Strong Drop Research Articles

Holistic view on cation interdiffusion during processing and operation of garnet all-solid-state batteries

All-solid-state batteries based on the active cathode material LiCoO2 (LCO), a garnet-type Li7La3Zr2O12 (LLZO) electrolyte and a Li-metal anode are attracting a lot of attention as a robust and safe alternative to conventional lithium-ion batteries. The challenges in the practical realization of such cells are related to high-temperature sintering, which compacts the ceramic powder but also leads to undesirable material interactions such as cation interdiffusion and secondary phase formation. Even if high initial capacities can be achieved, the all-inorganic cells suffer from a strong capacity drop due to various degradation phenomena during processing and operation, which are not yet fully understood. In this study, the thermodynamic and kinetic aspects of co-sintering as well as the structural evolution of materials and interfaces during processing and operation of co-sintered LCO-LLZO cathodes are investigated in detail. A thermodynamic model for the interdiffusion of cations is derived and the effects of the diffusion of Al- and Co-ions, which occurs during the processing and cycling of the cells, are investigated. In LLZO, the diffusion of 0.13 Co per formula unit (pfu) has a negligible effect on ionic and electronic conductivity and electrochemical stability. In contrast, the substitution of 0.01 pfu Al and the induced disorder in the layer structure of LCO increases the polarization during cycling. All-inorganic cells fabricated with optimized sintering parameters to minimize interdiffusion between LCO and LLZO show good initial performance but similar degradation during cycling, as the used processing parameters result in a more porous microstructure leading to the development of cracks along the LLZO/LCO interface. The results obtained highlight the inherent instabilities of all-ceramic cathodes with unprotected LCO/LLZO interfaces, which require precise tuning of materials and processing parameters to achieve both high mechanical stability and low interdiffusion.

Experimental study of the upstream bathymetry effects on a ducted twin vertical axis turbine

Tidal turbines at sea are subject to complex flow conditions. Among that complexity, wide bathymetry obstacles can generate powerful coherent flow structures whose impact on horizontal axis tidal turbines was proved to be highly detrimental. Consequently, the present paper aims at studying the effects of such coherent flow structures on the response of another tidal turbine geometry, namely a bottom-mounted ducted twin vertical axis tidal turbine (2-VATT). We tested a 1/20 scale model of such a 2-VATT in Ifremer’s flume tank either with a flat bed or downstream of a wide bathymetry obstacle at a constant far upstream velocity and we measured the turbine response simultaneously with the flow velocity. These flow measurements make it possible to compute cross-correlations in order to analyse the influence of the velocity fluctuation on the turbine response. The results reveal a strong drop in the average power and loads coefficients of the 2-VATT combined with significantly larger fluctuation. The velocity deficit and the high level of turbulence in the obstacle wake is responsible for a 40% lower average power coefficient and more than 3 times higher standard deviation compared to the flat bed configuration. The loads standard deviations are multiplied by 2 for the drag and by 10 for the lift when the 2-VATT is downstream of the bathymetry obstacle. This behaviour strongly increases the risks of structural fatigue failure, but the turbine drifting or overturning risks under those conditions remain lower than with the flat bed. The power fluctuation increase appears to be mostly due to the flow shear in the obstacle wake whereas the load fluctuation is mostly due to the periodical passing of the coherent flow structures. Thus, a proper characterisation of the flow at each precise turbine locations prior deployment at sea is highly recommended to design their structure accordingly.

