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Foam stability tests were performed using sodium dodecyl sulfate (SDS) surfactant and SiO2 nanoparticles as foaming system at different asphaltene concentrations, and the half-life of CO2 foam was measured. The mechanism of foam stability reduction in the presence of asphaltene was analyzed by scanning electron microscope (SEM), UV adsorption spectrophotometric concentration measurement and Zeta potential measurement. When the mass ratio of synthetic oil to foam-formation suspension was 1:9 and the asphaltene mass fraction increased from 0 to 15%, the half-life of SDS-stabilized foams decreased from 751 s to 239 s, and the half-life of SDS/silica-stabilized foams decreased from 912 s to 298 s. When the mass ratio of synthetic oil to foam-formation suspension was 2:8 and the asphaltene mass fraction increased from 0 to 15%, the half-life of SDS-stabilized foams decreased from 526 s to 171 s, and the half-life of SDS/silica-stabilized foams decreased from 660 s to 205 s. In addition, due to asphaltene-SDS/silica interaction in the aqueous phase, the absolute value of Zeta potential decreases, and the surface charges of particles reduce, leading to the reduction of repulsive forces between two interfaces of thin liquid film, which in turn, damages the foam stability. [ABSTRACT FROM AUTHOR]

[Display omitted] • Effect of asphaltene structure and composition on its absorption onto dolomite surface is studied. • Asphaltenes are characterized by EDX, FTIR, DLS, FESEM, and elemental analysis. • The dolomites were analyzed by XRF, FTIR, BET, and DLS. • The N + S content and the aromatic nature of asphaltenes are important for adsorption of asphaltene. • Increasing the flow rate in dynamic experiments decreased asphaltene adsorption. Asphaltene precipitation/deposition is one of the main problems in petroleum industry at various stages. In this study, various controlling factors on the adsorption of different types of asphaltene on the surface of dolomite of different size, as one of the most abundant minerals in the reservoir is investigated. First, asphaltenes and adsorbents (dolomite) properties were analyzed via several analytical techniques. Then, adsorption of four asphaltene samples of various origins and chemical composition on dolomite at micron and nano size were carried out in both static and dynamic modes and results were examined following the adsorption process. Based on the static tests, the adsorption amount of asphaltenes on nano- and micro-dolomite was measured 3.52–11 mg/m2 and 0.82–2.74 mg/m2, respectively. The results revealed that the most significant parameters that would affect the asphaltene adsorption on dolomite as an adsorbent are the total nitrogen and sulfur (N + S) content and the aromaticity of the asphaltenes. Moreover, as the flow rate was increased three times in the dynamic experiments, a decrease of 15–25% in asphaltene adsorption was observed, which was attributed to physisorption of asphaltene on dolomite or due to higher flow velocities. Collectively, the findings of this study can enable us to better understand the mechanisms of asphaltene adsorption/precipitation on dolomite and lead to better management of oil production from dolomitic reservoirs. [ABSTRACT FROM AUTHOR]

• Application of ten Tetraalkylammonium and phosphonium salt were evaluated as asphaltenes and dispersant. • The systematic study using UV–vis spectroscopy was done to investigate interactions between asphaltenes and organic salts based on the size and the shape of the cations and anions. • The length of alkyl chain in cations and hydrophobicity of anion have crucial role in preventing of asphaltene stacking interactions. • This mechanistic study was revealed that the role of anions on the stability of asphaltene aggregates is more important than cations. Asphaltenes deposition is one of the most severe problems in the petroleum industry, imposing high costs on oil producer companies. The use of chemical dispersants reduces the risk of asphaltene deposition. For this purpose, a variety of chemicals with different structures and functional groups were designed and synthesized. Organic quaternary salts, such as ionic liquids, have been widely used to control asphaltene deposition over the last two decades, but the mechanism of their interaction with asphaltene has not been studied in detail. In this study, the interaction of ten commercial quaternary ammonium and phosphonium salts with asphaltene molecules was investigated using ultraviolet-visible (UV-Vis) spectroscopy. It was observed that the size, shape, and hydrophobicity of their cations or anions play an essential role in the dispersion of asphaltene aggregations. The results showed that the interaction of these quaternary salts is strongly influenced by the hydrophobic nature of the salt, and salts with more hydrophobic cations and anions, such as tetrabutylammonium iodide, tetrabutylammonium hexafluorophosphate, and cetyltrimethylammonium bromide, can better disperse asphaltene aggregations. The results also revealed that the role of anions such as iodide, and hexafluorophosphate in the dispersion of asphaltene aggregates is more important than cations. In addition, the results showed that except for tetramethylammonium bromide, the efficiency of the salts was increased with increasing concentration. [ABSTRACT FROM AUTHOR]

Population balance equation is widely used in modeling of particulate processes. In this work, the enlargement of asphaltene particles in a synthetic heptane-toluene mixture (Heptol) was experimentally investigated in a static mode and then modeled by using PBE. Aggregation is considered as sole responsible mechanism for size evolution. Three solution methods including two discretization methods, modified Hounslow (MH) method and Kumar cell average technique (KCAT), and one moment method, quadrature method of moments (QMOM), are considered. The simulation results were compared with experimental data to evaluate each method. The results of simulations indicate that moment method offers higher accuracy and less computational expense respect to discretized methods in prediction of asphaltenes aggregation. In the case of considering fractal structure, both methods inaccurately predicted the number and average diameter of asphaltene aggregates. [ABSTRACT FROM AUTHOR]

The utilization of chemical dispersants as a way of mitigating of oil spills in marine eco-system has been extensively documented worldwide. Hence, in this research we have successfully synthesized two amphiphilic asymmetric Dicaionic Ionic Liquids (DILs). The efficacy of these synthesized DILs as dispersants was assessed using the baffled flask test (BFT). The results indicated a dispersant effectiveness ranging from 47.98 % to 79.76 % for the dispersion of heavy crude oil across various temperature ranges (10–30 °C). These dispersant-to-oil ratios (DOR) were maintained at 3: 100 (V%), showcasing promising dispersant capabilities for mitigating heavy crude oil spills. Additionally, acute toxicity tests conducted on Nile tilapia and Oreochromis niloticus have demonstrated the relatively low toxicity of the IL-dispersants, with Lethal Concentration 50 (LC50) values exceeding 100 ppm after 96 h. This suggests a practically slight toxic effect on the tested fish. In summary, the newly developed IL-dispersants are considered to be conducive to environmentally benign oil spill remediation. • Synthesis of asymmetric Dicationic Ionic Liquids for oil spill dispersion • The studied DILs recorded high dispersion efficiency against the spilled crude oil. • Surface active parameters and emulsion stability were well studied. • DILs dispersants evidenced to be slightly toxic against acute toxicity test. [ABSTRACT FROM AUTHOR]

