Browsing by Author "Zorski, Tomasz"
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Item Budowa modeli geochemiczno-mineralogicznych na podstawie danych uzyskiwanych z zaawansowanych metod geofizyki jądrowej. Część 1(Institute of Nuclear Physics Polish Academy of Sciences, 2007) Woźnicka, Urszula; Cywicka-Jakiel, Teresa; Drabina, Andrzej; Dworak, Dominik; Tracz, Grzegorz; Drozdowicz, Krzysztof; Zorski, Tomasz; Ossowski, Andrzej; Środoń, Jan; Kawiak, Tadeusz; Bakowska, Dorota; Zielińska, Małgorzata; Zalewska, JadwigaAn extensive set of conventional and special core analysis measurements, complemented by additional chemical and mineralogical analyses was performed, forming the basis for the evaluation of the complex thin bedded gas-bearing shaly-sand formations of Miocene age in the Carpathian Foredeep region of Southern Poland. Mineralogy was established by using full elemental composition, XRD method, total surface area and cation exchange capacity (CEC). The analysis showed that the most important clay component is illite – smectite mixed layer. Statistical multivariate analysis of all data helped to set up a comprehensive general petrophysical model. For the notoriously difficult CEC information for the rock matrix we could establish a reliable correlation (corr. coefficient r2 around 0.95) between thermal neutron absorption cross section SIGMA and total natural radioactivity GR with CEC, with boron and rare earth elements the two most important SIGMA contributors in the rock matrix. This good correlation permits a continuous on-line CEC determination and therefore a reliable application of the Waxman-Smits water saturation model to properly take into account the clay mineral effects in evaluating water saturation.Item Correlation between Measurements and Monte-Carlo Calculations for the NNTE Logging-Tool(Institute of Nuclear Physics Polish Academy of Sciences, 2003) Drabina, Andrzej; Zorski, Tomasz; Woźnicka, UrszulaA correlation between Monte-Carlo simulations of the NNTE geophysical neutron logging-tool response and measurements made on the rock blocks at the calibration facility in Zielona Góra (Poland) has been examined. The NNTE tool is a recent achievement of Polish geophysicists. It is equipped with a neutron source and three detectors. The tool is designed to measure the thermal neutron absorption cross-section of geological formations in situ. The computer modelling is intended to complete the calibration measurements with simulated experiments in complicated borehole situations. A good correspondence between the simulated and real experiments is obvious demand. The simulations have been performed using the MCNP4C computer code. In the first approach elemental compositions of block rock matrices have been taken directly from the results of a chemical analysis. In the second approach boron B-10 has been added to the elemental compositions of rocks to compensate the difference between their absorption cross-section calculated from the elemental compositions and those known from the laboratory measurements. The very good agreement has been obtained between results of calculations and measurements. The high correlation creates the basis for further research on the influence of absorption cross-section of geological formation on the NNTE tool response.Item Monte Carlo simulation of the upgraded, neutron - gamma logging tool, SO-5-90-SN type. Comparison of the simulations and measurements(Institute of Nuclear Physics Polish Academy of Sciences, 2005) Cywicka-Jakiel, Teresa; Zorski, TomaszFor gas prospecting in the shaly-sand Miocene formations of the Carpathian Foredeep many complementary geophysical techniques are being used. The spectrometric Neutron-Gamma well Logging (sNGL) is one of the nuclear techniques being useful for the formation mineralogy identification. The results of the real and simulated sNGL experiments are compared in this report. These benchmark experiments were performed for determination of the main rock constituents: Si, Ca, Fe and H in the rock models which belong to the Polish calibration station in Zielona Góra (BGW). The upgraded n-gamma spectrometer, SO-5-90-SN type, has been applied in the measurements and was simulated using the Monte Carlo code (MCNP). The results of the real and simulated sNGL experiments are in good conformity. The H, Ca and Fe concentrations obtained from the simulations (“MCNP”) have been highly correlated with their reference (“chem”) concentrations. Squares of the correlation coefficients (R2) amount to 0.931, 0.969, 0.973, respectively. For the Si concentration (CSi), dependence CSiMCNP(CSichem) shows slightly lower R2 (0.972) than for dependence CSimeas(CSichem). This is mainly attributed to the unavailable B, Cl and Rare Earth Elements (REE) contents, of the BGW Zielona Góra rock models and to their geological inhomogeneities. Additional improvement of correlation between results of both experiments is also presented. It has been obtained when data from preliminary analyses for B, Cl and (REE) of two rock models were included in the simulations. The Fe concentration can be used as one of the indicators of the formation clay content, therefore an accurate quantification of this element in the rocks is of high importance. The BGW calibration station in Zielona Góra has limited number of the rock models, and Fe content is poorly diversified in them. Therefore the artificial rocks of different Fe