An improved estimation of stress drop and its application on induced earthquakes in the Weiyuan Shale Gas Field in China

SUMMARY Stress drop is a proxy of understanding earthquake source process, and it is controversial whether the stress drops of induced earthquakes associated with hydraulic fracturing and injection activities are similar to those of tectonic earthquakes. The measurement of stress drops is usually biased due to the limitations of observation means, or hidden issues in the estimation approaches. Utilizing a local short-period seismic network, we investigate the stress drops of induced earthquakes in Weiyuan Shale Gas Field in Sichuan Province, China from 2019 to 2020. Totally 11 844 earthquakes are involved in the analysis, and their stress drops are obtained using an improved approach on the basis of the traditional spectral decomposition method combined with a global optimization algorithm to avoid stacking of spectra that is found leading to source parameter underestimation. We divide the studied area into three subareas, and the results show strong stress drop heterogeneity across the entire region. We obtain an average stress drop of 2.29 MPa, piecewise stress drop dependence to earthquake magnitude, and complex depth dependence pattern. Our results indicate that stress drops of induced earthquakes are overall consistent with the induced earthquakes in other areas as well as tectonic earthquakes in different environments. Meanwhile, the complexity in the stress drop dependence to depth possibly reflects the variability of stress drops for different earthquake triggering mechanisms.

Cropland abandonment in the context of drought, economic restructuring, and migration in northeast Syria

Farmland abandonment is often associated with biophysical, political, or socio-economic changes, like droughts, economic reforms, rural-urban migration, or armed conflicts. Syria has seen several such changes in the period between 2000–2011, however, few assessments of how these factors have interacted with land abandonment have been carried out. In this study we investigate land abandonment patterns in northeast Syria, using a land use classification based on satellite data to indicate agricultural drought impacts and land abandonment. We combine these data with information on land use and migration patterns collected through a unique fieldwork, including surveys and interviews with Syrian farmers who had migrated to Turkey. Our analysis shows that drought coincided with a strong drop in cultivated croplands in 2008 and 2009. We also found a comparatively high cropland abandonment between 2001 and 2013, however no strong increases during or after drought years. Local insights indicate that migration took place during both normal years and drought years, and that most migrants had abandoned their lands after leaving Syria. We suggest that long-term mismanagement of water resources along with changes in the political economy, drove land abandonment in northeast Syria between 2001 and 2010. After 2011, armed conflict likely drove abandonment, but rates remained similar to the pre-conflict period. We discuss the potential of land abandonment as an indicator of rural migration in areas where migration data is sparse and conclude that more research is needed to understand the migration-land abandonment nexus, particularly in the Middle East.

Accurate complex-stacking-fault Gibbs energy in Ni3Al at high temperatures

To gain a deeper insight into the anomalous yield behavior of Ni3Al, it is essential to obtain temperature-dependent formation Gibbs energies of the relevant planar defects. Here, the Gibbs energy of the complex stacking fault (CSF) is evaluated using a recently proposed ab initio framework [Acta Materialia, 255 (2023) 118986], accounting for all thermal contributions—including anharmonicity and paramagnetism—up to the melting point. The CSF energy shows a moderate decrease from 300K to about 1200K, followed by a stronger drop. We demonstrate the necessity to carefully consider the individual thermal excitations. We also propose a way to analyze the origin of the significant anharmonic contribution to the CSF energy through atomic pair distributions at the CSF plane. With the newly available high-temperature CSF data, an increasing contribution to the energy barrier for the cross-slip process in Ni3Al with increasing temperature is unveiled, necessitating the refinement of existing analytical models.

Mapping the Decline with Redshift of Dusty Star-forming Galaxies Using JWST and SCUBA-2

We use JWST NIRCam observations of the massive lensing cluster field A2744 to develop a red galaxy selection of f F444W > 1 μJy and f F444W/f F150W > 3.5 that picks out all nine >4.5σ Atacama Large Millimeter/submillimeter Array 1.1 or 1.2 mm sources and 17 of the 19 >5σ SCUBA-2 850 μm sources in the covered areas. We show that by using the red galaxies as priors, we can probe deeper in the SCUBA-2 850 μm image. This gives a sample of 44 >3σ SCUBA-2 850 μm sources with accurate positions, photometric redshifts, and magnifications. To investigate why our red galaxy selection picks out the 850 μm sources, we next analyze an extended sample of 167 sources with f F444W > 0.05 μJy and f F444W/f F150W > 3.5. We find that the fainter f F444W sources in this sample are too faint to be detected in the SCUBA-2 850 μm image. We also show that there is a strong drop between z < 4 and z > 4 (a factor of around 5) in the ratio of the far-infrared luminosity estimated from the 850 μm flux to the ν (5000) at rest-frame 5000 Å. We argue that this result may be due to the high-redshift sources having less dust content than the lower-redshift sources.

