Journal articles on the topic 'Magnetotelluric prospecting Mathematical models'
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Dmitriev, V. I., and N. A. Mershchikova. "Mathematical models of marine magnetotelluric sounding." Computational Mathematics and Modeling 20, no. 2 (April 2009): 113–21. http://dx.doi.org/10.1007/s10598-009-9023-4.
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Ji, Yanju, Tingzhe Huang, Wanyu Huang, and Liangliang Rong. "Meshfree Method in Geophysical Electromagnetic Prospecting: The 2D Magnetotelluric Example." International Journal of Computational Methods 15, no. 02 (September 28, 2017): 1750084. http://dx.doi.org/10.1142/s0219876217500840.
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As an important supplement and development of traditional methods, the meshfree method has received a great deal of attention in the field of engineering calculation, and has been successfully used to solve many problems which traditional methods have difficulty in solving. However, the application of meshfree method is relatively less in the area of geophysics. In this paper, we apply the meshfree method to the numerical simulation of geophysical electromagnetic prospecting, taking the 2D magnetotelluric as an example and deduce the corresponding meshfree radial point interpolation method (RPIM) equivalent linear equations in detail. The high-efficiency and accurate solutions of large-scale sparse linear equations are solved by the quasi-minimal residual method based on Krylov subspace. The optimal values of the shape parameters are given by numerical experiments. The correctness of the meshfree method is verified by a layered model. The root mean square error of the calculation results is no more than 0.35%, its accuracy is superior to the finite element method. We also compare the meshfree solution with FEM solution by calculating an inclined vein body model, and the calculation results are in good agreement. A continuously changing fault model and undulating terrain model which traditional methods have difficulty in simulating are respectively calculated, the sectional profiles of the apparent resistivity accurately reflect the trend of the anomalies. The meshfree method does not require the complicated mesh generation, and the physical parameters are loaded at a series of points, thus it is especially suitable for the calculation of the complex geological models. With the rapid development of computational science, the meshfree techniques will certainly become a new robust numerical simulation method in geophysical electromagnetic prospecting.
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Lima, G. S., A. O. Souza, and G. I. Medina T. "COMPARATIVE STUDY OF DIFFERENT MODELS FOR CALCULATION OF DNI." Revista de Engenharia Térmica 17, no. 2 (December 28, 2018): 28. http://dx.doi.org/10.5380/reterm.v17i2.64127.
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For prospecting or design of Concentrating Solar Power (CSP) systems it is necessary to know the distribution of the Direct Normal Irradiance (DNI) of the region. However, due to the recurring operational problems of measuring instruments, the use of mathematical models estimating the local DNI can be a very useful tool. The objective of this work is to construct a mathematical model that is used in the calculation of the DNI using experimental data provided by the Laboratory of Tropical Environmental Variables (LAVAT/INPE). This model was compared with other mathematical models already present in the literature. The consideration of clean-sky was used, that is, the effects of cloudiness, among others, were neglected.
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Alekseev, Anatoly S., and Boris G. Mikhailenko. "Mathematical models of elastic wave processes in seismology and seismic prospecting: forward and inverse problems." Simulation Practice and Theory 7, no. 2 (April 1999): 125–51. http://dx.doi.org/10.1016/s0928-4869(98)00025-1.
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Moorkamp, M., A. Avdeeva, Ahmet T. Basokur, and Erhan Erdogan. "Inverting magnetotelluric data with distortion correction—stability, uniqueness and trade-off with model structure." Geophysical Journal International 222, no. 3 (June 4, 2020): 1620–38. http://dx.doi.org/10.1093/gji/ggaa278.
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SUMMARY Galvanic distortion of magnetotelluric (MT) data is a common effect that can impede the reliable imaging of subsurface structures. Recently, we presented an inversion approach that includes a mathematical description of the effect of galvanic distortion as inversion parameters and demonstrated its efficiency with real data. We now systematically investigate the stability of this inversion approach with respect to different inversion strategies, starting models and model parametrizations. We utilize a data set of 310 MT sites that were acquired for geothermal exploration. In addition to impedance tensor estimates over a broad frequency range, the data set also comprises transient electromagnetic measurements to determine near surface conductivity and estimates of distortion at each site. We therefore can compare our inversion approach to these distortion estimates and the resulting inversion models. Our experiments show that inversion with distortion correction produces stable results for various inversion strategies and for different starting models. Compared to inversions without distortion correction, we can reproduce the observed data better and reduce subsurface artefacts. In contrast, shifting the impedance curves at high frequencies to match the transient electromagnetic measurements reduces the misfit of the starting model, but does not have a strong impact on the final results. Thus our results suggest that including a description of distortion in the inversion is more efficient and should become a standard approach for MT inversion.