Thirteen polyalkyl acrylate-based depressor additives with C16-C26 alkyl groups containing 0–30 mol% of various polar groups (amide, amine, ammonium, N-vinylpyrrolidone, oligo(ethylene glycol)) have been synthesized and tested in 18 crude oil samples of significantly different compositions. It has been shown that the dependences of the depressor effect on the additive concentration pass through maxima. An approach that predicts the degree of decrease in pour point of oil in the presence of polyalkyl acrylate additives depending on the content of paraffin and resin-asphaltene components was proposed for the first time. A polyalkyl acrylate with C16-20 alkyl groups proved to be the most versatile additive. However, polymers with different lengths of alkyl groups or containing polar groups are more effective for some oils. [ABSTRACT FROM AUTHOR]

Quantitative liquid 1H and solid 13C CPMAS NMR spectroscopy were used in combination with qualitative DEPT (Distortionless Enhancement by Polarization Transfer) and liquid 13C NMR to investigate the molecular structural parameters of an Algerian asphaltenes. The molecular weight of the asphaltene ionisable species determined by positive Electro Spray Ionization mass spectrometry ESI was around 390 Da. The results indicate that the representative molecular structure of the asphaltenes contains PAH (Poly-aromatic hydrocarbon) core of 4–5 rings. The combination of 13C NMR/DEPT constitutes a good route for characterizing the chemical functions of asphaltenes. [ABSTRACT FROM AUTHOR]

Asphaltene precipitation and its subsequent deposition always remain a major concern for Oil industry. Formulation of a comprehensive and reliable risk management system for asphaltene prone wells and fields is a challenging task because of the influence of diverse factors. In this study, a decision support system is developed for the asphaltene risk assessment in wells and fields. Since, the data present in the literature is scarce and not consistent, therefore, a hypothetical data of fields and their wells was considered to conduct the study comprehensively. Three hypothetical fields namely; Field A, Field B and Field C were assumed and in each field ten wells were taken into consideration. A decision support system for assessing the risk of asphaltene prone wells was developed using one of the popular and powerful multi-criteria decision making technique i.e. Fuzzy Technique for Order of Preference by Similarity to Ideal Solution (Fuzzy TOPSIS) coupled with Analytic Hierarchy process (AHP). The risk of wells was evaluated using three criteria namely; Detection, Severity and Controls. These criteria were further sub-divided into sub-criteria and their data was assumed. The assumed data was transformed into Triangular fuzzy numbers for calculations. According to the final outcomes, Field A was proved be the most risky field followed by Field B and in the last comes Field C. The outcomes were further validated by other method namely; Fuzzy Complex Proportional Assessment (COPRAS) and all TOPSIS outcomes were found in good relationship with Fuzzy COPRAS. The proposed methodology proposed in this study will be landmark in risk ranking of asphaltene prone wells and fields. [ABSTRACT FROM AUTHOR]

Precipitation hardened nickel-based Alloy 725 (UNS N07725) has been proven susceptible to hydrogen embrittlement in oil and gas production. Moreover, current standards cannot differentiate unequivocally between acceptable and affected microstructures, making the development of an appropriate quality control test a priority for the oil and gas industry. Recently, Alloy 725 failures were associated with the precipitation of nanoscale Cr- and Mo-rich phases at grain boundaries (GBs). Since these intergranular precipitates could lead to Cr- and Mo-depletion along the decorated GBs (i.e., sensitization), the double-loop electrochemical potentiokinetic reactivation (DL-EPR) test was explored as an alternative approach to detect affected microstructures. Herein, the DL-EPR technique was optimized for Alloy 725 by testing three types of samples with different degrees of sensitization, including a full GB-decorated microstructure that was shown prone to hydrogen embrittlement in oil and gas service. The optimized DL-EPR test conditions were 2 M HCl + 1 M H2SO4 + 10−4 M KSCN aqueous solution at 30 °C with a 1.667 mV s−1 scan rate and a vertex potential of Ecorr + 700 mV. Results were reproducible and consistent with the degree of GB decoration determined using metallographic methods. The test procedure developed herein could lead to the standardization of the DL-EPR method for Alloy 725. [ABSTRACT FROM AUTHOR]

The impact of thermal cracking reaction on asphaltene structure and morphology has been investigated by using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The structural and morphological changes at a microscopic level were monitored by comparing the parent asphaltenes from different vacuum residues (VRs) to their corresponding thermally treated asphaltenes, obtained from the by-product pitch after thermal treatment. The SEM analysis indicated that the asphaltene aggregates extracted from atmospheric residues have smooth and rough surfaces with agglomerate particles and bright inclusions. The SEM images of asphaltene aggregates that are extracted from the pitch samples after mild cracking demonstrated cleavage fracture morphology with obvious reduction in inclusions sizes and intensities. The TEM analysis, on the other hand, indicated that the asphaltenes from residual oils have tangled structures, with edges similar to a cauliflower. The tangled structure is mainly credited to the alkyl side-chains that impede the aromatic sheets from stacking. At mild cracking (400 °C), the asphaltene began to exhibit well-ordered layer structures near the edges due to the rupture of the alkyl side-chains. However, the tangled structure has been preserved in the interior of the sample. As the reaction severity increases (415 °C), the stacking of aromatic sheets became more evident even in the sample interior. At the most severe cracking condition (430 °C), an obvious reduction in the cluster diameter has been observed, which mainly resulted from the reduction in the number of aromatic sheets per stack. [ABSTRACT FROM AUTHOR]

