In the southernmost part of the Svecofennian province in Finland, leucogranites and migmatites stemming from both igneous and sedimentary protoliths reflect the complex magmatic history of the Svecofennian orogeny between 1.89 and 1.82 Ga. Although the migmatites and leucogranites in southernmost Finland display similar ages as their counterparts elsewhere in the Southern Finland Subprovince, they differ in field appearance and composition. Field and petrographical observations reveal K-feldspar megacrysts of varying sizes in the migmatized early Svecofennian (c. 1.89–1.87 Ga)
supracrustal rocks and granitoids. Whole-rock geochemical analyses likewise display anomalously high K-contents in the early Svecofennian granitoids. Zircon U-Pb dating of migmatites and related leucogranites shows that a late Svecofennian partial melting event occurred at 1.84–1.82 Ga, possibly in several pulses. The morphological features of the migmatites as well as neosome mineralogy indicate a formation mechanism different from the dehydration melting prevalent elsewhere in the Subprovince.
Levin, Lev Yu., Semin, Mikhail A., Vshivkov, Aleksei N.
et al.
The article involves the study of the freezing process of medium-grained sand saturated with aqueous
NaCl solutions of various concentrations (0–104 g/l). The purpose of the study is to determine the influence of
NaCl concentration on heat and mass transfer processes. Freezing was initiated from one end of the sample; the
temperature field was recorded by eight thermocouples, while the moisture distribution was determined by
weighing followed by drying. The results confirmed a linear decrease in the freezing point of pore water with
increasing NaCl concentration, down to –7°C. It was found that in all tests, moisture redistribution occurred with
its accumulation near the freezing front. In non-saline samples this effect was most pronounced, which can be
attributed to the combined influence of thermodiffusion and phase pressure differences at the water–ice interface.
With increasing salinity, this effect weakened, and the contrast in moisture content between frozen and unfrozen
zones decreased. The obtained time-space distributions of temperature and moisture provide a basis for
parameterizing mathematical models of heat and mass transfer in frozen media, as well as serve as a starting
point for further studies of freezing processes in saline soils.
Abstract Facing the global low-carbon energy transition trend, the issue of energy sustainable development has attracted increasing attention. To promote the sustainable development of shale gas resources, investment in shale gas development should not only focus on economic benefit, but also consider environmental pollution and emission reduction. Therefore, investment of shale gas development involves multiple objectives, which requires multi-objective investment decision optimization research. This study innovatively combines investment decisions with sustainable development. A multi-objective decision-making optimization model for investment portfolio of shale gas green development is constructed to solve the optimization of shale gas block portfolio and the allocation of exploration and development investment amount under multiple competing objectives and constraints. The results show that shale gas favorable block with low single-well development cost, high initial average production, low methane emission and internal environmental cost will be selected into a Pareto optimum set, and the three objective functions of optimal investment portfolio have a wide range. In the process of determining the final scheme, when emission reduction effect is given priority, final investment schemes are the same regardless of the order of economic benefit and environmental pollution; when economic benefit or environmental pollution is given priority, the preference order of the other two objectives will affect the choice of final investment scheme.
Abstract A multi-disciplinary approach of volcano-stratigraphy, petrology and geochemistry has shed light on the pre-eruptive processes, the eruptive triggering, behaviour and the architecture of the magma plumbing system during the explosive cycle of Petrazza at ca. 77–75 ka (PaleoStromboli I eruptive epoch, Stromboli). This was the largest magnitude eruptive cycle in Stromboli and one of the largest of the entire Aeolian archipelago, able to produce Vulcanian to sub-Plinian/Plinian phases with distal deposits found in the tephrostratigraphic record of the Tyrrhenian sea and surroundings. Our study highlighted that, differently from the present-day activity, the large magnitude Petrazza eruptive cycle could be attributed to phases of closed-system conditions, as also testified by the in equilibrium presence of amphibole, indicative of a “steady-state” magmatic status of the system. The explosive activity is then attributed to strong depressurization underwent by the plumbing system due to the cyclic closure/opening of the shallow conduit, possibly also in association with lateral collapse events. As shown by textural and compositional studies on plagioclase crystals, this decompression was also able to recall amphibole bearing mafic magma from the deep portion of the plumbing system (5–15 km of depth).