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Савин, Михаил, Mihail Savin, Юрий Израильский, and Yuriy Izrailsky. "New capabilities of Chetaev´s model." Solnechno-Zemnaya Fizika 2, no. 2 (June 17, 2016): 86–92. http://dx.doi.org/10.12737/13465.
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This paper considers anomalies in the magnetotelluric field in the Pc3 range of geomagnetic pulsations. We present experimental data on Pc3 field recording which show negative (from Earth’s surface to air) energy fluxes Sz<0 and reflection coefficients |Q|>1. Using the model of inhomogeneous plane wave (Chetaev’s model), we try to analytically interpret anomalies of energy fluxes. According to a mathematical experiment there are two three-layer models with both electrical and magnetic modes satisfying the condition |Qh|>1. Here we discuss a possibility of explaining observable effects within the framework of the resonance model inhomogeneous plane wave — layered medium.
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Joel, Piameu Kwagag, Owona Angue Marie Louise-Clotilde, Ngatchou Evariste, Njingti Nfor, Kue Petou Rokis Malquaire, and Njandjock Nouck Philippe. "Identification of Geothermal Reservoirs in South Cameroon from a Combined Landsat 8 and AMT Data." International Journal of Geophysics 2022 (February 14, 2022): 1–17. http://dx.doi.org/10.1155/2022/1324766.
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This geothermal source prospecting work is carried out in order to respond to the energy deficit affecting the populations of South Cameroon in particular. The study combines audio-magnetotelluric (AMT) and Landsat 8 data for the geolocation of reservoirs, as well as the geological and tectonic information. The processing of these data defined 5 profiles and led to two-dimensional models of resistivity sections for each profile. The interpretation of the data identified a highly conductive zone with a resistivity ranged 1–10 Ω·m at an estimated depth of 1200 m in the locality of Menve’ele. The Landsat 8 data collected in this area during the same period enabled the elaboration of temperature and lineament anomaly maps of the study area. High-temperature areas with high lineament predominance correlate better with areas of low resistivity. For example, Menve’ele (A1) has a surface temperature range of 20°C–30°C and a high density of lineaments. By correlating these results with those provided by previous authors, the Menve’ele locality may be the target of a potential geothermal reservoir. A 3D resistivity model is built to better understand the variations of resistivity and their depths. The geological and tectonic information of the region confirm the tectonic origin of the faults and lineaments as well as the predominance of metamorphic and sedimentary formations.
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Niwas, Sri, and M. Israil. "Computation of apparent resistivities using an exponential approximation of kernel functions." GEOPHYSICS 51, no. 8 (August 1986): 1594–602. http://dx.doi.org/10.1190/1.1442210.
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We present a fresh approach to the mathematical computation of apparent resistivities in electrical prospecting. The method is based on an exponential approximation of the kernel function which reduces the integral equation for the potential over a layered earth to a simple algebraic equation. The coefficients in the approximation are obtained using a least‐squares inversion technique. A single, unified matrix equation allows computation of apparent resistivity values for arbitrary four‐electrode arrays over a layered earth. The unified G function automatically reduces to that of a symmetrical four‐electrode array and dipole array function with the proper interelectrode separation. Computations for some two‐, three‐, and four‐layer earth models (Schlumberger configuration), along with a few Wenner and radial dipole apparent resistivity values, demonstrate the versatility of this unified equation.
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ISSENOV, S. M. "PROBLEM ISSUES AND WAYS TO INCREASE THE EFFICIENCY OF SEISMIC SURVEY." Neft i gaz 1, no. 121 (April 15, 2020): 52–68. http://dx.doi.org/10.37878/2708-0080/2021-1.04.
