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The technological landscape for industrial processes handling asphaltene is evolving at a rapid pace due to the increase in the extraction of heavy crude oil. The main underlying challenges in this regard are the flow assurance, the recovery of the spent solvent, and the sophisticated extractor setup required to develop the process to an industrial scale. The number of studies focused on the handling of the asphaltene at the atomic and molecular scales is growing enormously in order to identify new sustainable solvents for the effective extraction of asphaltene from heavy crude oil or oil-bearing sands. This Perspective focuses on the importance of density functional theory and molecular dynamics simulations to explore the broader range of asphaltene inhibitors, e.g., nanoparticles, ionic liquids, and deep eutectic solvents, to prevent asphaltene precipitation. We provide a concise overview of the major accomplishments, analyze the aspects that require attention, and highlight the path-breaking studies having a significant impact on the process of chemical enhanced oil recovery from heavy crude oil reservoirs primarily based on atomistic and molecular simulations. [ABSTRACT FROM AUTHOR]

The present review focuses on the most recent advances in liquid‐phase NMR of asphaltenes, leaving apart an overwhelming amount of publications dealing with solid‐state NMR investigations in this field. Owing to the complexity of the coal‐derived products, and in particular, asphaltenes, their 1H and 13C NMR spectra consist of a number of overlapping signals belonging to different hydrocarbon types. Comprehensive studies of asphaltenes by means of NMR reveal the characteristic functional groups of their fractions together with the spectral regions in which they resonate. NMR studies of asphaltenes provide a straightforward guideline for their chemical composition and that of the related coal‐derived products. [ABSTRACT FROM AUTHOR]

Nanoparticles provide a promising, cost-effective eco-friendly solution to the challenges posed by heavy-oil reservoirs, significantly enhancing oil recovery rates by reducing viscosity without requiring extensive thermal inputs. In this study, carbon nanospheres (CNSs) and functionalized-CNSs nanofluids were prepared by incorporating surfactants (T80 or BMIMCl). These nanofluids were evaluated for their efficacy in upgrading crude oil, particularly focusing on viscosity-reduction. Rheological tests were conducted across varying shear rates (60–300 s−1) and concentrations (0.02–3 wt.%) to comprehensively assess the impact of these additives on the crude oil's proprieties. The results showed a notable enhancement in crude oil viscosity reduction, with the following order observed: CNS-TiO2 < CNS-TiO2/DMIMCl < CNS-TiO2/T80, yielding reduction rates of 95%, 95.83%, and 97.08%, respectively, at an optimal dosage of 2.75 wt.% and a shear rate of 300 s−1. The surface functionalization of CNS particles and their crystallinity are the main mechanisms driving the reduction in oil viscosity. Moreover, the properties of the crude oil were investigated upon the utilization of CNS-TiO2/T80 nanofluid. It was found that this nanofluid led to a substantial reduction in sulfur content by 78.32% and a significant decrease in the percentage of heavier molecules, ranging from C12 to C35 and up to C36, with 47.76% and 97.98%, respectively. [ABSTRACT FROM AUTHOR]

The relationship between saturate, aromatic, resin, and asphaltene (SARA) contents and asphalt properties remains unclear. This study aimed to propose a high‐throughput molecular dynamics simulation framework and demonstrate its application in rapidly building asphalt molecular models of various SARA ratios and predicting their properties, using density as an example. Based on the framework, 400 models with varying SARA ratios with different aging degrees were generated to calculate their densities and used to train machine learning algorithms. The ordinary least squares model achieved R2 values exceeding 80%, and quantitative formulas linking asphalt density to SARA ratios were derived. It was found that saturate content negatively correlates with asphalt density, while resin content positively correlates with asphalt density. Additionally, asphalt density and viscosity increase with aging, influenced simultaneously by the SARA ratio and aging degree. Overall, this paper creates a rapid, high‐throughput molecular simulation pathway to predict asphalt behavior. [ABSTRACT FROM AUTHOR]

