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17th International Conference on Geoinformatics - Theoretical and Applied Aspects
- Conference date: May 14-17, 2018
- Location: Kiev, Ukraine
- Published: 14 May 2018
41 - 60 of 125 results
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Study of the series of data of groundwater levels with passes
Authors M. Tymkiv, D. Kasiyanchuk, V. Danyliak and M. LevitskaSummaryOne of the main problems in working with these levels of groundwater is the incompleteness of the series. In this articl we consider the methods of filling the series of data of groundwater levels that have spaces. Correct filling of such series allows to characterize quantitatively the process of formation and change of hydrogeological conditions in time.
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Hydrodynamic regime of cave lakes and seismicity of Podillya (Ukraine)
Authors K. Bondar, M. Baryshnikova, A. Sachko, I. Tsiupa, V. Udovichenko and V. ApostolyukSummaryThe paper is devoted to the analysis of the series of water level monitoring observations in the Neogene gypsum startum of Podillya and to identification of the main factors determining the hydrodynamic regime of lakes in the caves of Mlynky and Ozerna. An attempt has been made to establish a connection between fluctuations in underground water levels with meteorological conditions on the surface and modern seismic activity.
For this purpose, the mathematical simulation of underground water level fluctuations was performed utilizing average daily air temperatures and precipitation, with subsequent comparison with the data of regime observations of water levels in cave lakes. Mapping of modern local earthquakes against the background of neotectonic activity and their spatial and temporal analysis was done.
The correlation of the simulated water level with actual measurements in the caves of Mlynky and Ozerna in the period from 2006 to 2014 and the difference in the period 2015–2017 is established. It was shown that a series of local earthquakes in 2012–2014 at the area of Mykulyntsi-Ternopil morphostructural-neotectonic node could have caused falling water content in the Neogene gypsum aquifer of Podillya in 2015–2017, as the seismic activity provoked opening of fractures in rocks and the absorption of water.
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On one integral criterion of reliability of geoinformation
Authors H.H. Guliyev, S.J. Akbarov, N. Yahnioglu and Y. SevdimaliyevSummaryA method of studying the problems of natural oscillation of a composite sphere is developed. Various variants of the composite sphere are studied considering preliminary deformation. The obtained results are necessary for further improvement of one of the integral criteria (periods of natural oscillations of the Earth caused by the strongest earthquakes) of the reliability of geoinformation.
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Modeling of filling process of the gas cap of geosoliton field
Authors M.V. Lubkov and O.O. LevchenkoSummaryOn the base of combined finite element — difference method, we carried out computer modeling of the filling process of gas cap of geosoliton field. According to obtained data analysis, filling process of the gas cap essentially depends on filtration parameters of considering porous reservoir, its size and characteristic fiches of the filling origins. Filling gas cap velocity mainly determined by origins power and less depends on their sizes and quantity. At the case of equal power origins, the filling gas cap velocity is proportional to the power of these origins. At the case, when different power origins act, the filling gas cap process passes irregularly. At the initial stages of filling process, excess pressure reservoir places closely correlate with origins installation. In the subsequent stages of filling, the pressure gradually aligns in all reservoir places and then regularly increases. As calculations show, regular filling of all gas cap region comes approximately over one hundred years since beginning of the process.
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Algorithm of modeling of acoustic monitoring of composite hierarchical inclusions
Authors O. Hachay, A. Khachay and O. KhachaySummaryA new method for modeling acoustic monitoring of a layered-block elastic medium with composite inclusions of various physical-mechanical hierarchical structures was developed. An iterative process for solving the direct problem is developed for the case of two hierarchical inclusions of l, m-ranks based on the use of 2D integro differential equations. The degree of hierarchy of inclusions is determined by the values of their ranks, which can be different. Hierarchical inclusions are located in different layers above each other: the upper is anomalously plastic, the second is anomalously dense. The degree of filling inclusions of each rank for all three hierarchical inclusions is different. The results of the simulation can be used to provide monitoring studies of the stability of the rock massif during its development by mass explosions followed by rocks laying.
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Difference between phase and group angles in ORT media
Authors A. Stovas, Y. Roganov and V. RoganovSummaryWe derive difference between phase and group angles in ORT media which is important for AVO/AVA problem. The difference between phase and group velocity vectors is also derived.
