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Groundwater monitoring in the area of Kopački rit : master's thesis
No full textU radu su prikazani i analizirani podaci razina podzemne vode u istražno-piezometarskim bušotinama na području Parka prirode Kopački rit te podaci dnevnih vodostaja rijeka Dunava i Drave na pet postaja koji su detaljnije obrađeni u programu WinSitu 5 te MS Excelu. Obrada podataka te interpretacija odabranih parametara na temelju količinskog stanja podzemnih voda daje temelj za izradu studije za revitalizaciju podzemnih voda što će omogućiti dugoročno i kvalitetno upravljanje vodnim ekosustavima Kopačkog rita. Osim monitoringa podzemnih voda u radu je prikazana recentna sedimentacija i erozija u Parku prirode Kopački rit.The paper presents and analyses data on groundwater levels in exploratory piezometer wells in the area of Kopacki rit Nature park, as well as data on daily water levels of Danube and Drava rivers at five stations which were processed in more detail in WinSitu 5 and MS Excel. Data processing and interpretation of selected parameters based on the quantitative state of groundwater provides the basis for the preparation of a study for the revitalization of groundwater, which will enable long term and high quality management oft he water ecosystems of Kopacki rit. In addition to groundwater monitoring, the paper presents recent sedimentation and erosion in the Kopački rit Nature Park
Techno-economic comparison of a gas heating and hot water preparation system with a system based on renewable energy sources : master's thesis
No full textKlimatske promjene dovode čovječanstvo na prekretnicu u kojoj je jedina prihvatljiva opcija održivi razvoj. Europska unija je postavila cilj da do 2050. godine bude ugljično neutralni kontinent, tj. da energetika EU bude potpuno neovisna o fosilnim gorivima. Jedan od načina za to u sektoru stanovanja jest korištenje nekog od obnovljivih izvora energije, kao npr. solarne panele, PV elektrane ili dizalice topline. Solarni paneli su uređaji koji služe za pripremu potrošne tople vode u kućanstvima. Postoji nekoliko vrsta prikazanih u ovom radu. PV elektrane su uređaji koji sunčevu svjetlosnu energiju u fotonaponskim ćelijama pretvaraju u električnu energiju koja se može koristiti na mjestu proizvodnje ili, ako je ima previše, slati izravno u električnu mrežu. Dizalice topline su uređaji koji imaju nekoliko različitih izvedbi. Dizalice topline koriste električnu energiju za uklanjanje topline s hladnijeg mjesta te je prenose na toplije mjesto, pružajući željenu temperaturu. Dizalice topline su se u ovom radu pokazale kao najefikasnije energentsko rješenje za obiteljsku kuću.Climate change is bringing humanity to a turning point where sustainable development is the only acceptable option. The European Union has set a goal to be a carbon-neutral continent by 2050, i.e. to make EU energy completely independent of fossil fuels. One way to do this in the housing sector is to use one of the renewable energy sources, such as solar panels, PV power plants or heat pumps. Solar panels are devices that are used to prepare domestic hot water. There are several species presented in this paper. PV power plants are devices that convert sunlight energy in photovoltaic cells into electricity that can be used at the point of production or, if there is too much, sent directly to the electricity grid. Heat pumps are devices that have several different designs. Heat pumps use electricity to remove heat from a colder location and pump it to a warmer location, providing the desired temperature. In this paper, heat pumps proved to be the most efficient energy solution for a family house
The impact of underwater blasting of fortresses on the environment : master's thesis
No full textMiniranje je suvremeni postupak za razaranje i drobljenje stijena, materijala i objekata energijom eksploziva. Djelovanje detoniranog eksplozivnog naboja u minskoj bušotini uzrokuje naprezanja koja dovode do frakturiranja i i drobljenja stijene. Prilikom radova na objektima prihvatnog terminala za ukapljeni plin na otoku Krku potrebno je bilo ukloniti elemente starog pristana, odnosno četiri podvodne utvrdice. U tu svrhu proveden je program opsežnih mjerenja utjecaja miniranja na okolinu, u vidu praćenja djelovanja tlačnog udarnog vala u vodi te mjerenja nastalih brzina oscilacija na pilotima. U radu su opisana, kako projektna rješenja parametara miniranja, tako i program mjerenja u svrhu zaštite okoline te analiza dobivenih rezultata mjerenja.Blasting is a modern technique for destroying and crushing rocks, materials and objects with the energy of explosives. The action of a detonated explosive charge in a mine bore causes stresses that lead to fracturing and crushing of the rock. During the works on the facilities of the reception terminal for liquefied gas on the island of Krk, it was necessary to remove elements of the old wharf, i.e. four underwater fortifications. For this purpose, a program of extensive measurements of the impact of blasting on the environment was carried out, in the form of monitoring the action of the pressure shock wave in the water and measuring the resulting velocities of oscillations on the piles. The thesis describes both the project solutions for the blasting parameters, as well as the measurement program for the purpose of environmental protection and the analysis of the obtained measurement results