Isolation, identification, and functional analysis of quorum sensing producing strain Pectobacterium atrosepticum associated with blackleg disease in potatoes

Potato is an important food and cash crop that production losses have a double effect on society, causing both a food security and financial crisis. The significant problem in the potato fields is blackleg of potato caused by Pectobacterium atrosepticum (Pa). The research concentrates on the isolation and characterization of P. atrosepticum, as one of the major causal organisms of the potato blackleg disease, in particular its prevalence in the Pakistani regions. Differential diagnosis by using biochemical methods and Koch’s Postulates, the etiological agent was identified. The involvement of N-Acyl Homoserine Lactones (NAHLs)-based quorum sensing (QS) in modulating Pa behaviors was clarified by the investigations. Novel QS inhibitors showing non-lethal quorum quenching capacity surfaced, however the long-term possibilities could be further improved. Initial data reflect a strong drop of virulence markers up to Day 16, which demonstrates the importance of increasing the knowledge of limiting influence arising from characteristics of bioactive substances or intrinsic ecological dynamics. Overall, this research contributes significantly to comprehending P. atrosepticum-associated threats and lays foundation for devising eco-friendly intervention tactics centered on quorum quenching paradigms.

A multi-proxy framework to detect insect defoliations in tree rings: a case study on pine processionary

Assessing and reconstructing the impacts of defoliation caused by insect herbivores on tree growth, carbon budget and water use, and differentiating these impacts from other stresses and disturbances such as droughts requires multi-proxy approaches. Here we present a methodological framework to pinpoint the impacts of pine processionary moth (Thaumetopoea pityocampa), a major winter-feeding defoliator, on tree cover (remote-sensing indices), radial growth and wood features (anatomy, density, lignin/carbohydrate ratio of cell walls, δ13C and δ18O of wood cellulose) of drought-prone pine (Pinus nigra) forests in north-eastern Spain. We compared host defoliated (D) and coexisting non-defoliated (ND) pines along with non-host oaks (Quercus faginea) following a strong insect outbreak occurring in 2016 at two climatically contrasting sites (cool-wet Huesca and warm-dry Teruel). Changes in tree-ring width and wood density were analyzed and their responses to climate variables (including a drought index) were compared between D and ND trees. The Normalized Difference Infrared Index showed reductions due to the outbreak of –47.3% and –55.6% in Huesca and Teruel, respectively. The D pines showed: a strong drop in growth (–96.3% on average), a reduction in tracheid lumen diameter (–35.0%) and lower lignin/carbohydrate ratios of tracheid cell-walls. Both pines and oaks showed synchronous growth reductions during dry years. In the wet Huesca site, lower wood δ13C values and a stronger coupling between δ13C and δ18O were observed in D as compared with ND pines. In the dry Teruel site, the minimum wood density of ND pines responded more negatively to spring drought than that of D pines. We argue that multi-proxy assessments that combine several variables have the potential to improve our ability to pinpoint and reconstruct insect outbreaks using tree-ring data.

Facile synthesis of spongy NiCo2O4 powders for lithium-ion storage

Spongy NiCo2O4 powders were prepared by solution combustion synthesis (SCS) method for lithium ions storage. The effects of combustion parameters including fuel type (l-lysine, glycine, and urea) and fuel amount on the lithium storage performance of NiCo2O4 powders were analyzed by various characterization techniques. Single-phase NiCo2O4 powders with extremely porous microstructure showed a strong drop of initial specific capacity up to 350 mAhg−1 which was recovered up to 666 mAhg−1 following 100 charge/discharge cycles. However, the NiCo2O4 powders prepared by the urea and l-lysine fuels with the compacted microstructure showed the capacity loss without any recovery. The spongy NiCo2O4 powders showed an acceptable capability rate performance (404 mAhg−1 @ 400 mAg−1).