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The physical capabilities of seismic prospecting and the main factors limiting the scope of solving target geological problems of research at the stages of exploration and additional exploration of hydrocarbon deposits are considered. The efficiency of structural-tectonic and dynamic problems of seismic exploration to be solved depend on the degree of correspondence to the real structure of the geological section of the basic mathematical models of the applied methods and technologies of field seismic survey, processing and interpretation of seismic data. The reliability of predicting the material composition of sediments and physical parameters of hydrocarbon reservoirs is determined by the achieved quantitative Signal / Noise estimates and the vertical resolution of the seismic record. The ways of increasing the efficiency of seismic exploration are discussed, including the practical results of the application of Multifocusing technologies, which expand the range of geological problems to be solved.
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Gavryushin, Nikolay Yu, Pavel A. Dergachev, and Pavel A. Kurbatov. "The Mathematical Model of an Electrodynamic Geophone." Vestnik MEI 3, no. 3 (2021): 33–40. http://dx.doi.org/10.24160/1993-6982-2021-3-33-40.
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Electrodynamic geophones are applied in seismic prospecting, seismology and security systems. Devices with a similar design can be used as a generator in devices for energy storage, in active vibration control systems, and for detection of shallow-buried objects, including mines. To control the quality of geophones and verify the constancy of their characteristics during the manufacture, it is necessary to measure their frequency response on a shake table. The mathematical model of the geophone developed by JSC Scientific Research Engineering Institute (Balashikha, Moscow region) installed on a shake table is considered. The geophone schematic design is given, and the sequence of its operation is described. The approach of dividing an electromechanical system into several subsystems with subsequently uniting them into a resulting model is used for developing the geophone overall mathematical model. Detailed descriptions of the electrical, magnetic, and mechanical subsystems are presented. The assumptions used in compiling the overall mathematical model describing the geophone operation on the shake table are listed. A system of equations describing the interaction of the subsystems is compiled. Detailed descriptions of the resulting mathematical model, each of its element, and the interface included in its composition are presented. To estimate the developed mathematical model, the results obtained from the calculations on it are compared with the results from testing two experimental samples in the geophone operating frequency band from 10 to 100 Hz. For better clarity, the obtained results are compared in graphical form. The comparison has shown that the discrepancy between the results does not exceed 5% by the output signal amplitude. From the viewpoint of practical implementation, the developed mathematical model can be used in designing new geophones with other parameters, for example, with another natural frequency, or with a higher value of the output signal. It can also be used to develop more complex mathematical models containing a geophone. The accomplished study became a basis for elaborating a more complex mathematical model of a geophone with two natural frequencies in the operating band.
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Mollo Neto, Mario, Lucélia Maria Casagrande, Camila Pires Cremasco, and Luís Roberto Almeida Gabriel Filho. "Prospecting and modeling of primary energy production indicators in Brazil supported by graph theory." Research, Society and Development 10, no. 10 (August 16, 2021): e485101019199. http://dx.doi.org/10.33448/rsd-v10i10.19199.
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This research presents a study on the scenario of primary energy production in Brazil over the period from 1970 to 2018, as well as the main sources that contributed to the national energy matrix. To map trends in primary energy production, Social Network Analysis was applied. Also are presented the mathematical models that represent the variation in the centrality and density of primary energy production. Based on the results and the literature on the economy of Brazil in the period between the years 1970 to 2018, it discuss the movements carried out by public policymakers that culminated in a reduction of investments in the sector, even that demand would always be growing. However, it would continue to be linked to the results of small increases in GDP and HDI. Another result was the evolution and of oil as a non-renewable primary source offer for the entire period of the research. Was perceived the alternation of offers from non-renewable sources that, starting with the predominance of firewood, passing on to the generation of hydraulic energy, the most important for two decades, and the substitution by-products derived from sugarcane, which extends until the year 2018. It was also observed that in the period from 2010 to 2018, the share of supply from renewable primary sources, in percentage terms, it is no longer so distant from the share of offers from non-renewable primary sources, almost even dividing availability for the composition of the Brazilian matrix.
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Gruzdev, R., and I. Rylsky. "THE USE OF AIRBORNE LIDARS IN HIGH-PRECISION GRAVITY PROSPECTING (ON THE EXAMPLE OF EASTERN TRANSBAIKALIA)." TRANSBAIKAL STATE UNIVERSITY JOURNAL 28, no. 2 (2022): 6–18. http://dx.doi.org/10.21209/2227-9245-2022-28-2-6-18.
