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6th Congress of the Balkan Geophysical Society
- Conference date: 03 Oct 2011 - 06 Oct 2011
- Location: Budapest, Hungary
- Published: 03 October 2011
141 - 158 of 158 results
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Integration of Geophysical Studies at the Tirana-Durres-Kavaja Region, Albania with Technology GIS
Authors F.V. Vinçani, P.L. Leka, P.K. Kosho and F.D. DaraDuring a period of 20 years in the region of Tirana-Durres-Kavaja (TDK), many geophysical studies have been carried out with Electrometric, Magnetometric, Gravimetric and Radiometric methods, with numerous data both in area and depth. Important place in these studies has taken Electrometry, mainly the method of resistivity. Results obtained in the most important regions of our country as Tirana, Durres and Kavaja provide the supporting basis for all infrastructure projects and major works. Diverse thematic and tasks that have been resolved belong to scientific-research issues: Geology, Environmental Geology, Engineering Geology, Hydrogeology, Minerals, and Quaternary Geology. To standardize the information collected over the years, to coordinate and to annex it to any other type of support information for further processing and reinterpretations, it is necessary to use technology GIS (International Geographical System) in order to integrate them.
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Investigation of Fractures Hydrodynamics by Reconstructing the Rock Surface using Image Processing
Authors A. Rabbani and S. JamshidiFractures are the vital arteries of the reservoir. In the low permeability formations such as tight carbonates and shale gases, fracture conductance plays an undeniable role. In the present study a computational method in rock surface reconstruction has been presented in order to consider the effect of rock roughness in the fracture permeability. Using magnified digital images of rock surface and a written code in MATLAB® software leads to present a reconstruction of the rock surface which is noticeably similar to initial digital two dimension images. This modeled surface can be related to rock roughness especially in the cases such as fractures which the reservoir fluid is macroscopically flowing on the rock surface. Finally, a comparison has been presented between the smoothed surface fractures, reconstructed surface beside correlations and the sinusoidal roughness surfaces.
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„Baron Eötvös’ Pendulum Measurements” in the National Geoarchive of Hungary
Authors É. Zsadányi and G.P. KovácsThis paper presents an overview of torsion balance measurements carried out on the territory of Hungary, based on the technical reports, maps, and other documents stored in the Hungarian national geoarchive. Roland Eötvös’ torsion balance was mostly used for mineral exploration, but the data are also used for geodetic purposes. The latest report on torsion balance survey delivered to the Archive up to now was completed in 2009; it also set the aim of investigating geoid features.
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Random Seismic Noise Attenuation using the Wavelet Transform
Authors S. Ouadfeul, L. Aliouane and S. EladjIn this paper we propose a technique of random noise attenuation from seismic data using the discrete and continuous wavelet transforms, firstly the discrete wavelet transform (DWT) is applied to denoise seismic data. This last is based on the threshold method applied at the modulus of the DWT. After we calculate the continuous wavelet transform of the denoised seismic seismogram, the final denoised seismic seismogram is the modulus of the continuous wavelet transform at the low scale. Application at a synthetic seismic seismogram shows the robustness of the proposed tool for random noises attenuation. We have applied this idea at a real seismic data of a vertical seismic profile realized in Algeria. Keywords: Seismic data, denoising, DWT, CWT, random noise.
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Enrichment of Data Quality by Using Check-shot and Sonic Log Data in Seismic Reflection Surveys
Authors M. Cetinkaya and A.I. KanliIn this study, sonic log and check-shot data were correlated eachother recorded from an oil well in the investigated area and there is a good correlation observed. Two important formations were discerned from the time values of the check-shot velocities of well-1 correlated with the surface seismic section. Aim of the study is to investigate and to determine the real depths and velocities of formations of the oil well by using correlated results between the check-shot data and sonic log data with the seismic reflection section.
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End of an Era
By D.E. FreedAcquisition of field seismic data has been burdened by the use of cables since its inception nearly 100 years ago. We have struggled with the design, manufacture, deployment, maintenance and limitations they impose on us from the beginning. It is time for us to consider relegating cables to the past.
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A Procedure to Improve Low Frequency Content of a Seismic Trace by Side Lobe Reduction
Authors H. Karsli and D. DondururIn a seismic trace the location of a reflector is indicated by a reflection wavelet which consists of a main lobe, surrounded by side lobes which add no extra information. Side lobes are result from the lack of the low frequency content in a reflection wavelet. The aim of the study is to reduce side lobes by using the complex trace envelope and thus improve low frequency content of a seismic trace. The method is based on comparing the energies in the reflection events in a seismic trace. The energies are calculated by summation and subtraction of the seismic trace with its envelope trace and thus a polarity table from proportion of these energies is obtained. The resulting polarity table is multiplied to the envelope trace and the result is an envelope trace that has positive valued reflection events and negative valued reflection events in agreement with the corresponding reflection coefficient. The result is that the main lobe in the seismic trace is increased whereas the side lobes are diminished. Tests are done on synthetic and real data. Consequently, low frequency content is improved and it may be stated that resolution and interpretability of the seismic data are increased.
