Trapping Mechanism Research Articles

Aluminum Fluorides as Noncovalent Lewis Acids in Proteins: The Case of Phosphoryl Transfer Enzymes.

The Protein Data Bank (PDB) was scrutinized for the presence of noncovalent O ⋅ ⋅ ⋅ Al Triel Bonding (TrB) interactions, involving protein residues (e. g. GLU and GLN), adenosine/guanine diphosphate moieties (ADP and GDP), water molecules and two aluminum fluorides (AlF3 and AlF4 -). The results were statistically analyzed, revealing a vast number of O ⋅ ⋅ ⋅ Al contacts in the active sites of phosphoryl transfer enzymes, with a marked directionality towards the Al σ-/π-hole. The physical nature of the TrBs studied herein was analyzed using Molecular Electrostatic Potential (MEP) maps, the Quantum Theory of Atoms in Molecules (QTAIM), the Non Covalent Interaction plot (NCIplot) visual index and Natural Bonding Orbital (NBO) studies. As far as our knowledge extends, it is the first time that O ⋅ ⋅ ⋅ Al TrBs are analyzed within a biological context, participating in protein trapping mechanisms related to phosphoryl transfer enzymes. Moreover, since they are involved in the stabilization of aluminum fluorides inside the protein's active site, we believe the results reported herein will be valuable for those scientists working in supramolecular chemistry, catalysis and rational drug design.

Backward test particle simulation of nonlinear cyclotron wave-particle interactions in the radiation belts

Wave-particle interaction plays a crucial role in the dynamics of the Earth’s radiation belts. Cyclotron resonance between coherent whistler mode electromagnetic waves and energetic electrons of the radiation belts is often called a coherent instability. Coherent instability leads to wave amplification/generation and particle acceleration/scattering. The effect of wave on particle’s distribution function is a key component of the instability. In general, whistler wave amplitude can grow over threshold of quasi-linear (linear) diffusion theory which analytically tracks the time-evolution of a particle distribution. Thus, a numerical approach is required to model the nonlinear wave induced perturbations on particle distribution function. A backward test particle model is used to determine the energetic electrons phase space dynamics as a result of coherent whistler wave instability. The results show the formation of a phase space features with much higher resolution than is available with forward scattering models. In the nonlinear regime the formation of electron phase space holes upstream of a monochromatic wave is observed. The results validate the nonlinear phase trapping mechanism that drives nonlinear whistler mode growth. The key differences in phase-space perturbations between the linear and nonlinear scenarios are also illustrated. For the linearized equations or for low (below threshold) wave amplitudes in the nonlinear case, there is no formation of a phase-space hole and both models show features that can be characterized as linear striations or ripples in phase-space.

Nitrogen-doped carbon quantum dot-decorated In2O3 synaptic transistors for neuromorphic computing

Nitrogen-doped carbon quantum dots (N-CQDs) are promising materials for electronic devices due to their variable bandgap and structural stability. Here, we integrate N-CQDs into In2O3 synaptic transistors with electrolyte gating, resulting in a hybrid structure. The surface functional groups and defects of N-CQDs empower the charge trapping mechanism, permitting controlled conduction and charge regulation, which are crucial for emulating linear and symmetric artificial synaptic devices. Devices incorporating N-CQDs demonstrate enhanced stability and memory characteristics, low energy consumption, consistent retention, and a significant hysteresis window across multiple voltage cycles. Finally, the study emulates biological synapses and cognitive functions, achieving an energy consumption of 10 fJ per synaptic event and a pattern recognition accuracy of 91.2% on the MNIST dataset in hardware neural networks. This work demonstrates the potential of well-manipulating charge trapping in N-CQDs to develop high-performance, nonvolatile synaptic devices.

