Heavy Components Research Articles

Calcium peroxide orchestrates virus-induced heavy metal resistome via shaping humeomics in sludge composting

This study aims to investigate the impact of calcium peroxide (CaO2) on compost humeomics and its effect on the toxicity removal of heavy metals (HMs), viral communities, and heavy metal resistance genes (HMRGs) during composting. The results indicate that CaO2 reduced the concentrations of toxic HMs As and Ni by 2.08 mg/kg and 10.41 mg/kg, respectively, compared to the control group (CK). Furthermore, it led to an increase in the stable fractions of As, Cu, Fe, and Ni by 6.32 %, 13.23 %, 3.09 %, and 3.01 % in the treatment group (T), respectively. CaO2 facilitated the transformation of heavy metal components, mitigated their harmful effects, induced their stabilization, and enhanced the humic quality. Metagenomic analysis shows that CaO2 effectively reduces the abundance of viruses (VRs) associated with HMRGs, leading to the inhibition and removal of HMRGs. Network analysis reveals that VRs, such as g__unclassified_f__Pithoviridae and g__unclassified_d__Viruses, which are related to toxic HMs, play a key role in regulating the hazardousness of pollutants in compost, and their abundance is effectively reduced by CaO2. Finally, mantel test analysis confirms that the Fenton-like reactions triggered by CaO2 and the succession of viral communities are crucial factors in pollutant removal. These results collectively indicate that under the influence of CaO2, the hazardousness of HMs, VRs, and HMRGs in the composting process is reduced, and they are effectively inhibited and removed.

Study on the Catalytic Oxidation Modification Effect of Heavy Oil at Low Temperature under the Action of Different Ligand Ferric-Based Systems

This work explores the low-temperature catalytic oxidation of heavy oil (140 °C), resulting in structural changes with reduced heavy components and increased light components. The catalytic oxidation system consists of a catalyst, an oxidant, and a proton donor. Four different complexes of iron-based catalysts were utilized: ferric oleate, iron naphthenate, EDTA–FeNa, and EDDHA–FeNa. Catalytic oxidation processes with these catalysts produced four types of oxygenated oil, which were then analyzed using group composition analysis and a viscosity test. The results show that EDDHA–FeNa is more favorable for the catalytic oxidation of heavy oil in a low-temperature environment, achieving a viscosity reduction rate of 78.57%. Furthermore, the catalytic performance of heavy oil oxidation was investigated using EDDHA–FeNa as catalyst under three conditions: the amount of catalyst, oxidant and reaction temperature. These findings may provide researchers valuable guidance and principles for the investigation and development of advanced catalytic viscosity reduction of heavy oil.

Evolution of Rheological and Microscopic Properties of Asphalt Binders under Fuel Corrosion

Vehicle fuel leaks can adversely affect the performance of asphalt pavements. To study the mechanisms of fuel corrosion damage in asphalt, four asphalt binders were selected in this study, and the evolution of their rheological and microscopic properties was investigated. Fuel corrosion caused continuous mass loss in asphalt binders. Base asphalt lost more than 50% of its mass after 24 h of fuel corrosion, while modified asphalts had better resistance. According to dynamic shear rheometer tests and multiple stress creep recovery tests, modifiers improved the high-temperature rheological properties of these asphalt binders. As the degree of fuel corrosion deepened, the indexes characterizing the high-temperature performance deteriorated. Rubber-modified asphalt showed the best resistance to high-temperature deformation, while the performance of LDPE-modified asphalt was more stable. In contrast, fuel corrosion improved the resistance of asphalt binders to low-temperature cracking to some extent: the creep strength (S) decreased as the creep rate (m) increased, and the resistance of SBS-modified asphalt to low-temperature cracking was optimal, with a 36% decrease in S-value after 24 h of fuel corrosion. Fourier transform infrared spectroscopy tests showed that diesel corrosion was a process of this physical dissolution, with no change in the chemical functional groups. Meanwhile, by using fluorescence images and analyzing the four-component test results, we found that fuel corrosion disrupted the stabilized structure formed by the modifiers, and the heavy components in the asphalt binders were converted into light components. This study reveals the evolution of the rheological and microscopic properties of asphalt under fuel corrosion, which can provide a reference for the optimization of fuel corrosion resistance in asphalt pavement.

