Geofizicheskiy Zhurnal

In memory of Oleh Maksymovych Rusakov (13.10.1936—13.12.2023)

В.І. Старостенко — 2024-02-25

In memory of Oleh Maksymovych Rusakov (13.10.1936—13.12.2023)

In memory of Valerii Korchyn (18.10.1941—14.01.2024)

Редколегія та співробітники Відділу петромагнетизму і морської геофізики — 2024-02-25

In memory of Valerii Korchyn (18.10.1941—14.01.2024)

Inna Pashkevych — 90 years old from the day of birth and 60th anniversary of work at the Subbotin Institute of Geophysics of the National Academy of Sciences of Ukraine.

V.I. Starostenko — 2024-02-25

Inna Pashkevych — 90 years old from the day of birth and 60th anniversary of work at the Subbotin
Institute of Geophysics of the National Academy of Sciences of Ukraine.

A few words about my mother, Inna Pashkevych. On the occasion of her 90th birthday and 60 years of work at the Institute of Geophysics.

E. Yeremenko — 2024-02-25

A few words about my mother, Inna Pashkevych. On the occasion of her 90th birthday and 60 years of work at the Institute of Geophysics.

To the 80th Anniversary of Volodymyr Kulyk

V.I. Starostenko — 2024-02-25

To the 80th Anniversary of Volodymyr Kulyk

Congratulations on the 90th anniversary of the Geological Journal

V.I. Starostenko — 2024-02-25

Congratulations on the 90th anniversary of the Geological Journal.

Selection of areas prospective for the search of primary hydrogen in the territory of Ukraine (based on the data of the 3D P-velocity model of the mantle)

T.O. Tsvetkova — 2024-02-25

The work aimed to identify promising areas for the search for primary hydrogen in Ukraine using a 3D P-velocity model of the mantle under Ukraine and its surroundings. The work uses a 3D P-velocity model of the mantle under the territory of Ukraine and its surroundings from a depth of 50 to 1700 km north of 50° NL and up to 2500 km to the south. The model is derived using ISC bulletin data from 1964 and is presented as horizontal and vertical cross-sections.

Since the manifestation of hydrogen is primarily associated with the release of ultra-deep fluid tracks in the mantle, a brief analysis of them was presented. A detailed analysis of all nine superdeep mantle fluids isolated on the territory of Ukraine and their velocity characteristics was carried out. A comparison of the location of the routes of passage of superdeep fluids and the velocity structure of the mantle of the considered territory showed that they are confined to tectonically activated areas. In order to confirm the possible presence of primary hydrogen in selected tracks of superdeep mantle fluids, heat flow density maps, a temperature map at a depth of 50 km, a map of the depth of the Moho boundary, a conductivity density map, and a fault map of the Ukrainian Shield were considered.

A comparative analysis of maps of the location of superdeep mantle fluids and regions on the territory of Ukraine with increased heat flow, increased depth of the Moho boundary, and the presence of mantle conductors and faults was carried out. Summarizing the results of the comparative analysis, the most promising areas for the search for primary hydrogen were selected, corresponding to the following routes of superdeep fluids: f12, the northeastern part of f3, the southern part of f4 (the area of the Dnipro-Donetsk basin), the southwestern part of f1 (the area of the Western Ukrainian oil and gas-bearing region) and f9 and f10 (region of the South Crimean oil and gas-bearing province).

Anisotropic media with singular slowness surfaces

Yu.V. Roganov — 2024-02-25

It is proved that if an anisotropic medium has an open set of singular directions, then this medium has two slowness surfaces that completely coincide. The coinciding slowness surfaces form one double singular slowness surface. The corresponding anisotropic medium is an elliptical orthorhombic (ORT) medium with equal stiffness coefficients c₄₄=c₅₅=c₆₆ rotated to an arbitrary coordinate system. Based on the representation of the Christoffel matrix as a uniaxial tensor and considering that the elements of the Christoffel matrix are quadratic forms in the components of the slowness vector, a system of homogeneous polynomial equations was derived. Then, the identical equalities between homogeneous polynomials are replaced by the equalities between their coefficients. As a result, a new system of equations is obtained, the solution of which is the values of the reduced (density normalized) stiffness coefficients in a medium with a singular surface. Conditions for the positive definite of the obtained stiffness matrix are studied. For the defined medium, the Christoffel equations and equations of group velocity surfaces are derived. The orthogonal rotation matrix that transforms the medium with a singular surface into an elliptic ORT medium in the canonical coordinate system is determined. In the canonical coordinate system, the slowness surfaces S₁ and S₂ waves coincide and are given by a sphere with a radius . The slowness surface of qP waves in the canonical coordinate system is an ellipsoid with semi-axes , , . The polarization vectors of S₁ and S₂ waves can be arbitrarily selected in the plane orthogonal to the polarization vector of the qP wave. However, the qP wave polarization vector can be significantly different from the wave vector. This feature should be taken into account in the joint processing and modelling of S and qP waves. The results are illustrated in one example of an elliptical ORT medium.