Implementacija Ti(III) redukcijske metode u svrhu određivanja izotopnog sastava dušika (δ15N) i kisika (δ18O) iz nitrata
No full textPollution of surface and groundwater by nitrate (NO3–) is one of the most serious environmental problems worldwide. The crucial isotopes for the sources and dynamics of nitrogen (N) in the aquatic environment are the nitrogen and oxygen isotope data of NO3-. The stable isotope of nitrogen (δ15N) in dissolved nitrate has been most commonly used to estimate NO3- sources in groundwater. However, measurement of the stable nitrogen isotope alone does not provide a definitive determination of NO3– origin, so the stable oxygen isotope (δ18O) must be used, i.e., a dual isotope approach. The analysis of NO3- for both δ15N and δ18O has been made possible by the development of various laboratory methods for sample preparation, each with its own advantages and disadvantages. Current methods such as the cadmium reduction method (Azide method) or the bacterial denitrification method require toxic chemicals or anaerobic bacterial cultures for NO3- reduction to N2O gas. In 2019, a new sample preparation method was developed (ALTABET et al., 2019), which is a simple one-step conversion method that utilizes Titanium( III) chloride reagent to reduce NO3– to N2O within septum sample vials: 2NO3 – (aq) + 8Ti+3 + 10H+ → N2O(g) +8Ti+4 + 5H2O A single sample preparation takes only a few minutes, followed by a 24-h reaction that generates N2O headspace gas for δ15N and δ18O analysis by IRMS or laser spectrometer. Briefly, Ti(III) chloride is preconditioned with zinc metal powder about 30 minutes before sample preparation to ensure efficiency by removing Ti(IV). The volume ratio of sample to reagent for groundwater samples is 10:1, 20:1, or 40:1. We found that higher amounts of Ti(III) reagent (10:1 and 20:1 ratios) gave slightly more accurate δ18O values. The δ15N values were most inaccurate at ratios of 10:1 and 40:1, but were more accurate at a 20:1 ratio of sample to reagent. Therefore, a 20:1 ratio is considered practical for further measurements. To ensure consistent N2O yields and 15N and 18O results, the N concentrations in each vial must be identical for all samples, laboratory controls, and standards. This is achieved by adding an appropriate volume of sample, degassed deionized water, 10% hydrochloric acid, and the preconditioned Ti(III) chloride reagent. The δ15N and δ18O isotope analyses were performed using the Isotopic N2O Laser Analyzer (GLA451-N2OI3), which was acquired as part of the CRO7002 project “Using Nitrogen and Oxygen Stable Isotopes in the Determination of Nitrate Origin in the Unsaturated and Saturated Zone of the Velika Gorica Wellfield”, funded by the International Atomic Energy Agency (IAEA). The described method is very competitive (simple, faster and more cost-effective) compared to the existing methods currently used in most laboratories worldwide, and its implementation at the Faculty of Mining, Geology and Petroleum Engineering (University of Zagreb) enabled the development of new research on the estimation of the origin of nitrate in groundwater
Middle Triassic syn-rift rhyolites and rhyolitic ignimbrites on the north-east margin of Adria (NE Slovenia, NW Croatia): possible source of rhyolitic tuffs (Pietra Verde) in the wider Dinaride area
No full textSrednjotrijaske magmatske i piroklastične stijene u području Adrie, odnosno šireg područja Dinarida i Južnih Alpa su česta pojava. To su uglavnom bazične magmatske stijene: bazalti, andezit-bazalti, rjeđe andeziti te riolitne piroklastične stijene (Pietra Verde). Izvorište riolitnog piroklastičnog detritusa u širem području Dinarida do sada nije jasno određeno. Trijaske kisele magmatske stijene poznate su samo na SZ rubu Adrie. U okviru projekta GOST istraživane su ove stijene na uzvisini Sv. Junger u SI Sloveniji, koje su determinirane kao rioliti, te na području Margečana na uzvisinama Gradišće, Hamec, Oštra Gorica i Sv. Duh u SZ Hrvatskoj, koje su određene kao riolitni ignimbriti. Rioliti imaju porfirnu strukturu i homogenu teksturu. Fenokristali su plagioklas i K-feldspat, a osnova je leukokratna, devitrificirana u sitnozrnati kvarc, feldspat i bijeli tinjac. Fenokristali plagioklasa su alterirani u sitnolistićavi bijeli tinjac i minerale glina. K-feldspat je svijež s alteriranim inkluzijama. Riolitni ignimbriti imaju debljinu veću od 100 m. Izdvajaju se (1) čvrsti laminirani folijativni tok riolitnih ignimbrita i (2) čvrsti masivni riolitni ignimbriti. Folijativne trake su