Within the framework of the elastoplastic model, the development of irreversible deformation during horizontal compression of a sedimentary layer lying on a rigid foundation is considered. The influence of strength parameters of the medium and friction in the base on the configuration of plasticity zones and localization of deformation has been studied. Analytical estimates are made of the depths at which irreversible deformation develops, as well as their changes as a result of an increase in horizontal stresses. With the help of numerical simulation, the features of the origin and development of localized shear bands are shown. Schemes are constructed illustrating the nature of the development of localization bands depending on the properties of the medium.

The paper presents a new data inversion technique for the transient electromagnetic method (TEM) by converting the measured signals into the frequency domain. The inversion involves a search for such earth model parameters that there is a consistency between the synthetic and field data. We use an optimization method, where through numerical simulation at each iteration the synthetic data are determined in accordance with the changing model parameters. Numerical simulation of TEM signals is a computationally expensive procedure, since the time-domain signal is usually calculated via the inverse Fourier transform of the frequency signal. Consequently, compared to the frequency signal, the time needed to calculate the time signal increases hundreds of times. It is proposed to transform the measured signals into the frequency domain and perform inversion therein, which significantly reduces the time expenditures. Transition into the frequency domain by the Fourier transform includes the extraction of the primary field from the signal, calculated by means of a special algorithm. This fact makes it possible to employ for the transformation a relatively small time interval actually used in TEM instead of an infinite one.

Among a large number of geophysical well logging methods, the spontaneous potential (SP) logging is a most demanded one for studying geological sections, and is widely used in all drilled wells. This paper presents a brief review of the main studies on the enhancement of a theoretical model for the SP phenomenon, and on the creation of algorithms for numerical modeling of SP logging data. First of all, we discuss the studies that were conducted shortly after the discovery of the phenomenon and became fundamental in the field of SP method theory. Most of the first works were aimed at identifying the key factors that influence the shape and amplitude of SP signals. The research vector of these works contributed to the creation of interpretation charts, which are widely used even today. This review also analyses the main results of the more recent theoretical works aimed at developing a quantitative SP logging model that takes into account the petrophysical properties of the geological environment, and works related to numerical approaches for the modeling of well logging data. In addition, to demonstrate the effectiveness of modern computational methods, the paper presents an original algorithm based on the finite element method and utilizing a correct physical and mathematical model of the SP phenomenon. The proposed approach makes it possible to calculate SP signals in the intervals of clayed reservoirs, with consideration to their porosity, water saturation, as well as the type and content of clay minerals. Comparison of the SP modeling results and field logging data obtained from wells in Western Siberian fields shows a high quality of our theoretical model. The presented review of key works devoted to the theoretical description of the SP method, as well as modern numerical approaches for analysing SP logging curves in complex geological conditions, demonstrates the potential of the SP method for new areas of practical application.

The background for creating an electromagnetic soil sounding apparatus with receiving and transmitting antennas separated by a distance of up to 100 meters is considered in this paper. The temperature and frequency dependences of the complex dielectric permittivity of multilayer clay soil are studied in conjunction with the results of numerical simulation of ultra-wideband log-periodic antennas immersed in the soil to a depth of 1.5 m. The choice of a high-voltage generator and pulse receiver is studied, and a structure of apparatus prototype is given. Based on the results of oscillograms’ and signal spectra measurements with 30 m antennas separation, and with reference to the soil temperature, estimates of the possible limits of change in the electrophysical parameters of the clay soil at a geophysical site are provided. Conclusions are drawn about ways to improve the apparatus in order to create a new technology for transient electromagnetic monitoring of permafrost.

Time-frequency analysis of 40-hour seismic records of the temporary seismological network, performed using a systematic visual inspection of seismograms, spectrograms, and signal spectra in small time windows (from 30 s to 10 min), made it possible to identify several manifestations of volcanic seismicity in the Mutnovsky fumarole field area, as well as some non-volcanic signals. The former includes signals interpreted as a volcano-tectonic earthquake (only a single event was found), multiple swarms of hybrid and long-period earthquakes, as well as a stable (constant for 40 hours) microseismic signal likely related to the gas-hydrothermal activity of fumarole fields in the northeastern crater of the volcano. For specific stations of the network, the differences between simultaneously recorded signals were considered, an assessment was made of the influence of natural factors characteristic of the study area: hydrogeological and meteorological.

The article highlights the functionality of the W-SEIS software developed at the IPGG SB RAS, designed to interpret 2D/3D seismic and drilling data. The application consists of a set of interconnected modules and utilities, each of which can be used as an independent software product. W-SEIS is a cross-platform software, it is developed using a client-service architecture and has high performance and imposes minimal system requirements on computer equipment.

In the work, a comprehensive interpretation of seismic materials and drilling data was carried out, sets of structural maps and isopach maps of seismogeological complexes were constructed, which served as the basis for structural-tectonic analysis and study of the history of the formation of the Srednetyungsky uplift, which controls gas deposits in the Upper Permian and Lower Triassic deposits. It is concluded that in the relief of the base of the Triassic, the Middle Tyung uplift was formed in the Cretaceous as a result of an increase in tectonic activity in the territory of the entire Vilyui hemisyneclise.

In this paper, we consider an example of obtaining data similar to seismic surveys in the process of conducting physical modeling. It is shown that the features of the data are close to those observed in a real experiment. This is proof of the possibility of testing the processing methods used in the practice of seismic exploration on the data of laboratory modeling of seismic surveys. In particular, the application of a certain set of processing procedures for the considered data related to the simulated environmental object showed that the resulting time sections contain all the inherent structural features of the model.

TEM survey under objects that containing superparamagnetic particles, the effects of magnetic viscosity can have a significant impact on the received signal. At present, such effects of magnetic viscosity are considered a nuisance, while some researchers point out that they contain useful information.

The article presents a mathematical modeling of impulse response of viscous remanent magnetization. Using the lognormal particle distribution model, various impulse responses of the magnetization were modeled. The results of attempts to restore the distribution parameters  and   of model impulse responses are presented. An estimate of the effectiveness of the inversion of synthetic impulse responses is given.

Features and main conclusions of publications devoted to the study of medium transverse-isotropic geoelectric models which are characterized by inclination of the electrical anisotropy axis relative to a logging tool are reviewed in this article. Such models can be defined either by horizontal and vertical conductivities (or their reciprocals, called resistivities) with a non-zero dip of a logging tool or by the conductivity tensor with the tilt of the principal axes.