Gas Inclusions Research Articles

STUDY OF INFLUENCE OF HIGHER HARMONICS ON RELIABILITY CABLE NETWORKS

This study is devoted to the analysis of the cable network of industrial enterprises with a significant number of cable lines with a voltage of 10 kV. A feature of this electric power supply unit is a powerful direct current valve electric drive for rolling production. The schematic diagram of the cable network is shown in the figure, the total length of the cables is more than 20 km. The results of previous experimental studies made it possible to determine the magnitude and spectrum of harmonics in this node, namely: in 5 harmonics do not exceed 1.5%, but abnormal n = 22—40 determine the value of the non-sinusoidal voltage coefficient within the limits of 5.5—8.9%, which exceeds the 5% norm. The plans of the conducted research also included the measurement of single-phase ground fault currents, which gave the following results for workshop substations: PS-4 — 24.2 A; PS-5 — 17.3 A; PS-5 — 14.8 A. Analyzing the problem of the reliability of cable networks, it is necessary to take into account one more indicator — the value of the leakage currents. A significant number of high-voltage cables are insulated with cable paper impregnated with oil-rosin mastic. Such insulation contains gas inclusions that, under the influence of high-frequency electric shocks, are ionized with subsequent neutralization, which leads to its local damage. Oscillograms of the supply voltage show a sharp shape of the curve as a result of the presence of higher harmonics, which causes the aging of the insulation due to the acceleration of physicochemical processes in the dielectric. Thus, the results of theoretical and experimental studies made it possible to substantiate the main factors that determine the operational reliability of cables, namely: the dynamics of leakage currents, the value of the coefficient of non-sinusoidal voltage caused by abnormal harmonics. Analysis of the specified characteristics allows you to assess the current state of the cable network and predict the reliability of work in the future.

Determination of the pressure and composition of wet gas fluid inclusions: An in situ Raman spectroscopic approach

Carbonaceous fluid within mineral-hosted inclusions provides important information for carbon cycle in deep Earth. In addition to CH4 and CO2, heavy hydrocarbons (e.g., C2H6 and C3H8) are frequently observed in carbonaceous fluid inclusions (i.e, wet gas inclusions with C1/∑Ci < 0.95). However, determination of the composition of such complex volatiles is difficult based on traditional microthermometric measurements. Here we carried out experimental calibrations on Raman spectroscopic measurements of the pressure (P) and composition of the CH4 ± C2H6 ± C3H8 ± H2S system at room temperature and 0.1–130 MPa. We confirmed that the C–H symmetric stretching vibration band of CH4 [ν1(CH4), ∼2917 cm−1] shifted to lower wavenumber with rising pressure, thus the P-ν1(CH4) relationship could be applied to calculate the pressure of wet gas. It should be noted that the presence of C2+ and/or H2S will shift the [ν1(CH4)] to lower wavenumber at constant pressure (with the order of C3H8 ≥ H2S > C2H6). Obviously, the P-ν1(CH4) relationship derived from pure CH4 system could not be simply applied to wet gas inclusion, otherwise the pressure would be overestimated. To avoid the overlap of the C–H vibrations of CH4, C2H6 and C3H8, the peak areas and peak heights of the overtone vibration of CH4 [2ν4(CH4), ∼2580 cm−1], C–C symmetric stretching vibrations of C2H6 [ν3(C2H6), ∼995 cm−1] and C3H8 [ν8(C3H8), ∼868 cm−1], and S–H symmetric stretching vibration of H2S [ν1(H2S), ∼2612 cm−1] were fitted using Gaussian + Lorentz functions. The obtained peak areas and peak heights were then used to calculate the Raman quantification factors (F factor and G factor, respectively) of C2H6, C3H8 and H2S relative to CH4, respectively. Both the F factor and G factor increased with rising pressure, whereas the FC2H6, FC3H8 and GH2S kept nearly constant at ∼5.69, 6.39 and 153.8, respectively in high pressure gas mixtures (e.g., >30 MPa). Therefore, for inclusions with higher internal pressure, the molar ratio of CH4, C2H6, C3H8 and H2S could be determined by the aforementioned F and G factors. This method was applied to the calcite-hosted single-phase gas inclusions in the Upper Permian Changxing Formation carbonate reservoir from the eastern Sichuan Basin (South China). Our results indicated that the trapping pressure would be obviously overestimated if the presence of heavy hydrocarbons was not taken into account.