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Modeling of oil filtration processes in the vertically heterogeneous reservoirs
By M.V. LubkovSummaryOn the base of combined finite element - difference method, we carried out computer modeling of the oil filtration processes in the vertically heterogeneous reservoirs. According to obtained data analysis, the efficiency of reservoir oil production process in the three phase vertically heterogeneous medium (water, oil, gas) mainly depends on reservoir oil filtration parameters distributions, oil penetrating reservoir border conditions and essentially on the oil-saturated concentration reservoir places localization. Intensity of the oil producing process is defined by the area of decreasing oil reservoir pressure in the vicinity of acting bottomhole. The larger this area the more intensive oil producing process goes. Therefore the effectiveness of oil producing process in vertically heterogeneous oil accommodating reservoirs directly depends on accuracy of the oil-saturated concentrated places localization and respective installation of the acting bottomhole.
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The statistical simulation algorithm of random fields on the sphere by the aircraft magnetometry data
Authors Z. Vyzhva, V. Demidov and A. VyzhvaSummaryIt is proposed to apply statistical simulation methods of r of random field ealizations on the sphere, to solve the problems of conditional maps, adding of data to achieve the necessary precision, and other such problems in geophysics. The approximation theorems and built on their base algorithm of statistical simulation of Gaussian isotropic random fields on the sphere using the spectral representation was considered. Model example — the aircraft magnetometry data on the great area. It is divided into deterministic and random components for data analysis. The deterministic component is proposed to approximate by cubic splines and the stationary random component is proposed to modeling on the basis of spectral expansions of random fields on the sphere.
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Numerical modeling of hydraulic fracture permeability in viscoelastic rocks
By B.P. MaslovSummaryHydraulic fracturing to exploit hydrocarbons resources has been often used for the last decades. So it is very important to create computer models to simulate these very complex and practically useful phenomena. The new microstructural approach proposed to estimate permeability and to analyze the fluid transfer in porous isotropic nonlinear viscoelastic medium. Numerical Carson and Fast Fourier (FFT) integral transformations for the viscous effects estimation in zone of local stress concentration near grains and pores are used.
The analytical solutions and numerical algorithms for the prediction of viscoelastic creep and relaxation functions are proposed for the case of the multi-media with complex microstructure. Influence of the tri-axial stress state on the local parameters of creep deformations and effective permeability is evaluated. Deformation, permeability and fracture of natural geological materials such as limestone, granite, and soil are very influenced by the presence of micro-defects and porosity, which can cause inelastic effects even in purely hydrostatic load. A network of micro-cracks leads to low strength in the absence of external pressure, significant nonlinear elasticity, and sensitivity to the loading rate. Some examples of numerical modeling are presented. Permeability coefficients and fracture parameters obtained in laboratory experiments are compared with prediction results.
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Neural networks technologies in oil and gas well logging
By O. KarpenkoSummaryThe artificial neural network (ANNs) is an effective tool for making empirically grounded decisions in cases where either the mathematical model of the research object or the process theory is absent or underdeveloped. Every year there are increases the number of investigations on the use of ANNs technology in the oil and gas well logging. Application of ANNs technology in the well logging of complexly constructed, thin-layered sections is a very promising direction for increasing the efficiency of qualitative and quantitative interpretation of geophysical data. The main directions of the implementation of ANNs in the well logging are: 1. Creation the synthetic curve of the geophysical parameter, if it is absent for any reason among other geophysical data. 2. Evaluation of capacitive-filtration characteristics of rocks in a well section with the using of the created ANNs. 3. Detection the rocks-reservoir and determination of their saturation in the sections of wells on the basis of original algorithms using ANNs. 4. Improvement of the resolution of the curve of the geophysical parameter on the basis of the created model of ANNs.
The conservatism of traditional approaches to the interpretation of geophysical data restrains the wider use of neural networks in practice.
