Multicomponent Oil Research Articles

Natural convection characteristics of novel immersion liquid applied to battery thermal management in static mode

Battery thermal management (BTM) based on immersion liquid is a novel and promising technology due to its excellent thermal performance. However, the natural convection characteristics of immersion liquid are crucial yet often neglected for the design of immersion-based BTM. In this study, a typical BTM unit and module are designed utilizing a multi-component oil as the immersion liquid. To characterize the effect of natural convection, a rigorously validated model coupled with heat transfer and natural convection is developed. For the BTM unit, the impact of varying space occupied by immersion liquid is investigated. The increase in the thickness of the immersion liquid progressively enhances the natural convection effect. The Grashof number in the vertical interlayer of finite space helps assess the strength of natural convection of the BTM unit. Furthermore, a comparison of the BTM module with and without natural convection is performed. The results show that the natural convection effect enhances heat dissipation but reduces thermal uniformity in static mode. When the thickness of immersion liquid is 10 mm, the natural convection effect results in a decrease of 1.4 °C in the average battery temperature. Meanwhile, the battery temperature difference increases from 1.27 °C to 3.14 °C, and the average temperature of the terminals and busbars increases by >1 °C. This study can provide a foundation and reference for the BTM design based on immersion liquid.

Surface Chemistry Study of Normal and Diseased Human Meibum Films Prior to and after Supplementation with Tear Mimetic Eyedrop Formulation

Ophthalmic nanoemulsions that can treat the deficiencies of meibum (MGS) in Meibomian gland disease and restore its functionality in the tear film are greatly sought. The Rohto Dry Aid (RDA) formulation employs TEARSHIELD TECHNOLOGYTM, which uses a multicomponent oil phase of polar and non-polar lipid-like molecules selected to mimic the profiles of healthy meibum. Thus, the interactions of RDA with “diseased” Meibomian (dMGS) films merit deeper analysis, as these interactions might offer important clues for both the development of new ocular formulations and the processes behind the therapeutic action of the nanoemulsions. Pseudobinary dMGS/RDA films were spread at the air–water surface of the Langmuir trough. Surface pressure-area isocycles and stress relaxations were used to access the layer’s response to blink-like cycling and dilatational viscoelasticity, respectively, while film morphology was recorded via Brewster angle microscopy. It was found that RDA is able to reverse the brittleness and to restore the stability of “diseased” MGS films and thus to revert the layer’s properties to the functionality of healthy Meibomian lipids. Therefore, in order to effectively treat dry eyes with MGS-oriented therapy, ophthalmic nanoemulsions warrant more research.

Multi-component oil–water two phase flow in quartz and kerogen nanopores: A molecular dynamics study

Two-phase flow of oil and water frequently occurs within shale nanopores. Unique phenomena, like liquid–liquid slip at the oil–water interface, have been noted within the alkane-water system. However, in the case of realistic crude oil, the presence of highly polar components like asphaltene and toluene may introduce intricate migration behaviors near phase interfaces. Consequently, it is imperative to thoroughly explore the influence of these realistic crude oil components on flow behavior. This paper employs a comparative approach to examine the impact of polar components present in crude oil on two-phase nanoflow by molecular dynamic simulations. The investigation employs a mixed alkanes model (encompassing methane, propane, octane, and tetradecane) and a black oil model (comprising a range of alkanes, toluene, and asphaltene) to analyze the behavior of oil–water two-phase flow within quartz and kerogen nanopores, respectively. Four water adsorption layers near the quartz with an individual thickness of 0.23 nm and three alkane adsorption layers near the kerogen surface with an individual thickness of 0.45 nm were observed. Near the oil–water interface region, it indicated that toluene and asphaltene tend to accumulate, leading to a reduction of alkane aggregation in that region. Such aggregation of toluene and asphaltene imparts an interfacial viscosity increase of 2.67 to 3.47 times, substantially diminishing the enhancement of liquid–liquid slip. Based Hagen-Poiseuille equation, we proposed a simplified mathematical model in which the liquid–liquid slip was neglected and the oil–water interface region was omitted. Compared with the results from molecular dynamic simulations, such a simplified model is validated and effective for the description of oil–water two-phase nanoflows containing toluene and asphaltene, and ensures that the relative error of flow rate remains below 0.5 %. This study provides valuable insights into the two-phase flow of oil–water in nanopores, particularly measuring the effect of liquid–liquid slip under the different crude oil components conditions.