Further study on the genesis of lamellar calcite veins in lacustrine black shale—A case study of Paleogene in Dongying Depression, China

Lamellar calcite veins are prevalent in carbonate-rich, lacustrine dark shale. The formation mechanisms of these veins have been extensively debated, focusing on factors such as timing, depth, material source, and driving forces. This paper examines dark lacustrine shale lamellar calcite veins in the Paleogene strata of Dongying Depression, using various analytical techniques: petrography, isotope geochemistry, cathodoluminescence, inclusion thermometry, and electron probe micro-analysis. Two distinct types of calcite veins have been identified: granular calcite veins and sparry calcite veins. These two types differ significantly in color, grain structure, morphology, and inclusions. Through further investigation, it was observed that vein generation occurred from the shallow burial period to the maturation of organic matter, with a transition from granular calcite veins to sparry calcite veins. The granular calcite veins exhibit characteristics associated with the shallow burial period, including plastically deformed laminae and veins, the development of strawberry pyrite, the absence of oil and gas, weak fractionation in oxygen isotopes, and their contact relationship with sparry calcite veins. These granular calcite veins were likely influenced by the reduction of sulfate bacteria. On the other hand, sparry calcite veins with fibrous grains are antitaxial and closely linked to the evolution and maturation of organic matter. They contain oil and gas inclusions and show a distribution range of homogenization temperature between 90 °C and 120 °C and strong fractionation in oxygen isotopes, indicating formation during the hydrocarbon expulsion period. The carbon isotope analysis of the surrounding rocks and veins suggests that the material for vein formation originates from the shale itself, specifically authigenic micritic calcite modified by the action of methanogens. The opening of horizontal fractures and vein formation is likely driven by fluid overpressure resulting from undercompaction and hydrocarbon expulsion. Veins may form rapidly or through multi-stage composite processes. Early veins are predominantly formed in situ, while late veins are a result of continuous fluid migration and convergence. Furthermore, the veins continue to undergo modification even after formation. This study emphasizes that the formation of lamellar calcite veins in shale is a complex diagenetic process influenced by multiple factors: biology, organic matter, and inorganic processes, all operating at various stages throughout the shale's diagenetic history.

In situ U-Pb dating of carbonate veins in Cambrian shales constrains fluid flow and hydrocarbon evolution at the southeastern margin of the Upper Yangtze platform, southwestern China

Fluid flow in sedimentary basins not only impacts redistribution of the geothermal cycle and precipitation of ore deposits, but also exerts control on hydrocarbon migration and accumulation. However, reconstructing the history of fluid flow in basins that have experienced multiple tectonic deformation events is exceedingly difficult. Here, we examined petrography, in situ U-Pb geochronology, and rare earth element (REE) and C-O isotope geochemistry, as well as fluid inclusion microthermometry of fracture fillings within the Cambrian Niutitang Formation shales at the southeastern margin of the Upper Yangtze platform, southwestern China. The results show that four main fluid flow pulses are identified based on cathodoluminescence images, U-Pb ages, and geochemical data, namely, 446−428 Ma (fibrous calcite and barytocalcite), 343−329 Ma (calcite I), 113 Ma (calcite II), and 63 Ma (calcite III). The fibrous calcite (ca. 446 Ma) and barytocalcite (ca. 428 Ma) veins, corresponding to the late Caledonian Orogeny, show significantly positive Eu-Y anomalies, negative Ce anomalies, and enrichment in heavy REE, similar to their host rocks, suggesting that the mineral-forming fluids were derived mainly from dissolution of the host rocks. An abundance of bitumen inclusions with homogenization temperatures (Th) of 93.1−137.4 °C and high salinities (5−8 wt%) indicate that the first fluid flow pulse occurred during the oil generation stage in a closed fluid system. Calcite I (ca. 343−329 Ma) exhibits REE depletion and high Y/Ho ratios, a low fluid inclusion salinity (2−10 wt%) with Th = 78.4−125.8 °C, and C-O isotopic compositions similar to the underlying marine carbonates. This suggests that calcite I formed in an open fluid system, which was related to the transition from compression to extension during the Hercynian Orogeny. The pre-existing faults were reactivated and opened, resulting in the leakage and reconstruction of hydrocarbon reservoirs. Calcite II (ca. 113.4 Ma) has similar REE+Y patterns and C-O isotopic compositions to the host rocks. It contains abundant single-phase hydrocarbon gas (CH4) inclusions with high Th (164.1−211.1 °C) and salinity (6−14 wt%) values, indicating that the third phase fluid was derived largely from the host rocks and migrated during the early Yanshanian Orogeny. Lastly, calcite III (ca. 62.7 Ma) exhibits extremely low REE concentrations, low δ13CPDB [Peedee belemnite] values (−6.74‰), and low fluid inclusion salinities (0.3−7.0 wt%) with Th = 61.9−97.1 °C, suggesting that the fourth fluid flow pulse was affected by meteoric water to some extent. This can be interpreted to represent an open fluid system, which caused gas dispersion in the Niutitang Formation shales. Our findings provide important references for reconstructing the history of fluid flow in tectonically complex basins worldwide.