Investigation of the permeability build-up method in the bottom-hole zone of the pay zone

In oil wells, the bottomhole formation zone is subjected to various influences during drilling, development and operation. The porous medium of the bottomhole zone is clogged by heavy components of the produced products and rock particles, reducing permeability and production. Various technologies are used to restore bottomhole permeability. A new method has been developed, including injection of a composition containing aqueous sodium bicarbonate solution with the addition of a chemical reagent, light oil and an acid solution into the formation. The essence of the acid treatment new method of heterogeneous terrigenous formations is that high permeable zones are blocked by a foam system, and injection of acid solution activates low-permeable zones. The new method developed in laboratory conditions was tested in field conditions. The test results showed that the set objectives were achieved.

Distinctions of the Emergence of Convective Flows at the “Diffusion–Convections” Boundary in Isothermal Ternary Gas Mixtures with Carbon Dioxide

This study discusses the influence of the composition of a ternary gas mixture on the possibility of occurrence of convective instability under isothermal conditions due to the difference in the diffusion abilities of the components. A numerical study was carried out to study the change in “diffusion–concentration gravitational convection” modes in an isothermal three-component gas mixture He + CO2 − N2. The mixing process in the system under study was modeled at different initial carbon dioxide contents. To carry out a numerical experiment, a mathematical algorithm based on the D2Q9 model of lattice Boltzmann equations was used for modeling the flow of gases. We show that the model presented in the paper allows one to study the occurrence of convective structures at different heavy component contents (carbon dioxide). It has been established that in the system under study, the instability of the mechanical equilibrium occurs when the content of carbon dioxide in the mixture is more than 0.3 mole fractions. The characteristic times for the onset of convective instability and the subsequent creation of structural formations, the values of which depend on the initial content of carbon dioxide in the mixture, have been determined. Distributions of concentration, pressure and kinetic energy that allow one to specify the types of mixing and explain the occurrence of convection for a situation where, at the initial moment of time, the density of the gas mixture in the upper part of the diffusion channel is less than in the lower one, were obtained.

Propagation of Combustion Front within Fractured Shale and Its Influence on Shale Structure and Crude Oil Properties: An Experimental Study

Summary The in-situ combustion (ISC) technique has emerged as a significant approach for shale oil production. However, currently, there is a lack of experimental evidence supporting the stable propagation of combustion front within fractured shale. This study aimed to investigate the combustion characteristics within fractured shale by using a self-designed combustion tube (CT) and an experimental scheme. Subsequently, an analysis of shale structure and oil properties was conducted. The results demonstrated that while the combustion front could propagate through shale with a single fracture width of approximately 43 μm, the combustion intensity gradually diminished, leading to an inability to sustain stable propagation in the later part of the oil-detritus mixtures. The combustion intensity within the shale was enhanced by preheating the shale at 250°C, resulting in an improved oil recovery from 67.8% to 77.9%. The findings indicated that the complex fractured shale allowed for the stable propagation of the combustion front without a significant decrease in combustion intensity. Moreover, the T2 spectrum analysis of shale revealed a gradual expansion of the pore-fracture structure and improved shale connectivity after combustion. The T1-T2 response illustrated the transformation of solid and heavy components into lighter components. Furthermore, the content of saturates and H in the oil increased after combustion, whereas there was a significant decrease in resins, O, and S. Overall, this study provided technical evidence supporting the feasibility of employing the ISC technique for the development of shale oil reservoirs with additional fractures.

Identification and evaluation of shale oil micro-migration and its petroleum geological significance