Flow regime transition of multicomponent oil in shale nanopores

Understanding the shale oil flow mechanism in nanopores is crucial for optimizing development strategies and enhancing recovery in shale oil reservoirs. Despite the widespread use of molecular dynamics simulations in studying shale oil flow, oversimplified shale oil and shale nanopore models compromise result reliability, and a definitive shale oil flow regime has yet to be established. This study, employing validated molecular models, investigated 26-component oil flow in authentic shale kerogen and quartz nanopores. For the first time, we elucidated the nonlinear flux increase due to flow regime transition with pressure gradient. At low pressure gradients, shale oil flux gradually increased with a parabolic velocity profile. With the increasing pressure gradient, the velocity profile shifted from parabolic to piston-like, especially in quartz nanopores, indicating a positive slip velocity. Consequently, the shale oil flux increased significantly. At high pressure gradients, the growth of shale oil flux decelerated while maintaining a piston-like velocity profile. Through analysis of density distribution and oil-wall interactions, we revealed that oil desorption and redistribution triggered the flow regime transition. The flow regime transition occurred with the widening of quartz nanopores. Increased nanopore width and temperature notably enhanced shale oil flow. This study underscored the importance of accounting for shale oil’s multicomponent properties and roughness and composition of shale nanopores. It determined shale oil flow regimes under various conditions, advancing our comprehension of shale oil flow mechanisms in realistic settings and furnishing a theoretical foundation for enhancing shale oil recovery.

Guidelines for parenteral nutrition in preterm infants: The American Society for Parenteral and Enteral Nutrition.

Parenteral nutrition (PN) is prescribed for preterm infants until nutrition needs are met via the enteral route, but unanswered questions remain regarding PN best practices in this population. An interdisciplinary committee was assembled to answer 12 questions concerning the provision of PN to preterm infants. The Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) process was used. Questions addressed parenteral macronutrient doses, lipid injectable emulsion (ILE) composition, and clinically relevant outcomes, including PNALD, early childhood growth, and neurodevelopment. Preterm infants with congenital gastrointestinal disorders or infants already diagnosed with necrotizing enterocolitis or PN-associated liver disease (PNALD) at study entry were excluded. The committee reviewed 2460 citations published between 2001 and 2023 and evaluated 57 clinical trials. For most questions, quality of evidence was very low. Most analyses yielded no significant differences between comparison groups. A multicomponent oil ILE was associated with a reduction in stage 3 or higher retinopathy of prematurity (ROP) compared to an ILE containing 100% soybean oil. For all other questions, expert opinion was provided. Most clinical outcomes were not significantly different between comparison groups when evaluating timing of PN initiation, amino acid dose, and ILE composition. Future clinical trials should standardize outcome definitions to permit statistical conflation of data, thereby permitting more evidence based recommendations in future guidelines. This guideline has been approved by the ASPEN 2022-2023 Board of Directors.

Soil Nematodes of Northern Meadows and Agrocoenoses as Bioindicators of the Transformation Degree in Soil Ecosystems

This paper examines the effect exercised by agricultural intensity on soil nematode communities inhabiting natural meadows, hayfields, and monocrop agrocoenoses in the Republic of Karelia. The diversity of the soil nematode fauna in natural meadows is similar to that in hayfields, but it significantly decreases in agrocoenoses. The abundance of nematodes reaches the highest values in soils of meadows and decreases as land use intensity goes up. Bacterial feeders predominate in the eco-trophic structure of nematode communities in all types of biocoenoses reaching the maximum share in agrocoenoses. The relative abundance of predators and nematodes associated with plants in agrocoenoses is significantly lower compared to natural meadows and hayfields. Ecological indices computed for nematode communities indicate the presence of a stable and multicomponent soil ecosystem in meadows. The CI index reflecting the predominant pathway of organic matter decomposition indicates an active participation of bacteria in the destruction. Values of the SI and CI indices decrease in agrocoenoses, while the EI index increases. Such a ratio between indices specifies simplified food web and a disturbed soil ecosystem in agrocoenoses. Discriminant analysis shows that, of all studied biocoenoses, only agrocoenoses and natural meadows can be differentiated statistically significantly based on differences in the SI index. However, the identified positive effect of latitude on the SI index in agrocoenoses indicates that the application of this parameter to northern ecosystems has some limitations.