Pneumoparotitis in a child. Clinical observation

Emphysematous parotitis is a casuistically rare disease of the parotid salivary gland. Especially in childhood, a rare clinical observation of idiopathic emphysematous parotitis in an 11-yearold child with a pronounced edema of the right half of the face without signs of intoxication is presented. Massive gas inclusions in the soft tissues of the face and neck were detected by ultrasound, minimal ones – in the anterior mediastinum. The diagnosis was confirmed by CT and MRI. Recovery was on the background of conservative therapy. The publication is illustrated with data of radiologic scans, supplemented with a brief review of the literature.

Pb-Zn mineralization formed from coupled hydrocarbon-bearing and hydrothermal fluids in the Ediacaran strata in the central Sichuan Basin, China

Hydrocarbon-bearing fluid plays a crucial role in the Pb-Zn mineralization process. The hydrocarbon role is still the subject of metallogenic research. This study determined the metal and sulfur sources and the hydrocarbon role in the mineralization instigated by mixing of hydrothermal and hydrocarbon-bearing fluids in the central Sichuan Basin based on petrography, fluid inclusion geochemistry, S and Pb isotope compositions, and changes in hydrocarbon phases and components. The results indicated that hydrothermal input significantly improved the salinity and temperature of reservoir fluids. Hydrothermal stages can be divided into three: (Ⅰ) pyrite and dolomite, (Ⅱ) quartz and sphalerite, and (Ⅲ) galena. Solid bitumen was formed at stage Ⅱ, and the oil inclusions were converted into gas inclusions from stage Ⅰ to Ⅱ, suggesting that the hydrothermal fluids caused the oil cracking. The Pb isotope compositions of pyrite, sphalerite, and galena showed that the Pb-Zn deposit had two metal sources from surface karst and hydrothermal fluids. Raman spectroscopy and sulfur isotope compositions implied that H2S formed during hydrothermal input was generated from TSR resulting from hydrothermal sulfate. The H2S produced by TSR preferentially led to the precipitation of metals (Pb, Zn, and Fe) derived from the hydrothermal fluid, followed by the precipitation of metals derived from the karst fluid. After the metal elements in the reservoir were depleted, the remaining H2S was conserved together with the natural gas in the reservoir. This study unravels the transformation of oil to gas and the H2S generation in the reservoir through hydrocarbon inclusion analysis in the metallogenic study, providing new insight into the Pb-Zn mineralization involving hydrocarbon-bearing fluid participation.

Rigorous hybrid machine learning approaches for interfacial tension modeling in brine-hydrogen/cushion gas systems: Implication for hydrogen geo-storage in the presence of cushion gas

In light of the environmental consequences linked to the burning of fossil fuels, there is a mounting push to devise cleaner means of energy generation. The production of hydrogen is gaining momentum as a favored avenue for enabling the shift toward sustainable energy. Effective hydrogen storage is crucial for sustainable energy solutions, and the inclusion of cushion gas in geological storage could aid in maintaining formation pressure during hydrogen reproduction while expanding pore volumes for gas by preventing water presence in pores. Accurately controlling hydrogen behavior and interactions in porous media is crucial for successful storage, with interfacial tension between gas and water playing a significant role in the trapping and mobilizing the phases. Thus, developing a predictive tool to simulate interfacial tension measurements is essential. This study employs various intelligent modeling techniques, including Adaptive Neuro-Fuzzy Inference System, Multilayer Perceptron optimized with Bayesian Regularization, Levenberg-Marquardt, and Scaled Conjugate Gradient algorithm, Grey Wolf Optimizer-based Least Squares Boosting (GWO-LSBOOST), GWO-based Radial Basis Function, GWO-based Least Squares Support Vector Machine, and Extreme Learning Machine (ELM), to develop interfacial tension models for brine-hydrogen/cushion gas systems. Applying these models developed based on diverse theories, structures, and performance characteristics helps identify the optimal predictor for the target parameter. The evaluation of the models was carried out using 2868 experimental data points. The achieved results demonstrated the satisfactory performance of different modeling techniques (with R2 falling within the range of 0.8979 to 0.9960), however, GWO-LSBOOST outperformed others (improving R2 from 0.8979 to 0.9960 and AARE% from 5.5714 % to 0.8060 %, compared to ELM). Leverage outlier identification and trend estimation analysis confirmed the statistical reliability of the dataset and the GWO-LSBOOST model. The formulated strategies offer a promising framework applicable for incorporating the gas-water interfacial tension in simulating various stages of gas injection/ reproduction in underground hydrogen storage.