Asphaltene deposition may pose serious challenges to flow assurance of crude oil in well columns. Different aggregation kinetics would partly be responsible for asphaltene particle growth ending in deposition on the surface of well columns. This work primarily investigates the thermophoretic deposition velocity caused by temperature gradients inside well columns for various asphaltene aggregation kinetics, including crossover behaviour, sedimentation, reaction-limited aggregation (RLA), and diffusion-limited aggregation (DLA). To do so, the experimental observations of size distribution for a live crude oil was performed at 80 °C and pressure range of 4500–5500 psia. Moreover, various patterns of different size distributions were gathered from the literature for the sake of comparison. Next, a well column in southern Iran was selected to study the kinetic behaviour of thermophoretic velocity of deposition, with a difference between geothermal and static temperatures of around 5 to 50 °C. The non-isothermal deposition velocity was shown to decrease from the top to the bottom of the well column, according to the findings of the study. The results also revealed that the thermophoretic velocity decreases as particle size increases and vice versa. This was confirmed by examining a comparably large range of asphaltene particle sizes, ranging from approximately 100 nm to roughly 9 µm. Practical implications of these findings were also discussed which would provide guidance for mitigation of asphaltene deposition in well columns. [ABSTRACT FROM AUTHOR]

Gas injection is a well-known method for enhancing oil recovery (EOR). The utilization of greenhouse gases, such as carbon dioxide (CO2) or flue gas, offers the dual advantage of reducing greenhouse gas emissions while potentially enhancing the sweep efficiency in oil recovery. Nevertheless, one of the notable challenges encountered when using these gases is the precipitation and deposition of asphaltenes, leading to formation damage and a decrease in reservoir permeability, particularly in the case of light oil reservoirs. In this study, CO2 and flue gas were injected into an elongated core sample comprising four individual core plugs under reservoir conditions to displace the light live oil. The recovery factor and asphaltene deposition along the core holder were assessed and compared as two crucial parameters within the gas injection scenario. Our results indicate a significantly higher recovery factor of 86% achieved with CO2 injection compared to 36% with flue gas injection, attributable to differences in their interfacial tension and miscibility. However, the CO2 injection method exhibits more pronounced formation damage. Individual assessment of each core plug reveals that permeability impairment is most acute in the initial two core plugs, situated closer to the injection face of the extended core. These findings enhance our understanding of the mechanisms contributing to permeability impairment resulting from asphaltene deposition during CO2 and flue gas injection for EOR. [ABSTRACT FROM AUTHOR]

Using smart or low salinity waters known as green processes gained increasing attention due to their unique features and their positive impacts on the environment. In light of this fact and since there is limited knowledge about the effects of salts under engineered concentrations or binary mixtures and crude oil fractions on the interfacial tension (IFT) reduction and wettability alteration of the resinous (RSO) and asphaltenic synthetic oil (ASO), the current investigation is designed and performed for the first time. Moreover, the dynamic behavior of the IFT variation was carefully investigated and the relaxation time was obtained and modeled to see the impact of mono and divalent salts individually and in binary conditions. The relaxation times revealed that the lowest adsorption times were obtained for NaCl/CaCl2 brine regardless of the examined oil types of ASO and RSO due to the high movement affinity of the polar functional groups toward the interface consequently reducing the required time for coverage and packing of active agents at the interface. Finally, the measured contact angle values revealed a significant effect of binary salts on the wettability alteration toward strongly water-wet conditions, especially for the RSO and ASO compared with crude oil. [ABSTRACT FROM AUTHOR]

Asphaltene, often regarded as an undesirable by‐product of petroleum processing, possesses abundant reserves but limited market value. In this study, a simple and environmentally friendly solvent extraction method is conducted under ambient conditions to convert low‐value asphaltene into high‐value asphaltene‐based fluorescent carbon nanosheets (a‐FCS). This approach yields dual‐switch a‐FCS capable of emitting orange‐red fluorescence in solid‐state or water environment and exhibiting blue‐to‐yellow fluorescence in organic solvents. Moreover, the redshift observed in the fluorescence emission wavelength in the solvent is attributed to its intrinsic self‐assembly behavior, which becomes more pronounced with increasing concentration. Upon introduction to water, hydrophobic interactions induce the aggregation of a‐FCS. This aggregation triggers the orange‐red fluorescence by restricting intramolecular rotation on the surface, a phenomenon facilitated by the entanglement of aliphatic chains from asphaltene molecules. This unique property makes them applicable in anti‐counterfeiting and determination of ethanol content in aqueous solution. [ABSTRACT FROM AUTHOR]