Boundary of recent activation and seismicity on the platform part of Ukraine

V.V. Gordienko — 2024-02-25

The purpose of the work is to clarify the boundaries of the recent activation (RA) zone in the platform part of Ukraine. Such limitations are evident for the Alpine Carpathian geosyncline and the Hercynian-Cimmerian Scythian plate. For the East European Platform, the edge of the zone is determined by the magnitude of the mantle gravity anomaly. This option gives a more definite result than the previously used complex of geological and geophysical data. The applied technique, in addition to the usual two-dimensional density modeling along DSS profiles, includes the processing of the obtained data by kriging. This allows you to fill in the area between the profiles and trace the detailed shape of the zone boundary. The magnitude of the anomaly at the edge of the active region was calculated. In the center of the zone, the studied perturbation (the difference between the gravitational effect of the crust and the observed field) is 30—40 mGl, at the edge — 20 mGl. An estimate of the error in determining the anomaly was made, it turned out to be at the level of 10 mGl. The value at the boundary is less than the tripled error. In this situation, a special procedure is needed to detect spatial variations in the position of the boundary. For this, for the first time, two of its calculation options were used: using kriging and using artificial profiles located between the real ones. The crustal sections under the artificial ones were average between the real ones, the observed field on the artificial profile was used. An average difference in the boundary position of 13 km was obtained. The practically important question of the ecological consequences of manifestations of activity in the RA zone on the platform is considered. Seismicity does not pose a significant threat, as does the release of helium with anomalous isotopy and hydrogen. Catastrophes happen precisely during the exploitation of gas and coal deposits, and not as a result of the natural evolution of these objects.

Reservoir-triggered seismicity: case study of the Dnister Hydro Power Complex (Ukraine)

K. Tretyak — 2024-02-25

The work considers the seismic activity around the Dnister Hydro Power Complex in the Dnister Reservoir area from 2012 to 2021. Maximum local magnitude of earthquakes for the studied period is M_L=3.4. Hypocenters of earthquakes are at the depth of 1—3 km. They are located nearby to previously established faults and contacts of structures with a different lithological composition. Artificial water level regulation in the reservoir is related to the operation of the Dnister Hydro Power Plant and, according to our results, probably affects the occurrence of seismic events. Although the maximum water level changes only by 8.7 m, the region has increased natural seismicity and is located in the transition zone between 6^thand 7^thisoseims according to the seismic zoning map of Ukraine. Accumulated natural stresses can be triggered into earthquakes when there is a sudden change in water pressure. The seismicity of the region around the Dnister Reservoir was investigated for 10 years, taking into account the water level data in the reservoir, as well as comparing the location of earthquakes with the State Geological Map of the Crystalline Foundation. The profile of the State Geological Map of the Crystalline Foundation with the projected earthquakes hypocenters allowed to indicate that a significant number of earthquakes are located between different lithological structures. In order to assess the interrelationship between seismicity and water level changes in the reservoir, 111 periods of lowering or filling of the reservoir were selected. Parameters of seismic activity within the periods were calculated and analysed. Correlation between the sum of logarithms of energy with water volume changes and pressure changes in the Dnister Reservoir was established. Considering linear dependence it is possible to predict potential intensity of local seismicity caused by water level changes in the Dnister Reservoir.