Natural hydrogen in low temperature geofluids in a Precambrian granite, South Australia. Implications for hydrogen generation and movement in the upper crust

Natural hydrogen (H2) has the potential to be a low-carbon fuel and energy source, playing a crucial role in achieving a clean, secure, and affordable energy future. However, our understanding of the generation, migration, and accumulation of H2 in the subsurface remains poorly constrained. Increasing evidence suggests that H2 is abundantly and widely present in various geological settings, making them viable targets for exploration of this emerging resource. Reports have indicated the presence of hydrogen-dominated natural gas in vintage boreholes located in the Yorke Peninsula and Kangaroo Island, South Australia. These boreholes were drilled in Cambrian sedimentary cover over Precambrian terranes that host iron ore, copper or gold ore deposits. To gain insight into these occurrences, rock samples were examined from the Roxby Downs granite, a Mesoproterozoic pluton associated with the Hiltaba Suite event (1.59 Ga), belonging to the same magmatic origin as the Yorke Peninsula basement.Our investigation revealed metasomatic fluid circulation, evidenced by alteration of feldspar and mafic grains, as well as discrete cemented fractures within the granite. In some of these fracture-fill cements, we discovered water and gas inclusions containing hydrogen. The formation of the hydrogen-bearing cements occurred at paleo-temperatures ranging from 170 °C to the present-day 55 °C. Analysing the oxygen isotope values of the quartz cements and considering their fluid inclusion temperatures, a marine water signature as the source of water in equilibrium with the quartz cements was identified.To constrain the fluid history, neon and argon isotope signatures from the fluid inclusion gases were measured from the granite and separated quartz grains. Nucleogenic neon isotopes increased with depth along specific production lines. While this is consistent with long-lived fluid within the granite and increasing fluid residence with depth, separated quartz grains show less variation with depth and suggest that younger fluids were introduced, triggering alteration of less robust minerals, visible in bulk granite. Petrographic analyses identified hydrolytic alterations of mafic minerals into magnetite, and subsequently magnetite to hematite, as sources of hydrogen and contributors to the observed increase in pore water salinity. Our findings highlight that natural hydrogen can be produced and retained in granites at low temperatures, expanding beyond the commonly reported alteration processes observed in mafic and ultramafic rocks.

Selective Noble Gas Inclusion in Pentagon-Dodecahedral X20-Cages.

Using DFT-based computational chemistry calculations (ωB97XD/def2-tzvp//ωB97XD/def2-svp/svpfit + ZPE(ωB97XD/def2-svp/svpfit)), binding energies of noble gases encapsulated in a series of dodecahedrane molecules (general formula: X20H20 where X = C, Si, Ge, Sn and Pb, and X20 where X = N, P, As, Sb and Bi) were calculated to learn about the noble gas selectivity. Based on calculated binding energies, the Sn20H20 cage can best accommodate noble gases with a medium size radius (Ar and Kr), while the Pb20H20 dodecahedrane cage is best suited for noble gases with the larger radii (Xe and Rn). On the other hand, from the elements of the V main group of the periodic table, the Bi20 cage has shown the best results to selectively encapsulate Ar and Kr, with the amounts of energy being released being -5.24 kcal/mol and -6.13 kcal/mol, respectively. By monitoring the geometric changes of all here-reported host cages upon encapsulating the noble gas guest, the host has shown minor to no flexibility, testifying to the high rigidity of the dodecahedrane structure which was further reflected in very high encapsulating energies.