First-principles study of hydrogen trapping and diffusion mechanisms in vanadium carbide with connecting carbon vacancies

Understanding the trapping and diffusion mechanism of hydrogen in vanadium carbide (VC) precipitates is crucial for exploring the issue of hydrogen embrittlement in steel. Although there is widespread consensus that VC can trap hydrogen, the mechanism by which hydrogen diffuses into VC is still unclear. In this study, we used first-principles calculation methods to study the influence of different spacings of carbon vacancies on the trapping and diffusion of hydrogen in VC. The increase in the number of C vacancies makes it easier for vacancies to trap hydrogen, and hydrogen tend to fill up C vacancies. The diffusion of hydrogen into VC only occurs via neighboring C vacancies at a distance of 0.295 nm (connecting vacancies), leading to a diffusion barrier of 0.63–0.78 eV. This is consistent with experimental results and validates the experimental speculation that the diffusion of hydrogen in VC requires a connecting C vacancy grid.

Revealing Yukon’s hidden treasure: an atomic-scale investigation of Carlin-type gold mineralization in the Nadaleen Trend, Canada

AbstractThe invisible-gold deposits known as Carlin-type are becoming more important as easier to find deposits are progressively depleted. The combination of the invisible nature of the Au in these deposits, as well as the limited surface indicators of these deposits, makes exploration to find new Carlin-type deposits extremely difficult. Comprehensive mineralization models are essential to find new Carlin-type deposits in similar geologic settings. The Nadaleen Trend of Yukon, Canada, is one such district where an improved understanding of this deposit type has led to new discoveries. Previous studies compared and contrasted the tectonic setting, host rock depositional setting, structural preparation, and mineralization style of the Nadaleen Trend with those in Carlin-type localities, Nevada. However, the comparisons at an atomic scale, between Carlin-type Au deposits in the Nadaleen Trend and those in Nevada, has yet to be investigated. This study fills this knowledge gap by combining high resolution microanalytical techniques with atom probe tomography to examine the distribution of Au and other trace elements in the Nadaleen Trend, compare them to a representative Carlin-type deposit in Nevada (Turquoise Ridge), and determine how widespread the mineralization model is. Our findings show that in the Nadaleen Trend, as in Nevada, Au is generally directly linked with As at the macro to atomic scale, and is incorporated into As/Au rich overgrowths on sedimentary/diagenetic pyrite. Gold-rich pyrite rims in the Nadaleen Trend are generally smaller than those found in Nevada (0.5–2 µm vs > 10 µm), although the ore grades appear comparable. We find that the Au in the pyrite of the Nadaleen Trend is homogenously distributed (i.e. lattice bound) at the atomic scale, but that there is a notable enrichment of As surrounding individual Au atoms. These findings are in agreement with those from previous work on a representative deposit in Nevada, and support the assertation that As is the key ingredient in facilitating the incorporation of Au into the pyrite lattice. Arsenic as an essential component in the trapping mechanisms of Au in CTG deposits, is something that has been as to yet underappreciated in the current models of CTG deposit formation.

Natural Self-Purification of Creek Ecosystems: The Role of Foam Formation in Pollutant Absorption and Microbial Decomposition

<p style="text-align:justify;text-indent:36.0pt;"><span style="font-family:"Times New Roman","serif";font-size:12.0pt;line-height:115%;" lang="EN">This study investigates the natural self-purification ability of a creek through the process of froth formation. The research focuses on the creek's capacity to clean itself by capturing and removing pollutants naturally. The problem addressed is the accumulation of organic and inorganic contaminants in the water, which poses a threat to the aquatic ecosystem. The proposed solution explores how naturally formed froth can act as an effective mechanism for trapping and eliminating a wide range of pollutants. The froth formation is driven by biological processes, including the decomposition of organic matter by fungi, bacteria, Archaea, Algae, Virsus, Protozoa and animal parasites. These processes release biological surfactants and biogas microbubbles, which, combined with dissolved air and pollutants, lead to the creation of froth enriched with contaminants. The findings confirm that the creek has a natural ability to purify itself, as the froth effectively absorbs and collects dissolved pollutants. This process reduces the organic load in the water, thereby improving water quality. The study demonstrates that froth formation is a vital subprocess in the self-purification of river ecosystems, particularly through microbial decomposition of organic material. This natural mechanism supports water treatment by enhancing the removal of contaminants. The research validates the hypothesis that the creek's froth formation plays a significant role in its self-cleaning process, offering insights into the potential for natural water purification methods.</span></p>