The seismicity of the Carpathians in 2022

S.T. Verbytskyi — 2024-02-25

According to the results of observations at the seismic stations of the Carpathian region of Ukraine in 2022, the main parameters of 50 earthquakes in the range of energy classes K_R=5.7÷13.7 were obtained. The parameters of seismometric equipment at active seismic stations are given. A catalog of earthquakes, their distribution by regions and energy classes, a map of epicenters, graphs of seismic energy release, and the number of earthquakes in the region by month are presented. A brief description of the seismicity of certain seismically active areas of the Carpathian region is given. The total energy allocated to the region was ΣЕ=5.06·10¹³ J, which is higher than last year’s level of ΣЕ=3.13·10¹² J. This year, increased seismic activity was observed in the Vrancea Mountains, where 20 earthquakes of energy class K_R=9.1÷13.7 were recorded. Their total seismic energy was ΣE=5.06·10¹³J. The foci of the Vrancea earthquakes are concentrated at a depth of h=80÷152 km (18 events) and h=20 km (2 events). 10 earthquakes with energy class K_R=5.8÷8.0 were registered in Transcarpathia. Their total seismic energy was ΣE=2.78·10⁸ J. The strongest was recorded on March 28 with K_R=8.0 at 05^h01^m at a depth of h=2.4 km. For the past seven years, Transcarpathia has been practically in a seismic lull. On the territory of Bukovyna this year, there is also a decrease in seismic activity compared to 2021. A total of 9 earthquakes with energy class K_R=6.9÷8.4 and total seismic energy ΣЕ=8.41·10⁸ J were registered here. The foci of earthquakes are in the earth’s crust at a depth of h=1.8÷15 km. In seismically active areas such as the Southern Carpathians, Transylvania, and Bacau, only one earthquake was recorded in 2022, while no event was recorded in the Kryšana and Banat regions. The regional Carpathian hodograph was used to determine the main parameters of earthquakes in Transcarpathia, and the Jeffreys-Bullen hodograph was used for earthquakes in the Vrancea zone and six other regions.

Reservoir properties of effusive rocks of the Muradkhanli field (Azerbaijan)

V.M. Seidov — 2024-02-25

The presence of oil accumulations in igneous rocks has been known for quite a long time. Geologists estimate that oil reserves in eruptive and weathered metamorphic rocks reach 1 % of the world’s proven oil reserves. At the Shaimskoye field (Western Siberia), oil is found in the weathered granites of the basement. Oil has been found in eruptive rocks in Texas (USA) fields, the most famous of which is the Litton Springs field. Oil is found in metamorphosed shales in the western part of the Los Angeles basin, the porosity of which is caused by the development of cracks in the roof of crystalline shales. Petroleum is extracted from serpentinites in Cuba. Basic igneous rocks contain petroleum at the Ferbro field in Mexico.At the Khukhrinsky gas field, which islocated at the north-western end of the Dnieper-Donets depression, the crystalline basement rocks are oil and gas bearing, from which commercial hydrocarbon inflows have been obtained. In the White Tiger field (Bach Ho), located on the southern shelf of Vietnam, commercial oil accumulations are also found in crystalline basement rocks.

At the Muradkhanli field in Azerbaijan, the industrial accumulation of petroleum belongs to the igneous rocks of the Upper Cretaceous age. The natural oil and gas reservoir of the Muradkhanli field is confined to the erosion zone of the upper part of the section of these rocks.

This work aims to determine the reservoir properties of the rocks of the Muradkhanli deposit, which belong to igneous rocks, in different ways.

The method of estimation of final oil recovery of complex structure reservoirs was proposed for useful capacity and oil recovery of homogeneous media; different variants of the volumetric method were used for reservoirs with complex structures of pore space filling a complex and heterogeneous natural reservoir; values of hydrocarbon reserves of increased and secondary capacity were calculated for the study interval; distributions of oil reserves with right-sided asymmetry, where Mo<Me<X, were presented; it was determined that in effusive cores oil saturation and fluid filtration are caused by tectonic fracturing and cavernousness.

Permeability varies in a wide range: 0.73·10^–15—1.31·10^–15 m²; the largest specific fraction of crack density is in the range 0—0.1 cm/cm², the average value is 0.29 cm/cm², with crack depth they decrease from 0.9 to 0.1 cm/cm².

The studies have shown that the natural reservoir of oil and gas in the Muradhanli field is associated with the erosion zone of the upper part of the igneous rock section.