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In the production of high-precision gravimetric studies at ore deposits, an important factor is the methodical correctness of the work, which directly affects the subsequent costs and life cycle of a geological exploration enterprise. It is known, that gravimetric survey, in addition to the actual stage of measurements on the ground, includes the stage of eliminating errors introduced into the measurements by external fields and objects, in particular, the terrain. Methods existing and adopted at the state level involve the use of materials from cartographic funds (topographic maps at a scale of 1:100,000 - 1:25,000 and larger). It is also allowed to use open (free) terrain models. These materials are distinguished by a common characteristic feature - the lack of detail in thedisplay of the microrelief and steep inclined surfaces (slopes, walls, faults, incisions). These elements have a significant effect on the field values, measured by gravimeters, especially when measurements, are taken at points located at a small distance from the specified forms. In addition, the existing methods do not involve calculations using digital elevation models built from initial data with a high density of elevations (with a step of a few meters or more). All this creates the prerequisites for an insufficiently complete consideration of corrections in gravimetric measurements. At the same time, the technical capabilities of modern aviation remote sensing equipment make it possible to quickly obtain a high-precision digital model of the terrain over large areas. The most accurate, versatile and promising technology in this respect is the method of airborne laser (lidar) scanning. In this paper, the authors consider a methodology for performing work using both airborne laser scanning of the relief and other types of data (topographic maps 1:25,000, open data models). As part of the research, calculations were also made of the final corrections for the influence of the terrain and a comparison of the results obtained with each other. With the help of mathematical modeling and cartographic algebra, matrices (grids) of design parameters were constructed. The results of the study are clearly demonstrated in diagrams and diagrams, substantiating and illustrating the high information content of the study
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Murzina, E. V., A. V. Pospeev, I. K. Seminskiy, I. V. Buddo, D. B. Nemtseva, V. S. Emelianov, and Y. A. Agafonov. "Features of high-density transient electromagnetic sounding data inversion under oil and gas prospecting in the Nepa-Botuoba anteclise area." Earth sciences and subsoil use 45, no. 2 (July 2, 2022): 137–51. http://dx.doi.org/10.21285/2686-9993-2022-45-2-137-151.
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The data of near-field transient electromagnetic sounding, which are widely used for the purposes of oil and gas exploration within the Nepa-Botuoba anteclise, are typically interpreted in terms of quasi-horizontally-layered models of media. The purpose of this study is to develop an approach to the inversion of transient electromagnetic sounding curves obtained via high-density 3D observation networks. The study was based on mathematical modeling, whose results allowed to estimate the lateral spatial parameters of a non-stationary electromagnetic field as well as to understand the differences between the results of one-dimensional inversion of the transient electromagnetic sounding data and the true parameters of the target horizon. As a result, the characteristic of the electromagnetic field described by an exponential function and used in the lateral-constraint inversion of high-density electromagnetic sounding was obtained. The proposed approach was tested on the practical data within the site under investigation located on the slope of the Nepa-Botuobа anteclise. It is shown that the use of spatial discrepancy under TEM sounding data inversion makes it possible to obtain geoelectric models characterized by lateral consistency of section geoelectric parameters. The application of the spatial stacking-based approach in the inversion process allows to increase the solution stability of the inverse problem of the near-field TEM sounding data.
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CHANG, Chi, and Viktor M. ZAERNYUK. "Gold production in the Russian Federation: The analysis and forecast." National Interests: Priorities and Security 17, no. 7 (July 15, 2021): 1326–43. http://dx.doi.org/10.24891/ni.17.7.1326.
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Subject. The article discusses possible lines for improving the methodological framework of the long-term economic forecast of gold production in the Russian Federation, relying upon the mathematical apparatus of econometric models. Objectives. We devise an economic-mathematical model for predicting the gold production with respect to the specifics of the economic development in Russia’s gold mining industry. Methods. The study is based in the correlation and regression methods for analyzing publicly available statistical data on the gold market. The least square method is taken as the methodological approach to designing the economic-mathematical model for forecasting. Results. Each gold deposit is found to be distinctive, having its own qualities, which seriously differ from those of other gold deposit. As a result of the analysis, we discovered key factors, which significantly influence the gold production, such as demand and price for gold, the amount and quality of geological reserves of gold, the amount of investment to be made in geological prospecting, national exchange rate and key rate of the Bank of Russia. We substantiated the use of the linear three-factor model, which involves gold production volumes in Russia, demand for gold, national exchange rate and price for gold as regressors. According to our estimates, in the Russian Federation, gold production will have reached 370–380 tons by 2025. Conclusions. Based on the least square method, the structural forecast apparatus does not account for geological and geographic-economic distinctions of gold deposits due to their unique nature. Therefore, determining regressors for the model, we predominantly focuses on open access data.