A novel technique for quantifying the fate of CO2 injected in oil reservoir for geological utilization and storage

CO2-enhanced oil recovery (CO2-EOR) is a potential CO2 capture, utilization, and storage technology. In particular, CO2 can break the hydrochemical balance of water–rock and converts into carbonate minerals which are the most stable sequestration phase. The water–rock reactions are complex kinetic processes because the rate of dissolution/precipitation of minerals are vary with the pH of the formation water. However, studies on the effect of geochemical reactions on CO2-EOR processes are lacking, and the fate of CO2 cannot be accurately quantified. In this study, we combine the characteristics of the oil phase into the thermal–hydraulic–chemical TOUGHREACT simulator to consider various water–rock geochemical kinetic reactions in CO2-EOR. Therefore, the distribution phase of CO2 can be determined completely in the reservoir. Our analyses use the realistic fluid property (pressure–volume–temperature) of multicomponent oil phase–CO2 mixtures. The model considers the possible geochemical reactions and the resulting changes in porosity and permeability. The results indicate that in gas–water cycle of 9% hydrocarbon pore volume CO2 slug, the largest distributed phase of CO2 is the gas phase, accounting for 52.2% during the CO2 injection period. After water injection, the solubility of CO2 in the oil phase increases, and CO2 is mostly dissolved in the oil phase, accounting for 53.0%. Without considering the water–rock geochemical reactions will result in an underestimation of the dissolved aqueous phase and correspondingly the others were overestimated. The maximum error of the distributed quantity is up to 6.4% of the total injection. In addition, the omission of water–rock reactions result in an underestimation of the oil recovery. Comparing with the CO2 storage in a saline aquifer, dissolution of CO2 in oil phase in CO2-EOR scenario dampens the effect of buoyancy, which leads to higher sequestration capacity for the same footprint of storage reservoir.

Functionalized silica nanoparticles within a multicomponent oil emulsion by molecular dynamic study

Molecular dynamics simulations were employed to study hydroxylated and functionalized SiO2 nanoparticles (NPs) within a light crude oil under different temperatures. The model oil comprised a combination of aromatics, alkanes, and cycloalkanes, while the hydroxylation, PEGlyation, and sulfonation of the NPs were evaluated. The effects of functional size were considered for PEGlyated NPs. Interestingly, benzene clusters dispersed in the oil phase were formed for all systems studied; clusters of 9 and 11 molecules were the most common. The benzene clusters adsorbed onto the NPs, forming a surrounding shell approximately 10 Å in width. The agglomeration of aromatic molecules was more evident for hydroxylation covering: the density of benzene molecules in the first shell of aromatic molecules surrounding the NPs decreased in the order NP-H, NP-SA, NP-EG, and NP-PEG2 and reached a maximum for hydroxylated NPs, where the hydrocarbons form a first shell of molecules ∼25 Å in width. The density of benzenes is 24% greater than in pristine oil. Compared to other coverings, this effect reduces the NP–oil interfacial tension for the hydroxylated NPs by about 15%. Our results indicated that the adsorption of benzene on NPs and the NPs–oil interfacial tension could be tuned by the NP covering. This degree of control is highly desirable for applications of NPs in enhanced oil recovery processes.

The variability of acrylamide content in potato French fries depending on the oil used and deep-frying conditions

The research aimed to investigate the variability of the acrylamide content in French potato fries depending on the type of oil and the length and conditions of deep-frying. Deep-frozen pre-fried potato French fries primarily intended for catering establishments were deep-fried parallel in two oils (multi-component oil and rapeseed oil) at the same conditions (175 °C/4 min and 200 °C/3 min) until the limit for total polar compounds (TPCs) content (24%) was reached. The samples were analysed immediately after removal from the package, after the first frying and when the TPCs was exceeded. High-performance liquid chromatography/electrospray ionization tandem mass spectrometry (HPLC/ESI-MS/MS) was used to determine acrylamide. Mathematical and statistical evaluation of the results was according to the indicators of descriptive characteristics, i.e., arithmetic mean, standard deviation (SD), and coefficient of variation (%). Analysis of variance (ANOVA) was used to compare groups, i.e., the assumption of agreement of variance was verified by the F test (F). All pairwise differences in means were tested using Tukey's HSD test (Honest Significantly Different) and Scheffe´s test. The critical value of α, compared to the standardized difference between the means, was established using our chosen risk of 5%. The highest acrylamide values were measured in samples deep-fried in rapeseed oil at 200 °C/3 min in sample 2b (451.13 µg/kg when deep-fried immediately) and in sample 2d (383.24 µg/kg after exceeding TPCs). The lowest values of acrylamide were found in samples deep-fried in multi-component oil at a temperature of 200 °C/3 min in sample 1d (183.35 µg/kg after exceeding TPCs) and at a temperature of 175 °C/4 min in sample 1c (240.75 µg/kg after exceeding TPCs). The decreased tendency of acrylamide in both types of oils and variants of temperature after exceeding TPCs compared to the state immediately after frying is confirmed for all samples. Potato-based products are a significant source of acrylamide production and subsequent consumption. Monitoring its presence in food is, therefore, an important legislative requirement.

