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Rezerve i proizvodnja nafte iz nekonvencionalnih ležišta u Sjedinjenim Američkim Državama : završni rad
No full textNaftna industrija je dugi niz desetljeća glavni pokretač američkog gospodarstva. SAD su bile veliki uvoznik nafte te je svaka promjena na svjetskom naftnom tržištu imala veliki utjecaj na američko gospodarstvo. Posljednja dva desetljeća rezerve nafte iz konvencionalnih ležišta u SAD-u se smanjuju, a potrebe za energijom sve više rastu. To je usmjerilo industriju na razvoj i primjenu novih tehnologija kojima bi se nafta mogla pridobivati iz nekonvencionalnih ležišta. Na engleskom jeziku nafta pridobivena iz ovakvih ležišta zajednički se naziva tight oil, gdje riječ tight sugerira malu propusnost stijena iz kojih nije moguće proizvoditi naftu u zadovoljavajućim količinama bez primjene tehnologija horizontalnog bušenja i hidrauličkog frakturiranja. Hidrauličko frakturiranje je postupak utiskivanja fluida za frakturiranje u ležište radi stvaranja pukotina čime se može povećati proizvodnja. Razvoj proizvodnje nafte iz slabo propusnih ležišta značajno je utjecao na tržište nafte tako da su SAD postale velesila u proizvodnji nafte u 21. stoljeću i od velikog uvoznika postale izvoznik nafte. Dokazane rezerve nafte u SAD su se tijekom 21. stoljeća gotovo udvostručile zahvaljujući velikom udjelu nekonvencionalne nafte. Najveća područja proizvodnje nafte iz nekonvencionalnih ležišta su Bakken, Eagle Ford i ležišta Permskog bazena
Procjena poroznosti korištenjem karotaže gustoće, neutronske i zvučne karotaže - primjer pješčenjačkih ležišta u Savskoj depresiji : završni rad
No full textPoroznost stijene je jedan od najvažnijih parametara koji možemo dobiti putem karotažnih mjerenja te se kao takva koristi za daljnje određivanje brojnih drugih svojstava ležišta. Postoje razni načini na koje se može određivati poroznost. To mogu biti laboratorijska mjerenja na uzorcima jezgara koja su obično smatrana najtočnijom metodom, s obzirom da se izravnim putem određuje poroznost, ali mogu biti i neizravne metode određivanja, poput karotažnih mjerenja. Najveći nedostatak karotažnih mjerenja je upravo u toj neizravnosti, odnosno činjenici da se potrebno osloniti na dodatne podatke i pretpostavke uvjeta i fizikalnih svojstava stijena na kojima se provodi mjerenje. To nerijetko dovodi do odstupanja i nepravilnosti prilikom interpretacije podataka, naročito ako se radi o složenijim geološkim uvjetima. Ipak, korištenjem softvera prilikom interpretacije i nekoliko karotažnih mjerenja, kao što su karotaža gustoće, zvučna i neutronska karotaža, omogućava se dobra procjena, te se mogu dobiti zadovoljavajuće vrijednosti koje značajnije ne odstupaju od onih dobivenih laboratorijskim putem
Triaxial force sensor calibration for rock cutting simulation : master's thesis
No full textU ovom radu prikazana je problematika umjeravanja senzora za mjerenje sile pri obradi AG kamena. Rad je predložio izradu dodataka za umjeravanje gdje se sa utezima mogu dobiti željene sile, a dodatak je tako napravljen da osigurava samocentriranje utega, a time i dobru ponovljivost pozicije gdje se uteg smješta. Također predložena je izrada drugog dodatka koji osigurava okomitost pojedinih osi nakon jednog niveliranja tj. da se ne mora niveliranje provoditi za svaku od osi. Napravljena je analiza utjecajnih veličina i proračun mjerne nesigurnosti svakog koraka koji se predviđa, gdje je zaključeno da je kut pod kojim se sve nalazi najveća utjecajna veličina te procesu niveliranja treba posvetiti najveću pažnju. Obavljeno je umjeravanje te su provedene analize podataka. Dobivena je matrica senzora za manji i veći raspon umjeravanja. Navedeno je upotrijebljeno za prikaz proračuna tj. korištenja kada se senzor koristi za mjerenje. Također, obavljena je usporedba što se događa ako se ne koristi matrica i njen inverz u oba smjera proračuna.This paper presents the challenges of sensor calibration for force measurement during the processing of natural stone. The paper proposes the creation of calibration attachments, which use weights to achieve desired forces. The attachment is designed to ensure self-centering of the weights, thereby ensuring consistent reproducibility of the weight placement position. Additionally, the paper suggests creating another attachment that ensures the perpendicularity of individual axes after a single leveling, eliminating the need for separate leveling for each axis. An analysis of influential variables and the calculation of measurement uncertainty for each predicted step were conducted. It was concluded that the angle at which everything is positioned is the most significant variable, emphasizing the need for careful attention to the leveling process. Sensor calibration was performed, and data analysis was carried out. A sensor matrix was obtained for measurement and a broader calibration range. This was used to demonstrate calculations and usage scenarios when the sensor is applied for measurement. Furthermore, a comparison was made to assess the impact of not using the matrix and its inverse in both calculation directions
