Geofizicheskiy Zhurnal

Kinematic and dynamic processing of seismic data along EUROBRIDGE’97 profile

2025-09-22T11:25:31+03:00

The article presents the principal procedures for kinematic and dynamic processing of wavefields observed using the deep Wide-Angle Reflection and Refraction seismic profiling method. It demonstrates that combining their results enhances the level of subsequent interpretation.

Kinematic processing of seismic data is a conventional approach, typically based on ray-tracing modeling, which produces a calculated velocity model of the medium. These velocity parameters are the input data for dynamic processing.

Dynamic processing operates with the amplitude-frequency and phase characteristics of the wavefield, involving the construction of an image of the deep section with its existing interfaces and tectonic features of the study area. In global practice, the main procedures of dynamic processing include various migration techniques; however, they are not designed for processing WARR data recorded at large distances of several hundred kilometers from the source. At the S. Subbotin Institute of Geophysics of National Academy of Sciences of Ukraine, a specialized finite-difference migration method for reflected/refracted waves has been developed specifically for Wide-Angle Reflection and Refraction data processing.

Both kinematic and dynamic processing were applied to wavefields recorded along the EUROBRIDGE’97 seismic profile. Two alternative velocity models are presented, showing a similar overall structure along the profile down to a depth of 15 km, along with a migrated image to the same depth obtained using the finite-difference migration method for reflected/refracted waves.

Application of dynamic processing to the seismic dataset has, for the first time, produced an image of the deep structure of the crystalline basement along the EUROBRIDGE’97 profile, providing additional structural details to the results of kinematic processing.

Focal mechanism of the November 9, 2023, Mw 4.1 earthquake in northern Thailand determined by full-waveform inversion

2025-10-21T14:49:35+03:00

A Mw 4.1 earthquake occurred in northern Thailand (19.498°N, 98.518°E) on 09 November 2023 (centroid time: 07:30:19.86 UTC), within the seismically active Shan-Thai terrane. Source parameter determination employed full-waveform inversion utilizing three-component seismic data from ten regional stations at distances of 73—108 km, operated by the Thai Meteorological Department’s seismic monitoring network, the Department of Mineral Resources network of Thailand, and the Myanmar National Seismic Network. The inversion methodology utilized the ISOLA software package, implementing iterative deconvolution based on the six-element moment tensor framework, and incorporated a minimal 1D velocity model with station corrections specifically calibrated for northern Thailand. Data preprocessing included instrumental response removal, baseline corrections, and band-pass filtering. Green’s functions were computed using the frequency-wave number integration technique within a 0.03—0.10 Hz frequency band. Moment tensor inversion yielded a predominantly strike-slip mechanism with two nodal planes: plane 1 (strike=1°, dip=59°, rake=–148°) and plane 2 (strike=253°, dip=63°, rake=–35°) with 75 % double-couple and –1.2 % CLVD components. Grid search analysis systematically explored source depths from 0—35 km and determined an optimal centroid depth of 2.5 km, with maximum correlation coefficients exceeding 0.4 within the 2—4 km depth range. Waveform analysis demonstrates variance reduction values ranging from 0.40 to 0.80 at near-regional stations (Δ<250 km), indicating robust source parameter determination. The focal mechanism and seismicity distribution indicate strain release along an NE-SW trending structure, located 17 km west of the N-S trending Wiang Haeng fault system.

Use of neural networks for studying nontraditional hydrocarbon reservoirs (an example of Visean black shales of the Dnipro-Donets Basin)

2025-12-08T12:02:10+02:00

The paper presents a study of Visean-stage clay shales of the Dnieper-Donets Basin using a neural network algorithm.

The Dnieper-Donets Basin is among Ukraine’s prospective regions for shale gas exploration. Given the need to boost hydrocarbon production from depleted fields through non-traditional approaches, detailed geological and geophysical characterization of shale-gas-bearing strata is both timely and promising.