Taking the Lower Permian Fengcheng Formation shale in Mahu Sag of Junggar Basin, NW China, as an example, core observation, test analysis, geological analysis and numerical simulation were applied to identify the shale oil micro-migration phenomenon. The hydrocarbon micro-migration in shale oil was quantitatively evaluated and verified by a self-created hydrocarbon expulsion potential method, and the petroleum geological significance of shale oil micro-migration evaluation was determined. Results show that significant micro-migration can be recognized between the organic-rich lamina and organic-poor lamina. The organic-rich lamina has strong hydrocarbon generation ability. The heavy components of hydrocarbon preferentially retained by kerogen swelling or adsorption, while the light components of hydrocarbon were migrated and accumulated to the interbedded felsic or carbonate organic-poor laminae as free oil. About 69% of the Fengcheng Formation shale samples in Well MY1 exhibit hydrocarbon charging phenomenon, while 31% of those exhibit hydrocarbon expulsion phenomenon. The reliability of the micro-migration evaluation results was verified by combining the group components based on the geochromatography effect, two-dimension nuclear magnetic resonance analysis, and the geochemical behavior of inorganic manganese elements in the process of hydrocarbon migration. Micro-migration is a bridge connecting the hydrocarbon accumulation elements in shale formations, which reflects the whole process of shale oil generation, expulsion and accumulation, and controls the content and composition of shale oil. The identification and evaluation of shale oil micro-migration will provide new perspectives for dynamically differential enrichment mechanism of shale oil and establishing a “multi-peak model in oil generation” of shale.

Evaluation of Worker Radiation Exposure during the Kori Unit 1 Steam Generator Dismantling Process

Kori Unit 1 was permanently shut down on June 18, 2017. Since then, Korea is actively preparing for the decommissioning of the nuclear power plant. Because decommissioning work is performed in a radioactive environment, worker radiation exposure is a significant consideration. In this study, worker radiation exposure is evaluated during the steam generator, one of the heavy components of nuclear power plant, dismantling process. A radiation evaluation for the dismantling process is performed using the code RESRAD-BUILD. A steam generator dismantling scenario and optimal cutting method are designed to evaluate worker radiation exposure, considering pipe dimensions, cutting tool speed, and experience in steam generator replacement. The evaluation results are derived for each work type and year. As a result of the evaluation, worker radiation exposure is 7.5 man-mSv at the year of planned decommissioning.

Prediction of Cross-Section-Dependent ADI Microstructures by Experimental Heat Treatment Simulation

Heavy section Austempered Ductile Iron (ADI) components may contain pearlitic or a mixed microstructure (mixture of pearlite and ausferrite) in their centres besides ausferrite. As a result, mechanical properties are not homogeneously distributed across the thicknesses of the components. The oversizing of the components therefore leads to unnecessary material expenses in foundries. In order to avoid the complex manufacturing process of heavy section ADI components and subsequent investigations, preliminary tests were performed with smaller test samples. Here, temperature-time curves were detected during heat treatment at different depths. Material samples of the customised composition were heat treated in a dilatometer under the same heat treatment conditions according to different sections of the cast component. A variation of the quenching rates was conducted to investigate the influence on the mixed microstructure formation and ratio of pearlitic and ausferritic microstructures. A comparison of the conventionally heat-treated and dilatometer produced microstructures proved the successful application for heavy section parts and enables microstructure predictions with small samples only. In this way, there is no requirement of expensive tests with high-mass components.

The transmission of isotopic signals from precipitation to groundwater and its controls: An experimental study with soil cylinders of various soil textures and burial depths in a monsoon region

The use of stable isotopic composition in groundwater as a paleoclimatic proxy assumes that the isotopic values in groundwater are inherited from the corresponding values in the source precipitation. However, several studies have observed that groundwater δ18O (δ18Og) is not always in accordance with the average δ18O of precipitation (δ18Op). The cause of this inconsistency is still the subject of debate. Significant reduced isotopic variability and potential deviations from precipitation to groundwater because of the aquifer itself (e.g., groundwater buried depths and soil texture) and external precipitation characteristics (e.g., rainfall intensity and duration) have been poorly quantified in terms of identifying the dominant factors. To investigate the controls on the transmission of isotopic signals from precipitation to groundwater, we present new stable isotope data for precipitation and groundwater from an experimental site using eight soil cylinders of different soil textures and burial depths in a monsoon region. We collected data at inter-event sampling intervals (30 min) during and after two heavy precipitation events (daily amounts higher than 10 mm). Our results demonstrated a significant disparity between the average isotopic values of heavy rainfall and light rainfall, despite both exhibiting decreasing isotopic patterns throughout the course of the rainfall event. Various degrees of attenuation of isotopic variations were found in outflow waters with different groundwater burial depths (GBDs) and soil textures after rainfall events. The isotopic variations were not synchronized with the outflow changes. Specifically, there were evident outflow lags in response to heavy rainfall, especially in the lysimeters with GBDs deeper than 0.5 m, while the greatest isotopic variation was observed in the early infiltrating stage. Redundancy analysis indicated that precipitation amount was the most important contributor to the outflow variation (∼51 %, p < 0.05), while GBD was the key factor for isotopic temporal variation (∼52 %, p < 0.05). These results concurred with the clustering of principal component analysis results. The mixing of soil water and heavy rainfall event components was observed in four lysimeters with mixing proportions fP varying in the range of 7 %–51 %, indicating the effective recharge from heavy rainfall. Soil evaporation was highlighted with samples located parallel to the local meteoric water line. It is recommended that groundwater isotopes in paleoclimatic studies are used with additional constraints that consider disproportionate recharge from intense rainfall, past chaotic fluctuations in groundwater dynamics, and distortions introduced by evaporation.

