of Seamounts on the Enrichment of Rare Earth Elements in Sediments—A Case Study of the Marcus-Wake Seamounts in the Western Pacific Ocean

Deep-sea sediments enriched in rare earth elements and yttrium (REY-rich sediments) are widely distributed on the deep-sea floor, and their formation mechanism remains elusive. Although studies have recognized the link between seamounts and REY-rich sediments, in-depth analysis of the specific roles and effects of seamounts in the formation of REY-rich sediments is lacking. In this study, we analyzed surface sediments from the Marcus-Wake Seamounts for grain size, geochemistry, and mineral composition and classified the samples into three types: samples with moderate REY content and dominated by terrestrial detritus; samples with high REY and authigenic mineral content; and samples rich in CaCO3 but poor in REY. The REY in the sediments of the study area partly originate from Asian dust input and partly from seawater and/or pore water, and are mainly enriched in REY carrier particles including bioapatite fossils and micronodules. The amount of REY carrier particles influences the REY content in the sediments. The current field, primary productivity, weathering process, and depositional environment around seamounts are different from those of abyssal plains, which are conducive to the formation of REY-rich sediments. Strong bottom currents may exist in the southeastern direction of some large seamounts (e.g., Niulang Guyot), leading to the selective accumulation of REY-rich bioapatite fossils and micronodules, resulting in the formation of REY-rich sediments.

Provenance and sedimentary environment of REY-rich sediments from the Wharton Basin, Indian Ocean

Rare earth elements and yttrium (REY) in deep-sea sediments have emerged as potential strategic resources. In order to investigate the provenance, sedimentary environment, and mechanism of REY enrichment of pelagic sediments in Indian Ocean, we analyzed the grain size, bulk major and trace element concentrations and mineralogy of clay fractions (<2 μm) of sediments in the Wharton Basin, Indian Ocean. Based on the characteristics of biostratigraphic, we speculated that the sediments were deposited during the period from 11 Ma to 2 Ma. Sediments in the upper part (0–100 cm) of the sequence were mainly derived from aeolian material in Australia, whereas sediments in the lower part (100–258 cm) were mainly sourced from volcanic and hydrothermal materials which associated with submarine volcanic activity. The oxygen-rich environment below the calcite compensation depth (CCD) is crucial for the formation of REY-rich sediments. Additionally, there is a strong correlation between ΣREY, clay-grained sediments, Al2O3, and Fe2O3, suggesting that clay fractions contribute significantly to the enrichment of REY in the deep-sea sediments.

Origin of the Filizchay ore field (the southern slope of the Greater Caucasus)

&#x0D; &#x0D; &#x0D; he article deals with the origin of the Filizchay ore field, which is a valuable object for the extraction of zinc, lead, copper, silver as well as for the extraction of the associated com- ponents. The data and types (VMS, SEDEX, VMT) of the pyrite deposits in the world have been briefly presented. Their comparative analysis has been carried out and it has been revealed that the Filizchay ore field is very different from the VMS-type pyrite deposits and it belongs to the SEDEX type. A direct relationship with vol- canism has not been observed in this deposit. Unlike the containing rocks related to volcanism in the Filizchay field , there are fine-rhyth- mic flyschoids with packages of sandstones, clay shales and silt-clay shales . The ratio of the natural ore types composed of the different mineral associations, with stages of the folded and disjunctive dislocations, allows us to divide the process of the deposit formation into the following three stages of the ore formation: 1. deposits of the massive hydrothermal-sedimentary essentially pyrite ores; 2. formation of the hydrothermal-metasomatic ores of the pyrite-copper-polymetallic composition; 3. deposition of the hydrothermal-meta- morphogenic ores of the copper-pyrrhotite composition. The available data indicate a favorable environment for sedimentary pyrite ore formation subject to a significant role of Corg. and sulfate-reducing bacteria. Moreover, the hydrothermal-sedimentary processes played the main role in the accumulation of the main volume of the sulfide masses. On the basis of the sulfur isotopic composition (according to Zairi, 1992) of the main minerals (pyrite, galena, sphalerite, pyrrhotite, chalcopyrite) from various types of the Filizchay ore field ores it was concluded that the deposit formation occurred from several portions of the entered hydrothermal solutions. It was found that by the period of accumulation of sediments of the ore-bearing horizon in the northern block – there occurred outpouring of the spilites and basalts in the narrow trough-like depression. The iron sulfides supplying the more southern basin with stagnant waters can be associated with their post-volcanic exhalations (as primary sources). The Filizchay ore field being connected with basaltic volcanism is combined according to formation method. It has been formed due to components which have been carried out by hydrothermal flows and due to basalts, which are associated with underwater alteration. The temperatures of the primary pyrite-polymetallic ores formation are relatively low (200-100 0С).&#x0D; &#x0D; &#x0D;