The oil and gas potential of combustible shales is largely governed by the content of organic matter, specifically the total organic carbon. For estimating total organic carbon in organic-rich rocks from wireline logs, the Passey method is widely used. We propose a new approach to forecasting organic-matter content in the target intervals when only a limited suite of logs and a restricted core dataset are available. The approach leverages state-of-the-art techniques, namely, a neural-network algorithm. Rapid advances in neural networks have encouraged their uptake in geophysical workflows, especially where input data are sparse. For this work, we employed a three-layer neural network of the multilayer Perceptron type, which directly maps inputs to outputs through successive neuron layers.

We demonstrate that combining the common Passey technique with a neural-network algorithm not only yields sufficiently accurate predictions of organic-matter content within shale intervals but also refine previously obtained results.

Low-amplitude faults revealed by seismic attribute analysis in the Khasilat field of the Absheron oil and gas bearing region

2025-10-09T10:04:20+03:00

The Khasilat field, located within the Absheron oil-and-gas-bearing region, was selected as the primary research object due to its geological complexity and proven hydrocarbon potential. A concise yet informative description of the research site is presented, emphasizing the comprehensive suite of geological and geophysical investigations. These include stratigraphic and lithological analyses and advanced geophysical methods such as vertical seismic profiling. Particular attention is paid to the Qala Suite deposits that represent the main oil-bearing horizon within the study area; their lithological composition, structural setting, and reservoir characteristics are briefly outlined.

The main issue of the paper concerns the detection and interpretation of tectonic disturbances manifested in the seismic wave-field. Seismic methods, especially when applied in high-resolution formats, are recognized as essential tools for revealing the structural fabric of subsurface formations. Disjunctive dislocations, including faults and fractures, play a critical role in the evolution of hydrocarbon systems.They influence both the accumulation and migration of fluids, as well as the integrity of reservoir traps. For this reason, the detailed mapping of such structural features is crucial for reliable geological modelling and resource evaluation. In this study, seismic attribute analysis techniques including coherence, dip, and azimuth cubes were applied to identify and delineate fault systems. The interpretation results revealed numerous faults aligned in a north-south orientation, along with several transverse faults trending west-east, indicating a complex and potentially productive tectonic framework within the region.

Geoelectric research of the Precarpathian oil and gas region along the Bylychi-Hlyboka profile

2025-08-21T12:12:08+03:00

The article presents the results of magnetotelluric sounding and magnetovariational profiling studies carried out in 2024 within the Precarpathian Trough to investigate the deep structure of the lithosphere searching for electrical conductivity anomalies that may be caused by the penetration of fluids from the crust and mantle into the upper layers of the geological section and may serve as an important source for all subsequent processes of oil and gas field formation. Synchronous modern magnetotelluric surveys were performed along the Bylychi—Hlyboka profile at fourteen observation sites, providing a space-time pattern of the distribution of geomagnetic variations and the electric field on the Earth’s surface. The experimental data were processed using the PRC_MTMV software package, and the response functions—tippers for geomagnetic variation periods ranging from 30 to 3400 s — and the curves of apparent resistivity (amplitude values and impedance phases) for periods ranging from 10 to 10000 s were analyzed. According to the results of the joint analysis of MT sounding and magnetovariational profiling data, the profile is divided into two parts. In the northern part the upper boundary of the conductor lies at depths of 20—50 km. It is located within the area of concentration of oil and gas fields of the Boryslav—Pokutskyi district and modern seismic activity. This northern part may represent a continuation of the sublatitudinal asthenospheric conductor identified in previous studies. The southern part is characterized by the presence of conductors at depths of about 20 km. The new geoelectric parameters described in the paper will be further used in constructing a three-dimensional model of the geologically complex Carpathian region.