Revealing grain refinement and hydrogen trapping mechanism for anti-hydrogen susceptibility of Nb-alloyed 34MnB5 press hardened steel

Hydrogen embrittlement (HE) extant a substantial concern to press-hardened steel (PHS) owing to superior strength. The high strength to light-weight automobile structures necessitates the advancement of superior HE resistance PHS. This study investigated the HE susceptibility of Nb-microalloyed PHS by slow strain rate tensile testing, u-shaped constant bending load test, and thermal desorption spectroscopy. Nb enhances microstructure and HE resistance by introducing retained austenite, refining prior austenite grains (21.14–13.73 μm), forming low-angle grain boundaries, and nano-scale precipitates. Nb-alloyed steel exhibits no-cracking over 300 h under high pre-bending stress and decreases elongation loss up to 48% in hydrogen environment as compared to Nb-free steel. Diffusible H-content in 0.12 wt% Nb-steel reduces to 14.9% of that in Nb-free steel owing to enhanced hydrogen traps, the Fcc/Bcc matrix, and carbide precipitation. The multi-phase microstructure with nano-scale NbC precipitation impeded the localized H-dispersion, enhancing the HE resistance in PHS despite its high strength.

Excess Energy Released Due To Proton-Proton Collisions in Condensed Matter Could Be Due To Laboratory-Made Micro Black Holes

While sodium metal dissolution in concentrated (2M) Epsom solution is very peaceful under stirring conditions in about 5 to 10s, its dissolution in a dilute (0.85) Epsom solution has turned very violent. Nearly 30s after the addition of Na, the solution exploded accompanied by the vaporization of the glass beaker. Only sodium aerosol and tiny molten needles of glass were seen around indicating a very high temperature (>1000 0C) has indeed been reached. The timing of the explosion has indicated that hydrogen released during sodium dissolution has got trapped in the salt solution and subsequent energy build-up has caused the excess energy release. A viable trapping mechanism involving the exchange of 2 hydrogen ions (H22+) with an Mg2+ ion in cavitation-induced nanocrystals of Epsom has been proposed in this regard. The two hydrogen ions are stabilized at the cation vacancy (cavity) by dative bonds with the two hydrogen ions in the water molecule trapped at a neighboring sulphate vacancy. Spring-like action between the two protons trapped at the cation vacancy due to oscillations caused by two opposing forces – one by cavitation and the other by coulombic repulsion eventually appear to have led to the collision of hydrogen ions at relativistic speeds in condensed matter. To start with, the two protons in the H22+ species are confined in a small space (72 pm cavity) at a single crystal cation lattice site in Na2SO4 nanocrystal which increases their head-on collision probability at high energies. There is no upper limit to the energies achieved through p-p collisions in this species as the Cavitation-Coulombic Repulsion Oscillations (CCRO) can continue until the endpoint is reached. Regeneration of a nanocrystal over a sufficiently small time scale and regeneration effect prior to cavitation collapse are all important so laws of thermodynamics are not violated. Extra dimensions of gravity at short distances, if present, could also assist in the high energies required for the production of mini black holes in condensed matter. Such black holes lose mass very quickly through the emission of Hawking radiation observed in the form of explosion with mass-energy equivalence of E = mc2. The possibility of tapping such explosive energy for peaceful purposes is discussed. As such it constitutes the third kind of atomic energy humans have entertained, the first two being fission and fusion.