Floating oil and sediments can interact to form oil-particle aggregates (OPAs) in marine environments. Laboratory batch experiments were conducted to investigate the effects of the concentration and size of sediment, temperature, oil types and chemical dispersant on the formation of OPAs. The results showed that the mass of OPAs and oil-particle aggregation rate are mainly related to the sediment concentration. Under the same mass concentration, more oil droplets can be trapped by smaller particles. Nevertheless, larger particles tend to interact more quickly with oil droplets. The effect of temperature on the formation of OPAs is substantially attributed to its influence on oil viscosity, and there is a threshold for oil viscosity which will bring about the maximum OPAs. Spilled oil with a high asphaltene can interact more effectively with the sediments. Appropriate addition of chemical dispersant is favorable for the formation of OPAs while excess addition will inhibit it. Unlabelled Image • Particle concentration affects the aggregation rate and oil trapping efficiency. • Smaller particles trap more oil droplets, while larger ones aggregate more quickly. • Temperature dominates the formation of OPAs by its influence on oil viscosity. • Spilled oil with a high asphaltene can interact more effectively with the sediments. • Appropriate addition of chemical dispersant is favorable for the formation of OPAs. [ABSTRACT FROM AUTHOR]

The formation of a durable nanoadsorbent, known as DFC oMn 2 O 4 /IL@Ru(II), was achieved by binding a complex of Ru (II) trisbipyridine with ionic liquids (IL) to a dendritic fibrous CoMn 2 O 4 (DFC oMn 2 O 4). The resulting DFC oMn 2 O 4 /IL@Ru(II) was characterized using various techniques such as X-ray diffraction analysis (XRD), fourier-transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), thermal gravimetric analysis (TGA), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), and scanning electron microscopy (SEM). DFC oMn 2 O 4 /IL@Ru(II) was then employed as an environmentally friendly adsorbent for the removal and adsorption of asphaltene from petroleum. The presence of fibrous CoMn 2 O 4 categories enhanced the adsorption capacity and facilitated the recovery of the adsorbent without significantly reducing the efficiency. The results demonstrated a clear synergistic effect between dendritic fibrous CoMn 2 O 4 and the IL@Ru(II) categories, exhibiting a strong correlation. The utilization of the DFC oMn 2 O 4 /IL@Ru(II) system resulted in quasi-second-order adsorption kinetics. The experiment was conducted using the Taguchi method to minimize costs and time. Various amounts of asphaltene, temperatures, and adsorbent quantities were examined. Minitab software was deployed to evaluate the impact of these variables on asphaltene adsorption. The presence of ionic liquid groups enhanced the solubility of the heterogeneous adsorbent in environmentally friendly solvents, thereby enhancing function and reducing the time. [ABSTRACT FROM AUTHOR]

Highlights • The colloidal dispersion system of oil was investigated by thermodynamics analysis and calculation. • Asphaltenes severely restrained desorption efficiency and rate of oil in desorption process. • Desorption of asphaltenes mainly depended on resins because of carry-over effect. • Two mechanisms (solvent effect and carry-over effect) were analyzed in desorption process of oily sludge. Abstract In this study, the solvent extraction experiment was investigated to probe the desorption behaviors and desorption mechanism of oily sludge with n-heptane as solvent. Desorption isotherms were analyzed and fitted by Langmuir, Freundlich and Redlich-Peterson equations at different temperatures. Then, the thermodynamics parameters such as standard free energy (Δ G°), standard enthalpy (Δ H°) and standard entropy (Δ S°) were calculated. Based on thermodynamics analysis and calculation, oil was proved to exist in the form of the colloidal dispersion system. In addition, the kinetics was fitted by the pseudo-first-order kinetic model and the pseudo-second-order kinetic model. Kinetic studies showed that desorption process of asphaltenes was restrained severely due to strong interactions between sludge and asphaltenes, and resins played a crucial role in asphaltenes desorption. The desorption mechanism was discussed based on experimental results and further analysis. The solvent effect and carry-over effect were deemed to be crucial to oil desorption. The carry-over effect is generated from electrostatic interactions, hydrogen bonds, electron donor-acceptor and π-π interactions, which was also the essence of asphaltenes desorption. Graphical abstract Image, graphical abstract [ABSTRACT FROM AUTHOR]

Homologous series of n-alkenes and dimethylalkanes with the odd or even number of carbon atoms in the molecule have been identified in chloroform extracts from the organic matter of Upper Paleozoic deposits of the Vilyui syneclise penetrated by the superdeep well SV-27 at depths below 5 km. It is presumed that these unusual hydrocarbons resulted from the destruction of asphaltene occlusions under severe P-T conditions at great depths and that the hydrocarbon generation began in the zone of postdiagenetic transformations of sediments. This hypothesis was tested in the sections of deposits whose organic matter underwent catagenesis of different grades. On the basis of these results, zones of emergence, transition, and destruction of occlusions have been recognized. [ABSTRACT FROM AUTHOR]

Digital oil, a realistic molecular model of crude oil for a target reservoir, opens a new door to understand properties of crude oil under a wide range of thermodynamic conditions. In this study, we constructed a digital oil to model a light crude oil using analytical experiments after separating the light crude oil into gas, light and heavy fractions, and asphaltenes. The gas and light fractions were analyzed by gas chromatography (GC), and 105 kinds of molecules, including normal alkanes, isoalkanes, naphthenes, alkylbenzenes, and polyaromatics (with a maximum of three aromatic rings), were directly identified. The heavy fraction and asphaltenes were analyzed by elemental analysis, molecular-weight (MW) measurement with gel-permeation chromatography (GPC), and hydrogen and carbon nuclear-magnetic-resonance (NMR) spectroscopy, and represented by the quantitative molecular-representation method, which provides a mixture model imitating distributions of the crude-oil sample. Because of the low weight concentration of asphaltenes in the light crude oil (approximately 0.1 wt%), the digital oil model was constructed by mixing the gas, light-, and heavy-fraction models. To confirm the validity of the digital oil, density and viscosity were calculated over a wide range of pressures at the reservoir temperature by molecular-dynamics (MD) simulations. Because only experimental data for the liquid phase were available, we predicted the liquid components of the digital oil at pressures lower than 16.3 MPa (i.e., the bubblepoint pressure) by flash calculation, and calculated the liquid density by MD simulation. The calculated densities coincided with the experimental values at all pressures in the range from 0.1 to 29.5 MPa. We calculated the viscosity of the liquid phase at the same pressures by two independent methods. The calculated viscosities were in good agreement with each other. Moreover, the viscosity change with pressure was consistent with the experimental data. As a step for application of digital oil to predict asphaltene-precipitation risk, we calculated dimerization free energy of asphaltenes (which we regarded as asphaltene self-association energy) in the digital oil at the reservoir condition, using MD simulation with the umbrella sampling method. The calculated value is consistent with reported values used in phase-equilibrium calculation. Digital oil is a powerful tool to help us understand mechanisms of molecular-scale phenomena in oil reservoirs and solve problems in the upstream and downstream petroleum industry. [ABSTRACT FROM AUTHOR]