Study on the influence of steam state on seepage, production, migration and deposition of offshore heavy oilfields

In this paper, the influence of steam state on seepage, production, migration and deposition are refined, and the superiority of superheated steam is confirmed. Firstly, the relative permeability of oil-water and oil-steam in offshore cores was measured to analyze flowing characteristics. Then the cyclic steam stimulation of long core was conducted with supersaturated, saturated and superheated steam, and the recovery capacity was quantified, the difference in composition of produced oil was analyzed. Finally, the CT scanning and digital core 3D reconstruction were performed to visualize the influence of steam state on migration of heavy oil components. The results show that the temperature has a significantly higher effect on seepage capacity than permeability, which can effectively broaden the co-seepage range and reduce residual oil saturation. The total recovery of superheated steam is 12 % and 7 % higher than the other two steam respectively, and the main recovery cycle is the former four rounds, which accounts for over 85 % of total recovery. The retention of heavy components can reduce porosity by 4 %∼7 %, superheated steam can alleviate blockage and increase the porosity by over 2 %. This work is expected to provide valuable insights into the application of superheated steam in offshore heavy oilfields.

Improving the efficiency of oil field development based on the use of thermochemical treatment technology

The article is devoted to improving the technology of effect the oil reservoir and the bottomhole zone of production and injection wells. Based on laboratory experimental studies, a new technology that allows increasing oil displacement from a porous medium, as well as increasing well productivity has been developed. The composition of the proposed composition includes a strong oxidizing agent, low and trihydric alcohols, surfactants, etc. When the components of the composition interact, an exothermic reaction occurs, as a result of which a large amount of heat and gas are released in the bottomhole zone. Due to the released heat, the viscosity of heavy oil components, deposited in a porous medium and worsening the filtration characteristics of the formation, decreases. As a result of the impact of the composition, the permeability of the bottomhole zone, the productivity of production and injectivity of injection wells increase. Since the exothermic reaction takes place in the formation itself, this allows increasing the thermal effects.

Effect of Tributyl Citrate as a Cosolvent on the Phase Behavior of Crude Oil during CO2 Injection Process

The current research on CO2 cosolvent primarily focuses on reducing the minimum miscibility pressure and improving oil recovery. However, investigations into the impact of additive agents on the phase behavior of crude oil during the CO2 injection process are relatively limited. In this study, we introduced tributyl citrate as a cosolvent to the CO2 injection process. By comparing the phase parameters of crude oil and changes in component composition in the residual oil before and after the addition of tributyl citrate, we explored the influence patterns of this cosolvent during CO2 injection. The experiments show that the optimum concentration of tributyl citrate is 0.3%. After the addition of tributyl citrate, the bubble point pressure of crude oil is reduced from 14.28 MPa to 13.36 MPa, and the density is decreased from 1.00 g/cm3 to 0.95 g/cm3. These alterations of bubble point pressure and density indicate an enhanced solubility of CO2 and improved miscibility with the oil, coinciding with an increased volume expansion coefficient rising from 1.12 to 1.18 under 20 MPa and a decrease in viscosity from 0.73 mPa·s to 0.64 mPa·s. Tributyl citrate primarily affects the properties of crude oil by reducing interfacial tension and the content of heavy components in the dissolution system. The addition of tributyl citrate stabilizes the deposition trend of heavy components in crude oil and promotes the transformation of heavy components into light components, thereby enhancing the efficiency of CO2 extraction. This study provides valuable insights into a novel and simple method to further increase oil recovery in the CO2 injection process.