SALTECTA – salt diapirs and active tectonics in the Central Adriatic
No full textSrednji Jadran je predgorje dvaju orogenih sustava – Dinarida na sjeveroistoku i Apenina na jugozapadu. Osim velike debljine naslaga, to područje obilježava i specifična predgorska tektonika te brojne solne strukture. Te halokinetske strukture različito su prikazivane na objavljenim preglednim kartama i ilustracijama geoloških profila, a tek sporadično na interpretiranim seizmičkim profilima. Solni dijapiri čine impozantne potpovršinske strukture koje mjestimice izbijaju na površinu i tako utječu na morfologiju (batimetriju) tog područja. Solne strukture srednjeg Jadrana su znanstveno nedovoljno istražene, a nije istraživana niti uzročno-posljedična veza halokinetike i umjerene seizmičke aktivnosti koja obilježava to područje. Pretpostavlja se da je izdizanje soli vezano uz neotektonsku reaktivaciju mezozojskih rasjeda, od kojih su neki vjerojatno i danas aktivni. Projektom se namjeravaju interpretirati najnoviji 2D seizmički profili odobreni od strane Agencije za ugljikovodike (AZU), reinterpretirati gravimetrijski podatci, definirati glavni rasjedi te 3D modelirati geometrija odabranih solnih struktura. Strukturno-tektonski sklop (re)definirat će se na pučinskim otocima srednjeg Jadrana (slika 1). Uspoređivanjem prostornog rasporeda epicentara i hipocentara zabilježenih potresa s interpretiranim geološkim strukturama, pokušat će se razjasniti povezanost aktivne tektonike sa solnim strukturama. Istraživanjem i datiranjem najmlađih (kvartarnih) naslaga pokušat će se definirati neotektonska aktivnost solnih dijapira. Istraživanjem odabranih markantnih (sub)recentnih erozijskih oblika nastojat će se procijeniti prošla i buduća seizmotektonska aktivnost i seizmogeohazardi
Stop 3 : Minjera bauxites – upper Santonian/ upper Cenomanian – lower Eocene unconformity
No full textThe 3rd stop comprises a group of smaller Palaeogene bauxite bodies located in the valley of the Mirna river in Istria, called Minjera bauxites. Compared to other Palaeogene bauxites from Istria, they are characterised by their complete or partial reduction and subsequent pyritization. Such pyritized bauxites have been documented throughout the Jurassic and Palaeogene in the Mediterranean bauxite belt, with the best examples found in Montenegro (DRAGOVIĆ, 1989; RADUSINOVIĆ & PAPADOPOULOS, 2021), Hungary (BARDOSSY, 1982), and Greece (ECONOMOU- ELIOPOULOS et al., 2022; LASKOU & ECONOMOU- ELIOPOULOS, 2007, 2013). This pyritization phase is epigenetic in all these deposits as well as in the Minjera bauxites and is related to the transgression that succeeded the bauxitization phase. This unique grey bauxite from the Minjera locality was mined in the past for the production of alum and vitriol, which were obtained by processing pyritized bauxite. Only the grey bauxite was used as ore, while the mined non-pyritized red bauxite, which occurred in some Minjera bauxites, was left on tailing heaps in the area. Mining in Minjera probably dates back to the 16th century, but was historically documented from 1784 to 1824 (D’AMBROSI, 1926), when the mine was in operation. The Minjera bauxite deposits are of great importance as they are the first locality where bauxite was mined in the world. There are visible differences in the type of mining between the individual bauxite bodies, as many larger bauxite bodies contain adits indicating underground mining, while some of the smaller bauxites do not contain adits and were probably surface mined. Most of the deposits are present as large and sub-vertical canyon-type ore bodies (20–30 m thick), while the rest are smaller (< 5 m thick) and have mainly sinkhole morphology. The main part of the canyon-type deposits is located on the northern side of the Mirna River in this area, while the sinkhole type and smaller canyon-type deposits are found on the southern side, indicating the variability of the palaeotopography during the formation of the Minjera bauxites.