Physical understanding of a normally off p-GaN/AlGaN/GaN HEMT gate stack and a review of VTH measurement techniques

Abstract In this report a comprehensive review of the variations in threshold voltage (VTH) resulting from diverse VTH measurement bias conditions employed by leading manufacturers, as well as VTH extraction techniques is made. Notably, a standard deviation of 15% is observed in threshold voltage values due to variations in measurement bias conditions. This variation is attributed to the change in the lateral electic field conditions across gate and drain which occurs due to the change in bias conditions. Additionally, a simplified physical interpretation of the gate stack in p-GaN gate normally-off AlGaN/GaN on Si HEMTs is made. The formation of the two-dimensional electron gas (2DEG), the charge balance within the pGaN/AlGaN/GaN gate stack, and an analytical expression for threshold voltage are examined. Furthermore, various trapping mechanisms within the gate stack are reviewed to comprehend the dynamic conditions potentially contributing to threshold voltage instability during nominal operation.

Flexible X-ray Imaging and Stable Information Storage of SrF2:Eu Based on Radio-Photoluminescence.

X-ray imaging has garnered widespread interest in biomedical diagnosis and nondestructive detection. The exploration of radio-photoluminescence has hastened the advancement of X-ray information storage. However, significant challenges persist in achieving the prolonged imaging of curved objects without attenuation. Here, europium-doped strontium fluoride (SrF2:Eu) is meticulously created to exhibit a linear response to an extensive range of X-ray doses (maximum dose > 5000 Gy), showcasing excellent X-ray information reading/erasing reusability properties (10 cycles). This is accompanied by a red-to-blue emission transition under UV excitation, sustaining for 150 days without attenuation. To elucidate the phenomena of irradiated photoluminescent discoloration and the reversible X-ray storage of SrF2:Eu, we propose an electron-vacancy trap (valence conversion) mechanism, information stably retained by the SrF2:Eu-based device under ambient conditions due to high energy barriers. The time-lapse readout capability is further demonstrated for three-dimensional imaging of curved objects (10 lp mm-1) based on SrF2:Eu embedded within a polydimethylsiloxane (SrF2:Eu@PDMS). The SrF2:Eu demonstrates time-lapse imaging, reversible radio-photoluminescence, and recoverable X-ray storage, offering a promising avenue for optical information encryption and anticounterfeiting applications.

Hydrogen diffusion and trapping in a cryogenic processed high-Cr ferrous alloy

The effect of hydrogen diffusion and trapping was studied in a high-Cr ferrous alloy using an inverted scanning Kelvin probe and thermal desorption spectroscopy in correlation with microstructure and residual stress study. In addition, different processing of ferritic/martensitic 9Cr1WTaV alloy (EUROFER97) was tested in correlation with observed selected properties to observe induced changes in material degradation and surface. The activation energies for hydrogen traps were shown to have distinct peaks corresponding to different trapping mechanisms, including matrix dislocations and grain boundaries. For the cryogenically treated sample, an additional peak was also identified and correlated with increased carbide precipitation.

Improved Charge Recombination Efficiency in Organic Light‐Emitting Transistors via Luminescent Radicals

AbstractLuminescent radicals are attracting attention as emitters in electroluminescent devices thanks to the exploitation of doublet excitons. Recent studies reveal that exciton formation in radical organic light‐emitting diodes (OLEDs) primarily occurs through a charge trapping mechanism. Although typically detrimental for OLEDs, this might be a key process to elucidate light emission in organic light‐emitting transistors (OLETs). Here, a unipolar n‐type architecture suitable for the implementation of radical emitters is introduced, designed based on computational calculations. The operation of the as‐realized devices incorporating the newly synthesized [2,6‐dichloro‐4‐(2,6‐dimethoxyphenyl)phenyl](3,5‐dichloro‐4‐pyridyl) (2,4,6‐trichlorophenyl)methyl radical is investigated via transient electroluminescence measurements to demonstrate the occurrence of long‐living emission ascribed to the charge trapping mechanisms. Moreover, a comprehensive understanding of the processes governing radical‐OLET is obtained by recording complete 2D maps of both optical and electrical response of the device as a function of applied voltages. Notably, the trapping of electrons by radical moieties is demonstrated to generate a negative charge density in the emissive layer that facilitates holes to be injected: increasing the balance of opposite charge carriers, a tenfold enhancement of the external quantum efficiency (EQE) at the proper source‐drain and source‐gate voltage conditions is reported to reach a maximum EQE value of 0.2%.