Sampling and classifier modification to DSMART for disaggregating soil polygon maps

DSMART has been widely used to disaggregate multi-component soil polygon map units into raster maps. The algorithm randomly selects (simple random sampling approach) an equal number of synthetic sample points from all map units and assigns soil classes proportionate to the map unit composition using the C5.0 algorithm. Conditional Latin Hypercube sampling (cLHS) is a maximally stratified random sampling that guarantees full coverage of multivariate distribution. cLHS has shown success in digital soil mapping as it optimizes sample point selection based on environmental covariates. Information-driven stratification and sampling may help improve the assignment of soil classes within map units. The objective of this study was to compare cLHS against simple random sampling (SRS) approach using three classifier algorithms in DSMART to disaggregate the soil great group and soil series maps of a sub-watershed in Southern Ontario, Canada, as a case study example. SRS and cLHS were applied in two methods, sampling “by polygon” and “by area”, and three classifiers selected were C5.0, random forest (RF), and k-nearest neighbor (K-NN) (a total of twelve combinations − 4 sampling approaches and 3 classifier algorithms). The original R-code of the DSMART package was modified to incorporate cLHS sampling and change classifier algorithms. For the soil great group predictions, RF performed better in combination with “by polygon” SRS and “by polygon” cLHS approaches (Kappa scores 0.57). For the soil series predictions, C5.0 and “by area” cLHS approach (Kappa score 0.50) performed well compared to other combinations (Kappa score 0.25–0.44). Overall, cLHS performed marginally better with C5.0 and RF while, SRS performed better with K-NN. Disaggregated maps using cLHS generated lower prediction uncertainty values.

Numerical simulation of temperature distribution of heat flow on reservoir tanks connected in a series

The flow of temperature distribution through a medium in thermodynamic studies plays an important role in understanding physical phenomena in chemical science and petroleum engineering, while temperature distribution indicates the degree of reaction that must be undergone to obtain the final product. Therefore, this paper aims to present and apply the exponential matrix algorithm (EMA), differential transformation algorithm (DTA), and Runge-Kutta (RK5) to simulate the temperature distribution in five heating tanks in series. successive preheating of multicomponent oil solutions. A mathematical model of the energy balance equations of the reservoir is considered. Two computer experiments were performed to test and investigate the relationship between two constant parameters appearing in the model. Numerical simulation of saturated steam Tsteam temperature of 500 °C and 1000 °C used to heat the tanks and initial temperature T035°Cand100°C of the first tank feed oil are considered. The fluids in the reservoirs were considered homogeneous throughout the experiment and changes in the cell configuration at two constant parameters were presented in the 2D plot control with the use of the MAPLE 18 software package. The study revealed the nature of the temperature distribution that the higher temperature distribution is obtained when heat is transferred from the first tank to the fifth tank and the reverse reaction occurs in all five reservoirs when ψ = 0.0025 and ω = 0.0025 respectively. Numerical results obtained are prototypes of oil temperature distribution performed under laboratory conditions in a thermodynamic experiment.

Application of the Maxwell–Stefan theory in modeling gas diffusion experiments into isolated oil droplets by water

We have used the Maxwell–Stefan diffusion theory to model the mass transfer between tertiary-injected gas and residual oil blocked by water, in order to predict the time required for the rupture of the water barrier due to oil swelling. We have also designed and conducted a set of visualization micromodel experiments on various pure and multicomponent oil–gas systems to measure the water rupture time in tertiary gas injection processes. The experimental results show that the initial pressure and dimensions of the system, the oil and gas composition, and the gas solubility in water control the oil swelling process. The experimentally measured rupture times are then employed to evaluate the reliability of the model and to compare its accuracy with that of a similar one using classical Fick's law. Our modeling results show that both models are able to estimate the water rupture time for pure systems with an acceptable precision. As for multicomponent mixtures, however, only the Maxwell–Stefan theory is capable of modeling the molecular diffusion process correctly and yields values close to reality, while the use of Fick's law would lead to erroneous results. Deficiency of the latter model becomes more acute when the diffusion direction in reality is contrary to what the model indicates, which leads to failure in calculating any value for rupture time at all for these cases.