The study presented here uses order-of-one--or o(1)--scaling analysis to identify dimensionless groups specific to asphaltene deposition along production tubing. The precipitation and subsequent deposition of asphaltene can lead to significant complications related to oilfield production. Aside from the many complications within a reservoir as well as surface equipment, the reduction in cross-sectional area caused by its deposition leads to increased pressure losses, reductions in volumetric flow capacity, and possible flow perturbations within a wellbore. Attempts to mitigate these adverse effects have focused on both hindering the precipitation of asphaltene and preventing its deposition after precipitated. The study used here attempts to quantify various hydrodynamic controls specific to asphaltene deposition. With o(1) scaling analysis, four independent dimensionless groups were generated from momentum and mass-balance equations relating hydrodynamic effects to the rate of asphaltene deposition. The dimensionless group π4 was of particular interest because of its inherent relationship to the rate of deposition. This group was compared with both data and existing correlations taken from literature, and noticeable trends in the deposition rate with respect to average stream velocity were observed. One of the most important trends discerned by these comparisons was a clear distinction whereby the rate of asphaltene deposition, related through π4, decreases with increasing Reynolds numbers (Re) in lower ranges, but actually increases in higher ranges. Although the data did not cover the specific region of transition, various correlations suggest a clear cutoff between what was deemed a favorable regime, or Regime I, and a nonfavorable regime, or Regime II. [ABSTRACT FROM AUTHOR]

Thirteen crude oil samples from fractured basement reservoir rocks in the Bayoot oilfield, Masila Basin were studied to describe oil characteristics and to provide information on the source of organic matter input and the genetic link between oils and their potential source rock in the basin. The bulk geochemical results of whole oil and gasoline hydrocarbons indicate that the Bayoot oils are normal crude oil, with high hydrocarbons of more than 60%. The hydrocarbons are dominated by normal, branched and cyclic alkanes a substantial of the light aromatic compounds, suggesting aliphatic oil-prone kerogen. The high abundant of normal, branched and cyclic alkanes also indicate that the Bayoot oils are not biodegradation oils. The biomarker distributions of isoprenoid, hopane, aromatic and sterane and their cross and triangular plots suggest that the Bayoot oils are grouped into one genetic family and were generated from marine clay-rich source rock that received mixed organic matter and deposited under suboxic conditions. The biomarker distributions of the Bayoot oils are consistent with those of the Late Jurassic Madbi source rock in the basin. Biomarker maturity and oil compositions data also indicate that the Bayoot oils were generated from mature source rock with peak oil-window maturity. [ABSTRACT FROM AUTHOR]

Low-salinity waterflooding (LSW) is ineffective when reservoir rock is strongly water-wet or when crude oil is not asphaltenic. Success of LSW relies heavily on the ability of injected brine to alter surface chemistry of reservoir crude-oil brine/rock (COBR) interfaces. Implementation of LSW in carbonate reservoirs is especially challenging because of high reservoir-brine salinity and, more importantly, because of high reactivity of the rock minerals. Both features complicate understanding of the COBR surface chemistries pertinent to successful LSW. Here, we tackle the complex physicochemical processes in chemically active carbonates flooded with diluted brine that is saturated with atmospheric carbon dioxide (CO2) and possibly supplemented with additional ionic species, such as sulfates or phosphates. When waterflooding carbonate reservoirs, rock equilibrates with the injected brine over short distances. Injected-brine ion speciation is shifted substantially in the presence of reactive carbonate rock. Our new calculations demonstrate that rock-equilibrated aqueous pH is slightly alkaline quite independent of injected-brine pH. We establish, for the first time, that CO2 content of a carbonate reservoir, originating from CO2-rich crude oil and gas, plays a dominant role in setting aqueous pH and rock-surface speciation. A simple ion-complexing model predicts the calcite-surface charge as a function of composition of reservoir brine. The surface charge of calcite may be positive or negative, depending on speciation of reservoir brine in contact with the calcite. There is no single point of zero charge; all dissolved aqueous species are charge determining. Rock-equilibrated aqueous composition controls the calcitesurface ion-exchange behavior, not the injected-brine composition. At high ionic strength, the electrical double layer collapses and is no longer diffuse. All surface charges are located directly in the inner and outer Helmholtz planes. Our evaluation of calcite bulk and surface equilibria draws several important inferences about the proposed LSW oil-recovery mechanisms. Diffuse double-layer expansion (DLE) is impossible for brine ionic strength greater than 0.1 molar. Because of rapid rock/brine equilibration, the dissolution mechanism for releasing adhered oil is eliminated. Also, fines mobilization and concomitant oil release cannot occur because there are few loose fines and clays in a majority of carbonates. LSW cannot be a low-interfacial-tension alkaline flood because carbonate dissolution exhausts all injected base near the wellbore and lowers pH to that set by the rock and by formation CO2. In spite of diffuse double-layer collapse in carbonate reservoirs, surface ion-exchange oil release remains feasible, but unproved. [ABSTRACT FROM AUTHOR]

A predictive but tunable model for the liquid viscosity of characterized crude oils was developed by use of the generalized Walther correlation (Walther 1931; Yarranton et al. 2013). The crude oils are each characterized into maltene pseudocomponents and a single C5-asphaltene component. The viscosity model requires two pseudocomponent parameters (A and B), two whole-oil parameters (δ1 and δ2), and binary-interaction parameters. The asphaltene parameters were determined experimentally and fixed for all cases. Correlations were developed for the maltene-pseudo-component parameters and the binary-interaction parameters. The required data are the absolute temperature, pressure, the C5-asphaltene content, the specific gravity (SG) and molecular weight (MW) of the oil, and the boiling-point distribution of the maltenes. The SG and MW distributions of the maltenes are also required, but are generated from existing correlations. The proposed model predicted the viscosity of five western Canadian and two Colombian bitumens; three American, one Mexican, one Venezuelan, and one European heavy oil; and also a conventional oil from the Middle East with an overall average deviation of 57%. Tuning to a single viscosity data point with a single tuning parameter reduced the overall deviation to 8%, close to the 4% deviation obtained when the model was fitted to the data. [ABSTRACT FROM AUTHOR]