Stop 4 : terra rossa soil profile in the Koroniki vineyard : Upper Eocene – Recent Unconformity
No full textTerra rossa, the term introduced by TUĆAN (1912), is a generic term that refers to a soil formed in a Mediterranean climate that is red in colour, well-structured, high in Fe oxides strongly associated with clay minerals and overlying carbonate rocks (PRIORI et al., 2008). The term is commonly used by pedologists, geologists, archaeologists, geomorphologists, and sedimentologists in the Mediterranean region and in areas with continuously humid climates in the Western (e.g., Caribbean, Indiana, Wisconsin) and Eastern Hemispheres (e.g., southern Australia). In the WRB classification system, terra rossa soils can be classified as Cambisols, Luvisols, Nitisols (PRIORI et al., 2008), Leptosols (e.g., MUHS et al., 2010), and Lixisols (DURN et al., 2023). However, terra rossa is also referred to as a relict soil, polygenetic soil, palaeosol, pedosediment vetusol, lithified palaeosol, pedosedimentary complex, soil sediment, and sediment by various researchers (e.g., CREMASCHI, 1987; MIRABELLA et al., 1992; ALTAY, 1997; BENAC & DURN, 1997; BRONGER & BRUHN-LOBIN, 1997; DURN et al., 1999, 2007, 2014, 2018, 2023; DURN, 2003: FEDOROFF & COURTY, 2013; ZHANG et al., 2018; JONES, 2021; TRAVÉ et al., 2021)
Plan upravljanja istraživačkim podacima na HRZZ projektu Razvoj metodologije procjene podložnosti na klizanje za planiranje namjene zemljišta primjenom LiDAR tehnologije, LandSlidePLan (HRZZ IP-2019-04-9900)
No full textSecondary (anthropogenic) REE sources
No full textThe workshop "Rare Earth Elements value chain gaps and opportunities in the ADRIA region" is organized as part of the EIT project RECO2MAG - Novel grain boundaries engineered resource efficient Nd-Fe-B permanent magnets (financed by EIT KIC Raw Material)
Generiranje bušotinskih modela geofizičkih parametara uporabom strojnog učenja (polje Gola)
No full textIn the area of the Gola field, the Upper Miocene deposits of the western part of the Drava depression represent a sequence of sediments consisting of sandstone, siltstone, marl and their transitional lithofacies. The sandstone deposits, i.e., the main reservoir rocks, mostly occur in lenticular forms (KRPAN et al., 2018), which makes it difficult to spatially correlate. These deposits were formed in a brackish lake environment in the zone of the lake littoral and part of the sublittoral and represent sediments of channel fills and underwater fans deposited from turbidites (TADEJ, 2011). In order to improve the interpretation of well logging data in the research area, different machine learning models were tested. In this study, regression analysis was used for acoustic log and porosity predictions. The regression belongs to supervised learning models, which means that the learning is based on already known values of the required variables. Algorithmic processing of a large amount of data is only possible if the matrix of input data is not singular, i.e. its determinant is not zero. The problem with data preparation is the fact that most logging data sets are in the form of a singular matrix, that is, most wells are missing a certain number of values at certain depth intervals (MCDONALD, 2021). For this reason, the missing values were added to existing well depth intervals after predictive modelling by machine learning. Various statistical methods used to analyse data, including correlation and regression, assume that the data have normal distribution. Most algorithms are also based on the assumption that the variables are around zero to one and that they are comparable to each other. For this reason, prior to testing the algorithms, the data were standardized, normalized, or transformed depending on the algorithms used (SEMENIKHIN & BELOZEROV, 2019). Based on the correlation matrix, 14 variables (logs) were determined for the calculation of the forecast model. A total of six regression models were used to predict the acoustic logs and porosity values. The base model was calculated using the Support Vector Regression (SVR) algorithm (Fig. 1), as the goal was to determine the boundaries of acceptable predictions. The measure of accuracy for regression models, amongst others, is the coefficient of determination R2, which indicates how well the predicted and measured values correlate. For the base model, at the shallower depths the predicted values follow the trend of the measured ones but at the greater depths the predictions fall out of the trend, which makes the results unreliable. The most accurate model was generated using the K-Nearest Neighbour (KNN) algorithm, where the coefficient of determination was over 0.9 (Fig. 1). The greatest advantages of predicting the values using trained models are the ability to fill in missing logging data and the short time required to get the initial image of the subsurface. Based on the predicted values, the further processing and interpretation methods are determined more quickly