Modeling the Effect of Mineral Particles of Mixture of Sandy Soil on Its Physical–Mechanical Properties Based on the Triangular Nomogram

Soil is regarded as a multi-component, multi-phase (solid, liquid and gaseous) dynamic system. The solid component, especially soil mineral particles, has a significant influence on the properties of soil, including its physical, physical–chemical and physical–mechanical properties. By studying the literature, we know that the majority of studies have explained the influence of mineral particles on the physical and physical–mechanical properties of soil bino–mixtures (sand–silt, sand–clay, coarse sand, etc.) through two-dimensional figures. Obviously, for multi-component soil, these two-dimensional figures are not sufficient and should be improved in order to show the influence of soil particles more comprehensively. Therefore, in this paper, we applied a new model—the triangular nomogram—to describe and analyze the change in the inter-friction angle of soil mixtures under different particle size distributions. Through the obtained result, we found that the triangular nomogram is an effective model that can be used to analyze and simulate the properties of soil mixtures.

Особливості забруднення ґрунтів нафтою та нафтопродуктами: огляд

Soil pollution is inevitable in course of oil extraction, transporting, storage, refining and usage of oil products. The affected soils lose their initial value and spread pollutants into the environment: air, ground- and surface waters, food chains. Effective environmental protection is impossible without reliable information about the state of polluted soil. An understanding of changes, which undergoes soil after oil (oil products) ingress, its ecological evaluation gives an opportunity to determine the state of the soil ecosystem and to select remediation measures, effective under given natural conditions. The article elucidates the influence of various oil fractions on the morphological, physical, physicochemical and chemical properties of soils. The regularities of vertical and lateral oil migration through the soil were considered. The oil pollution resilience of different types of soils was also presented. The reaction of live organisms: germs, mesofauna, algoflora and plants on the influence of oil pollution was highlighted. An important aspect is a generalization of approaches towards the evaluation of the ecological state of oil- and oilproduct- polluted soil because the threshold limit values of oil and the products of its refining in the soil are not established in Ukrainian legislation. Our overview showed that multicomponent oil contamination, its temporal transformation, cumulative properties, high stability and toxicity, variability of hydrocarbon contents, absence of the threshold limit values for most oil products, inability to take into account the ecological hazard of joint action of hydrocarbons, products of their decomposition and interaction with other substances, present in water and soil, require complex approach towards solution of the problem. The first important stage of it is the integral evaluation of the ecological state of the soil.

К ВОПРОСУ РАЗРАБОТКИ ЛАБОРАТОРНОЙ УСТАНОВКИ ДЛЯ МОДЕЛЬНОГО ИССЛЕДОВАНИЯ ДЕГРАДАЦИИ ПОЧВ (НА ПРИМЕРЕ ВОДНОЙ ЭРОЗИИ)

Purpose: development of a laboratory facility for multicomponent soil analysis in model experiments on their sprinkling. Materials and methods of research. The works of Russian and foreign scientists, patents, laboratory facilities presented in specialized laboratories were used as a material for the study. Research methods included patent search, analysis and synthesis of the data obtained. Results and discussions. To conduct field experiments, an appropriate technical base which may require both the allocation of experimental plots for field studies in the surveyed areas, and significant costs, is needed, so laboratory experiments are the best alternative for model study of various processes and factors. In laboratory installations, the soil is placed in special containers called a flume, an erosive flume, or a hydraulic flume (hydroflume). Depending on the objectives of the study, various installations are used to ensure the water flow to the soil surface: a jet-drop tube, a sprinkler, a perforated plate with a thermostat. A laboratory facility “installation for studying the processes of water erosion of soils” was proposed by scientists of Russian Scientific Research Institute of Land Reclamation Problems. The laboratory installation includes all necessary equipment for conducting experiments with great variability. It can be used to model the terrain slope, rain intensity, the angle of its fall, the study of infiltration, etc. Conclusions. To obtain more accurate results, it is necessary to use multicomponent installations that allow simulating a combination of a large number of factors. The proposed laboratory facility has a wide range of possibilities for studying the erosion resistance of soils, the composition of surface runoff and infiltration, as well as the efficiency of a number of reclamation measures.