Selecting an appropriate equation of state (EOS) to model asphaltene precipitation in compositional wellbore and reservoir simulators is still unclear in the literature. Recent studies have shown that the PC-SAFT model is more appropriate for modeling asphaltene precipitation compared to the commonly used solid model. The main objective of this paper is to compare the solid and PC-SAFT models in both static and dynamic asphaltene modeling. Through fluid characterization, the capabilities of both models are compared to reproduce precipitation experimental data. The results show that both solid and PC-SAFT models are capable of predicting the amount of asphaltene precipitation with high accuracy. Although the matching process using the PC-SAFT model is much easier, the properly tuned solid model is also able to reproduce the experimental data with the same quality as the PC-SAFT model. The simulation results show that the PC-SAFT model is superior to the solid model in terms of the extrapolation accuracy when the experimental data are not available for the simulation conditions (i.e., variation in temperature, pressure, and fluid composition in the reservoir/wellbore). However, both models are applicable for interpolation when the experimental data cover the entire range of the simulation condition. The wellbore simulations show that although the trend of asphaltene deposition is similar for both models, the solid model using Peng-Robinson EOS overestimates the amount of asphaltene precipitation and deposition in the wellbore compared to the PC-SAFT model. On the other hand, the simulation procedure using the PC-SAFT model takes much more computational time as this model uses an iterative solution to obtain the density roots and the phase equilibrium calculation. [ABSTRACT FROM AUTHOR]

This study was designed to determine the aromatics to saturate ratios in three Nigerian Niger Delta crude oils to ascertain the crude oil source with the highest asphaltene risk. Three crude oil samples were collected from different locations: Kokori, Afiesere and Nembe in the Niger Delta region, Nigeria. The physical properties of the crudes (viscosity, density, API gravity) were determined. Saturates, aromatics, resins, asphaltenes (SARA) fractionation method was employed to separate different components in the crude oil. The composition and concentration of the saturates and aromatics hydrocarbon fractions were determined using a gas chromatograph. Results showed that API gravities ranged from 34° to 39° indicating that the three crudes are light. n -Heptane precipitation showed that Kokori crude had the highest weight percent concentration of asphaltenes (2.33%) and Afiesere crude, the least (1.91%). The gas chromatographic analysis of the saturates and aromatics showed that the total concentrations (mg/L) of all the saturates in Kokori, Afiesere, and Nembe were 871.26, 885.56, and 780.21 respectively while the total concentration of all the aromatics in the crudes were 80.15, 89.73 and 75.11 respectively. The aromatics to saturate ratios were computed and the results showed that this ratio decreased in the order Kokori crude < Nembe crude < Afiesere crude. This implies that Kokori crude with the lowest ratio will cause most asphaltene deposition problems than the other crudes. [ABSTRACT FROM AUTHOR]

Both LDI-TOF and MALDI-TOF Mass spectroscopy experiments of an Algerian asphaltene derived from a deposit were performed. LDI mass experiments were conducted for both linear and reflectron modes under laser wavelength/attenuation variation. The different LDI-Mass spectra show that mass distribution depends on experimental condition for masses below 1000 amu and that the average molecular weight is around 650 for the polar fraction and beyond 1000 amu for non-polar ones. The use of different matrices as CHCA, HABA and Dithranol changes slightly the aspect of the spectra. [ABSTRACT FROM AUTHOR]

Precipitation and deposition of asphaltene are undesirable phenomena that arise during petroleum production which give rise to a pronounced rate of increase in operational cost and adversely affect production rates as well. Hence, it is imperative to develop a mathematical model for the assessment of asphaltene stability in crude oil. In the present study, delta RI which constitutes the difference between refractive index of crude oil ( RI ) and refractive index of crude oil at the onset of asphaltene precipitation ( PRI ) is employed as the principal factor for determining the asphaltene stability of the region. Fuzzy logic is a potent tool capable of extracting the underlying dependency between SARA fractions (saturate, aromatic, resin, and asphaltene) data and delta RI for the inexpensive and rapid diagnosis of asphaltene stability. In this study a novel strategy known as hybrid genetic algorithm-pattern search (GA-PS) is suggested for the development of an optimal fuzzy logic model as a reliable alternative for the widely-applied subtractive clustering (SC) method. While SC solely optimizes mean of input Gaussian membership functions (GMFs), GA-PS tool optimizes both mean and variance of input GMFs. Comparison between GA-PS and SC methods confirmed the capability of GA-PS for developing an optimal fuzzy logic model. [ABSTRACT FROM AUTHOR]

The accelerating-rate calorimeter (ARC) is unique for its exceptional adiabaticity, its sensitivity, and its sample universality. Accelerating Rate Calorimetry is one of the screening tests used to determine the suitability for air-injection enhanced oil recovery (EOR). These tests show oil reactivity and exothermicity over a broad range of temperatures: low-temperature range (LTR), negative-temperature-gradient region (NTGR), and high-temperature range (HTR). An experimental and simulation study was carried out to expand understanding and interpretation of the data derived from high-pressure closed-ARC tests. Athabasca bitumen was used for the experimental study in a closed ARC at 13.89 MPag (2000 psig) to identify the temperature ranges over which the oil reacts with oxygen in the injected air. Self-heat rate from accelerating-rate calorimetry and massloss rates from the differential thermogravimetric analysis show the influence of mass transfer of oxygen within bitumen in the LTR and HTR. A numerical model was developed to integrate the concept of mass transfer with a reaction-kinetic model. The model incorporates solubility of oxygen with partition equilibrium coefficient (K-value) as a medium to introduce oxygen into the bitumen layer, which later transfers throughout oil layer by diffusion. This model considers both low- and high-temperature oxidation (LTO and HTO), and thermal-cracking reactions, as described in traditional reaction-kinetic models of in-situ-combustion (ISC) processes. Results show that formation of an asphaltenes film in the LTR caused by oxidation of maltenes obstructs oxygen (mass-transfer restriction) penetration into the bitumen layer. The simulated result shows that, by integrating mass transfer with the kinetic model, it is possible to predict the NTGR. Viscosity and temperature dependence on the mass transfer of oxygen is linear. As time passes and chemical reaction becomes more important with increasing temperature, the relationship deviates from linearity. With increasing temperature, the influence of chemical interaction on the oxygen distribution becomes greater, and this results in a shorter initial stage of mass transfer of oxygen within the bitumen film at low temperatures. This implies that the ARC can be a useful tool for understanding the effect of mass transfer on the oxidation characteristic for predicting LTR, NTGR, and HTR. [ABSTRACT FROM AUTHOR]