debljine od 1–10 cm. Izmjenjuju se vrlo tanki slojevi vitrofirnog, lapilno vitrofirnog i kristaloklastičnog riolitnog piroklastičnog toka. Lamine vitrofirnog riolitnog piroklastičnog toka izgrađene su od izmijenjenog matriks-potpornog piroklastičnog detritusa manjeg od 2 mm i devitrificirane staklaste osnove. Vitrofirni riolitni lapilni ignimbrit sadržava izmijenjene matriks-potporne do klast-potporne plovučce veće od 2 mm i kristaloklaste u devitrificiranoj staklastoj osnovi. Kristaloklastični riolitni piroklastični tok izgrađen je od kristaloklasta kvarca, albita (An0.0-4.5Ab95.1-99.9Or0.1-0.6) i K-feldspata (An0.0- 1.0Ab1.8-4.2Or95.0-98.4), kao i vrlo rijetkih čestica lapilnog plovučca, dok je matriks izmijenjen u fengit. Masivni čvrsti riolitni lapilni ignimbriti izgrađeni su od klast-potpornih do matriks-potpornih alteriranih lapilnih plovučaca, a rjeđe od kristaloklasta izmijenjenih feldspata i kvarca u devitrificiranoj staklastoj osnovi. Produkti izmjene u svim varijetetima su sitnozrnati kvarc i listići filosilikata. Alteracijski procesi su dvofazni: tijekom dijagenetskih procesa i postdijagenetskih tektonskih procesa kao što su dinamo-termalne metamorfne promjene, koje se očituju u klivažu uškriljavanja po kojem se razvija folijativni bijeli tinjac. Bijeli tinjac je fengit sa sadržajem 3.4 SiT a.p.f.u. Izvorište riolitnih tufova (Pietra Verde) na području Strahinjščice, Žumberačke gore i šireg područja Dinarida (Lika, Knin, Svilaja i dr.) mogu biti navedene istraživane eksplozivne riolitne vulkanske stijene SI ruba Adrie
Risk evaluation for coating thickness conformity assessment
No full textThis paper presents the conformity assessment process of the epoxy coating thickness applied on water pipes made of gray cast iron with the specifications given for this kind of coating appliance. An epoxy coating was applied to prevent a special form of corrosion called the graphitization of cast iron. In order for the pipe to withstand its designed service life, it is necessary to ensure the required thickness of the applied coating. In accordance with the EN 877 norm, the thickness of the epoxy coating on the pipes for the projected corrosiveness of the environment C4 and the durability of 20 years is at least 70 μm and this indicates the required accuracy of the product. To achieve the desired product quality, statistical control of the coating application process was carried out and the impact of uncertainty associated with the measurement result was analyzed. Considering the quality of the coating application process and the quality of the measuring system, and to ensure the quality of products and to reduce consumer risk, the optimal thickness of the coating was determined
Petrography of the Upper Miocene sandstones from the North Croatian Basin : understanding the genesis of the largest reservoirs in the southwestern part of the Pannonian Basin System
No full textThis paper presents a petrographic study of the Upper Miocene sandstones from exploration wells in the Sava and Drava Depressions in the North Croatian Basin (SW of the Pannonian Basin System), Central Europe. These sandstones represent the most important reservoir rocks for oil and gas in Croatia. A total of 130 core samples from depths of more than 3000 m were examined. The sandstones generally have a feldspatho–litho–quartzose (fLQ) composition. The modal composition of samples from the Sava Depression is Q39.2–61.0F8.9–26.0L26.1–42.3, and Q40.6–63.5F6.6–23.3L20.9–42.3 for those from the Drava Depression. Lithic fragments are dominated by extrabasinal carbonates with subordinate metamorphic grains (mostly schists) and less frequent magmatics (granitoids). Garnet, tourmaline, apatite, rutile, epidote, clinozoisite, zoisite, titanite, zircon, staurolite, and opaque minerals form the heavy mineral association and imply an area of provenance dominated by metamorphic rocks. The tectonic setting of the sandstones corresponds to recycled orogen, i.e., a subduction complex or fold-thrust belt. There are no significant compositional differences between the sandstone samples from the two depressions, thus indicating a common main source area and similar diagenetic processes in the subsurface. The sandstones originated from eroded parts of the uplifted Alpine–Carpathian fold belt and are distinct from the Lower and Middle Miocene sandstones in the North Croatian Basin. Observed variations in the sandstones’ composition with regards to geographic location and depth are associated with variations in the erosion of parent rocks, including subsequent modification of detrital sediment during transport, mixing, and deposition, as well as burial diagenesis. The Sava and Drava Depressions were part of Lake Pannon in the Late Miocene with no significant topographical obstacles between them for the inflow of the detritus. The study will therefore help with the correlation of the Upper Miocene reservoir rocks in various parts of the North Croatian Basin (as well as adjacent parts of the Pannonian Basin System) and thereby assist with future hydrocarbon exploration in this area