Murtadha Alkathim, Murtada Saleh Aljawad, Amjed Hassan
et al.
Abstract This research investigates the impact of different rock, acid, and reaction dynamic properties on the pore volume to breakthough (PVBT) at different acid injection rates using in-house developed two-scale continuum simulation model. We analyzed the parameters relation and developed a reliable machine learning model to accurately predict the PVBT at similar range of investigated parameters. In the simulation, it was found that different acid concentrations result in the same optimum injection velocity but at large contrast in PVBT between low and high acid concentration. However, other parameters such as diffusion coefficient and reaction rate exhibited an inverse PVBT behavior across optimum injection velocity due to change in acid transport and reaction behavior. After that, different reliable machine learning algorithms were employed to predict the optimum PVBT for carbonates matrix acidizing. The utilized machine learning models undergone multiple optimizations and comparison to obtain the most accurate prediction performance. The artificial neural network model with 2 hidden layers outperforms the other optimizations with 11.27% estimation error, 0.96 R2 and 0.98 correlation coefficient for the testing data set. Finally, an empirical correlation was developed to accurately estimate PVBT at a low cost and very short time compared to lab experiments and numerical simulation models. The novelty of this research stems from examining PVBT curves behavior by varying five matrix acidizing parameters independently, analyzing the correlation between these parameters and developing machine learning model for handy and reliable optimum PVBT estimation.
The hydrocarbon generation of source rocks is significantly influenced by organic matter type, chemical element composition, and structural characteristics of kerogen. We classified the organic matter types in the shale of the Lucaogou Formation, Jimusar Sag, Junggar Basin, using organic petrology and rock pyrolysis as well as kerogen element and Fourier transform infrared (FT-IR) spectroscopy analyses, and compared the hydrocarbon generation mechanisms of source rocks with different types of organic matter. The organic matter of the Lucaogou Formation contains mostly two types of hydrocarbon generating macerals, the lamalginite and the telalginite based on physical and optical properties (texture, fluorescence, and optical reflectance). The lamalginite is a continuous sheet of less than 5 μm thick and greater than 50 μm in length. It has strong yellow fluorescence. The telalginite occurs as discontinuous short strips or pear-shaped objects with length of 10–30 μm and relatively weak fluorescence. The lamalginite-dominated shale has higher atomic H/C and lower atomic O/C ratios, indicating better hydrocarbon generation potential, whereas the telalginite-dominated shale has higher N and S heteroatom contents. The results of FT-IR spectroscopy of the kerogen indicate that the lamalginite-dominated shale is rich in aliphatic groups with long linear methylene sequences. The aromatic groups content is relatively low, but the carboxyl/carbon group (CO) content is high. The aliphatic group content of the telalginite-dominated shale is relatively low, with short-branched chains. The aromatic group content is relatively high. The methyl vibration signal directly connected to the benzene ring is strong, and the sulfoxide (SO) group has a high-intensity peak. Our results provide new insights into distinguishing organic matter types in the Lucaogou Formation and understanding the hydrocarbon generation mechanisms of source rocks in saline lake basins.
Production of electric energy or power. Powerplants. Central stations
Franci Gabrovšek, Matej Blatnik, Nataša Ravbar
et al.