Pojava i mineralna kemija titanskog klinohumita iz mramora potoka Zorovac, Moslavačka gora, Hrvatska
No full textClinohumite is a scarce mineral, but is the most abundant mineral of the humite group which is characterized by a general formula of nM2SiO4x*M1-xTix(OH, F)2-2xO2x, where M stays for octahedrally coordinated Mg, Fe, Mn, Ca and Zn cations in declining order of abundance, x < 1 with n=1, 2, 3, 4 for norbergite, chondrodite, humite and clinohumite ( JONES et al., 1969). The occurrence of clinohumite is in the nature limited to only five rock types: kimberlites, Archean ultramafics, Alpine peridotites, carbonatites and marbles. However, despite the rarity of its occurrence, clinohumite is essential in understanding hydration and dehydration processes in the petrogenesis of mantle derived ultramafic bodies found in polymetamorphic Archaean terranes (NISHIO et al., 2019), but also in reconstruction of Ti mobility in the frame of crustal metamorphism linked to the clinohumite formation in forsterite marbles (KARMAKAR, 2021). Recently, the occurrence of humite-bearing marbles has been used for the reconstruction of the plate geometries during Neoproterozoic time, known as “humite epoch”, characterized by very water-rich, fluorinated fluid activity coeval with the waning stages of Pan-African tectono-thermal event (PRADEEPKUMAR & KRISHNANATH, 2000; FERNANDES & CHAVES, 2014). Clinohumite occurs in Croatia only in the grey marbles of Zorovac creek in the Moslavačka Gora and was described by BARIĆ (1972), GARAŠIĆ (1993) and BALEN et al. (2000). The Moslavačka gora is crystalline complex located in the SW part of the Pannonian Basin, in Croatia. It comprises metamorphic rocks of high-to medium-grade, predominately migmatites and gneisses and of medium grade, mostly metapelites and amphibolites, which intermittently surround granitoids of different kind (PAMIĆ, 1990). The Moslavačka Gora belongs to Sava zone (SCHMID et al., 2008), located between Laurasia and Gondwana, and was recognised as high-heat flow zone causing Cretaceous igneous and metamorphic events (BALEN & PETRINEC, 2011). Zircon dating of two mica-granite gave Cretaceous age and Early Ordovician age for metagranite (the most of the metamorphic complex), whereas the Cretaceous age of low pressure-high temperature (LP/HT) metapelite was obtained by monazite dating (STARIJAŠ et al., 2010).
The studied marbles occur as interlayers up to 50 cm thick in cordierite and diopside-amphibole schists. Mineral assemblages in marbles indicate three metamorphic events of different metamorphic grade. The highest grade mineral assemblage consists of forsterite+spinel+calcite+ pargasite. The most important forsterite+clinohumite+ calcite±phlogopite±tremolite assemblage occurred during LP/HT metamorphism, as result of replacement of fosterite by clinohumite. The textural relationships in the lowest grade mineral assemblage consisting of clinohumite+ spinel+calcite+chlorite+dolomite suggest that chlorite and dolomite grew at the expense of clinohumite, spinel and calcite (Fig. 1). Also replacement of forsterite by talc and serpentine belongs to this retrograde lowest grade metamorphism.
Microprobe analyses of clinohumite revelead that content of TiO2 varies between 0.88 (in the mineral parageneses with phlogopite) and 4.04 wt.% (in the mineral parageneses with amphiboles). The fluorine concentration in Ti-clinohumite shows negative correlation with titanium, and ranges from 1.30 to 3.16 wt.%. This is in accordance with expected substitution (Mg,Fe)+2(OH,F) = Ti+2(O). The ratio of F/(F+OH) in clinohumite or XFChu is in the range between 0.32 (in the parageneses with amphiboles) and 0.57 (in the parageneses with phlogopite). Content of H2O varies from 2.16 to 2.66 wt.%. The concentrations of MgO reach the values from 51.87 to 55.63 wt.% depending on the content of titanium and iron oxides, whereas FeO content ranges from 1.64 to 4.79 wt.%. The SiO2 content shows slight variation (37.07 and 37.63 wt.%). Other cations in Ti-clinohumite are present in negligible amounts.
Textural relationships and microprobe analyses reveal that Ti-clinohumite grew at the expense of forsterite caused by infiltration of titanian and fluorinated H2O-rich fluids. Such rare clinohumite marbles with remarkably similar mineral assemblages, textures and P-T-fluid metamorphic conditions and multiphase evolution are widespread in the dispersed Gondwana fragments (PRADEEPKUMAR & KRISHNANATH, 2000). Although the Cretaceous age of LP/HT metapelite was determinated in the Moslavačka Gora, because marbles are more sensitive than other rocks to the changes in fluid composition (FERRY, 1992), the LP/HT metamorphism in marbles is not necessarily comparable to the LP/HT metamorphism in the metapelites. I thank Rainer Altherr for his help in using the electron microprobe at the Institut für Petrographie und Geochemie, Fridericiana Universität Karlsruhe (TH), Germany