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Velasco, Maria Soledad, David Alumbaugh, and Emmanuel Schnetzler. "Multiphysics data modeling and imaging for exploration in the southern Rocky Mountains." Interpretation 6, no. 3 (August 1, 2018): SG59—SG78. http://dx.doi.org/10.1190/int-2017-0215.1.
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We carried out a multidata geophysics study in southern Colorado to explore for [Formula: see text] reservoirs in an area where seismic imaging is very limited due to the mountainous terrain, the presence of high-velocity volcanic rocks, and difficulty in obtaining land access permits. We have developed a modeling/interpretation methodology using ground magnetotelluric data as well as airborne magnetic and electromagnetic data combined with public domain gravity data and existing well and seismic data. We used the integration of these data sets to produce a series of 2D and 3D geophysical models that reveal basin architecture previously poorly defined through the analysis of limited seismic and well data alone. We found that this type of analysis aids in decreasing uncertainty in the interpreted geologic cross sections and a better understanding of the structural complexities of the region. Through the application of machine learning methods, we are also able to integrate several data sets into a mathematical framework resulting in a predictive model of spatial [Formula: see text] distribution. The integration of the interpretations from all data sets, predictive analytics results, and knowledge of [Formula: see text] production, allows us to delineate areas of interest for further exploration.
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Sarpong, F., M. T. Rashid, J. Owusu-Kwarteng, and C. Zhou. "Energy consumption and thermal properties of drying banana (musa ssp) under varied relative humidity." Ghana Journal of Agricultural Science 56, no. 2 (December 31, 2021): 22–33. http://dx.doi.org/10.4314/gjas.v56i2.3.
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The drying of banana slices was investigated under different relative humidity (RH) in a convective hot-air dryer. The experiments were conducted using 10, 20, 30 and 40% RH, 75oC and 2.0 m/s air velocity drying conditions. Drying kinetics, energy consumption and thermal properties were investigated. Eight mathematical models describing thin layer drying were employed and results were compared to their goodness of fit in terms of coefficient of correlation (R2), the root mean square error (RMSE) and the reduced chi square (χ2). The Midilli–Kucuk model could satisfactorily describe RH-convective drying of banana slices with R2, RMSE and χ2 in the ranges of 0.99947-0.99986, 0.00002-0.00008, and 0.0142-0.01618 respectively. For energy consumption, RH condition increased the energy consumption such that at every 10% increase in RH, a range of 17.9-41.0% increase in energy consumption was observed. In the case of thermal properties, endothermic peak revealed precise composition, fine particle size, and dispersion in a matrix of banana slices thus altering the transition in solid state. In effect, RH drying present new drying concept with prospecting thermodynamics absorbing properties. However, energy consumption issue needs to be addressed in further research.
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Issayeva, Lyudmila, Kuanysh Togizov, Agata Duczmal-Czernikiewicz, Madina Kurmangazhina, and Daulet Muratkhanov. "Ore-controlling factors as the basis for singling out the prospective areas within the Syrymbet rare-metal deposit, Northern Kazakhstan." Mining of Mineral Deposits 16, no. 2 (June 30, 2022): 14–21. http://dx.doi.org/10.33271/mining16.02.014.
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Purpose is prediction of the prospective areas within the Syrymbet deposit basing on the systematization and complementing of the ore-controlling factors of ore localization and predictive-prospecting criteria. Methods. The methodology of carrying out the research in terms of the indicated problem involves complex application of empiric, theoretical, and logical techniques of a general-purpose method of scientific knowledge. To model the ore bodies and distribution of ore content in them in the 3D format, the computer modelling (GIS-Micromine) methods were used; 2D modelling of a temperature field of the ore-bearing Syrymbet mass involved methods of mathematical modelling (Maple 10). The main conclusions were drawn by means of analysis and synthesis of the results obtained by the indicated methods. Findings.. The ore-controlling factors of the localization of rare metal ores were systematized and complemented by synthesizing the results of the analysis of 3D models of the deposit under consideration with the visualization of ore component contents within the ore bodies and their 2D sections in terms of the survey profiles where spatial distribution of tin content in the vertical section of this deposit was obtained. The factors were also updated by analyzing the thermodynamic conditions of the formation of ore stockworks where temperature conditions of the enclosing media in the area of ore formation were considered along with the intervals of the ore deposition temperatures. Originality. The results of scientific studies (computer and mathematical modelling) based on the empiric geological data helped solve not only the problems of ore formation theory but also the practical tasks concerning the improvement of methods for predicting the prospective areas within the deposit. Practical implications. The methodology of scientific study dealing with systematization of ore-controlling factors can be also used for other endogenous ore objects.