Asphaltenes and asphaltogene acids of organic matter (OM) of lacustrine sediments in the Novosibirsk and Tomsk Regions of West Siberia have been investigated by applying physical and physicochemical methods (elemental and X-ray diffraction analyses, IR, NMR, and EPR spectroscopy, Rock Eval pyrolysis, and electron microscopy). Compared with asphaltenes of dispersed OM at the early catagenesis stages, asphaltenes of OM at the diagenesis stage have a high number of hydrogen atoms and heteroatoms, a low degree of aromaticity, a low concentration of paramagnetic centers, a large number of carbon atoms in the long paraffin chains and oxygen-containing groups. Tetravalent vanadium is absent from asphaltenes of recent lacustrine sediments, and only complex compounds of copper have been identified. The sediments contain not asphaltenes but their precursors, protoasphaltenes. These are less condensed compounds with a looser nongraphite structure and a rather high petroleum potential. At the diagenesis stage, protoasphaltenes are immature protokerogen blocks. [ABSTRACT FROM AUTHOR]

The composition of saturated and aromatic hydrocarbons and the structural-group characteristics of resins and asphaltenes in four oils of northern West Siberia have been studied. As follows from the distribution of hydrocarbons, the Cenomanian oils (pools in the beds PK and K 2 c) of the Russkoe, Barsukovskoe, and Pangodinskoe fields are naphthenic and the Pangodinskoe oil sample from the Lower Cretaceous pool (bed BN 9 ) is methanoic. The hydrocarbon composition pattern of the saturated fraction and the characteristics of the heterocyclic components of these oils point to their formation from dispersed organic matter of mixed genesis in the oil window. Hence, the oil source rocks are localized at depths much greater than the present-day level of the oil pools. Secondary (cryptohypergene) alterations (oxidation and biodegradation) in the shallow-depth oils determined their current predominantly naphthenic composition and considerably hamper reconstruction of the types of initial dispersed organic matter. We assume that the mixed genetic type of the studied oils is not only due to their heterogeneous source but also due to the reorganization of primary oil pools at the Cenozoic stage of tectogenesis. The Cenomanian Russkoe and Pangodinskoe naphthenic oils are saturated with adamantoids, which can be selectively accumulated during biodegradation. [ABSTRACT FROM AUTHOR]

Asphaltene precipitation and deposition are drastic issues in the petroleum industry. Monitoring the asphaltene stability in crude oil is still a serious problem and has been subject of many studies. To investigate crude oil stability by saturate, aromatic, resin and asphaltene (SARA) analysis seven types of crudes with different components were used. The applied methods for SARA quantification are IP-143 and ASTM D893-69 and the colloidal instability index (CII) is computed from the SARA values as well. In comparison between CII results, the values of oil compositions demonstrated that the stability of asphaltenes in crude oils is a phenomenon that is related to all these components and it cannot be associated only with one of them, individually. [ABSTRACT FROM AUTHOR]

Crude oil pollution is environmentally ubiquitous and has become a global public concern about its impact on human health. Asphaltenes are the key components of heavy crude oil (HCO) that are underutilized due to their high viscosity and density, and yet, the associated information about biodegradation is extremely limited in the literature. In the present study, an indigenous bacterium with effective asphaltene-degrading activity was isolated from oil shale and identified as Pseudomonas stutzeri by a polyphasic taxonomic approach, named YWX-1. Supplemented with 75 g L−1 heavy crude oil as the sole carbon source for growth in basic mineral salts liquid medium (MSM), strain YWX-1 was able to remove 49% of asphaletene fractions within 14 days, when it was cultivated with an initial inoculation size of 1%. During the degradation process, the bioemulsifier produced by strain YWX-1 could emulsify HCO obviously into particles, as well as it had the ability to solubilize asphaletenes. The bioemulsifier was identified to be a mixture of polysaccharide and protein through Fourier transform infrared spectroscopy (FT-IR). The genome of strain YWX-1 contains one circular chromosome of 4488441 bp with 63.98% GC content and 4145 protein coding genes without any plasmid. Further genome annotation indicated that strain YWX-1 possesses a serial of genes involved in bio-emulsification and asphaltenes biodegradation. This work suggested that P. stutzeri YWX-1 could be a promising species for bioremediation of HCO and its genome analysis provided insight into the molecular basis of asphaltene biodegradation and bioemulsifier production. [Display omitted] • Strain YWX-1 is an efficient degrader of heavy crude oil (HCO). • Bioemulsifier improved the bioavailability of asphaltenes. • The asphaltenes-biodegradability is related to cytochrome c and chloroperoxidase. • The overview of bio-emulsification and biodegradation of asphaltenes was proposed. [ABSTRACT FROM AUTHOR]

Conversion of asphaltene, an undesirable and abundant waste from the petroleum industry, to value-added products can offer sustainability and economic benefit. In this study, asphaltene was acid-treated to become a low-cost and effective adsorbent for removing dye from wastewater. It was hypothesized that asphaltene functionalization with acids will change the surface properties of asphaltene, leading to improved adsorption capabilities. Through acid treatment, the surface area of asphaltenes was increased and oxygen or nitrogen functionalities were incorporated into their structure confirmed by Fourier-transform infrared spectroscopy (FTIR), elemental analysis, Scanning Electron Microscopy (SEM) images, and nitrogen adsorption-desorption isotherm. Batch adsorption experiments were conducted to evaluate the capacity of modified asphaltenes to remove methyl orange (MO) from aqueous solutions. The effect of asphaltene modification techniques, MO solution pH (3−11), asphaltene dosage (0.5–10.0 g/L), contact time, and experimental temperature (25–45 °C) were evaluated. The adsorption removal percentage of MO by modified asphaltene was about three times higher than that of non-modified asphaltene. Modified asphaltene had a maximum adsorption capacity of 7.9 mg/g at 25 °C and a solution pH of 3. Moreover, it is shown that Freundlich isotherm, pseudo-second-order, and intra-particle diffusion kinetic models describe the adsorption process very well. Finally, the regeneration of the asphaltene was achieved using ethanol, and the MO removal efficiency can still be as high as 64 % after 5 cycles (initial removal efficiency is 96 %). This study indicates that the modified asphaltene can be used as a low-cost adsorbent for treating wastewater containing dyes and other organic contaminants. [Display omitted] • Asphaltene waste was used as adsorbent to remove methyl orange from wastewater. • Acid treatment of asphaltene increased its surface area and adsorption capability. • Modified asphaltene had a maximum adsorption capacity of 7.9 mg/g at 25 °C. • The regeneration of the asphaltene was achieved using ethanol. • Isotherm and kinetic models were studied to describe the adsorption process. [ABSTRACT FROM AUTHOR]