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New Approach to Estimation of Probability of Rare Extreme Events for the Case of Small Samples: Application to Seismic Zoning Problem
Authors V.F. Pisarenko and M.V. RodkinSummaryThe theory of extreme values is a correct way for study of probability of occurrence of rare largest events. We use the Generalized Pareto Distribution (GPD) and the General Extreme Value Distribution (GEV). The unknown parameters of these distributions can be determined from the empirical data using the maximal likelihood approach. However, this method is optimal only for the case of fairly large (N>200–300) samples. We used numerical modeling and revealed that for the case of a small samples, the method of quantile is preferable in using the GPD approach, and the statistical moments method is preferable when using the GEV approach. Three data sets characterizing the distribution of earthquakes in subduction zones, regions of intracontinental seismicity, and in the mid-oceanic ridge zones were compiled and the parameters of the corresponding GPD and GEV distributions were determined. To obtain the similar results in the scale of the general seismic zoning problem we suggest to use the local characteristics of intensity of earthquake flow and the b-value and to characterize the tail behavior from data for the much wider areas. The preliminary results are discussed.
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Low-frequency scattering on a half-space filled with periodical inclined elastic layers with the slip on boundaries
Authors Yu. Roganov and V. RoganovSummaryA low-frequency effective model has been developed for a medium with periodical inclined elastic layers with the slip between layers.The boundary conditions are determined for low-frequency scattering at the boundary between elastic half-space and a half-space filled with an effective medium. These conditions depend on the incline angle of the layers. Based on the boundary conditions linear systems of equations for the reflection and transmission coefficients were derived. The theory is illustrated by three examples of calculating the reflection and transmission coefficients.
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Some properties of imaginary vectors and opportunity of their use at interpretation of the MT-data in 3D-models
More LessSummaryImaginary vectors which are produced on an impedance surface with vector impedance identity for harmonious fields are considered. Basic formulas for their calculation are resulted at various physical types of model of environment, physical filling these sizes is discussed. The result of calculation of a field of imaginary vectors for characteristic model of geological structure is offered as an example of an opportunity of use of imaginary vectors for visualization of the MT-data.
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Elastic behavior of the structured geophysical media
More LessSummaryBy applying FEM numerical simulation, the limits of the applicability of analytical formulas to determine the elastic moduli of structured geophysical media have been verified.
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Acoustic 2D modeling to determine the influence of aspect ratio and pore orientation on the acoustic properties of the rock
Authors V. Khalimendik and I. I. VirshyloSummaryThis paper describes the study of the results of acoustic 2D modeling to determine the influence of the shape, aspect ratio and orientation of pores on the acoustic properties of the rock. The size of the model for acoustic modeling is set by the size of the acoustic probe. To implement the modeling procedure in the “Tesseral ” software package, the model dimension was scaled so that the 0.1 mm voids occupied one grid cell, i.e. increased 104 times. Presented results of calculation of three models of sandstone with homogeneous composition of voids filled with water. The first model is filled by discs with 1 mm diameter, the second and tritium — by cracks with 1 mm diameter and 10 mm length, it oriented along and, respectively, across the wave propagation. The result of 2D modeling demonstrates that the different shape and orientation of voids in the matrix of the geological environment have different effects on its acoustic properties. Especially noticeable is the difference between the voids round shape and elongated in the direction of the wave propagation. These geometries significantly reduce the acoustic properties of the simulated environment. The opposite trend is observed between the voids of circular shape and elongated across the direction of the wave.
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Impact of accuracy in data on the inversion of gravitational anomalies
More LessSummaryThe research is devoted to the influence of accuracy of data on gravitational inversion. The purpose of the work was to determine the conditions for true determination of the geometry of gravitational sources for anomalies with noise. The method was to perform the inversion of the values of acceleration of gravity from three bodies of model section for three layers in two-dimensional version. Novelty is related to the definition of the percentage limit for the approximation between initial and calculated anomalies for data with noise in apparent density. An analysis of the gravitational inversion is made for the mass displacement algorithm and the genetic method. The practical significance is to determine the errors in the gravity data that need to be given for precise inversion. The method is used to interpret gravity data on sulphide deposits from Canada’s Northwest Territories. The inversion result is close to the drilling data. Knowledge of the influence of errors on gravitational data allows performing more reliable evaluation of the cut by density distribution, which is important for geological, search and environmental tasks.