Evolution of smoking-attributable cardiovascular mortality in Germany 1992-2020

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): Marga and Walter Boll Foundation, Kerpen, Germany. Background Despite comparatively weak tobacco control, smoking has steadily declined in Germany over the last 30 years. At the same time, while cardiovascular mortality rates have generally been decreasing in recent decades, population ageing leads to increasing numbers of deaths. Purpose To explore the impact of smoking prevalence on cardiovascular mortality against the background of these different trends at a population level, this study sought to quantify trends in smoking-attributable cardiovascular mortality (SACVM) in Germany over the past three decades. Methods Smoking and mortality statistics from 1992 to 2020 were obtained from the German Statistical Office, from which absolute and relative SACVM was calculated separately for each cardiovascular cause of death causally associated with smoking. The impact of population ageing was explored by comparing crude and age-standardized SACVM, respectively. To estimate the impact of population ageing on future SACVM, a forward projection until 2035 was modelled assuming constant mortality rates and a continuation of smoking trends. Results Results show that total absolute SACVM strongly declined over time, from about 71,900 cases in 1992 to about 42,000 cases in 2020, with a stronger drop in men (from about 51,200 to 26,400 cases) than in women (from about 20,700 to 15,600 cases). Somewhat stronger declines were seen for age-adjusted SACVM, with differences between crude and age-standardized SACVM being somewhat more distinct in men. Relative SACVM decreased overall, from 17.3% in 1992 to 14.6% in 2020. Sex-specific relative SACVM however showed differing trends: a strong decrease in men (from 29.3% to 18.8%) and a slight increase in women (8.6% to 10.6%). The forward projection of SACVM indicates a slight decline among men and a marked increase in women. Conclusions Results indicate that SACVM has strongly declined over the past three decades, even though being partly compensated by opposing trends in population ageing. The marked decrease in absolute SACVM seems to be mostly due to the general drop in cardiovascular mortality rates, and only partly due to declining smoking rates, particularly in women, where relative SACVM has even slightly increased. Over the next 15 years, population ageing and the increasing trend in relative SACVM among women might halt the recent declining trend in absolute SACVM. Hence, there is tremendous potential to curb the smoking-associated public health burden by implementing a comprehensive set of evidence-based tobacco control polices. Additionally, given still significant smoking rates in middle and old age, smoking cessation programs should be intensified.

The intensity of the cluster drop affects the bioactive compounds and fatty acid composition in hazelnuts

This study was conducted to determine how the intensity of the cluster drop effects nut traits, bioactive compounds, and fatty acid composition in Tombul, Palaz and Kalınkara hazelnut cultivars. The cluster drop significantly affected bioactive compounds and fatty acid composition while it did not affect the traits of the nuts. As cluster drop intensity increased, nut traits and bioactive compounds in all cultivars increased. Strong cluster drop intensity determined the highest total phenolics, total flavonoids, and antioxidant activity. Except for the Kalınkara cultivar, a low amount of linoleic acid was detected while high amounts of oleic and stearic acid were determined in slight cluster drop intensity. As cluster drop intensity increased, palmitic acid increased. Principal component analysis showed that the slight and intermediate drop intensity were generally associated with kernel length, oleic, linoleic, stearic, palmitoleic, 11-eicosenoic and arachidic acids. In contrast, strong intensity was associated with nut and kernel weight, kernel ratio, kernel width, kernel thickness, kernel size, bioactive compounds, and palmitic acid. As a result, the bioactive compounds and fatty acid composition, which are important for human health, was significantly affected by cluster drop intensity.