We describe asphaltene deposition and removal processes in metal capillaries. We induce asphaltene precipitation by adding an asphaltene precipitant, heptane, to a petroleum fluid. The mixture is then injected through a laboratory-scale capillary and allowed to deposit. We assess the reversal of the deposition by means of the use of two separate chemical treatments: (1) a strong organic acid surfactant and (2) an aromatic solvent. The strong organic acid surfactant, dodecyl benzene sulfonic acid (DBSA), was shown to completely dissolve asphaltenes by means of acid-base chemistry reactions at heteroatomic sites on the asphaltene molecules. We investigate the use of DBSA as an efficient removal agent, injecting it in a mixture of petroleum fluid after the deposit was already formed. An aromatic solvent, toluene, is also investigated in such a fashion to assess its ability in removing deposited asphaltenes. We find that DBSA can effectively remove asphaltene deposits within one pore-volume (PV) of injection and at concentrations roughly ten times less than that required by an aromatic solvent such as toluene. To the best of our knowledge, our current study is the first laboratory-scale investigation with surfactant chemicals to reverse asphaltene deposition in capillaries. [ABSTRACT FROM AUTHOR]

Asphaltene deposition leads to rigorous problems in petroleum industry such as relative permeability reduction, wettability alterations, and blockage of the flow with additional pressure drop in wellbore tubing, etc . Many attempts have been undertaken to develop reliable and accurate models to predict phase behavior of asphaltene. However, previously published models cannot couple static and dynamic behaviors of reservoir and its fluids. In this communication, a novel four-phase flow simulator has been developed considering asphaltene deposition as one of the phases, using finite volume formulation. A novel adaptive unstructured mesh generator technique has been introduced in which dynamic properties of reservoir are combined with static field parameters. The results of this study illustrated that the proposed methodology can accurately predict the oil sample properties, and the amount of asphaltene precipitation. Moreover, it was found that the proposed approach is faster and computationally less expensive compared to fine structured model. The proposed strategy can be applied in any reservoir simulator and provides asphaltene phase behavior and reservoir properties with high degree of accuracy. [ABSTRACT FROM AUTHOR]

Significance of Ionic Liquids (ILs), designer solvents, on inhibiting the asphaltene deposition provided the alternative solution to the problem. In this work, 34 anions and 3 cations comprising of 102 combinations of ILs were investigated for a model asphaltene molecule via quantum solvation software tool COSMO-RS (Conductor like Screening for Real Solvents). Validation is done by comparing literature values of activity coefficient at infinite dilution (IDAC) of alkanes, cycloalkanes and aromatic in 3 ILs with 111 data points at 3 sets of different temperatures. Percent relative absolute average deviation (%RAAD) was found to be 10%. Thereafter IDAC values were predicted for model asphaltene compound in the cations and anions combinations for performance analysis. It is found that smaller cation with sterically shielded large anion gave the large performance for removal of upgrading the asphaltenic crude oil. [ABSTRACT FROM AUTHOR]

Injection of CO 2 , as a redundant gas, is considered as one of the most viable options to enhance oil recovery. The performance of this process may though be compromised in the event of severe precipitation and deposition of asphaltene. In this study, the effect of Co 3 O 4 nanoparticles with various concentrations of 0.01, 0.1 and 1.0 wt% on precipitation of asphaltene during CO 2 injection was investigated by means of interfacial tension (IFT) measurements. The addition of Co 3 O 4 nanoparticles to synthetic solutions comprising of n-heptane, toluene and 5 wt% asphaltene and crude oil caused the IFT to decrease linearly as a function of pressure with two different slopes. In the first region, CO 2 dissolved in the oil phase while in the second region, asphaltene was prone to precipitation. The IFT reduced at lower slope in the second region. It was found that the addition of nanoparticles to the synthetic and crude oils resulted in more asphaltene particles adsorption on the surface of nanoparticles. In addition, more stable dispersion of asphaltene nano-aggregates could be attained. Consequently, the ultimate recovery of asphaltenic oil would take place in reservoir conditions during CO 2 injection due to less aggregation and precipitation of asphaltene particles. Finally, the optimum concentration of dispersed Co 3 O 4 nanoparticles was found to be 0.1 wt%. [ABSTRACT FROM AUTHOR]

Asphaltene precipitation and deposition within the reservoir formation is one of the main concerns during enhanced oil recovery (EOR) processes especially during the gas injection. In the current study, different aspects of carbon dioxide (CO 2 ) and nitrogen (N 2 ) injection in the reservoir, was thoroughly examined. The feasibility of using these gases as the injection gas was explored using Bayesian network-based screening method. After recombination and preparation of the live crude oil, precipitation of asphaltene using vanishing interfacial tension (VIT) method and core flooding experimentation was examined. Besides, swelling test was utilized to investigate the effect of CO 2 and N 2 injection on the expansion of live crude oil. The obtained results showed that recovery factor (RF) of CO 2 injected method in core flood test is higher than N 2 injection due to higher swelling and better miscibility conditions. Although, VIT measurements showed asphaltene precipitation during CO 2 injection, no sign of asphaltene deposition during core flood test at near bubble point pressure was observed. [ABSTRACT FROM AUTHOR]

This paper will present more-detailed discussion of asphaltene risk by updating new asphaltene-onset-pressure (AOP) results, and it will capture range-of-temperature conditions (i.e., from reservoir temperature to surface-operating temperature). For integrating these updates into the risk-matrix chart proposed in the previous work by Yonebayashi et al. (2013), geological heterogeneity of fluid-sampling location will be taken into account. A study of numerical modeling (applying the cubic-plus-association equation of state) treated the geological heterogeneity as a variation of asphaltene content, and reproduced asphaltene-precipitation envelopes, which were well-matched to the overall trend of experimental AOP detection. To conclude, this work reduced the uncertainty of the asphaltene-precipitation boundary at reservoir temperature, and showed a consistent shifting of the asphalteneprecipitation boundary by temperature range. [ABSTRACT FROM AUTHOR]