UROLITHIASIS IN MALE POM MIX DOGS

Dogs are one of the animals classified as pet animals, or it can be said to be animals that are close to humans. Feeding to dogs must be considered carefully, feeding patterns can affect urine pH, urine volume, and urine concentration which can cause the formation of mineral precipitation, such as uroliths consisting of various minerals. One of the health problems that occur in dogs due to nutritional imbalance is urolithiasis. Urolithiasis is the formation of sediment that is difficult to dissolve in the urinary tract. The purpose of this writing is to report the process of handling urolithiasis through cystotomy in a dog named Lucky with a male Pom mix dog breed aged 7 years and weighing 11 kg is a rescue dog. Lucky's dog experienced pain when urinating (stranguria), urine came out below normal (oligouria), bloody urine (hematuria), and had no appetite to eat and drink since 3 days before being treated. Dogs are usually given dry dog food feed mixed with rice and chicken with ad libitum portions. 1.5 years ago dogs had difficulty urinating but did not bleed. Based on the results of the history, clinical examination, supporting examinations in the form of chemical examination of urine and X-ray, the dog has urolithiasis. Dog cases are treated with cystotomy surgery to remove calculi by incision of urinary vesicles. Postoperative therapy, dogs are given an injection of the antibiotic cefotaxime sodium 20mg / kg body weight with the IM route and given anti-inflammatory tolfedine CS 4ml / kg body weight. Based on a series of examinations carried out, it can be concluded that animal cases have urolithiasis and handling cases of urolithiasis in dog cases can be done with cystotomy. To avoid the occurrence of urolithiasis in urinary vesica in dogs, client education is needed on how to maintain and select feed that contains balanced nutrition.

EFFECTS OF POROSITY ON THE STRENGTH AND MECHANICAL BEHAVIOUR OF POROUS GEO-MATERIALS UNDER CYCLIC LOADING

Most rocks in nature are porous and usually saturated with different fluids such as water, oil, and gas. The conventional and unconventional hydrocarbon reservoirs are mainly associated with sedimentary formations. The main rocks of these reservoirs are sandstone (porous rock), limestone and oil shale (tight rock), which are associated with varying porosity. Hence, porosity serves as a fundamental parameter for most reservoir rocks. In this research, the effect of porosity on the mechanical behaviour of geo-materials and its fatigue behaviour was investigated. For this purpose, a total of five geo-material sample groups with varying porosities were prepared and designated, i.e. groups A, B, C, D, and E. Group A exhibited the highest porosity 20-21.5%, while group E had the lowest porosity 2-3%, respectively. The conventional quasi-static strength tests and cycle loading tests with constant frequency and amplitude were performed on the samples and different results were obtained. The samples belonging to group E, with the lowest porosity (2-3%), exhibited the highest mechanical strength, elastic modulus and fracture toughness values and the lowest Poisson's ratio compared to those of higher porosity samples. During the cyclic loading period, the fatigue stress-life graph of the E group has the lowest slope compared to the other groups. It means that the slope of the graph increases as the porosity increases in all groups. Therefore, the E group has the lowest porosity and the longest fatigue life time, i.e. porosity and fatigue resistance have an inverse correlation.

Long-term filtration of particles in a porous medium

The formation of grout sediment in the pores of loose rock increases the water resistance of the soil and strengthens the foundation. A one-dimensional model of filtration in a porous medium considers the particles transport by the flow of a carrier fluid and the deposition of particles on the framework of a porous medium. The purpose of the work is to study the concentrations of suspended and settled particles of a suspension over a long time. Exact and asymptotic methods are used to obtain a solution to the model. The exact solution is presented in an implicit integral form. A set of solutions in the form of traveling waves with an arbitrary initial condition and their asymptotics are constructed. For the exact solution, an explicit second-order asymptotic solution for a long time is obtained as an expansion in decreasing exponents. Comparison of the asymptotic solution with the traveling waves makes it possible to choose a single traveling wave corresponding to the exact solution. The closeness of the traveling wave to the exact solution of the filtration model is verified numerically. The traveling wave found determines the explicit asymptotics of the concentration of deposited particles for a long time.