Scale-dependent theory of the disordered electron liquid

We review the scaling theory of disordered itinerant electrons with e−e interactions. We first show how to adjust the microscopic Fermi-liquid theory to the presence of disorder. Then we describe the non-linear sigma model (NLSM) with interactions (Finkel’stein’s model). This model is closely connected to the Fermi liquid, but is more generally applicable, since it can also be viewed as a minimal effective functional describing disordered interacting electrons. Our discussion emphasizes the general structure of the theory, and the connection of the scaling parameters to conservation laws. We then move on to discuss the metal–insulator transition (MIT) in the disordered electron liquid in two and three dimensions. Generally speaking, this MIT is a non-trivial example of a quantum phase transition. The NLSM approach allows to identify the dynamical exponent connecting the spatial and energy scales, which is central for the description of the kinetic and thermodynamic behavior of the system in the critical region of the MIT in three dimensions. In two dimensions, the system can be discussed in terms of a flow in the disorder-interaction phase plane, which is controlled by a fixed point. We demonstrate that the two-parameter RG-equations accurately describe electrons in Si-MOSFETs including the observed non-monotonic behavior of the resistance and its strong drop at low temperatures. The theory can also be applied to systems with an attractive interaction in the Cooper channel, where it describes the suppression of superconductivity in disordered amorphous films. We extend our discussion to heat transport in the two-dimensional electron liquid. Similar to the electric conductivity, the thermal conductivity also acquires logarithmic corrections induced by the interplay of the electron interaction and disorder. The resulting thermal conductivity can be calculated in the NLSM formalism after introducing so-called gravitational potentials. It may be concluded that the combined effect of disorder and e−e interactions determines all aspects of the physics of itinerant electrons in the presence of disorder.

Instability and dynamic behavior of arc attachments on electrodes and the effect on electrode erosion

Plasma interacting with electrodes is one of the most challenging issues in many industrial applications, such as power-interruption and plasma-metal erosion. Because of the concentration of arc attachments (root) and the voltage drop across the plasma sheath layer, the arc roots consume great amount of energy, which subsequently will increase the local temperature and erode the electrodes. Due to the nonequilibrium condition at plasma sheath, it is very difficult to quantitatively estimate the arc root temperature profile. The recognition of arc roots behavior, like instability and pattern formation, is important to estimate the electrode erosion. The potential drop arising through the sheath (double layer) is nonuniform. Due to thermionic field emission, the strong flux of charge carriers through the sheath will cause instability of the double layer, which weakens the inner potential gradient. As a result, the strong current dependent potential drop features a negative resistance. The existence of negative resistance causes the instability of arc attachments in the forms of immobility and constriction. Their interdependence between local current density and potential drop gives rise to the arc root formation that concentrates the energy into a small spot. Owing to the negative resistance, any perturbation will cause the current density in the sheath to grow to approximately infinity or decay to vanish, namely arc root formation or extinction. Thereby, the arc root instability provides the basis for the dynamic behavior of arc attachments and detachments on the electrodes, which will help to understand electrode erosion and avoid the damage from the arc plasma in engineering applications.

Potential of Good’s buffers to inhibit denaturation of myofibrillar protein upon freezing

The current systematic study sought to examine the potential use of three Good’s buffers (MES, MOPS and HEPES) in inhibiting myofibrillar protein (MFP) denaturation induced by acidity changes. The highest degree of acidity variation was found in the center and bottom of large bottles due to the freeze-concentration effect. Good’s buffer tended to basify during freezing, and it could prevent the crystallization of sodium phosphate (Na-P) buffer. Acidification upon freezing Na-P disrupted the natural conformation of MFP and induced the formation of large proteins aggregates with tight packing. The 15 mM MES, 20 mM MOPS, and 30 mM HEPES were respectively added to neutralize the strong acidity drop induced by freezing 20 mM Na-P, and all of them significantly improved the stability of the MFP conformation (P < 0.05). This work is not only critical to meet the growing demand for protein, but also groundbreaking for broadening the applicability of Good’s buffers in the food industry.

Strong quenching of dye fluorescence in monomeric perylene orange/TMDC hybrid structures.

