НАУКИ О ЗЕМЛЕ. ГЕОЛОГИЧЕСКИЕ НАУКИ

A study of the scale effect on the reservoir permeability and porosity over a wide range of the void structure appears to be a significant research task. In this work, we aimed to investigate the scale effect over a wide range of alternating reservoir properties, depending on changes in the void structure, as well as to assess the feasibility of using a whole core with a retained drilling diameter in determining the permeability and porosity of complex reservoirs. For the first time, core samples are proposed to be selected on the basis of space zoning, which takes into consideration the void structure and the scale effect. Filtration studies using such samples are expected to correctly reflect the physical and hydrodynamic characteristics of the reservoir, thus being valuable for calculating reserves and designing project documentation. Based on the performed linear discriminant analysis, the practical problem of dividing the D3fm object of the Tedinskoye oil field by the type of productive sediment reservoir is solved. In addition, an analysis of the results of physical and hydrodynamic studies confirmed the significance of the scale effect when studying the porosity and permeability properties of complex reservoirs. A significant effect of the void structure on the value of residual water-oil saturation is demonstrated. The feasibility of using whole core samples is substantiated, taking into account the quantitative measure of the scale effect differentiated over a wide range of porosity and permeability when determining the boundary values of porosity for carbonate deposits of the D3fm object of the Tedinskoye oil field. The obtained results show that the calculation of geological and recoverable reserves should take into account both the scale effect and the structural features of the void.

The article provides information on the outcrops of the Neogene-Quaternary riverine sediments of the North-Western Black Sea coastal area. A description of five outcrops of fluvial deposits located on the territory of the modern basins of the Dniester and Prut rivers is given. Based on the granulometric composition of the sediments and the presence in them of the fossil shells of freshwater bivalve mollusks (Bivalvia: Unionoida), an assumption has been made about the characteristics of the ancient river ecosystems of the Dniester and Prut on different Pliocene and Pleistocene time sections. A review of the data in the body of literature on the geological age of the studied outcrops was undertaken. The localities considered provide information on the sedimentation conditions in this region from the Pliocene to the Late Pleistocene. Previously, various approaches were used for dating such rocks and for determining the stratigraphic position of fossil material found in them. The article considers the method of amino acids racemization as one of the approaches. Racemization allows to obtain new data on the stratigraphy of Neogene-Quaternary riverine sediments and to solve the problem of their dating. The sampling principles of carbonate material for the analysis of amino acids from the mollusk shells and features of sample preparation are described. Five amino acids were used: aspartic acid (Asp), glutamic acid (Glu), leucine (Leu), phenylalanine (Phe) and isoleucine (Ile). The D/L ratios were analyzed (amino acid racemization (or AAR) is the interconversion of amino acids from one chiral form (the L – (laevo) amino acids which are the building blocks of proteins) to a mixture of L- and D- (dextro) forms. The extent of racemization is measured by the ratio of D/L isomers (it increases as a function of time and temperature and can be used for geochronology) from the same group of fossils (genera), which were preserved under similar environmental conditions, inorganic geochemistry and thermal histories. Based on the obtained values, it can be concluded that the analysis of the racemization of amino acids is useful for determining the geological age of fossil shells of freshwater bivalve mollusks, but there are limitations regarding age. In the shells of the Pliocene sites, the values of some amino acids are close to one, indicating that the racemization took place. D/L values in shells from Pleistocene localities allowed the determination of their stratigraphic position.

The objective of the research is to identify the main patterns of spatial distribution of natural and anthropogenic radionuclides (RN) in Naryan-Mar. Urban soils are formed by means of natural soil transformation with the participation of technogenic sedimentogenesis, which leads to disturbance of natural RN migration processes and contributes to the complex structure of natural and anthropogenic RNs contamination of tundra soils. The specific activity of anthropogenic (134Cs, 137Cs) and natural (226Ra, 232Th, 40K) RNs in Naryan-Mar soil was determined. The local low-intensity anomalies (LLIA) of anthropogenic RNs result from transboundary transfer; 134Cs and 137Cs are concentrated in soils with a well-shaped vegetable layer. 226Ra and 232Th LLIAs are confined to regions with stone buildings. 40K LLIAs are conditioned by high density of grassland vegetation involving 40K in the biological cycle. The statistical manipulation of the acquired data involved correlation and factor analysis techniques. The statistical analysis demonstrated a moderate and salient correlation between the content of 232Th and 40K in the soils of the areas built up with wooden houses and the soils of the recreation area, respectively. There is a salient correlation between the content of 134Cs and 40K as well as between 134Cs and 232Th in the soils of the recreation area. The area occupied by technological buildings demonstrates salient and high negative correlations between the content of 226Ra and radionuclides of 40K and 234Th. The multidirectional nature of the 226Ra and 232Th accumulation processes can be explained by their different mobility in the environment. A factor analysis of the specific activities of the radionuclides in the soils (based on the varimax method) revealed that the strongest factor (28%) conjointly regulates the 134Cs and 40K content, which testifies to their affiliation to non-mobile cationogenic elements. The second factor (25%) identified through an analysis of the overall data array may signify that organic matter plays a major role in the 137Cs retention.