Cretaceous Petroleum System Elements in the Komombo Basin, Egypt

The petroleum system elements in the Komombo Basin have not yet been fully assessed. This study aims to evaluate source rocks, reservoirs, and seals within the basin by integrating 2D seismic profiles, and well logs together with geochemical, core, and petrophysical data. Four source rocks are identified within the Cretaceous shale intervals of the B member of the Six Hills, upper Maghrabi, Quseir, and Dakhla formations. The quality of the B member, upper Maghrabi, and Quseir source rocks is good to very good, while the Dakhla Formation demonstrates good to excellent quality. Geochemical characteristics vary across the basin, with higher kerogen quality and thermal maturity observed in the depocenter compared to the flanks. Four reservoirs are recognized in the basin, including the A member, C member, sandstones within D-G members of the Six Hills, and Sabaya-Maghrabi formations. The A member reservoir demonstrates moderate reservoir quality, while the C member reservoir displays fair quality. Numerous sandstones with 15-25% porosity values are observed within the D-G members. The Sabaya-Maghrabi reservoir generally exhibits good to very good quality and is characterized by high porosity and varying permeability. Due to their high organic matter content, the Dakhla and Quseir formations show potential as unconventional reservoirs. Several shale units within the Komombo Basin serve as potential seal rocks. These include the B member of the Six Hills, Abu Ballas, upper Maghrabi, and Taref formations, as well as intra-formational shales within the reservoir rocks. Seismic interpretation indicates faults are the predominant trapping mechanism in the basin.

Geochemistry in Geological CO2 Sequestration: A Comprehensive Review

The increasing level of anthropogenic CO2 in the atmosphere has made it imperative to investigate an efficient method for carbon sequestration. Geological carbon sequestration presents a viable path to mitigate greenhouse gas emissions by sequestering the captured CO2 deep underground in rock formations to store it permanently. Geochemistry, as the cornerstone of geological CO2 sequestration (GCS), plays an indispensable role. Therefore, it is not just timely but also urgent to undertake a comprehensive review of studies conducted in this area, articulate gaps and findings, and give directions for future research areas. This paper reviews geochemistry in terms of the sequestration of CO2 in geological formations, addressing mechanisms of trapping, challenges, and ways of mitigating challenges in trapping mechanisms; mineralization and methods of accelerating mineralization; and the interaction between rock, brine, and CO2 for the long-term containment and storage of CO2. Mixing CO2 with brine before or during injection, using microbes, selecting sedimentary reservoirs with reactive minerals, co-injection of carbonate anhydrase, and enhancing the surface area of reactive minerals are some of the mechanisms used to enhance mineral trapping in GCS applications. This review also addresses the potential challenges and opportunities associated with geological CO2 storage. Challenges include caprock integrity, understanding the lasting effects of storing CO2 on geological formations, developing reliable models for monitoring CO2–brine–rock interactions, CO2 impurities, and addressing public concerns about safety and environmental impacts. Conversely, opportunities in the sequestration of CO2 lie in the vast potential for storing CO2 in geological formations like depleted oil and gas reservoirs, saline aquifers, coal seams, and enhanced oil recovery (EOR) sites. Opportunities include improved geochemical trapping of CO2, optimized storage capacity, improved sealing integrity, managed wellbore leakage risk, and use of sealant materials to reduce leakage risk. Furthermore, the potential impact of advancements in geochemical research, understanding geochemical reactions, addressing the challenges, and leveraging the opportunities in GCS are crucial for achieving sustainable carbon mitigation and combating global warming effectively.