Paleo fluid system change from deep burial to exhumation of the Precambrian petroleum reservoirs in the Sichuan Basin, China: Evidence from P-T-X records

Economically viable accumulations of hydrocarbons hosted in the Precambrian rocks are globally rare, as a protracted history available for them to escape or be destroyed due to various processes including thermal and bacterial degradations and tectonic disruption. A recent gas discovery in the late Ediacaran dolomites of the Sichuan Basin (SW China) provides an opportunity to understand the formation and preservation of ancient petroleum systems. Paleo fluid pressure-temperature-composition (P-T-X) conditions from deep burial to exhumation are evaluated from microthermometry and Raman data obtained from fluid inclusions.We identified three texturally distinct generations of gas-bearing fluid inclusion assemblages (FIAs), which delineate an operating petroleum system where gas remigrated during exhumation that followed oil cracking during deep burial. The older FIAs (types 1 and 2) show a petrographic association with bitumen and are interpreted to be the result of thermal cracking. Type 1 FIAs formed through in-situ cracking of pre-existing oil inclusions and have recorded the paleo oil charge during the middle Triassic to early Jurassic. Type 2 FIAs were trapped during the prolonged intra-reservoir oil cracking that occurred between the late Jurassic and late Cretaceous. Our pore pressure calculations indicate overpressured conditions, a result of active gas generation during thermal cracking. Lithostatic overpressures accumulated and were sustained under weak tectonic compression prior to peak burial.Type 3 FIAs have been interpreted as reflective of the gas-bearing system reactivation during exhumation. These FIAs indicate the relative reduction in the proportion of aqueous to gas inclusions, which may be due to a decrease in water saturation following gas emplacement. Uplift processes during early exhumation likely facilitated breaching of the system and remobilization of fluids, resulting in gas escape and overpressure release. The drastic increase in formation water salinity, which was documented in the fluid inclusion dataset, points to the arrival of hypersaline brine during the Eocene to Oligocene. This brine could have originated either from the lower Cambrian evaporated CaCl2 seawater or from the dissolution of the lower-middle Triassic halite. From the late Miocene to present, progressively exhumed reservoirs may have received an influx of relatively fresh water from shallow aquifers, as shown by the correspondence between P-T-X records and present-day reservoir conditions.

Co-electrolysis of seawater and carbon dioxide inside a microfluidic reactor to synthesize speciality organics

We report co-electrolysis of seawater and carbon dioxide (CO2) gas in a solar cell-integrated membraneless microfluidic reactor for continuous synthesis of organic products. The microfluidic reactor was fabricated using polydimethylsiloxane substrate comprising of a central microchannel with a pair of inlets for injection of CO2 gas and seawater and an outlet for removal of organic products. A pair of copper electrodes were inserted into microchannel to ensure its direct interaction with incoming CO2 gas and seawater as they pass into the microchannel. The coupling of solar cell panels with electrodes generated a high-intensity electrical field across the electrodes at low voltage, which facilitated the co-electrolysis of CO2 and seawater. The paired electrolysis of CO2 gas and seawater produced a range of industrially important organics under influence of solar cell-mediated external electric field. The, as synthesized, organic compounds were collected downstream and identified using characterization techniques. Furthermore, the probable underlying electrochemical reaction mechanisms near the electrodes were proposed for synthesis of organic products. The inclusion of greenhouse CO2 gas as reactant, seawater as electrolyte, and solar energy as an inexpensive electric source for co-electrolysis initiation makes the microreactor a low-cost and sustainable alternative for CO2 sequestration and synthesis of organic compounds.

Study on Oil and Gas Inclusions and Oil and Gas Accumulation Stages in Majiatan Area, Western Margin of Ordos Basin

The western edge of the Ordos Basin has abundant oil and gas resources. To explore the stages and direction of hydrocarbon fluids migration in petroliferous basins, the hydrocarbon-bearing strata in the Majiatan area on the west margin of the Ordos Basin was analyzed based on petrographic observations, homogenization temperature, salinity and composition of inclusions. The inclusions can be identified as five types. Type I, II and III inclusions exhibit abundant hydrocarbon content, whereas Type IV and V show poor hydrocarbon content. Based on homogenization temperature and salinity analysis, the five types of inclusions can be divided into two-stage formation, Type I, II and III included in the early stage and Type IV and V formed in the late stage. The direction of the hydrocarbon fluid migration of the early and late stages was from the southeast to the northwest, and the difference between the two stages of hydrocarbon fluid migration and inclusions formation depends on the fault activity from the Triassic to the Jurassic. This study is of great significance for future exploration of oil and gas in the Ordos Basin's western margin.

