Reconstruction of seismotectonic deformations of Asia in different layers of the Earth’s crust

The calculation of seismotectonic deformations for different depth levels 1–15, 16–35, 36–70 km was performed according to the data of 1819 mechanisms of earthquake foci that occurred in Central Asia (φ = 25° – 60° N, λ=60° – 115° E) for the period from 1976 to the end of July 2020 with M>4.7. The orientation of the main axes of the strain tensor reconstructed from the mechanisms of earthquake foci with M>4.7 coincide at different depth levels with mainly submeridional and north-eastern shortening and varying elongation from sublatitude to north-western and near-vertical. The consistency of the orientation of the main axes of shortening and elongation reconstructed from seismological materials and from the published results of calculating GPS observations, is traced.

Determination of formation dip and strike from transient LWD electromagnetic measurements

An original method has been developed for estimating formation dip and strike from transient induction LWD data, based on focusing in the time domain. The focusing consists in decomposing the measured signals into a time series and diagonalizing the matrix of focused magnetic field components. We have implemented the method and comprehensively tested it in horizontally-layered media used for LWD data inversion to solve geosteering problems and evaluate the formation resistivity. Estimates of the angles contribute to reliable geosteering when choosing a direction of drilling, as well as when inverting data for a complex earth model. A significant reduction in the resource intensity of inversion and model equivalence is achieved by reducing the number of determined parameters.

Detection of records of weak local earthquakes using neural networks

Manual processing of large volumes of continuous observations produced by local seismic networks takes a lot of time, therefore, to solve this problem, automatic algorithms for detecting seismic events are used. Deterministic methods for solving the problem of detection, which do an excellent job of detecting intensive earthquakes, face critical problems when detecting weak seismic events (earthquakes). They are based on principles based on the calculation of energy, which causes multiple errors in detection: weak seismic events may not be detected, and high-amplitude noise may be mistakenly detected as an event. In our work, we propose a detection method capable of surpassing deterministic methods in detecting events on seismograms, successfully detecting a similar or more events with fewer false detections.

Lateral scanning logging while drilling data processing using convolutional neural networks

This article discusses a new approach to processing lateral scanning logging while drilling data based on a combination of three-dimensional numerical modeling and convolutional neural networks. We prepared dataset for training neural networks. Dataset contains realistic synthetic resistivity images and geoelectric layer boundary layouts, obtained based on true values of their spatial orientation parameters. Using convolutional neural networks two algorithms have been developed and programmatically implemented: suppression of random noise and detection of layer boundaries on the resistivity images. The developed algorithms allow fast and accurate processing of large amounts of data, while, due to the absence of full-connection layers in the neural networks’ architectures, it is possible to process resistivity images of arbitrary length.

Results of studying the azimuthal anisotropy of the paleozoic basement with vsp technique at the Bystrovka vibroseismic test site

At the Bystrovka vibroseismic test site (Novosibirsk region) 3-component refracted waves profiling was performed at three intersecting lines. Shear waves analysis made possible to detect anisotropy of the Paleozoic basement occurring at depth of about 10 m and to suggest symmetry elements of this medium along with their orientation. Compressional waves data were used to construct depth sections estimating head waves velocities. These velocities demonstrate significant variation in lines of different orientation. The results obtained agree with previously performed VSP.

Structural description and tectonic development history of the mesozoic deposits in the Vilyui hemisyneclise

We present the interpretation of 2D seismic data in the Vilyui hemisyneclise located in the Republic of Sakha (Yakutia). The model identifies structural and tectonic features and tectonic development history of the Mesozoic deposits in the Vilyui hemisyneclise. Structure contour maps for the reflecting horizons of the Mesozoic are qualitatively the same. Traced faults attenuate at various stratigraphic levels. The structures of the hemisyneclise are known to be formed during the Cretaceous stage of development.

Velocity models fitting for the seismic events location within the Baikal rift zone

Whereas the defined velocity model plays a key role in the process of seismic events localization, so selection of the model as much as possible corresponding to the real velocity conditions of the investigated area becomes a crucial task. Basing on the analyses of published results of the Lake Baikal area seismic study a layered P-waves models for two situations defined: For the high velocity consolidated rock on the lake banks and low velocity sediments up to 10 km thick under the lake bottom.

Overview of modern hardware and software for near surface electromagnetic sounding in the frequency domain

For the study of the first ten meters of the ground, instruments operating in the frequency domain are most widely used. The compactness, speed of operation, ease of operation of such equipment, as well as the quality of the information obtained, determine its applicability for solving a wide range of issues: from searching for local objects to identifying structural features of the upper part of the section. The article provides an overview of current hardware and software developments for near surface electromagnetic soundings in the frequency domain. A description of all types of non-contact equipment from major world manufacturers is given. The features of both the hardware itself and the approaches to their implementation are described. Methods of primary processing and data inversion are considered. Conclusions are drawn about the need to find new ways to eliminate of equipment deficiencies.

Criteria for petroleum potential and forecast of oil and gas prospective zones in the Achimov deposits of the Gydan Peninsula

The structure and seismogeological characteristics of the Achimov strata of the Gydan Peninsula are considered. Geological and geophysical criteria for the regional forecast of oil and gas potential, taking into account the clinoform structure of the Berriasian-Lower Aptian deposits, are proposed. Based on the interpretation of drilling data and 2D seismic exploration, predictive maps of the thickness of sand bodies were constructed, depocenters of accumulation of sandy material were mapped. Seismostratigraphic studies, which are based on a comprehensive analysis of the wave pattern of time seismic sections, dynamic and seismic facies analyzes, as well as paleotectonic and paleogeomorphological reconstructions, made it possible to identify the Salmanovskaya and Yuzhno-Gydanskaya oil and gas zones in the Achimov strata of the Gydan Peninsula.

Research of the microseismicity location algorithm

In this paper, we propose the algorithm for locating microseismic events by the method of directed summation of energy envelopes over a network of stations. The algorithm is based on a back projection technology, which allows visualizing the intensity of seismic emission by layer. A comparative stability and robustness analysis of the proposed method with the method using the semblance is carried out.