Review on spontaneous imbibition mechanisms in gas-water systems: Impacts on unconventional gas production and CO2 geo-sequestration

Spontaneous imbibition, a fundamental process in porous media, involves the displacement of a non-wetting phase by a wetting phase driven by capillary pressure. It plays a key role in various applications, particularly in unconventional gas production and greenhouse gas geo-sequestration. Despite extensive research in this area, conflicting results and explanations persist regarding imbibition phenomena, particularly in gas-water systems. This paper aims to address this gap by providing a comprehensive review of basic concepts, mechanical analyses, pore-filling patterns, front evolutions, and influencing factors associated with spontaneous imbibition. Mechanical factors including capillary force, viscous force, gravitational force, hydrostatic force, inertial force, capillary back force, and dead end force, play crucial roles in water imbibition with different boundary types. The pore-filling pattern significantly affects microscopic fluid distribution and front evolution during the imbibition process. To resolve conflicting findings, we systematically analyze the influencing factors of spontaneous imbibition within gas-water systems, encompassing rock properties, fluid characteristics, rock-fluid interactions, and reservoir properties. Furthermore, we present an in-depth discussion on the imbibition and trapping mechanisms relevant to unconventional gas production and CO2 geo-sequestration, providing insights into force analyses and influencing factors. Gas production strategies and favorable conditions for CO2 capillary trapping are proposed. Finally, we outline existing knowledge gaps and suggest potential directions for future research. This review thus provides useful insights and suggestions for advancing our understanding of spontaneous imbibition within gas-water systems and optimizing unconventional gas production and CO2 geo-sequestration practices.

Feasibility study of underground CO2 storage through Water Alternative Gas (WAG) operation: A case study in Southwestern Ontario

Geological CO2 storage (GCS) offers a promising, low-risk, long-term solution for carbon sequestration. This study assesses the feasibility of GCS water-alternating-gas (WAG) operations in a brine formation targeted for the Western Ontario GCS plan. The Cambrian strata shows potential for CO2 storage but faces challenges like limited lateral extension and geopolitical issues from plume migration. To mitigate these risks, a deep evaluation of CO2 trapping mechanisms is crucial. CO2 dissolution into brine provides secure storage by reducing the free plume. The proposed WAG operation promotes dissolution, using a vertical equilibrium model coupled with a black oil model to estimate CO2 trapping proportions during and post-injection. The Taguchi design of experiments investigates various WAG scenarios with minimal simulations, reducing numerical costs. Sensitivity analysis/optimization of WAG parameters, including water extraction rate (WER), water injection rate (WIT), and CO2 injection time (CIT), ranked their effectiveness in CO2 dissolution. Optimal WAG operations can reduce the free plume by 49 % and increase the dissolution ratio from 0.26 to 0.52. CIT and WIT were found to be the most influential factors, contributing 42 % and 31 % to CO2 dissolution, and 43 % and 34 % to overall CO2 trapping, respectively, while WER exhibited a lower impact of 8–9%.

Pore-scale numerical investigation on spontaneous imbibition in natural fracture with heterogeneous wettability using the volume of fluid method

Understanding the spontaneous imbibition in the natural fracture with heterogeneous wettability is crucial for predicting and mitigating the impacts of unstable displacement on unconventional recovery. In this paper, the fracture structured mesh model is reconstructed based on the micro-computed tomography (micro-CT) image of naturally fractured tight sandstone. The mineralogy map-based modeling method for heterogeneous-wetting fracture is developed by combining the thin section images, X-ray diffraction (XRD) analysis, and multiple point statistics method. The simulation of the single-phase flow is performed to test the mesh independence. The effects of gravity and wettability on spontaneous imbibition in natural fracture and corresponding imbibition front dynamics are analyzed and discussed using the volume of fluid (VOF) method. The results show that (1) The structured mesh reconstruction method proposed in this paper can more effectively preserve the fracture structure compared to the unstructured mesh reconstruction method. (2) Gravity has a negligible impact on the pore-scale spontaneous imbibition in natural fracture. Under homogeneous-wetting conditions, spontaneous imbibition in natural fracture consistently exhibits stable displacement without significant residual gas formation. However, under the heterogeneous-wetting condition, the spontaneous imbibition displays typical capillary fingering, resulting in approximately 24.04% of the gas being trapped after spontaneous imbibition. The residual gas trapping mechanisms mainly include adhered, isolated, and connected gas. (3) Under both homogeneous- and heterogeneous-wetting conditions, the imbibing water saturation and the length of the imbibition front are proportional to the power of imbibition time during spontaneous imbibition in the natural fracture.