Pullout behavior of a polymeric strap in compacted dry granular material
No full textStrap reinforcement is very commonly used as reinforcement material in mechanically stabilized earth walls (MSEW). Metal straps are mostly used as reinforcement material. However, in humid climates, where the risk of damage to metal straps due to corrosion is high, the use of geosynthetic straps is quite justified. In the Croatian coastal region, geosynthetic straps were used as reinforcement for two very high MSEWs. In both cases, the backfill material crushed stone aggregate from the neighboring site was used. According to the relevant standards, it is recommended that the backfill material should have a uniformity coefficient of Cu ≥ 4.0. To meet these requirements, it is usually necessary to sieve and crush the backfill material. To evaluate the influence of the uniformity coefficient on the friction interaction coefficient between a geosynthetic strap and a crushed stone aggregate, a series of pullout tests with different confining stresses and aggregate grain size distributions were conducted. The pullout tests were performed for three different uniformity coefficients of the crushed stone aggregate. The results confirmed the justification to use backfill material with a uniformity coefficient higher than 4.0. The pullout tests were performed with one strap, two closely spaced straps, and two separated straps. The results showed that lateral friction contributes to the pullout force in the amount of 16.1% of the total force
Revitalization modelling of a mature oil field with bottom-type aquifer into geothermal resource—reservoir engineering and techno-economic challenges
No full textThe possibilities of using geothermal energy are slowly expanding to all areas of energy consumption, so the assessment of geothermal potential has become the backbone of energy policies in countries that have the potential. Countries and companies that have experience in the oil and gas industry are increasingly exploring the possibilities of first using the acquired knowledge, and then using the existing oil and gas infrastructure for the use of geothermal energy. For this reason, it is necessary to analyse the possibilities of using the existing infrastructure with all its limitations to maximise the energy potential of geothermal energy. The existing oil infrastructure, especially the wells, is in many cases not suitable for the production of brine and it is necessary to analyse the maximum impact of each well for the production of geothermal energy, with particular attention to the equipment installed in the well and the thickness of the geothermal reservoir in the oil and gas fields that would be suitable for the production of brine
Defining heat in place for the discovered geothermal brine reservoirs in the Croatian part of Pannonian Basin
No full textOne of the important sources of renewable energy is geothermal heat. Its special feature of being independent 24/7 ensures the stability and security of the system, either for electricity or heat production. Geothermal energy has a local character and is limited by the geological characteristics of each state. In the Republic of Croatia, the development of geothermal energy is closely related to the development of the oil industry, as geothermal deposits were discovered during oil and gas exploration. Considering the established temperature gradients in Croatia, there is a greater possibility of using geothermal energy, and for this, it is necessary to evaluate its full potential and possibilities of use. The aim of this research is to determine the heat potential of the Croatian part of the Pannonian Basin System (CPBS), a part of Croatia with exceptional geothermal potential, based on the analysis of a large amount of well data with confirmed water inflow. In order to estimate the heat in place, the available data on the presence of inflow, temperature, and porosity, as well as permeability and volume for each well/reservoir included in the assessment, were considered. In geothermal reservoirs, one of the most important pieces of data besides petrophysical and thermodynamic data is the potential of the well, i.e., the maximum flow under certain permeability and porosity conditions. To define this, the productivity index was made dependent on the permeability of each well, and the inflow in each well was risked using Monte Carlo for three main geological phases in CPBS, which subsequently influenced inflow and spacing between production and injection wells. The beta-PERT distribution for permeability is used in Monte Carlo simulation to determine the most likely values and produce a distribution that resembles the real probability distribution. As a result, geothermal potential was mapped according to the obtained values of heat in place for part of the CPBS covered with analysed wells