Conceptual approaches to rehabilitation of pesticide-polluted soils of Ukraine

The Concept of Rehabilitation of Contaminated Soils has been developed, which substantiates the ways to restore areas contaminated with persistent organic pesticides. The practical implementation of the Concept will contribute to the transfer of existing land use systems to the principles of sustainable agricultural development, as well as the preservation, reproduction and expansion of biodiversity, as well as improving the environmental safety of agro-ecosystems for sustainable development of the Agrosphere. The Concept combines ways of practical implementation of environmentally friendly methods of cleaning pesticide-contaminated areas and further use of rehabilitated land in the process of agricultural activity in Ukraine. The problem of pesticide pollution of agroecosystems is proposed to be solved by using scientifically sound ecologically safe methods of soil remediation with multicomponent pesticide pollution developed at the Institute of Agroecology and Environmental Management of NAAS, in particular using bioremediation methods. The following are proposed for use: methods of agroecological monitoring of areas contaminated with persistent organic pollutants, methods of phytotesting and phytoremediation of soils contaminated with resistant pesticides. For phytoremediation of contaminated soils, it is proposed to use annual cultivated (barley, wheat, beans, soybeans, zucchini, pumpkin) and wild (dandelion, bitter wormwood, common wormwood, wheatgrass) species of plant-mediators, which are suitable for phytostabilation and in the conditions of multicomponent soil pollution. The main stages of the Concept implementation are: complex agroecological monitoring of soils contaminated with residues of persistent organic pollutants (POPs); comprehensive ecotoxicological assessment of soil condition; determining the degree of chemical degradation of soils; adaptation of remediation technologies to the specifics of the area in need of cleaning; introduction of ecologically safe remediation methods into practical use; realization of prospects of further use of rehabilitated soils in various branches of agriculture; taking into account the ecological and economic efficiency of the use of remediation methods. Possibility and ways of using restored areas in the process of agricultural activity, taking into account the main stages of implementation of the Concept are set out in the developed in the Institute of Agroecology and Environmental Management of NAAS «Scientific and methodological recommendations for restoration of soil contaminated with organochlorine pesticides depending on their toxicity» and «Scientific and methodological recommendations for the use of restored areas in the process of agricultural activity».

Simulation of Seismic Wave Propagation in a Multicomponent Oil Deposit Model

A seismic survey is perhaps the most common geophysical technique used to locate potential oil and natural gas deposits in the geologic structures. Thanks to the rapid development of modern high-performance computing systems, the computer simulation technology plays a crucial role in processing the field data. The precision of the full-waveform inversion (FWI) essentially depends on the quality of the direct problem solver. This paper introduces a new approach to the numerical simulation of wave processes in complex heterogeneous media. The linear elasticity theory is applied to simulate the dynamic behavior of curvilinear geological layers. In contrast to the conventional approach, the producing oil formation is described in the frame of a porous fluid-filled model. It allows us to explicitly take into account the porosity, oil density, and other physical parameters. The method of setting the physically correct contact conditions between the reservoir and the geological massif based on the transport equation solution for Riemann invariants was successfully implemented. The grid-characteristic method, previously thoroughly verified on acoustic and elastic problems, was adopted. The explicit time-stepping procedure was derived for a two-dimensional case with a method of splitting along coordinate axes. This method guarantees the preservation of the scheme approximation order. The potential application of the new method to a complex model based on the data from the famous Russian oil deposit — the Bazhen Formation — is demonstrated. The seismic responses were registered on the wave fields and synthetic seismograms. The novelty of this paper relates to a uniform approach to the wave propagation simulation in the heterogeneous medium containing contacting subdomains with different rheology types.