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Advanced features for the optimal gridding of high gradient gravity data
More LessSummaryPurpose. Geological organizations of Ukraine create digital data banks for surveys, including gravimetric ones. New standards for data processing involve the use of GIS and the means for creating digital maps of geophysical fields. The results of their digitization are ambiguous. The features of interpolation methods for different initial information are analyzed.
Design/Methodology/Approach. Interpolation of gravity field with different qualitative characteristics for 12 methods of gridding is made. Piecewise linear interpolation is applied. The smoothness of the curve is ensured by interpolating the nodes with arcs of circles (parabolas) and cubic curves, but the latter method is unsuitable for the exact approximation of the gradient field of gravity. Recommendations on the choice of parameters have been developed.
Findings. The choice of the optimal method of data interpolation determines the content of the digitization of isoline maps. Comparison of the results of the approximation of gravity data by different methods has shown that none of the methods approaches the exact solution. Methods are indicated that give acceptable accuracy and certain conditions for their action are given.
The complexities of preliminary processing of initial measurements, including adequate display of the observation grid, are studied, the criteria for their improvement are proved by optimizing the gridding parameters for a particular survey and use of the data controlled filtering. To obtain a meaningful solution, you need to clarify the nature of the input data, and for different physical parameters of the environment, you need to use different methods of the problem. Recommendations for the application of methods for generating digital maps of gravitational anomalies are developed.
Practical value/implications. These steps reduce by ~ 10–15% the uncertainty in solving inverse problems. To increase the contrast, linear convolution filters and non-linear filters should be used. Recommendations are applied to the technology of digitization of paper maps of isolines.
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Taking into account selection in search for connections of tidal forces with earthquakes
Authors A.M. Kazantsev and L.V. KazantsevaSummaryUsually, the search for possible connections of earthquakes with the Moon and the Sun is carried out using the available earthquake databases. Each database contains a sample of seismic events, the completeness of which for the whole Earth depends on both magnitudes and the hypocenters depth. It is extremely important to take into account the selectivity of each database in order to establish the real connections of earthquakes with the cosmic bodies.
There were analyzed some earthquake databases relative to the completeness of the presented events against the magnitudes and depths of the hypocenters. Examples of possible false conclusions on the connections of tidal forces with earthquakes, which are obtained without taking into account selection, are given.
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Interpolation techniques to visualize underground structures with high accuracy using fewer GPR data
Authors M. Özkan Okay and R. SametSummaryGround Penetrating Radar (GPR) is widely used to collect the data from near surface depth. GPR data allow the users to visualize and interpret the underground structures quickly and with high accuracy. The obtained accuracy depends on such data collection parameters as sampling rate, trace and profile intervals. In order to visualize the underground structure with high accuracy, the sampling rate should be selected high and the trace and profile intervals should be selected small. Due to the high sampling rate and small trace and profile intervals the size of the collected GPR data becomes bigger. However, collecting the big data will increase both cost and time loss. In this paper, a methodology and Mean interpolation technique are proposed to reduce the cost and time loss by decreasing the size of collected data as much as possible and to increase an accuracy of underground structures by applying the interpolation techniques to the collected raw data. The proposed Mean and standard Cubic and Linear interpolation techniques were implemented on real GPR data. The obtained results showed that the similarity ratio between original and interpolated GPR data is about 95–98%.
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Application of frequency-resonance method of remote sensing data processing for geothermal water accumulation searching and mapping
Authors S. Levashov, N. Yakymchuk, I. Korchagin, R.I. Kutas, D. Majcin and D. BozhezhaSummaryThe results of application of the frequency-resonance technology of remote sensing data processing within the search areas in Mongolia, Nevada (USA), Turkey and Ukraine are analyzed. Anomalous zones of the “thermal water” type have been found at all survey areas, which deserve of detailed study and drilling. The drilled geothermal wells in two surveyed areas in Turkey fell into the contours of the anomalous zones of the “thermal water” type, found within them. According to the vertical scanning data, the depths and thicknesses of the aquifers are determined, and the water temperature in them is estimated. For a more confident search for zones of accumulation of fresh (mineralized, geothermal) water, it is necessary to process remote sensing data at a scale of 1:10 000 and larger. The results of frequency-resonance processing of satellite images can be verified and refined by ground-based directprospecting geoelectric methods of FSPEF and VERS.
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