ВЫЯВЛЕНИЕ ПАЛЕОГИДРОДИНАМИЧЕСКИХ ОБСТАНОВОК ОСАДКОНАКОПЛЕНИЯ ПО ДАННЫМ ГРАНУЛОМЕТРИЧЕСКОГО АНАЛИЗА ДОННЫХ ОТЛОЖЕНИЙ МАЛЫХ ОЗЕР ШОКШИНСКОЙ ГРЯДЫ (КАРЕЛИЯ)1

The paper examines the grain size distribution of bottom sediments of lakes in the Shoksha Ridge area, Karelia, to elucidate howdeglaciation and formation of the Onego Ice Lake basin proceeded. A sequence of bottom sediments of Lake Anashkino and two sediment sequences of Lake Rzhanoe were studied, and lithostratigraphy of the sediment cores was described. The grain size compositions of the 9.32-10.32m sequence from Lake Anashkino and the 2.5-6.52 m sequence from Lake Rzhanoye were analyzed. The study revealed features of the bottomsediment fractions distribution along the depth of occurrence. Paleo-hydrodynamic sedimentation environments were identified using grain sizeanalysis. Lake Anashkino bottom sediments of a 9.96–10.31 m horizon, represented by silt and fine-grained sand, were deposited under conditions of highly dynamic shallowing (decrease in the water level of Onego Ice Lake). The upper part of sediments (9.32–9.92 m), represented by clayey silt mixed with fine-grained sand, accumulated under weak flow conditions. Paleo-hydrodynamic sedimentationenvironments in Lake Rzhanoye were characterized by alternation of highflow conditions (5.36-6.23 m, 6.31-6.32 m, 6.47-6.48 m) and weak flowconditions (2.50-4.88 m, 6.28-6.29 m, 6.30-6.31 m, 6.37-6.45 m, 6.51-6.52 m). This is possibly due to the dynamics of the decrease in the waterlevel of Onego Ice Lake and the formation of small isolated lakes.In the process of the formation of bottom sediments of small lakes of the Shoksha Ridge during the period of intensive changes in thelandscapes, outlines and levels of Onego Ice Lake at the transition from the late Pleistocene to Holocene, against a shift from nival to humid climate,we note a change in sedimentation conditionsin the bottom sediments of the two studied lakes – Anashkino and Rzhanoe – from highly dynamic(flowing conditions, decrease in water level of Onego Ice Lake) to weakly flowing, in the conditions of isolation of the lakes and formation ofmodern small lakes.

Biogeochemical features of the formation of Holocene sediments in Lake Dukhovoe (Eastern Baikalia)

A 6-meter core of Holocene sediments from Lake Dukhovoe was studied. As shown by the radiocarbon dating of lacustrine sediments, Lake Dukhovoe was formed in the Early Holocene (10 cal ka BP). The upper 180 cm of sediment is represented by sapropel, and the boundary of lake sediments is at 293 cm. This is an early stage of lake evolution, devoid of biogenic sedimentation. The microbiological studies of the sediment were carried out, which showed a high total number of heterotrophic bacteria in the upper (0–15 cm) and deeper (110–180 cm) sapropel intervals. Mineral bottom sediments (180–293 cm) are characterized by the presence of groups of phosphorus-reducing and ferromanganese bacteria. The contents of Na, Mg, Al, Si, Al, Ca, Fe, Mn, Zr and Cr in sapropel are within the average concentrations for the earth’s crust, and U and Mo exceed them.

Role of Biochemical Processes in the Formation of Waters and Bottom Sediments after Reduction in the Anthropogenic Pollution

Role of Biochemical Processes in the Formation of Waters and Bottom Sediments after Reduction in the Anthropogenic Pollution

Use of composites to control bottomhole zones at high reservoir temperatures

It is found that one of the ways to increase the depth of penetration, as well as to prevent the formation of sediments, is the use of systems that contribute to the generating formation of hydrofluoric acid in reservoirs due to the ability to maintain a limited concentration of hydrofluoric acid over time. It is shown that the method of generating formation of hydrofluoric acid based on chelate compounds and ammonium hydrofluoride is a simultaneous solution to the problems associated with high temperature and the formation of secondary precipitates. Due to the strong properties of chelate compounds, some of them, which are adsorbed on the surface of the formation of the bottomhole zone, play the role of an inhibitor of salt deposition and protect the bottomhole zone from contamination with inorganic salts for a long time.