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Short History of Technological Development in Geophysical Surveys & Processing in INA E&P
Authors N. Kovačić, K. Pejić and T. RužićSince establishing of E&P in 1952, exploration works have been carried out constantly, firstly throughout Croatia & the neighbouring countries and in the later years worldwide. INA has started with its data processing in 1968 applying digital processing. From 1969 the processing was performed on the TIAC/TIDAR computer having memory capacity of 4K. At the same time the GSI software package was used. The new UNIVAC 1110 computer and Geocom software packages were purchased in 1974. Those tools were used until 1981 when they were replaced by UNIVAC 1170 computers and Digitech software packages. To be in line with fast IT development, INA purchased the IBM computer with 4341 RAID processor and software package manufactured by Western Geophysical in 1984. Then, the new IBM RISC computer and Western Geophysical’s Omega software package were in use from 1994. To extend its processing data capacities INA purchased the new computer manufactured by Silicon Graphics in 1997. The extra memory was added to it in 2001 and 2004. Finally, the Xeon CPU model (HDD – 20 TB, RAM – 88 GB) was purchased in 2007. The Omega software package has remained in use, currently in its improved 2009 version (OMEGA2).
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Easy Control of the Transition Band Width in Hyperbolic Tangent Filters by a New Parameterization
By A.T. BasokurA new parameterization of the hyperbolic tangent function is suggested for easy control of the width of the transition region between the limiting values of -1 and 1. The hyperbolic tangent function approaches the signum function as the suggested half-width parameter approaches zero. This permits definition of the rectangular function as the limiting case of a combination of two shifted hyperbolic tangent functions. Since all types of ideal frequency selective filters are derived from the combination of some rectangular functions, the hyperbolic tangent window can also be used for the same purpose. The suggested filters are continuities in the whole space and provide an opportunity for easy control of the width of the passband, transition band and stopband through adjustment of the half-width parameter. The formulation and examples are provided for low-, band-, high-pass, and band-stopping two-dimensional filters. However, the results can easily be generalized for any type of frequency selective filter.
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Seismic modelling and AVA Analysis of Hydrocarbon Traps
Authors N. Ocakoglu and R.F. GomezSeismic data can be used in hydrocarbon exploration both to observe the hydrocarbon indicators (HCI’s) such as bright spot, flat spot, dim spot and bottom simulating reflector (BSR) and to identify hydrocarbon traps in the geological structure. This involved modelling and computing synthetic seismograms. In this study, forward seismic modelling of three hydrocarbon traps were performed by ray tracing method to produce synthetic seismograms and to identify the HCI’s. Additionally, Amplitude-versus-angle (AVA) curves of each HCI’s was calculated to indicate how the reflection coefficients change with the density and the P and S wave velocities of each layer such as oil, gas, gas hydrate or water saturated sediments. Modelling results show that hight reflection amplitudes in sediment/gas, sediment/oil contacts and in gas hydrate saturated sediments such as bright spots and BSR horizon. Additionally, gas/oil and oil/water contacts are well defined as flat spots in the seismograms. Due to AVA responses of these contacts, AVA curve of sediment/gas contact shows the most particular change in amplitudes with increasing incident angle of seismic wave.
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Using Feature Extraction Techniques to Construct New Meta-attributes from Seismic
Authors S. Hemmatpour, M. Mirani Taradeh, M. Aliyari Shoorehdeli and H. HashemiDetecting gas chimneys is the focus of this paper. This can be achieved using a new technique that combines seismic attributes in a special way. We search through different data volumes seeking specific types of combined attributes to detect gas chimneys. These new combinations of seismic attributes called "meta-attributes". In this paper, feature extraction techniques (PCA,FSS-PCA and LDA) are used to combine seismic attributes. It is demonstrated that LDA is a good technique for constructing one meta-attribute from the number of seismic attributes in gas chimney detection problem.