Hydrocarbon Accumulation Periods in the Upper Paleozoic Strata of the Western Ordos Basin, China, Based on Fluid Inclusions and Basin Modeling.

The upper Paleozoic strata in the western part of the Ordos Basin have rich oil and gas resources but low exploration levels. These strata were subjected to multiple tectonic events, such as the Caledonian, Hercynian, Indosinian, and Himalayan movements, which led to a relatively complex process of hydrocarbon accumulation in the study area. These strata also have obvious structural segmentation in the north-south direction. However, the accumulation periods of the upper Paleozoic strata in different structural sections of the western Ordos Basin and their differences are poorly understood. A total of 65 sandstone samples from the upper Paleozoic reservoirs in 16 representative wells were selected for fluid inclusion analyses. The results of fluid inclusion analyses, combined with the burial-thermal histories of representative wells, were used to determine the hydrocarbon accumulation periods of the main layers and summarize their patterns in different structural regions and layers. The results show that the formation of fluid inclusions in the main upper Paleozoic strata can be divided into two stages. The first-stage inclusions mainly occur in secondary quartz edges, and the second-stage inclusions mainly occur in healed microcracks. The inclusion types are dominantly hydrocarbon-bearing, brine, and minor nonhydrocarbon gas inclusions. The hydrocarbon components are mostly CH4 and minor asphaltene, and the nonhydrocarbon gases are dominantly CO2 and minor SO2. The homogenization temperatures of the brine inclusions associated with hydrocarbon inclusions in major layers in the study area have a wide distribution and multiple peaks; the main peaks in the central part of a given tectonic area are slightly lower than those in the eastern part, and the main peaks in a given location tend to increase with decreasing burial depth. Hydrocarbon accumulation in the upper Paleozoic strata in the study area mainly occurred in the Early and Middle Jurassic and Early Cretaceous. The Early and Middle Jurassic were the mature oil and gas accumulation periods, and the Early Cretaceous was the high-maturity natural gas accumulation period and the most critical accumulation period. The accumulation period in the central part of a given structural region occurred earlier than that in the eastern part, and the accumulation period in different layers in a given location gradually shifted at a later time from deep to shallow.

PROSPECTS FOR THE USE OF WOVEN METAL MESHES AS PHASE SEPARATORS

The constant complication of the tasks that arise before spacecraft during their flight mission puts very high demands on the fuel supply system. First of all, during orbital flight, very often there is a need to restart the main engines, or a constant supply of fuel to the engines of the control system. It is necessary to deliver fuel from tanks to engine combustion chambers in conditions of practical weightlessness. To ensure the ingress of fuel components from the tank into the drain line without gas inclusions, a fuel continuity system is added to the fuel supply system. &#x0D; Among the various systems for ensuring fuel continuity, the most widespread over the past fifty years have been mesh phase separators, the main working element of which is woven metal mesh.&#x0D; The paper considers the basic properties of systems of this type, their main design parameters from the point of view of the possibility of their improvement and the possibility of use in future designs of spacecraft. Considerable attention is paid to the shortcomings inherent in systems of this type. Possible ways to eliminate the limitations of the use of mesh phase separators through the development of new engineering design techniques and the use of modern technologies to create analogues of woven metal meshes, which are devoid of their main drawbacks, are considered.

Quartz-Hosted Fluid Inclusions in Commercial Ores of Various Type at the Verninskoe Gold Deposit, Bodaibo District, Russia

The paper presents data on quartz-hosted fluid inclusions in commercial ores of various type (veinlet−disseminated and vein) of the Verninskoe gold deposit. The ores of various types were found out to significantly vary in the values of some of their physicochemical parameters of the fluids and in the composition of these fluids. The fluids that formed the gold veins have a somewhat higher initial temperature (356–246°C), a higher density of carbon dioxide in gas inclusions (1.00–0.84 g/cm3), and a higher fluid pressure (3170–1390 bar) than those of the fluids that formed the veinlet–disseminated ores (330–252°C, 0.87–0.54 g/cm3, and 1960–570 bar, respectively). The fluids that formed the gold veins were enriched in CО2, Sr, Ag, Ga, Ge, Mn, Fe, Ni, Sn, Ba, and REE, whereas the fluids that formed veinlet–disseminated mineralization were richer in HCO−3, Br, Sb, V, and Au. This situations may be explained by the interaction of the deep fluid with the terrigenous host rocks in the course of ore deposition. When vein quartz crystallized in relatively wide fractures, the fluid interacted with host rocks and changed not as much as when the veinlet−disseminated ores were formed in narrow fractures. The initial parameters of the fluid that formed the vein quartz were thus the closest to the characteristics of the fluid that transported the ore components, and the comparison of these data with the parameters of the fluids that formed the veinlet–disseminated mineralization demonstrates that they changed in the course of ore deposition. The mineral-forming fluids likely came from a deep-sitting source, and the mineral-forming processes may have involve granitoid-derived fluids.