Characterization and Partitioning Behavior of Creosote in Different Matrices: Soil, Water, and Air

Creosote is a multicomponent oil classified as a dense non-aqueous phase liquid (DNAPL) produced from coal tar distillation. The concept of phase distribution is critical in decision-making to remediate contaminated sites. The creosote mass transfer between sorbed, aqueous, vapor, and DNAPL phases is controlled by physicochemical characteristics, geology of the site, and environment conditions. This study evaluated phase distribution of the main polycyclic aromatic hydrocarbons (PAHs) of creosote in a sandy soil with low organic matter content. The creosote was collected from a contaminated site in Sao Paulo, Brazil, and was characterized by gas chromatography–mass spectrometry (GC-MS). Clean soil was collected upgradient from the same area. Initially, the soil was artificially contaminated with creosote. After, the contaminated soil was put in contact with clean water in sealed vials for 72 h. Samples of the soil, vapor, and liquid phases were collected and analyzed by GC-MS. In total, 50 compounds were identified in the creosote, and 9 PAHs were selected to be studied, which represented around 30% of total creosote mass. The major contaminant concentration was detected in the sorbed phase. For instance, naphthalene mass was distributed in sorbed (33.0%), DNAPL (1.5%), aqueous (3.4%), and vapor (0.2%) phases. The results provided an understanding of the contaminant species partitioning that occurs in a real contaminated site.

Multicomponent Diffusion Modeling of Cyclic Solvent Injection in Ultratight Reservoirs

Summary We present a new semianalytical compositional model designed for primary production of multicomponent oil and cyclic solvent injection in ultratight oil reservoirs that is dependent on diffusion-dominated transport within the matrix (k < 200 nd) coupled to advection-dominated transport in the fractures. The semianalytical model consists of a well-mixed tank model for the fractures coupled to diffusive transport within the matrix. Production of oil, gas, and water from the fractures to the well is proportional to its phase mobility. The matrix allows for differing effective-diffusion coefficients for each component. Because there are no gridblocks within the matrix, the analytical solution is computationally less expensive than numerical simulation while capturing the steep, nonmonotonic compositional changes occurring a short distance into the matrix that result from multiple injection cycles. The Peng-Robinson equation of state (PR EOS) (Robinson and Peng 1978) is used to calculate phase behavior with time within the fractures and to initialize density and mass concentrations within the matrix based on the semianalytical framework. The coupled convective (fracture) and diffusive (matrix) model is validated with several laboratory- and field-scale cases. For primary recovery, the results show that the model correctly reproduces the pressure and oil-recovery declines observed in the field. We show that the hydrocarbon-recovery mechanism for solvent huff ’n’ puff (HnP) is facilitated by greater density reduction and compositional changes. Two solvents are considered in HnP calculations: carbon dioxide (CO2) and methane (CH4). Recovery of heavier components is enhanced with CO2 compared with CH4 within the reservoir (matrix and fractures). Furthermore, the results demonstrate that multiple HnP cycles constrained to surface injection are needed to enhance density and compositional gradients, and therefore oil recovery. Although shorter soaks are better for short-term recovery (i.e., 3 to 5 years), longer soaks maximize recovery over a longer time frame (i.e., 10 to 15 years). This paper provides a limiting case model based on diffusive matrix transport and convective fracture transport to determine the optimal number/duration of cycles and when to start the HnP process after primary recovery.

Brine-Oil Interfacial Tension Modeling: Assessment of Machine Learning Techniques Combined with Molecular Dynamics.

The physical chemistry mechanisms behind the oil-brine interface phenomena are not yet fully clarified. The knowledge of the relation between brine composition and concentration for a given oil may lead to the ionic tuning of the injected solution on geochemical and enhanced oil recovery processes. Thus, it is worth examining the parameters influencing the interfacial properties. In this context, we have combined machine learning (ML) techniques with classical molecular dynamics simulations (MD) to predict oil/brine interfacial tensions (IFT) effectively and compared this process to a linear regression (LR) method. To diversify our data set, we have introduced a new atomistic crude oil model (medium) with 36 different types of hydrocarbon molecules. The MD simulations were performed for mono- and multicomponent (toluene, heptane, Heptol, light, and medium) oil systems interfaced with sulfate and chloride brines with varying cations (Na+, K+, Ca2+, and Mg2+) and salinity concentration. Thus, a consistent IFT data set was built for the ML training and LR fitting at room temperature and pressure conditions, over the feature space considering oil density, oil composition, salinity, and ionic concentrations. On the basis of gradient boosted (GB) algorithms, we have observed that the dominant quantities affecting the IFT are related to the oil attributes and the salinity concentration, and no specific ion dominates the IFT changes. When the obtained LR model was validated against MD and experimental data from the literature, the error varied up to 2% and 9%, respectively, showing a robust and consistent transferability. The combination of MD simulations and ML techniques may provide a fast and cost-effective IFT determination over multiple and complex fluid-fluid and fluid-solid interfaces.