-
Date submitted2024-04-10
-
Date accepted2024-10-14
-
Date published2024-11-12
The influence of ocean anoxia on conditions for the Domanik deposits formation
The article considers one of conditions for the Domanik facies formation on the example of Tatarstan and Bashkortostan. The main emphasis is on the influence of anoxic paleobasin conditions on the high-carbon strata formation. A detailed study of the hydrocarbon composition of Domanik deposits made it possible to find characteristic biomarkers in their composition. They are based on the composition and structure of diagenetic products of biological compounds composing the sulphur bacteria living in anoxic/euxinic paleobasin conditions. Such compounds include C40 diaryl isoprenoids – isorenieratane and paleorenieratane. C10 tetramethylbenzenes also occupy a special place in the Domanik deposits study. Their appearance in the composition of organic matter of these deposits results from the transformation of sulphur bacteria compounds. Diaryl isoprenoids and tetramethylbenzenes are a reliable indicator of anoxic conditions of the Domanik deposits formation. The thermodynamic state of the hydrocarbon environment can be determined from the ratio of tetramethylbenzene isomers.
-
Date submitted2024-05-03
-
Date accepted2024-09-05
-
Date published2024-11-12
Platinum group elements as geochemical indicators in the study of oil polygenesis
This study examines elements of the platinum group (PGE), primarily platinum and palladium, as geochemical indicators in the investigation of oil polygenesis. It has been found that, like other trace elements such as nickel, vanadium, and cobalt, platinum group elements and gold can occur in oil fields at both background levels and in elevated or even anomalously high concentrations. The objective of this research is to analyze PGE and trace elements as geochemical markers to identify the geological factors, including endogenous processes, responsible for these unusually high concentrations in oil. A comprehensive review of the literature on this subject was conducted, along with new data on the presence of precious metals in oils from Russia and globally. The study explores the geological mechanisms behind elevated PGE concentrations in oils, utilizing atomic absorption spectroscopy with atomization in the HGA-500 graphite furnace to measure PGE content. Previously, the tellurium co-deposition method (ISO 10478:1994) was used to isolate noble metals from associated elements. Possible geological origins of abnormally high concentrations of platinum metals in oils have been identified. These include endogenous factors such as the spatial proximity of oil fields to ultrabasic rock massifs, the effects of contact-metasomatic processes, and influences from mantle dynamics. Moreover, data concerning mantle elements can serve as indicators of the depth origins of certain hydrocarbon fluids, thus contributing to the study of oil polygenesis.
-
Date submitted2024-05-13
-
Date accepted2024-09-05
-
Date published2024-11-12
Potential trace element markers of naphthogenesis processes: modeling and experimentation
With the growing demand for hydrocarbon energy resources, there is a need to involve oil fields at deeper horizons in processing and increase the profitability of their development. Reduction of expenses on prospecting works is possible at revealing and substantiation of physicochemical markers of the naphthogenesis processes. One of the key markers is the transition metals content, which are both a measure of oil age and markers of potential associated processes in the migration and formation of hydrocarbons in the Earth's strata. The elemental composition of samples of oil and reservoir rocks of the Timan-Pechora field was studied. Based on the results of thermodynamic modeling, plausible processes of contact rock minerals transformation were proposed. Based on the results of molecular modeling the probable structure of vanadium and nickel host molecules in the heavy fraction of oils is proposed. The ratios of transition metal and sulfur contents were experimentally established, and assumptions about possible mechanisms of formation of deep hydrocarbon reservoirs were made. Analysis of the obtained ratios of transition metal contents in reservoir rocks and oil samples allowed to suggest possible processes of mantle fluids contact with the host rock and subsequent accumulation of hydrocarbons on sorption active rocks. According to the combined results of experimental and theoretical studies it was found that polymers of heavy fraction more selectively capture vanadium, which indicates the predominance of vanadium content in oil-bearing rocks in relation to the content of nickel. In this case, oil acts as a transport of transition metals, leaching them from the bedrock.