Selective Laser Melting Additive Manufactured Tantalum: Effect of Microstructure and Impurities on the Strengthening-Toughing Mechanism.

The balance between the strength and the toughness of pure tantalum (Ta) fabricated with selective laser melting (SLM) additive manufacturing is a major challenge due to the defect generation and affinity for oxygen and nitrogen. This study investigated the effects of energy density and post-vacuum annealing on the relative density and microstructure of SLMed tantalum. The influences of microstructure and impurities on strength and toughness were mainly analyzed. The results indicated that the toughness of SLMed tantalum significantly increased due to a reduction in pore defects and oxygen-nitrogen impurities, with energy density decreasing from 342 J/mm3 to 190 J/mm3. The oxygen impurities mainly stemmed from the gas inclusions of tantalum powders, while nitrogen impurities were mainly from the chemical reaction between the molten liquid tantalum and nitrogen in the atmosphere. The proportion of <110> texture decreased after vacuum-annealing at 1200 °C, while that of the <100> texture increased. Concurrently, the density of dislocations and small-angle grain boundaries significantly decreased while the resistance of the deformation dislocation slip was significantly reduced, enhancing the fractured elongation up to 28% at the expense of 14% tensile strength.

Introducing realistic distributions of gas bubble size and inclusion aspect ratio to model the coexistence of gas hydrate and free gas

The coexisting free gas within the hydrate stability zone is recognized by laboratory and field studies. The conventional resistivity method fails to obtain hydrate saturation in the sediment with gas hydrate and free gas because both of them are electrical insulators. Hydrate saturation can be obtained from a velocity log based on a certain rock physics model. However, few studies of rock physics have been conducted on gas and hydrate coexistence. In this study, a more realistic distribution of gas bubble size and inclusion aspect ratio was introduced into an effective medium model to elucidate how such coexistence affects velocity and attenuation at a broad-band frequency. The modeling results obtained indicate that such coexistence decreases P-wave velocity at low frequencies, while increases P- and S-wave velocities at high frequencies. The velocity decrease of P-wave at low frequencies is attributed to the overwhelming effect of gas bubble vibration, while it seems not to affect P-wave velocity at high frequencies significantly. Moreover, coexisting gas hydrate and free gas may strengthen P-wave attenuation at the broad-band frequency range. It is found that the damping of oscillating gas bubbles dominates P-wave attenuation at low frequencies, while squirt flow in the porous hydrate is more likely to contribute to P-wave attenuation at high frequencies. Hydrate morphology is also a significant factor affecting P-wave velocity and attenuation at high frequencies. This research reveals that rock physics modeling can provide insight into how to characterize the coexisting gas hydrate and free gas as referring to the acoustic velocity and attenuation at seismic, sonic, and ultrasonic frequencies.

Yedoma. Part 3. Annals of geocryological research, study of radiocarbon age, the stable-isotope composition studies in the 21st century