Hybrid structures with an interface between two different materials with properly aligned energy levels facilitate photo-induced charge separation to be exploited in optoelectronic applications. Particularly, the combination of 2D transition metal dichalcogenides (TMDCs) and dye molecules offers strong light-matter interaction, tailorable band level alignments, and high fluorescence quantum yields. In this work, we aim at the charge or energy transfer-related quenching of the fluorescence of the dye perylene orange (PO) when isolated molecules are brought onto monolayer TMDCs via thermal vapor deposition. Here, micro-photoluminescence spectroscopy revealed a strong intensity drop of the PO fluorescence. For the TMDC emission, in contrast, we observed a relative growth of the trion versus exciton contribution. In addition, fluorescence imaging lifetime microscopy quantified the intensity quenching to a factor of about 103 and demonstrated a drastic lifetime reduction from 3 ns to values much shorter than the 100 ps width of the instrument response function. From the ratio of the intensity quenching that is attributed to hole or energy transfer from dye to semiconductor, we deduce a time constant of several picoseconds at most, pointing to an efficient charge separation suitable for optoelectronic devices.

Mathematical Modeling of ROS Production and Diode-like Behavior in the SDHA/SDHB Subcomplex of Succinate Dehydrogenases in Reverse Quinol-Fumarate Reductase Direction

Succinate dehydrogenase (SDH) plays an important role in reverse electron transfer during hypoxia/anoxia, in particular, in ischemia, when blood supply to an organ is disrupted, and oxygen is not available. It was detected in the voltammetry studies about three decades ago that the SDHA/SDHB subcomplex of SDH can have such a strong nonlinear property as a "tunnel-diode" behavior in reverse quinol-fumarate reductase direction. The molecular and kinetic mechanisms of this phenomenon, that is, a strong drop in the rate of fumarate reduction as the driving force is increased, are still unclear. In order to account for this property of SDH, we developed and analyzed a mechanistic computational model of reverse electron transfer in the SDHA/SDHB subcomplex of SDH. It was shown that a decrease in the rate of succinate release from the active center during fumarate reduction quantitatively explains the experimentally observed tunnel-diode behavior in SDH and threshold values of the electrode potential of about -80 mV. Computational analysis of ROS production in the SDHA/SDHB subcomplex of SDH during reverse electron transfer predicts that the rate of ROS production decreases when the tunnel-diode behavior appears. These results predict a low rate of ROS production by the SDHA/SDHB subcomplex of SDH during ischemia.

Redshift evolution of galaxy group X-ray properties in the Simba simulations

ABSTRACT We examine the evolution of intragroup gas rest-frame X-ray scaling relations for group-sized haloes (M500 = 1012.3–1015 M⊙) in the Simba galaxy formation simulation. X-ray luminosity LX versus M500 shows increasing deviation from self-similarity from z = 3 → 0, with M500 &amp;lt; 1013.5 M⊙ haloes exhibiting a large reduction in LX and slight increase in X-ray luminosity-weighted temperature TX. These shifts are driven by a strong drop in fgas with time for these haloes, and coincides with the onset of Simba’s black hole (BH) jet feedback, occurring when MBH &amp;gt; 107.5 M⊙ and Eddington ratio &amp;lt;0.2, in group haloes at z ∼ 1.5. The connection with BH feedback is corroborated by fBH ≡ MBH/M500 in M500 &amp;lt; 1013.5 M⊙ haloes being strongly anticorrelated with LX and fgas at $z\lesssim 1.5$. This is further reflected in the scatter of LX − TX: haloes with small fBH lie near self-similarity, while those with the highest fBH lie furthest below. Turning off jet feedback results in mostly self-similar behaviour down to z = 0. For the X-ray weighted metallicity ZX, stellar feedback impacts the enrichment of halo gas. Finally, halo profiles show that jet feedback flattens the electron density and entropy profiles, and introduces a core in X-ray surface brightness, particularly at M500 &amp;lt; 1013.5 M⊙. This argues that in Simba, intragroup X-ray evolution is largely driven by jet feedback removing hot gas from the cores of massive groups, and expelling gas altogether in less massive groups.