A study of Quaternary deposits in the coastal zone of a continental shelf based on thermoluminescence and remote sensing

2025-11-13T11:34:36+02:00

Currently, systematic and comprehensive research is required in order to determine the age of geological deposits. This approach is based on a combination of ground, laboratory, and remote sensing techniques. This increases the accuracy, efficiency and objectivity of the results obtained. New remote sensing techniques and laboratory methods can be used to analyse and systematise information about the genesis, age and characteristics of sediments. Paleomagnetic, dosimetric, lithological, biostratigraphic, and remote sensing methods are used for geochronological tasks, determining the age of geological objects and the stratigraphic division of sediments. This combination of geological methods and remote sensing approaches is also used to study changes in river basins and the open sea. In this study, the remote sensing approach is the primary stage in research of Quaternary deposits in the coastal zone of the continental shelf. The second stage involves the usage of the thermoluminescence method to determine the age of the deposits. Sentinel-2 images were used to visualise the Quaternary deposits. It was determined that these deposits include marine and middle-lower Anthropocene alluvial and estuarine-marine deposits. We compiled and analysed two maps of Quaternary sand deposits between the mouth of the Dniester River and the Black Sea. The advantages of multispectral images are their wide coverage area and high monitoring frequency. After using the remote sensing approaches to determine the age of the deposits, a thermoluminescence method was applied, taking into account the rate of radiation defect formation and the accumulated energy of the sample under study. The thermoluminescence method is based on solving a first-order differential equation to derive a formula for the age parameter. The method is an effective technique for dating sediments and studying the correlation of various Quaternary sediments.

Geological and geophysical studies for assessing the energy potential of land-sea transition zones of the Azov-Black sea region

2025-12-29T22:58:23+02:00

The article is devoted to integrated geological and geophysical investigations of land-sea transition zones of the Azov-Black Sea region (the Western Black Sea area and the Kerch Bay-Azov Sea). These zones, which are strategically important for hydrocarbon exploration, cover more than 30,000 km2 and are extremely challenging for the application of conventional seismic exploration methods. This is primarily due to specific physical-geographical conditions and technological limitations. Such studies are critically important for reducing the risk of «dry» drilling and attracting investment, as well as for addressing engineering and safety issues in the context of post-war reconstruction.

A detailed analysis of two key areas the Western Black Sea area and the Kerch Peninsula is presented. In the Western Black Sea area, the most promising zone extends from Lake Sasyk to Lake Alibey, with a forecast estimate of undiscovered resources of 20—30 thousand tonnes of oil equivalent (TOE) per 1 km2, associated with Paleozoic (Silurian, Devonian, Carboniferous) and Mesozoic deposits. The Kerch area is also among the most promising regions (20—30 thousand TOE per 1 km2), where hydrocarbon potential has been proven in Neogene (Tortonian) and Oligocene deposits and is also expected in older complexes (Cretaceous and Jurassic).

In the transition zones of the northeastern part of the Kerch Peninsula (Kerch Bay-Azov Sea), exploration seismic surveys using the 2D CMP (CDP) method were conducted by the State Enterprise «Ukrgeophysica» during 2009—2011. Five seismic profiles with a total length of 43.64 km were acquired; they cross anticlinal structures including the Velykotarkhansky and Baksynsky mud volcanoes. The obtained migrated time sections allowed for a detailed reconstruction of the geological structure of the transition zone and the internal structure of mud volcanoes, confirming their genetic relationship with anticlinal folds.

Seismic methods, particularly the 3D seismic surveying, represent the only effective tool for identifying and delineating prospective structures in transition zones. Comprehensive geophysical investigation of these areas is critically important not only for realizing Ukraine’s energy potential but also for engineering geophysics (mapping weak soils, designing landslide protection structures) and seismic microzonation. These studies provide a scientific basis for the sustainable development of transport infrastructure and for ensuring the safety of coastal territories.

On the 100th anniversary of Stanislav Tymofiyovych Zvolsky (December 15, 1925—June 28, 2018).

2025-12-29T19:47:02+02:00

December 15, 2025 marked the 100th anniversary of the birth of Stanislav Timofeevich Zvolsky, a famous scientist in the field of nuclear geophysics, a leading researcher at the S.I. Subbotin Institute of Geophysics of the NAS of Ukraine, Doctor of Geological and Mineralogical Sciences, laureate of the V.I. Vernadsky Prize.