The second decade and the beginning of the third decade of the XXI century in yedoma research were characterized by a variety of high-precision measurements of gas inclusions, molecular biomarkers, and DNA. The purpose of this paper is to analyze the most notable publications of 2010–2023 devoted to radiocarbon dating and stable isotope studies of yedoma in the Russian and North American Arctic. AMS dating and stable isotope analysis continued at Lomonosov Moscow State University (Yu.K. Vasil’chuk, A.C. Vasil’chuk, N.A. Budantseva, I.D. Streletskaya, Ju.N. Chizhova, J.Yu. Vasil’chuk), especially detailed on the yedoma of Batagay, Seyakha, Kotelny, and Faddeevsky islands. Active research was continued by the participants of the Russian-German expedition (A. Yu. Derevyagin, A. I. Kizyakov, S. Wetterich, T. Opel, J. Strauss, G. Grosse and L. Schirrmeister) on the yedoma sections of the New Siberian Islands. They studied the Batagay yedoma together with J. Murton and K. Ashastina. Researchers from the University of Fairbanks (M. Kanevskiy, Y. Shur, M. Jorgenson, and E. Stephani) studied in detail the yedoma of the Itkillik River valley, as well as new yedoma sections in the Fox Tunnel, where radiocarbon and isotope studies were also carried out by M.S. Lachniet and A. Sloat from the University of Las Vegas. Research has begun on molecular biomarkers and DNA (E. Willerslev, T. J&amp;#248;rgensen) in yedoma. The study of PAHs in yedoma ice wedges has also begun (Yu.K. Vasil’chuk). It is emphasized that isotopic data is not an end in itself for research; the next step, paleotemperature reconstruction based on these data, is necessary and logically justified. The accuracy and reliability of the proposed paleotemperature-isotope equations are considered.

Decipher hydrocarbon generation and accumulation based on fluid inclusion and chronology: A case study from the Upper Paleozoic buried-hills in Huanghua Depression, Bohai Bay Basin

Deciphering hydrocarbon generation and accumulation stage is of significance to understand oil and gas evolution and seek exploration targets. Taking the Upper Paleozoic buried-hills in the Huanghua Depression, Bohai Bay Basin, as a case study, hydrocarbon generation environment and detailed accumulation process are revealed by fluid inclusions observations, Laser Raman spectroscopy, Fourier Infrared spectroscopy, and K–Ar isotope measurements. The results show that both oil and gas inclusion were captured in the quartz overgrowth, dissolved feldspar and calcite microfractures, showing blue to dark brown fluoresce. The grains containing oil inclusions index (GOI) of oil, oil & gas and gas being 25%, 65%, and 10% and the inclusions with abundant methyl groups and short chains, both indicate high thermal maturity. One series of fluids inclusion is generally observed, evidenced by the concentrated homogenization temperature of 135–145 °C and salinity of 3%–15 w.t.% NaCl equiv, indicating one primary charging stage. The gas and gas & liquid inclusions mainly contain CH4, with also peaks indicating CO2 and N2. The Carboniferous and Permian biomarkers show reducing environment with brackish water, with organic matter sources both from marine and continental. The relative content of ααα20RC27, ααα20RC28, and ααα20RC29 exhibit source contributions both from algae and higher plants, and mainly of II2 to III kerogen. Both coal derived gas and oil associated hydrocarbons are identified from most of the buried-hills. Combining the fluid homogenization temperature and salinity, as well as the thermal evolution history, the hydrocarbon generated from the Upper Paleozoic was concentrated at the end of the Eocene (40 Ma±), while the beginning of charging is 60 Ma±. The Wumaying Buried-hill is of only coal derived gas and has potential for inner coal measure natural gas exploration. The results provide a detailed understanding of hydrocarbon accumulations in the study area, which can also be reference for improving petroleum exploration efficiency in similar basins.

Evaluation of Behavior of Continuous Bubbles Rising in a Gallium Alloy under Influence of Horizontal Magnetic Field by Using a High-speed Ultrasonic Tomography

In the continuous casting process, argon gas is injected into the tundish to homogenize the molten steel and remove the undesired inclusion. Furthermore, the molten steel flow is controlled by applying a magnetic field to the mold. The inclusion of argon gas as the molten steel flows into the mold can lead to product defects. Therefore, it is essential to predict the motion of the bubble in liquid metals under influence of the magnetic field, and further investigations are required for the liquid-metal two-phase flows. However, measurement techniques which can be applicable to opaque fluids such as liquid meat are limited. The authors have developed a high-speed ultrasonic tomography for measuring bubbles motion and investigated the behavior of continuously released bubbles motion in gallium alloy under influence of a horizontal magnetic field. The ultrasonic tomography measurements were carried out with 500 frames per second. It was shown that as the magnetic field strength increases, the variation of the bubble passing position in the measurement cross-section becomes smaller. Furthermore, it was confirmed that the distribution changed slightly depending on the direction of the applied magnetic field and that the bubbles tended to distribute in the direction perpendicular to the magnetic field. This trend changes depending on the difference in the gas flow rate. It is thought that the greater the influence of the wake, the more pronounced the anisotropy of the distribution.