Influence of Electromagnetic Activation of Cement Paste and Nano-Modification by Rice Straw Biochar on the Structure and Characteristics of Concrete

One main global problem is the accumulation of a large amount of agricultural waste. This problem causes environmental pollution and requires an immediate comprehensive solution. The purpose of this study was scientific substantiation and experimental testing, at the micro- and macro levels, of the joint influence of electromagnetic activation of cement paste and nano-modification by rice straw biochar on the strength and strain properties of concrete. In addition to standard methods, the methods of electromagnetic activation, scanning electron microscopy, and energy dispersive spectrometry were used. The results of the joint influence of electro-magnetic activation and nano-modification by rice straw biochar on the strength and strain characteristics of concrete were experimentally verified and confirmed by microstructure analysis. Electromagnetic treatment of the cement paste increased the compressive strength, axial compressive strength, tensile strength in bending, and axial tensile strength of concrete. The best performance was demonstrated by electromagnetically-activated concrete containing 5 wt.% rice straw biochar. Strength characteristics increased from 23% to 28% depending on the type of strength, ultimate tensile strains decreased by 14%, and ultimate compressive strains by 8% in comparison with the control concrete composition. Replacing part of the cement with 10 wt.% and 15 wt.% rice straw biochar led to a strong drop in strength characteristics from 14 to 34% and an increase in strain characteristics from 9 to 21%. Scanning electron microscopy showed a denser and more uniform structure of electromagnetically activated samples.

Nowcasting Russia’s key macroeconomic variables using machine learning

The article developed a methodology for nowcasting and short-term forecasting key Russian macroeconomic aggregates: real GDP, consumption, investment, export, import, using machine learning methods: boosting, elastic net, and random forest. The set of predictors included indicators of the stock market, money market, surveys, world prices for resources, price indices, and other statistical indicators of different frequency, from daily to quarterly. Our approach makes available a detailed examination of the changes in forecasts with the flow of new information. For most of the considered variables, a monotonic non-deterioration of the forecast quality was obtained with an expansion of available information. Furthermore, machine learning methods have shown significant superiority in predictive performance over naive prediction. The considered methods within the framework of the pseudo-experiment quickly showed a strong drop in real GDP, household consumption, and other variables in the context of the spread of the COVID-19 pandemic in the 2nd and 3rd quarters of 2020.

Mitigating Water Production from High Viscosity Oil Wells in Unconsolidated Sandstone Formations

Summary Large reserves of high-viscous oil in Kuwait call for improved oil recovery scenarios. In Kuwaiti unconsolidated sandstone formations, the sandstone intervals represent extensive reservoir intervals of sand separated by laterally extensive nonreservoir intervals that comprise finer-grained argillaceous sands, silts, and muds. The reservoir is shallow with high permeability (above 1,000 md) and under bottom aquifer pressure support. Due to strong viscosity contrast between oil and water, after breakthrough, the water cut rises quickly, resulting in strong loss of production efficiency. Mitigating water production is thus mandatory to improve production conditions. The candidate wells have two to three open intervals in different rock facies with comingle production. The total perforated length is between 38 and 48 ft. Production is through progressing cavity pumps (PCP) at a rate of around 300 B/D, and basic sediment and water is between 71 and 87%. The technology applied utilizes pregelled size-controlled product [small microgels (SMG Microgels)] having relative permeability modification (RPM) properties; that is, inducing a strong drop of relative permeability to water without affecting oil relative permeability. The size is chosen to selectively treat the high-permeability water producing zones while preserving the lower-permeability oil zones. The chemical can also withstand downhole harsh conditions such as salinity of around 170,000 ppm and presence of 2% H2S. The treatment consisted of bullhead injection of 300 bbl of pregelled chemical through-tubing. The first results seem very favorable, since for two wells, the water cut has dropped from 80 to 40% with almost same gross production rate. The incremental oil is more than 100 BOPD. The third well did not show marked change after water system operation (WSO) treatment. The wells are under continuous monitoring to assess long-term performance. Such result, if confirmed, may lead to high possibilities for the improvement of heavy oil reservoir production under aquifer support by mitigating water production with simple chemical bullhead injection.