The aquifers of alpine karst and high karst plateaus are abundant water resources. They are difficult to characterise due to their complex, partly glaciokarstic, evolution in active tectonic environments, and an unsaturated zone up to two kilometres thick. We present and discuss the results of a tracing test in the alpine karst of the Julian Alps (Slovenia), more precisely in the Migovec System, the longest cave system in Slovenia (length = 43 km, depth = 972 m). The cave extends below a mountain ridge that separates the Soča and Sava Valleys, thus forming a topographic divide between the Adriatic and Black Sea basins, which gives the test greater regional significance. In early September 2019, three kilograms of uranine were injected into a perched lake in a remote part of the system, approximately 900 metres below the plateau and 100 metres above the low water table. All known springs in the valleys on either side of the mountain were monitored by manual or instrumental sampling and a field fluorometer. Due to the unexpectedly dry season, no tracer was detected at any site for two months until a heavy rainfall event in early November. Subsequently, about 60-65 % of the tracer mass appeared within 60 hours in the Tolminka River. No tracer was detected at other sites, either because
it was not present or because it was highly diluted. The study suggests that the lake containing the tracer is bypassed by the vadose flow and that the tracer was only mobilised during large events when the lake became part of the epihreatic flow. The linear peak flow velocity from the injection site to the Tolminka Spring was only about 1.7 m/h. However, assuming that the tracer was only mobilised by the large rain event, the velocity would be 70 m/h. The study highlights the challenges and pitfalls of water tracing in alpine karst systems and suggests ways to avoid them.
The highly siderophile element (HSE) or platinum group element (PGE) and Os isotope systematics of basaltic volcanics have recently received a significant attention because of their potential to constrain the petrological processes on magma generation and evolution. The HSE and Os isotope data, which are generally observed at very low concentrations in basalts and obtained by modern enrichment and analytical techniques, are frequently used in petrological studies. The HSE contents and ratios from whole-rock analysis of basalts, and combined evaluation with the theoretical knowledge and modelling of HSE behaviour during the partial melting of mantle and the differentiation of basaltic magma would provide opportunity for geochemical modelling on mantle melting. Besides, HSE contents and Pd-PGE/Ir-PGE ratios are important indicators for the nature of mantle sulfides, the sulfur saturation conditions of the mantle source, sulfide segregation, fractional crystallization, crustal assimilation and partial melting degrees in the origin and evolution of mantle-derived magmas. Therefore, in addition to the traditional whole-rock geochemical data obtained from Cenozoic aged basalts observed widely in Turkey, HSE and Os isotope systematics of these basalts can contribute to define the geochemical features of the mantle source, and to model petrological processes which are effective in the magma evolution.
Dolines are small to intermediate enclosed depressions and are the most numerous karst feature in Slovenia. They are circular in plan form and vary in diameter from a few metres to over a kilometre. They are developed in limestone, dolomite, carbonate breccia and conglomerate and occupy different geomorphic settings. They were formed by various processes like dissolution, collapse, suffosion and transformation of caves to surface features by denudation. Publicly accessible lidar data, provided by a nationwide laser scanning project of Slovenia, was used for this study. To catalogue the dolines, we manually label a fraction of the digital elevation model (DEM) with a binary mask indicating if the area is a doline or not. We then train a slightly modified u-net, a type of machine learning algorithm, on the labelled territory. Using the trained algorithm, we infer the binary mask on the entire DEM. We convert the resulting mask into an ESRI Shapefile and manually verify the results. We note that the training and inference are error prone on types of relief that were less common in the training set (e.g., the relatively uncommon collapse dolines). We believe manual verification mitigates most of these errors, so the resulting map is a good basis for the doline study. We have made our georeferenced catalogue of dolines available at https://dolines.org/ (Mihevc & Mihevc 2021). Dolines are found in most of the karst areas, except mountains where they were eroded by glacial action or covered by glacial deposits. We detected 471,192 dolines and divided them into three genetic types. Most abundant are solution dolines (470,325). The average doline is 9 m deep, has a diameter of 42 m and a volume of 14,098 m3. The density of dolines on levelled surfaces can be as high as 500/ per km2. They are absent from the floors of poljes and steeper slopes, and are less abundant on sloping surfaces. We have identified 314 dolines to be of collapse origin. The mean depth of collapse dolines is 49 m, and 20 of them are deeper than 100 m. The mean volume is 1.2 million m3, with the largest having a volume of 11.6 million m3. Most of the collapse dolines can be found close to ponors or springs or corridors where large underground rivers flow. We have detected 553 suffosion dolines formed by suffosion of sediments in blind valleys or on poljes. This basic data set for dolines enables further study and comparison of dolines with the geology and topography of the karst.