contents have been simulated and spectrometer sensitivity, to the changes of the Fe contents, has been estimated.Item Monte Carlo Simulations of the Spectrometric n-Gamma Well Logging. Comparison of Simulations and Measurements for the SO-5-90 Logging Tool(Institute of Nuclear Physics Polish Academy of Sciences, 2004) Cywicka-Jakiel, Teresa; Zorski, TomaszThe results of the Monte Carlo simulations (MCNP code) of the spectrometric neutron-gamma well logging (sNGL) are presented. The sNGL can be very useful for the precise lithology determination, what is especially important for oil and gas prospecting in shally–sand formations. Possibility of determination of the Si, Ca and Fe content in rocks by means of the analysis of gamma ray spectra induced by the captured neutrons is well known for 40 years at least [Larionov, 1969]. Preliminary sNGL experiments performed at the Polish Calibration Station in Zielona Góra, using a simple borehole spectrometer equipped with the isotopic Am-Be neutron source and the BGO detector, fully confirmed this possibility. MCNP simulations of the sNGL experiments have been done for the SO-5-90 neutron-gamma spectrometer and for the lithology models (standards) of the Calibration Station. The concentrations of H, Si, Ca and Fe in these models have been determined from the real and simulated experiments using the simulated (“MCNP”) and measured (“meas”) spectra of gamma-rays from neutron interactions with the rock nuclei. The H, Si and Ca concentrations obtained from the simulated experiment are well correlated with their reference values, known from the chemical (“chem”) analyses - regarded as true values. Squares of the correlation coefficients (R2) amount to 0.992, 0.988 and 0.984, respectively. For Fe, a lower R2 has occurred for the linear dependence FeMCNP(Fechem) than for Femeas(Fechem) amounting to 0.834 and 0.923 respectively. Although the established correlations between results of the real and simulated sNGL experiments show the high values of correlation coefficients, the noticeable improvement of these correlations is expected for the fully verified chemical composition of the Zielona Góra standards and for improved parameters of the n-gamma spectrometer. The usefulness of the MCNP code for modeling the spectrometric neutron-gamma logging tool responses is confirmed. The possibility of the fast and accurate computer simulations opens a new field for development of the spectrometric n-gamma logging. Especially the influence of such disturbing factors as borehole conditions, borehole and formation salinities or presence of the additional rock elements (like B, S, K, Gd ) must be precisely known when the quantitative determination of Si, Ca and Fe is required.Item Numeryczne modelowanie wpływu niejednorodności otoczenia odwiertu poziomego na odpowiedź sondy gęstościowej gamma-gamma(Institute of Nuclear Physics Polish Academy of Sciences, 2009) Zorski, Tomasz; Woźnicka, Urszula; Wiącek, Urszula; Kowalik, Krzysztof; Dworak, DominikThe response of the spectrometric gamma-gamma density tool in borehole conditions has been numerically simulated. A transport of gamma rays from a point source situated in a borehole tool through the rock medium to the detectors has been simulated using the MCNP code. An influence of heterogeneity of a rock medium surrounding the borehole on the response of detectors in the probe has been examined. The heterogeneity results from the presence of the interface between two different geological layers parallel to the borehole axis. Such conditions happen in horizontal logging practice when the borehole is drilled along the boundary of geological layer. It is possible to assess the distance from the boundary on the basis of the response of the gamma-gamma density tool, using the classic interpretation procedure “spine&ribs. We take advantage of the effect of different densities of the bordered layers. When the boundary is far-away the response of the probe fits to the “spine” curve and when the boundary is close – the response fits to the “rib”. The presented examples show the wide possibilities of numerical modeling of the complex borehole geometry and of applications to solve difficult interpretation problems of the nuclear borehole logging.Item Symulacje numeryczne odpowiedzi głębokościowej sondy NNTE w formacjach cienkowarstwowych nachylonych do osi odwiertu. Założenia i obliczenia wstępne metodą Monte Carlo(Institute of Nuclear Physics Polish Academy of Sciences, 2011) Woźnicka, Urszula; Dworak, Dominik; Wiącek, Urszula; Zorski, TomaszBasic assumptions for calculation of well-logging profiles, expected from measurements of the neutron logging tools (type of NNTE) are presented. The report includes also results of the first tests and calculations. The NNTE tool responses were simulated using MCNP - the well-known Monte Carlo code. The general model consists of a huge rock, intersected by a borehole. A thin, flat rock layer of different lithology crosses that huge rock under an angle to the borehole. Numerous combinations of the model parameters - various porosities and neutron absorption cross-sections of the rocks as well as different layer thicknesses and angles - have been considered. The final results should be instantly useful for elaboration of the well-logging interpretation procedures for directional drillings, where the rock layers are usually sloped, or even highly inclined to the borehole axis.