Recovering hydrocarbon from oily sludge using supercritical CO2: Experiments and a new method for predicting optimal conditions

A novel methodology considering phase behavior and hydrogen bonding association between asphaltene and water was developed to predict the optimal conditions during hydrocarbon recovery from oily sludge (OS) using supercritical CO2 (SCCO2). The predicted optimal extraction temperature and pressure for Fuling OS are 23 MPa and 333.15 K, respectively. After performing systematic experimental studies, time was found to positively affect extraction efficiency, whereas temperature and pressure had negative effects beyond 25 MPa and 323.15 K (i.e., the measured optimal conditions of Fuling OS). The extraction efficiency under these conditions reached 11.02%. Compared with unprocessed OS, processed OS had a different crystalline structure, more homogeneous particle size, and lower spectral peak intensity. Additionally, sixteen-carbon chains (C16) or shorter were recovered more easily than heavier components. The distribution of carbon number in OS was unaffected by the extraction process, indicating that SCCO2 extraction did not change the hydrocarbon composition.

Selective extraction of aromatics from residual oil with subcritical water

Based on theoretical calculations and experimental characterizations, the extraction of heavy oil components using subcritical water (Sub-CW) as an extraction solvent was studied in the temperature range of 250–325 °C. According to theoretical calculations, small-scale polycyclic aromatic hydrocarbons (PAHs) are preferentially dissolved in Sub-CW. Meanwhile, the dissolution of heavy oil molecules with large-scale aromatic structures and heterocyclic rings in Sub-CW is hindered. The increase in temperature reduces the hydrogen bonding force between water molecules and the van der Waals repulsion between Sub-CW and PAHs, promoting the dissolution of PAHs in Sub-CW. Extraction experiments applied in a semi-continuous device confirm that Sub-CW selectively extracts aromatic hydrocarbons from heavy oil. Increasing extraction temperature increases the yield of the extract. The aromatic hydrocarbon content in the extract at 325 °C reaches 80 wt%, which is 27 wt% higher than feedstock value. In addition, the asphaltene content in the extract is reduced from the feedstock value of 14 wt% to 2 wt%.

Experimental Study on Water-in-Heavy-Oil Droplets Stability and Viscosity Variations in the Dilution Process of Water-in-Heavy-Oil Emulsions by Light Crude Oil

The main objective of this study is to put forward effective schemes for alleviating reservoir choke caused by emulsification or Jamin’s effect using the dilution method by light crude oil, as well as sharply increased viscosity. In this study, water-in-heavy-oil (W/O) emulsions with varying water fractions were prepared with heavy oil from Bohai Bay, China. Mixtures of W/O emulsions and light crude oil samples (light oil and light heavy oil) with varied dilution ratio (1:9, 2:8, 3:7) are tested, respectively by the electron microscope and by the rheometer. W/O droplets’ distribution and viscosity variations are obtained to evaluate the emulsion stability and viscosity reduction effects by dilution. Results show that W/O droplets, size distribution range increases with the increase of water fractions. W/O droplets with larger size tend to be broken first in the dilution process. Light oil could reduce emulsions’ viscosity more effectively than light heavy oil. Viscosity reduction mechanisms by dilution could be concluded as the synergistic effects of dissolving heavy components and weakening oil–water film stability. Therefore, light oil is suggested as the optimal one for solving formation plugging. The poor performance of Richardson model is related to the re-emulsification between free water and crude oil favored by light heavy oil, and demulsification favored by light oil. The modified model shows a significant improvement in prediction accuracy, especially for W/O emulsions with large water fractions. This study demonstrates a promising and practical strategy of solving heavy oil well shutdown problems and viscosity increasing by injecting light crude oil in the thermal stimulation.