Abstract Evaluating reservoir performance could be challenging, especially when available data are only limited to pressures and rates from oil field production and/or injection wells. Numerical simulation is a typical approach to estimate reservoir properties using the history match process by reconciling field observations and model predictions. Performing numerical simulations can be computationally expensive by considering a large number of grids required to capture the spatial variation in geological properties, detailed structural complexity of the reservoir, and numerical time steps to cover different periods of oil recovery. In this work, a simplified physics-based model is used to estimate specific reservoir parameters during CO2 storage into a depleted oil reservoir. The governing equation is based on the integrated capacitance resistance model algorithm. A multivariate linear regression method is used for estimating reservoir parameters (injectivity index and compressibility). Synthetic scenarios were generated using a multiphase flow numerical simulator. Then, the results of the simplified physics-based model in terms of the estimated fluid compressibility were compared against the simulation results. CO2 injection data including bottom hole pressure and injection rate were also gathered from a depleted oil reef in Michigan Basin. A field application of the simplified physics-based model was presented to estimate above-mentioned parameters for the case of CO2 storage in a depleted oil reservoir in Michigan Basin. The results of this work show that this simple lumped parameter model can be used for a quick estimation of the specific reservoir parameters and its changes over the CO2 injection period.
Abstract Improving the accuracy and enhancing the reliability of controlled-source electromagnetic (CSEM) inversion in oil exploration in order to identify the interface between oil and water is a great challenge. In this paper, we proposed a variable-angle geometry imaging method by moving the source of CSEM (MCSEM). Firstly, based on the concept of multi-channel transient electromagnetic method, we obtained the quantitative relationship between the offset and detection depth, and then the geometry imaging principle of MCSEM was set up. Secondly, the feasibility study of the geometry imaging method was tested through the 1-D and 3-D forward modeling. Finally, by analyzing the collected field data of MCSEM method in Daqing oil reservoir, high-accuracy pseudo-apparent resistivity profile was obtained based on the geometry imaging method with the help of well-logging calibration. The results showed good compatibility with the 2-D TEM resistivity inversion which demonstrates that the MCSEM has great prospect potential in the identification of oil–water interface explorations.
Nasser Madani, Bijan Biranvand, Asghar Naderi
et al.
Abstract Deterministic modeling lonely provides a unique boundary layout, depending on the geological interpretation or interpolation from the hard available data. Changing the interpreter’s attitude or interpolation parameters leads to displacing the location of these borders. In contrary, probabilistic modeling of geological domains such as lithofacies is a critical aspect to providing information to take proper decision in the case of evaluation of oil reservoirs parameters, that is, applicable for quantification of uncertainty along the boundaries. These stochastic modeling manifests itself dramatically beyond this occasion. Conventional approaches of probabilistic modeling (object and pixel-based) mostly suffers from consideration of contact knowledge on the simulated domains. Plurigaussian simulation algorithm, in contrast, allows reproducing the complex transitions among the lithofacies domains and has found wide acceptance for modeling petroleum reservoirs. Stationary assumption for this framework has implications on the homogeneous characterization of the lithofacies. In this case, the proportion is assumed constant and the covariance function as a typical feature of spatial continuity depends only on the Euclidean distances between two points. But, whenever there exists a heterogeneity phenomenon in the region, this assumption does not urge model to generate the desired variability of the underlying proportion of facies over the domain. Geophysical attributes as a secondary variable in this place, plays an important role for generation of the realistic contact relationship between the simulated categories. In this paper, a hierarchical plurigaussian simulation approach is used to construct multiple realizations of lithofacies by incorporating the acoustic impedance as soft data through an oil reservoir in Iran.