Hydrocarbon Potential and Basin Analysis of the Southern Permian Basin, North Sea: Evaluating Key Plays in the Turonian and Carboniferous

This research provides an in-depth basin analysis and evaluates the hydrocarbon potential in the Southern Permian Basin, North Sea, Netherlands. It employs a thorough approach, including interpreting well logs, analysing petrophysical data, mapping faults and horizons, converting time to depth, and calculating reserves. The study highlights two key plays: the Turonian play (Barremian Formation) and the Carboniferous play (Rotliegend Formation). Petrophysical analysis of the Turonian Formation shows porosity values between 8.9% and 16% and net-to-gross ratios ranging from 0.6 to 1.0, indicating variable reservoir quality with a 45% geological chance of success. In contrast, the Carboniferous play, which includes Rotliegend marine sandstones, has a 45% chance of success but benefits from better porosity and permeability than the Turonian Formation. The research produced time and depth structure maps, clarifying trap mechanisms and identifying potential leads. With its promising results, the Southern Permian Basin presents a significant opportunity for future exploration and development. However, the study notes several limitations, such as issues with power stability, the need for more 3D seismic data and missing logs like neutron and density for some wells. Addressing these issues by improving data collection and operational conditions is crucial, as it could enhance exploration accuracy and increase the chances of success in the Southern Permian Basin. It also highlights the potential for further research in this area.

Techno-economic-environmental study of CO2 and aqueous formate solution injection for geologic carbon storage and enhanced oil recovery

As carbon capture, utilization, and storage (CCUS), carbon-dioxide enhanced oil recovery (CO2 EOR) has inherent shortcomings, such as inefficient oil recovery and carbon storage, and low storage security with mobile CO2. This paper presents a techno-economic-environmental analysis of using formate species, a product of CO2 electrochemical reduction, as an alternative carbon carrier for sequestration and EOR in a carbonate oil reservoir in the Gulf of Mexico Basin. CO2 injection, water-alternating-CO2 injection, and aqueous formate solution injection were compared using a compositional reservoir simulation model and an economic calculator. Formate solution injection yielded greater levels of oil recovery and net carbon storage, where the carbon-bearing species resided in the dense aqueous phase without having to rely on petrophysical trapping mechanisms (structural and capillary). The enhanced oil production, net carbon storage, and storage security can be promoted by providing formate-based CCUS with more incentives (e.g., greater tax credit) in comparison to CO2-based CCUS for EOR and the manufacture of chemicals and products. In establishing carbon storage incentive policies and regulations, policymakers should include alternative carbon carriers.

A data-driven dual-optimization hybrid machine learning model for predicting carbon dioxide trapping efficiency in saline aquifers: Application in carbon capture and storage

Geological carbon sequestration (GCS) is a promising method to reduce global carbon emissions. To better understand the CO2 trapping mechanism, the CO2 sequestration process was simulated through a physics-based reservoir simulator, and the residual trapping (RTI) and solubility trapping (STI) efficiencies were analyzed. Through the experiments, a database containing 4543 data points with reservoir physical parameters and rock properties was established. In this study, a kernel extreme learning machine (KELM) model based on variational mode decomposition (VMD) and dung beetle optimization optimizer (DBO) was proposed to perform the prediction task. Through the VMD, the original data sequences were decomposed and combined, and the obtained subsequences were executed modeling prediction and reconstruction respectively. The reliability of the prediction model was confirmed to be greater than 97.71% through domain analysis. In addition, it was applied to a tight gas reservoir in China in to confirm its validity in field applications. Comparative results indicated a high agreement between the prediction results and the simulation results, suggesting that the proposed method can complement numerical simulations and help users understand the application of machine learning in carbon capture and storage (CCS).