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Vladimir, Filatov. "Evaluating tectonic dislocations formation under the action of stresses at the Upper Kama potassium salt deposits." Izvestiya vysshikh uchebnykh zavedenii. Gornyi zhurnal, no. 2 (April 20, 2022): 57–67. http://dx.doi.org/10.21440/0536-1028-2022-2-57-67.
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Introduction. The studies of the tectonic structure, dynamic behavior and prediction of the areas of the most probable manifestation of hazardous dynamic events at the Upper Kama potassium salt deposits (VKMKS) revealed that active faults, nodal structures, fracture zones and individual fractures in the oversalt, salt and subsalt rocks exercise a decisive influence on the violation of the steady state of geological structure. The regional stress field and a large number of local factors caused by folding, basement tectonics (catagenetic and supergene leaching), exogenous (weathering and unloading) and endogenous (halokinesis) processes in the oversalt strata, the growth of dome structures, etc. cause tectonic dislocations in the VKMKS. Cracks and fissure zones have currently been incidentally mapped and quantitatively studied mainly in mine workings in the productive part of the deposit, to a lesser extent in the oversalt rock, and scarcely in subsalt deposits. A detailed high-precision gravity prospecting along with other geophysical methods is currently the only effective method for tectonic dislocations mapping in the rock mass of the VKMKS. Methods for the widespread and systematic mapping of tectonic dislocations both in plan and in section within the VKMKS have not been developed yet. However, the evaluation of kinematic tectonic dislocations development in bulk can be obtained to some extent by analyzing the qualitative and quantitative characteristics of the natural stress field. It is due to the fact that dislocations are formed only when the acting stress exceeds the limit of the corresponding longterm strength of rocks forming the object under study. Methods of research. Tectonic dislocations of various kinematic types are formed under the action of stresses. Kinematic dislocations depend on the relationships between the stress principal values. Therefore, to solve the problem of kinematic type in the Solikamsk depression (SD) and VKMKS, the data of natural stress field components measurement in Ural mine workings were analyzed, the regularities of its behavior in plan and depth were determined, which served as the basis for two mathematical models, regional and local. Research results. Mathematical modeling was carried out, giving a quantification of stress components behavior regularities with the depth for the tectonic and physical-geological conditions of SD and VKMKS. Conclusions. The data on the change in stress components, obtained from mathematical modeling for two models of the geological environment, made it possible to predict the regularities in formation of tectonic dislocations of various kinematic types at different depths in SD and VKMKS at the regional and detailed scale levels.
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Ageenkov, E. V., A. A. Sitnikov, and E. N. Vodneva. "Results of Mathematical Simulation of Transient Processes for the Sea Shelf Conditions." Russian Geology and Geophysics 63, no. 7 (July 1, 2022): 802–15. http://dx.doi.org/10.2113/rgg20204260.