-
Date submitted2022-10-29
-
Date accepted2023-02-13
-
Date published2023-04-25
The use of unmanned aerial photography for interpreting the technogenic transformation of the natural environment during the oilfield operation
The traditional approach to monitoring observations of the technogenic processes development in oilfields, which consists in determining the concentration of marker pollutants in various natural environments, does not provide the necessary completeness of information and the efficiency of its receipt. The paper considers an example of expanding the range of observations due to unmanned aerial photography and a number of other methods. Interpretation signs (for panchromatic survey) were determined that register such consequences of technogenic transformation of the natural environment as mechanogenesis, bitumization, and halogenesis. Technogenic mechanogenesis is understood as a physical violation of the integrity of ecosystems, the movement of soils and grounds. Bitumization is expressed in the migration of petroleum hydrocarbons through soils, ground, surface, subsurface, and underground waters, and their destruction. Salt migration in these media is defined as halogenesis. The most reliable indicators are linearly elongated areas of dead forests, dark red spots in drying microdepressions and reservoirs. It was found out that the oilfield impact on the raised bog leads to anthropogenic eutrophication, the introduction of plant species, uncharacteristic coenotic groups, the replacement of subshrubs with grasses, and morphometric changes in forest pine. In the peat deposits of the disturbed area, an unusual interlayer of whitish, undecomposed moss was recorded. The moment of the beginning of a pronounced technogenic transformation was registered in the course of work with the archive of multispectral space images. Continuous remote sensing with the help of unmanned aerial photography and interpretation by sedimentological, geobotanical methods significantly expand the possibilities of studying the technogenic transformation of the natural environment. To ensure environmental safety, it is advisable to develop remote methods and technologies to include them in the environmental monitoring system.
-
Date submitted2021-06-10
-
Date accepted2021-07-27
-
Date published2021-10-21
Defects of diamond crystal structure as an indicator of crystallogenesis
- Authors:
- Evgeny A. Vasilev
Based on the study of a representative collections of diamonds from diamondiferous formations of the Urals and deposits of the Arkhangelsk and Yakutian diamond provinces, we established patterns of zonal and sectoral distribution of crystal structure defects in crystals of different morphological types, identified the specifics of crystals formed at different stages of crystallogenesis and performed a comprehensive analysis of constitutional and population diversity of diamonds in different formations. We identified three stages in the crystallogenesis cycle, which correspond to normal and tangential mechanisms of growth and the stage of changing crystal habit shape. At the stage of changing crystal habit shape, insufficient carbon supersaturation obstructs normal growth mechanism, and the facets develop from existing surfaces. Due to the absent stage of growth layer nucleation, formation of new {111} surfaces occurs much faster compared to tangential growth mechanism. This effect allows to explain the absence of cuboids with highly transformed nitrogen defects at the A-B 1 stage: they have all been refaceted by a regenerative mechanism. Based on the revealed patterns, a model of diamond crystallogenesis was developed, which takes into account the regularities of growth evolution, thermal history and morphological diversity of the crystals. The model implies the possibility of a multiply repetitive crystallization cycle and the existence of an intermediate chamber; it allows to explain the sequence of changes in morphology and defect-impurity composition of crystals, as well as a combination of constitutional and population diversity of diamonds from different geological formations.
-
Date submitted2020-08-20
-
Date accepted2021-04-01
-
Date published2021-06-24
Features of the mineral and chemical composition of the Northwest manganese ore occurrence in the Highveld region, South Africa
- Authors:
- Aleksandr N. Evdokimov
- Benedict L. Pharoe
The Northwest manganese ore mineralisation is located at a relative distance from traditionally known manganese mining areas in a new manganese-bearing region (Highveld) in the Northwest Province, Republic of South Africa. The ore occurrence was studied on farms: Buchansvale 61 IQ, Weltevreden 517 JQ, Rhenosterhoek 343 JP and Kafferskraal 306 JP. The data obtained from studying the geology of the area pointed out to interests regarding the development criterias for search of similar ore mineralisations in the northwest region of South Africa. The ore occurs predominantly in the form of powdered manganese wad, manganese nodules and crusts, confined to the karstic structures of the upper section of the dolomites. X-ray powder diffraction (XRD), Scanning electron microscopy with energy dispersive link (SEM-EDS) and X-ray fluorescence were utilized to unveil the mineral and chemical composition of the ore samples. The present study therefore presents the results on both chemical and mineral composition of manganese ores, and their depth and longitudinal distribution. Karstic areas causing an increased local thickness of the ore body were identified. The geochemical and microspcopic study of the ores indicates their supergene nature. The main ore minerals includes cryptomelane, lithiophorite, purolusite, hollandite and romanechite associated with impurity components of Ba, Ce, Co, La, Cr, Zn and V.