Accurate knowledge of static and dynamic characteristics of the reservoir plays a key role in precise evaluation of the field performance. Pressure and temperature variations of the reservoir as well as precipitation of complex components like asphaltene during reservoir production change its characteristics including fluid flow and reservoir permeability. This effect is more significant in gas condensate fractured reservoirs; therefore, application of a dynamic mesh for accurate simulation of the reservoir is inevitable. In this paper, a novel technique has been proposed for generating a dynamic mesh in which static and dynamic parameters of a gas condensate fractured reservoir are combined with the capability of updating. Static parameters including permeability distribution and the location of active wells were combined with fluid patterns in the reservoir. This approach led to generating an element size map, and subsequently was applied for unstructured mesh generation. Afterward, this technique was applied in a multi-phase flow compositional simulator. Moreover, an auto-tune PVT package was developed for properties estimation. The priority of this package was freely choosing the number of regression parameters for properties estimation. To evaluate the performance of the developed model, the results for this model were compared with those obtained by uniform grid model. A grouping technique was also developed in the compositional simulator, to optimize the computation algorithm in terms of the CPU time. It was found that the proposed method provides more accurate results for the recovery of gas reservoir compared with the uniform grid model. Moreover, it is faster and computationally less expensive than the fine model. In addition, the proposed model would provide us with a new and different approach for studying the flow and rock physics and simulating fractured reservoirs, which could be an alternative to dual porosity-dual permeability methods. [ABSTRACT FROM AUTHOR]

The research study of the effect caused by the temperature factor, additives, and magnetic field on the kinetics of sedimentation and pour point of high-paraffin low-resin oil demonstrated that treatment with the additives leads to decrease in oil sludge formation, variation of sedimentation rate and kinetics, however, joint effect of the additive and magnetic field provides no synergistic effect. [ABSTRACT FROM AUTHOR]

The results analysis of fractional and material composition of the cracking products of Ashalchinskoye and Karmalskoye bitumen deposits was presented in this work. The effect of bitumen ozone-oxygen mixture pretreatment followed by cracking on thermolysis processes was investigated. It was shown that molecules of resins and asphaltenes containing large amounts of aliphatic fragments in its structure readily undergo thermal decomposition to form additional distillate fractions. Low content of aliphatic fragments leads to aromatization of the naphthenic cycles in the molecule of resins and asphaltenes, the thermal degradation reactions proceed in high yields of gas and coke. [ABSTRACT FROM AUTHOR]

The effect of a composite material based on micron iron powder, modified with cobalt and nickel ions on the composition of oils with different contents of heteroatoms and resin-asphaltene components (a mixture of West Siberian light oils and Usinskaya heavy oil) is studied. It is shown using analytical methods, including elemental and structural group analysis, GC-MS, IR and 1 H-NMR - spectroscopy that a composite based on micron sized iron powder modified with cobalt and nickel ions could be used for pretreatment of hydrocarbon feedstock with high content of heteroatom components. It is found out during treatment of the mixture of light West Siberian oil that its qualitative composition remains virtually invariable. Heavy oil treatment from the Usinskoye oil field using composite results in a decreased concentration of nitrogen and organic sulfur compounds. [ABSTRACT FROM AUTHOR]

This work was aimed to study the pyrolysis behaviour and mechanisms of Buton oil sand via both experimentation and kinetic analysis. The non-isothermal pyrolysis experiments of the oil sand and its main organic component, bitumen, were carried out using a thermogravimetric analyser (TGA) operating at various heating rates of 2, 5, 10 and 20Kmin −1 from room temperature to 823 K and in a nitrogen atmosphere. The activation energy of the oil sand pyrolysis was estimated using an integral model-free method based on the TGA experimental data. The results showed that the content of the bitumen in the oil sand was approximately 18% by weight and the pyrolysis process of the bitumen completed at 823 K regardless of the heating rate. The calculated activation energy strongly depended on the degree of pyrolysis conversion (ranging from 100kJmol −1 to 250kJmol −1 ). Good agreement between the kinetic modelling and experimental data of dependence of conversion degree on temperature was obtained, suggesting that the integral model-free method can serve as an effective tool to predict the pyrolysis behaviour of the oil sand. [ABSTRACT FROM AUTHOR]

Solvent injection into heavy-oil reservoirs is quite complex because of the asphaltene destabilization that occurs because of the changes in temperature, pressure, and solvent type dissolved in oil. As a result of this destabilization, the asphaltene flocculates, agglomerates, and eventually plugs the pores in the reservoir because of the formation of asphaltene clusters. In solvent applications, light-molecular-weight hydrocarbon solvents are preferred because of their high diffusion coefficient; however, as the carbon number of n-alkane solvents decreases, asphaltene precipitation increases. Therefore, the selection of the solvent and application condition is highly critical in cold and thermally aided solvent applications. In this research, low-carbon-number n-alkane (propane, n-hexane, and n-decane) and a distillate-hydrocarbon (obtained from a heavy-oil-upgrading facility) injection into glass-bead-pack systems saturated with heavy oil (87,651 and 20,918 cp at 25°C) were evaluated at different pressure conditions that are applicable to typical Canadian oil-sand reservoirs (698-2068 kPa) and temperatures (25-120°C). First, the asphaltene behavior of different solvents at different pressures and temperatures was studied through deasphalting work in a pressure/volume/temperature (PVT) cell in previous work [Moreno and Babadagli (2013)]. By use of quantitative (amount of asphaltene precipitated) and qualitative (microscopic images of asphaltene clusters) observations, asphaltenes were classified in terms of their shape, size, and quantity for different oil/solvent types, pressure, and temperature. Continually, the same n-alkane, distillate-hydrocarbon solvents, and heavy oil were used in gravity-stable-displacement glass-bead-pack experiments. 3-D (cylindrical) glass-bead-pack experiments were carried out at the same temperature and pressure conditions used for the PVT experiments. The operational conditions, oil composition, and solvent type showed significant effects on oil-recovery factor. Asphaltene deposition and residual oil saturation (ROS) in the glass-bead pack and the amount of asphaltene in the produced oil were measured, and the standard saturate, aromatic, resin, and asphaltene (SARA) analysis was applied to determine the optimal operating conditions yielding the highest recoveries with minimal pore plugging. Moreover, the pore-plugging process was analyzed through a visual scanning electron microscope (SEM) and optical microscope to find the different organic deposition formation and agglomeration. Oil production was evaluated by use of microscope visualization, viscosity reduction, and refractive-index values. Eventually, optimal application conditions for solvent and thermally aided solvent injection were listed for a wide range of heavy-oil and solvent types. [ABSTRACT FROM AUTHOR]