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Abstract —Electrical exploration measurements in water areas and on land are carried out to study the electromagnetic (EM) properties of geological formations. A distinctive feature of aquatic electrical exploration is associated with the specific influence of a water column. Numerical calculations of the EM signal of the transient process for electrical lines in the axial region of the source under the conditions of marine waters with a depth of 50 to 250 m are presented in order to demonstrate how an induced polarization (IP) signal manifests itself in a transient process signal on different setups, to identify differences in the manifestation of galvanic induced polarization (GIP) and induction-induced polarization (IIP) in a transient process signal, and to substantiate these differences. The influence of the setup dimensions on the manifestation of IP during a transient process is studied by analyzing a change in the transient signal (ΔU(t)), the final difference of the transient process signal (Δ2U(t)) and transform P1(t) (ratio of these values) for a horizontal electrical setup with a source (AB) 50 to 2000 m in length, a three-electrode measuring line (M1M2M3) 50 to 2000 m in length, a distance between the source centers and the measuring line M1M3 (spacing, r) from 100 to 4000 m. Some of these parameters are used in differential-normalized electrical prospecting (DNME). The comparison of ΔU(t) and Δ2U(t) and their transforms in conducting and conducting-polarizable models under the same conditions is performed. The setup is placed on the surface and inside a conducting medium (a sea shelf water column) with a conducting polarizable base (geologic medium (ground) covered with a water layer). The polarizability of the base is taken into account by introducing a frequency-dependent resistivity using the Cole—Cole equation. It is shown by the calculations performed that the transient process components associated with the formation of an EM field and with GIP and IIP manifest themselves in dissimilar ways on differently sized setups at various depths. In a water area, IP manifests itself in two ways, being associated with both galvanic and eddy currents. In previous practical measurements, IIP was considered to be associated with interference, but this signal is simulated and can be regarded as information about IP. The factor influencing the IP manifestation in a transient process signal is a reduced setup height (hΔ), i.e., a distance between a setup and a sea bottom (polarizable base of the model) attributed to the AB line. Depending on the reduced setup height, the IP signal in transform P1(t) can manifest itself as an ascending branch at later times or appear as a descending branch passing into the negative values of P1. The pulse impact duration and the transient process measurements affect the contrasting manifestation of the polarizable base in the signal, but the measurements performed when the setup is being towed impose certain restrictions. The optimal parameters of the EM survey for IP studies should ensure a sufficient polarization range and the proper quality of measurements. The software used in the calculations was developed by OOO Sibirskaya Geofizicheskaya Nauchno-Proizvodstvennaya Kompaniya.
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Dimola, Nunzio, Alessandro Coclite, Giuseppe Fanizza, and Tiziano Politi. "Bond-based peridynamics, a survey prospecting nonlocal theories of fluid-dynamics." Advances in Continuous and Discrete Models 2022, no. 1 (October 23, 2022). http://dx.doi.org/10.1186/s13662-022-03732-6.
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AbstractPeridynamic (PD) theories have become widespread in various research areas due to the ability of modeling discontinuity formation and evolution in materials. Bond-based peridynamics (BB-PD), notwithstanding some modeling limitations, is widely employed in numerical simulations due to its easy implementation combined with physical intuitiveness and stability. In this paper, we review and investigate several aspects of bond-based peridynamic models. We present a detailed description of peridynamics theory, applications, and numerical models. We display the employed BB-PD integral kernels together with their differences and commonalities; then we discuss some consequences of their mathematical structure. We critically analyze and comment on the kinematic role of nonlocality, the relation between kernel structure and material impenetrability, and the role of PD kernel nonlinearity in crack formation prediction. Finally, we propose and present the idea of extending BB-PD to fluids in the framework of fading memory material, drawing some perspectives for a deeper and more comprehensive understanding of the peridynamics in fluids.
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M. Giudici and L. Alfano. "Comparison between geoelectric and electromagnetic sounding responses in volcanic areas." Annals of Geophysics 40, no. 2 (March 18, 1997). http://dx.doi.org/10.4401/ag-3911.
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The structure of active and inactive volcanoes can be explored with electric and electromagnetic surveys. We test the actual applicability of prospecting methods that employ both stationary and time-varying fields, using mathematical models both for layered and complex structures. The geometry and the resistivities of the geological structures which are considered have been taken from real case studies reported in the literature. In particular we analyse the sensitivity of different methods to conductive and resistant bodies.
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"Mathematical modeling of the acoustic and elastic anisotropy of the shale reservoir rocks of the Dnipro-Donetsk depression." Visnyk of V. N. Karazin Kharkiv National University, series "Geology. Geography. Ecology", no. 50 (2019). http://dx.doi.org/10.26565/2410-7360-2019-50-03.