-
Date submitted2010-07-28
-
Date accepted2010-09-18
-
Date published2011-03-21
Assessment of alluvial gold-bearing raw materials from the permafrost zone for justification of combined geotechnology of gold heap leaching
- Authors:
- S. B. Tataurov
The paper presents results of cryogenetic impact on mineral composition and geotechnological properties of alluvial gold-bearing raw materials of natural and man-made origin. In particular, distinctive features in mineral composition of alluvial deposits are described within the permafrost zone and outside it as well as the nature, mechanisms and peculiar features in reduction of man-made gold amalgams are shown. The results obtained were used to justify the expediency of implementation of the combined heap gold ore leaching technology at alluvial deposits in the permafrost zone, which includes preliminary concentration of coarse, medium and fine gold as well as the gold amalgam.
-
Date submitted2008-10-09
-
Date accepted2008-12-12
-
Date published2009-12-11
New source of noble corundum in Kenya
- Authors:
- L. V. Kulachkov
- K. Kamwathi
- V. L. Shterhun
The large-scale occurrence of ruby and sapphire in Kenya is represented by contemporary river-bed and valley alluvial placers. The first ones are characterized by a high content of ruby (up to 10,4 ct/m 3 ), the second type is interesting due to the amount of forecasted resources: up to 2,3 million ct of ruby and 1,2 million ct of sapphire. It turned out to trace the mechanism of corundum concentrations forming, the mineral crystallized in Archean high-alumina gneisses affected by Precambrian basites (ultrabasites), and then survived a complicated way: – ancient eluvium – ancient alluvium – transportation by basaltic Pleistocenic magma – Holocenic weathering crust of volcanites – talus – contemporary alluvium.
-
Date submitted1951-08-23
-
Date accepted1951-10-03
-
Date published1952-11-20
Feldspars of ceramic pegmatites of the Southern Karelia
- Authors:
- S. A. Rudenko
Recently, a discussion has developed regarding the genesis of pegmatites. The beginning of this discussion was laid by D. S. Korzhinsky in 1937. In 1944, A. N. Zavaritsky demonstrated the inconsistency of the physicochemical substantiation of the pegmatite process proposed by Vogt and Niggli and accepted by A. E. Fersman. Later, in 1947, he put forward a new theory of the genesis of pegmatites, contradicting the idea that pegmatites are a product of direct crystallization of residual melt (A. E. Fersman's theory). According to A. N. Zavaritsky, the main structural features of pegmatites are created as a result of recrystallization of certain igneous rocks. Next, V. D. Nikitin, who studied ceramic and mica pegmatites (1946-1951), based on a detailed analysis of the relationships between individual minerals and structural components of pegmatites, developed ideas about the genesis of pegmatites of this specific type, which are basically consistent with the theory of A. N. Zavaritsky. However, much effort is still needed to more fully resolve issues related to establishing all the features of the transformations that both the deposits as a whole and the individual minerals that make them up undergo during the complex and lengthy process of pegmatite formation. This article highlights the main features of the evolution of feldspars in ceramic pegmatites of Southern Karelia.
-
Date submitted1950-08-15
-
Date accepted1950-10-13
-
Date published1951-08-08
Conditions for squeezing water and oil from clays
- Authors:
- V. D. Lomtadze
Studying the conditions of squeezing water and oil from clays is of exceptional importance for understanding the genesis of oil, oil fields, the formation of the salt composition of groundwater and the properties of clay sediments. Squeezing water and oil from clays is associated with the issue of clay compactibility. Clay compactibility has been studied many times, and there is extensive literature devoted to this issue. However, all these studies, in most cases, were conducted for engineering and construction purposes. Therefore, clay compaction was studied, as a rule, under low loads (4-6 kg/cm2). In addition, these studies were usually carried out to obtain the physical and mechanical characteristics of the soil. Only a few works are devoted to studying clay compactibility under higher loads.