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Lithostratigraphy of Nigeria - An Overiview
By K.A. ShittaNigeria lies very close to the equator (hot country) West coast Africa between latitude 4 N and 14 N degree and longitude 2 E and 15 E degree. The country is located at the Northern end of Eastern branch of west coast of Africa rift system. Nigeria geological set up comprises broadly sedimentary formation and crystalline basement complex, which occur more or less in equal proportion all over the country. The sediment is mainly Upper Cretaceous to recent in age while the basement complex rocks are thought to be Precambrian. The studied area lies between latitude 12.4" and 11.11"W and longitude 13.81" and 14.13" S. The studied area is underlain by Precambrian basement complex of southern western Nigeria .The major rock in the area is charnokite and granite rock. The granite rock which are member of the older granite suite occupy about 65% of the total area .The principal granite is petrographic variety are recognized .The fine grained biotite-granite medium-coarse, non porphyritic biotite -hornblende granite and coarse-porphyritic biotite -hornblende granite. Also three main textural type of Charnokitic rock are also distinguished are coarse grained, massive fine grained and gneissic fine grained. The mode of occurrence of rock is three
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Integration of Vertical Seismic Profiling (VSP) and Well Log Data in Seismic Reflection Surveys
Authors M. Akan and A.I. KanliSeismic reflection survey is the basic method used to determine stratigraphical traps in hydrocarbon explorations. The vertical seismic profiling (VSP) technique is applied to obtain high resolution seismic data in addition to the surface seismic reflection surveys in determination of oil included formations and in oil explorations. Additionally, there are various well log data recorded as the function of depth by several borehole geophysical tolls to be used for correlation with seismic data. In this study, a synthetic seismogram was derived from well log data and used for correlating to the seismic section with VSP data. Seven important formations were discerned after interpretation of VSP and well log data that matched with seismic reflection survey.
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Geoelectrical and Seismic Imaging of the Omalos Plateau, Crete, Greece
Authors N. Andronikidis, N. Economou, H. Hamdan, G.S. Kritikakis, E. Manoutsoglou and A. VafidisThis case study presents the results of a geophysical survey that was carried out in 2008-9 at Omalos plateau in Chania, Western Crete, Greece. During this survey we applied seismic methods as well as electrical tomography in order to image the active karstic structures of the Omalos polje. The resistivity and seismic velocity sections image properly karstic structures such as a doline to the south. In addition the geoelectrical sections outline the metamorphic carbonates relief (Tripali unit and Plattenkalk group), which appears highly irregular. At Omalos polje the thickness of post-Mesozoic deposits (terra rossa, clays, sands and gravels) ranges from 40-130 m.
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UCG Technology Assistance with Geophysical Methods on the Example of the Mecsek Research Area
By B.B. BurjanAt the current phase of the researches, to utilize the information of the database, to reuse the previously collected data, it is very important to continuously compare the archive documentation with the present geological results. Therefore the authenticity of the archive data is regularly verified with the help of different geophysical methods to support the calculation of the actual coal supply.
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Shale Gas Exploration and Production
By S. SunjayShale gas is natural gas from shale formations which acts as both the source and the reservoir for the natural gas. Each Shale gas reservoir has unique characteristics. Shale has low matrix permeability, so gas production in commercial quantities requires fractures to provide permeability . For a given matrix permeability and pressure, gas production are determined by the number and complexity of fractures created, their effective conductivity, and the ability to effectively reduce the pressure throughout the fracture network to initiate gas production. Understanding the relationship between fracture complexity, fracture conductivity, matrix permeability, and gas recovery is a fundamental challenge of shale-gas development. Shale gas reservoirs almost always have two different storage volumes(dual porosity) for hydrocarbons, the rock matrix and the natural fractures .Because of the plastic nature of shale formations, these natural fractures are generally closed due to the pressure of the overburden rock. Consequently, their very low, matrix permeability, usually on the order of hundreds of nanoDarcies (nD), makes unstimulated, conventional production impossible.
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Innovation of New Equations to Calculate the Removed Water Block by Mutual Solvents in Oil wells
Authors M. Karimi and M.R. AdelzadehWater block or water impeding in water and oil reservoirs, is one of formation damages caused by wellhead various operations natural water saturation increase in reservoirs. In these equations has been applied of extracted equations for overburden pressure (pressure imposed on the layers by the weight of overburden layers) a layer with definite dimensions using the experimental, microscopic and macroscopic data. These equations are incorporated in the framework of the petrophysic and geologic samples and infinite elements based on the core flood displacement experiments at laboratory. Afterwards, for two ranges of porosity (5.5 to 25%) which covers the types of rocks lithology, the water block equations are extracted to calculate the removed water block after injection of mutual solvents with acidity materials. As far as, the determination of removed water block amount after injection of base fluids mixed with mutual solvents during the acidizing operations is unclear, proposed equations can determine the quantity of removed water block using various parameters, and is applicable in all oil wells acidizing operations with dense and loose rocks.
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3D Temperature Distrubution of Balçova Geothermal Field and Modeling of Fault Related Cooling
Authors D. Yağcı and D. Düşünür DoğanThe West Anatolian region, characterized by high heat-flow, hosts many important geothermal fields as a result of its neotectonic activity. In this study, first, we compile the downhole temperature measurements data and the temperature conductivity coefficient values of various core and outcrop samples from the catalogs in order to calculate the heat-flow. Due to the dense monitoring well network, Balçova Geothermal Field was chosen for 3D temperature distribution modeling. We obtain 3D temperature distribution up to the 200m depth. Distribution of the geothermal fields mostly related with the active faults and young volcanics. Thus temperature modeling should include the effects of active faulting. In order to simulate the effects of faults on temperature distribution, we use finite element modeling.We have obtained temperature distrubution under the effects of fault related hydrothermal cooling.
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