Novel Effect of Post-Oxidation on the Comprehensive Performance of Plasma Nitriding Layer

In order to enhance the comprehensive performance of plasma nitrided heavy load components used in corrosive environments, post-oxidation was conducted under different conditions after plasma nitriding 42CrMo4 steel at 500 °C for 5 h. The results show that an oxide film composed of Fe3O4 and Fe2O3 was formed above the compound layer, resulting in a significant increase in corrosion resistance; the self-corrosion potential was greatly increased from −658.72 mV to −429.23 mV. Meanwhile, it needs to be emphasized that the characteristics of the plasma nitriding layer could be effectively adjusted as expected by post-oxidation. The compound layer thickness decreased from 9.41 μm to 3.62 μm by post-oxidation at 400 °C for 2 h, while the thickness of the effective hardening layer increased from 300 μm to 378 μm. Due to the expected change in the characteristics of the plasma nitriding layer, post-oxidation could simultaneously improve the toughness, hardness, and wear resistance of the samples; the brittleness level decreased from Grade 4 to Grade 1; the surface hardness increased from 765 HV0.05 to 825 HV0.05; and the wear rate decreased from 3 × 10−5 g·m−1·N−1 to 1.19 × 10−5 g·m−1·N−1, illustrating that the wear resistance was greatly improved.

Pyrolytic Modification of Heavy Coal Tar by Multi-Polymer Blending: Preparation of Ordered Carbonaceous Mesophase.

In order to achieve the high-value utilization of heavy tar for the production of enhanced-performance graphite foam carbon, the carbon mesophase was ready from the heavy component of low-temperature coal tar, and the coal tar was modified by styrene-butadiene-styrene (SBS), polyethylene (PE) and ethylene-vinyl-acetate (EVA) copolymers. The order degree of the carbonite mesophase was analyzed using a polarizing microscope test, Fourier transform infrared spectroscopy and X-ray diffraction to screen out the most suitable copolymer type and addition amount. Furthermore, the mechanism of modification by this copolymer was analyzed. The results showed that adding SBS, PE and EVA to coal tar would affect the order of carbonaceous mesophase; however, at an addition rate of 10.0 wt.%, the linear-structure SBS copolymer with a styrene/butadiene ratio (S/B) of 30/70 exhibited the optimal degree of ordering in the carbonaceous mesophase. Its foam carbon prepared by polymer modification is the only one that forms a graphitized structure, with d002 of 0.3430 nm, and the maximum values of Lc and La are 3.54 nm and 2.22 nm, respectively. This is because, under elevated pressure and high-temperature conditions, SBS underwent chain scission, releasing a more significant number of methyl and other free radicals that interacted with the coal tar constituents. As a result, it reduced the affinity density of heavy coal tar molecules, enhanced fluidity, promoted the stacking of condensed aromatic hydrocarbons and increased the content of soluble carbonaceous mesophase, ultimately leading to a more favorable alignment of the carbonaceous mesophase.

Подкритическая конвекция в коллоидах и жидких бинарных смесях с положительной термодиффузией

The paper analyzes convection of molecular binary mixtures and colloids with positive thermal diffusion that occurs in the case of heating from below and below the equilibrium stability threshold for a homogeneous liquid. The convection is pulsed in nature and is realized in the form of periodic bursts. Positive thermal diffusion displaces the heavy component into the upper cold layers of the liquid. There, the heavy component accumulates in the boundary layer, forming a growing unstable density stratification. When the inhomogeneity exceeds the critical value for a given geometry, a convective surge occurs, and the heavy component moves down to a stable position. The study has found the critical thickness of the boundary layer, the critical concentration difference at the boundaries of the cavity, and the time at which instability occurs. Based on the analysis of the problem of the concentration profile dynamics under the influence of gravitational sedimentation and thermal diffusion, experimental facts are explained – periodic convective bursts of the binary mixture in channels and in the Hele-Shaw cell below the critical Rayleigh number. The described mechanism probably explains the convection observed by other experimenters in a horizontal flat layer of magnetic fluids below the critical Rayleigh number at Ra &lt; 1708.

Improvement of model predictive control on a depropaniser: an industrial case study

In this work, improvements to a model predictive controller in an industrial facility is presented. A depropaniser column used to separate propane and propylene from heavier components was experiencing sporadic process instabilities which was impacting product purities. A soft sensor to measure C4 hydrocarbons was inaccurately predicting the actual composition, which caused the controller to behave erratically. A simple linear regression implementation improved the accuracy of the soft sensor significantly, which allowed further optimisation of the controller. Large benefits in process stability and propylene recovery were observed.