Maria Chavideh, Mohsen Tabatabaei Manesh, Mohammadali Makizadeh
The Oligo-Miocene Qazan granitoid body caused contact metamorphic of surrounding rocks and skarn formation in the wall limestone. The main intrusive rocks are essentially granite to diorite in composition. Two different types of skarn, exo and endoskarn have been developed. On the base of microprobe data, the northern skarn are characterized by zoning and the amounts of andradite and grossular changes oscillatory. While garnets from the southwestern skarn is predominantly andradite in composition. Using Fe/Ti vs. Al/ (Al+Fe+Mn) diagram that were calculated based on the mole percent of the used elements, it is estimated that about less than 50 percent hydrothermal waters were involved for the northern skarn whereas it was over this amount for the southwestern skarn. This leds to difference in garnet composition. The composition of clinopyroxene in both skarns is the same (diopside). As a result, hydrothermal fluids have not had much influence on pyroxene genesis. With regards to the occurrence of mineral assemblage and the presence of wollastonite in the skarns under study, these rocks have evolved in temperature above 500 ° C and O2 fugacity in the range of 10-17 to 10-15.
Qian-Yong Liang, Yong-Qiang Xiong, Jing Zhao
et al.
Abstract Three series of laboratory vaporization experiments were conducted to investigate the carbon isotope fractionation of low molecular weight hydrocarbons (LMWHs) during their progressive vaporization. In addition to the analysis of a synthetic oil mixture, individual compounds were also studied either as pure single phases or mixed with soil. This allowed influences of mixing effects and diffusion though soil on the fractionation to be elucidated. The LMWHs volatilized in two broad behavior patterns that depended on their molecular weight and boiling point. Vaporization significantly enriched the 13C present in the remaining components of the C6–C9 fraction, indicating that the vaporization is mainly kinetically controlled; the observed variations could be described with a Rayleigh fractionation model. In contrast, the heavier compounds (n-C10–n-C12) showed less mass loss and almost no significant isotopic fractionation during vaporization, indicating that the isotope characteristics remained sufficiently constant for these hydrocarbons to be used to identify the source of an oil sample, e.g., the specific oil field or the origin of a spill. Furthermore, comparative studies suggested that matrix effects should be considered when the carbon isotope ratios of hydrocarbons are applied in the field.
Encarnación Ruiz-Agudo, Alejandro Burgos-Cara, Cristina Ruiz-Agudo
et al.
The formation mechanism of abundant calcium oxalate biomaterials is unresolved. Here the authors show the early stages of calcium oxalate formation in pure and citrate-bearing solutions by using a titration set-up in conjunction with solution quenching, transmission electron microscopy and analytical ultracentrifugation.
Magmatic processes have usually been identified and evaluated using qualitative or semiquantitative geochemical or isotopic tools based on a restricted number of variables. However, a more complete and quantitative view could be reached applying multivariate analysis, mass balance techniques, and statistical tests. As an example, in this work a statistical and quantitative scheme is applied to analyze the geochemical features for the Sierra de las Cruces (SC) volcanic range (Mexican Volcanic Belt). In this locality, the volcanic activity (3.7 to 0.5 Ma) was dominantly dacitic, but the presence of spheroidal andesitic enclaves and/or diverse disequilibrium features in majority of lavas confirms the operation of magma mixing/mingling. New discriminant-function-based multidimensional diagrams were used to discriminate tectonic setting. Statistical tests of discordancy and significance were applied to evaluate the influence of the subducting Cocos plate, which seems to be rather negligible for the SC magmas in relation to several major and trace elements. A cluster analysis following Ward’s linkage rule was carried out to classify the SC volcanic rocks geochemical groups. Finally, two mass-balance schemes were applied for the quantitative evaluation of the proportion of the end-member components (dacitic and andesitic magmas) in the comingled lavas (binary mixtures).
Variations of soil/cave CO2 concentrations and further variables suchas temperature, humidity, and cave visitor attendance were studied in two sites of the Moravian Karst (CzechRepublic). All the variables showed the same seasonality; they were strongly correlated witheachother. The dependence of soil CO2 levels on soil air temperature and absolute humidity was confirmed. Individual effects could not be distinguished because of multicollinearity. The effect of vegetation on soil CO2 production was not recognized. Cave attendance was identified as the most significant predictor of cave CO2 levels. Other variables, soil CO2 and temperature gradients, were less significant. A spurious relationship was alternatively considered, in whichexternal temperature was the universal predictor of cave CO2 levels.