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The purpose of the work is to analyze the parameters of elastic and acoustic anisotropy in the study of a multicomponent reservoir rock model, which is represented by shale. Research theory To solve this problem, the methods of conditional moment functions using the Mori-Tanaka calculation scheme, as well as the ordinary least squares were used. The technique of effective elastic invariables mathematical modelling of unconventional shale reservoir rocks has been developed. Justification of the mathematical model Eight varieties of mathematical models that characterize the mineral composition, the structure of the void space and elastic properties that are characteristic for shale reservoir rocks of the Dnipro-Donetsk depression in Ukraine were substantiated and developed. The models are based on previous publications by the authors and the results of petrographic studies at the Institute of Geology. Results The authors for the first time carried out an analysis of elastic constant rock models, acoustic tensor components, linearity and shale parameters, isolines stereo projections of index surfaces of nine elastic anisotropy parameters, as well as Thomsen parameters. Acoustic data can be used to trace the change in the structure of the reservoir rock void space, the concentration of rock-forming minerals in the rock. Fracturing has a greater effect on rock structure than granular voids and mineral structure. The orientation of inclusions has the greatest influence on the coefficient of acoustic anisotropy, anisotropy coefficients in rocks, where the voids are oriented in the plane perpendicular to the borehole axis have the largest values (more than 20%). When calculating the Thomsen parameters, the parameters of elastic anisotropy were obtained. They characterize not only the mineral composition of the rocks but also the qualitative structure of the void space, the orientation of minerals and voids in the rocks. Thomsen parameters correlate with acoustic anisotropy parameters for shale reservoir models. The parameters of acoustic and elastic anisotropy are indicators in the studies of similar-type rocks with different types of mineral inclusions and the structure of the void space. The mathematical modelling of elastic and acoustic parameters which characterizes their anisotropy and was carried out by the authors is an important step in substantiating mathematical models of shale reservoir rocks. Such models can be used in the interpretation of geophysical data (seismic surveys and well logging) to make corrections for elastic anisotropy in prospecting and exploration of oil, gas and water saturated unconventional shale reservoir rocks of complex structure, and also to compile a database of mathematical models of reservoir rocks in the given region.
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Blatter, Daniel, Matthias Morzfeld, Kerry Key, and Steven Constable. "Uncertainty quantification for regularized inversion of electromagnetic geophysical data. Part II: Application in 1D and 2D problems." Geophysical Journal International, June 27, 2022. http://dx.doi.org/10.1093/gji/ggac242.
Full textAbstract:
Summary This paper is Part II of a two-part series on a mathematical and computational framework for computing a meaningful uncertainty quantification (UQ) for regularized inversions of electromagnetic data. In Part I, we explained the theory behind a sampling algorithm, which we call RTO-TKO, and in Part II, we showcase RTO-TKO in practice. We individually and jointly invert seafloor magnetotelluric (MT) and surface-towed controlled source electromagnetic field data, collected for imaging offshore freshened groundwater beneath the US Atlantic margin. We also invert seafloor MT data collected for subsalt imaging to produce 2D resistivity models and uncertainty estimates that characterize the salt body geometry and surrounding sediments. We compare the UQ of the RTO-TKO with results from trans-dimensional sampling, and explain the differences arising from different underlying (prior) assumptions of the two algorithms. We also discuss the practical implications of these findings. Most importantly, however, the 2D case study unambiguously demonstrates the computational advantages of RTO-TKO and its ability to make use of massive parallelism.
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"On the Issue of Research of Information Support of Sustainable Agricultural Landscapes Formation." Man and Environment. Issues of Neoecology, no. 34 (2020). http://dx.doi.org/10.26565/1992-4224-2020-34-18.
Full textAbstract:
Purpose. To characterize the methodological approaches that we develop in the formation of a system of information support for the creation and maintenance of the functioning of modern sustainable agricultural landscapes and to show the results of their implementation on the example of the territory of some agricultural enterprises of the Kharkiv region. Methods. Cartographic, geoinformation analysis, calculation, statistical and mathematical. Results. Some results of the work of the collective on the issues of information support for the creation and maintenance of the functioning of modern sustainable agricultural landscapes. Namely, verification of erosion models, studies of the functionality of shelter belts, the formation of an agroeconet (an extensive network of natural and quasi-natural landscapes) on agricultural land massifs, which ensures the maintenance of stable functioning of meso and macrolevel agrolandscapes, as well as the experience of using magnetic prospecting methods to verify the results of mathematical modeling of erosion processes. Conclusions. A number of methodological approaches to information support of the formation of sustainable agricultural landscapes in the natural and socio-economic conditions of Ukraine have been developed. They relate to the functioning of anti-erosion measures of permanent action, the processes of modern transformation of agro-landscapes, the ecological impact of erosion processes on the environment. The connection between the length of forest belts per unit of arable land and soil erosion is shown. A methodical approach has been developed to estimate the amount of soil washed away from arable land and to calculate the measures necessary to eliminate its harmful effects on the environment.