Asphaltene-resin-paraffin deposition (ARPD) is a complicated and prevalent issue in the oil and gas industry, impacting the efficiency and integrity of petroleum extraction, production, transportation and processing systems. Considering all witnessed ARPD problems in Azerbaijan oil fields, this paper proposed a chemical method and optimized the type and concentration of chemical inhibitors. Then, the effect of selected chemical reagents on inhibiting the ARPD amount and thus enhancing oil recovery was detected by reservoir simulation during both waterflooding and CO2 flooding production. Three new chemical compounds (namely, Chemical-A, Chemical-B and Chemical-C) were examined in laboratory conditions, and their impact on rheological properties of high-paraffin oilfield samples of Azerbaijan (X, Y and Z) were investigated. Experimental results show that Chemical-C with a concentration of 600 g/t has the best efficiency for alleviating the problems. After adding Chemical-C to the crude oil, the freezing point of oil was decreased from 12 °C to (−4) °C, the ARPD amount declined from 0.185 to 0.016 g, and oil effective viscosity was reduced from 16.2 mPa·s to 3.1 mPa·s. It was determined that for water and CO2 flooding, higher injection pressure resulted in reduced asphaltene precipitation. Adding the selected ARPD inhibitor, the oil recovery for waterflooding can increase from 52% to 62%, while it can rise from 55% to 68% for CO2 flooding. [ABSTRACT FROM AUTHOR]

The modulation of bulk properties including the cohesive strength and the solubility of the asphaltenes, due to the inclusion of graphene nanosheets and the thermoplastic polymer, is probed by performing all-atom classical molecular dynamics (MD) simulations. The impact of morphological heterogeneity, including the size of the aromatic core of the asphaltene molecule, the nature of the heteroatom attached to the aromatic core, the orientation of the graphene nanosheets, and the surface area of the nanomaterial, on the bulk properties of the model systems of nanocomposites and interfaces is explored. The cohesive strength of the asphaltene composites is significantly enhanced by the introduction of graphene nanosheets. The addition of styrene–butadiene–styrene (SBS) block copolymer into the graphene-reinforced asphaltene systems improves the cohesive strength, structural plasticity, and compatibility between the nanomaterial and the asphaltenes. The π–π stacking interaction between the graphitic surface and the aromatic core of the asphaltene is identified to be the major driving force for modulating the cohesive strength. The dispersion interaction maximizes in the hierarchical layered structure compared to the randomly oriented structure of the graphene nanosheets and the asphaltene molecules. The energetics of non-covalent interaction are further assessed within the framework of dispersion-corrected density functional theory (DFT)-based methods. The DFT-derived adsorption energies and thermochemical properties substantiate the stronger interaction and the thermodynamic favorability of the adsorption processes in both the gas phase and solvent medium (toluene). The simulated IR and Raman spectra are also analyzed to reveal the nature of the interaction. [ABSTRACT FROM AUTHOR]

Asphaltene precipitation in oil reservoirs, well equipment, and pipelines reduces production, causing pore blockage, wettability changes, and decreased efficiency. Asphaltenes, with their unique chemical structure, self-assemble via acid–base interactions and hydrogen bonding. Nano-inhibitors prevent asphaltene aggregation at the nanoscale under reservoir conditions. This study investigates the effect of two surface-modified nanoparticles, silica, and calcium carbonate, as asphaltene inhibitors and oil production agents. The impacts of these nano-inhibitors on asphaltene content, onset point, wettability, surface tension, and oil recovery factor were determined to understand their mechanism on asphaltene precipitation and oil production. Results demonstrate that these nano-inhibitors can significantly postpone the onset point of asphaltene precipitation, with varying performance. Calcium carbonate nano-inhibitor exhibits better efficiency at low concentrations, suspending asphaltene molecules in crude oil. In contrast, silica nano-inhibitor performs better at high concentrations. Wettability alteration and IFT reduction tests reveal that each nano-inhibitor performs optimally at specific concentrations. Silica nano-inhibitors exhibit better colloidal stability and improve oil recovery more than calcium carbonate nano-inhibitors, with maximum oil recovery factors of 33% at 0.1 wt.% for silica and 25% at 0.01 wt.% for calcium carbonate nano-inhibitors. [ABSTRACT FROM AUTHOR]

This study presents a novel method for separating asphaltene from crude oil at room temperature, eliminating the need for heating or refluxing. Traditional methods often suffer from high energy consumption, costly equipment, and safety risks associated with flammable steam. This research focuses on deasphalting heavy crude oil from southern Iraq, containing 3.934 wt.% of asphaltene. Using a lab-made flow injection analysis system, 27 experiments were conducted, varying solvent flow rates (10 mL/min to 50 mL/min), mixing coil lengths (200 cm to 300 cm), and combinations of aromatic and aliphatic solvents. An optimal design (custom) and response surface method (RSM) were employed to pinpoint the best conditions. The optimal deasphalting process involved a solvent flow rate of 50 ml/min, a 300 cm mixing coil, and a xylene/n-heptane (1:10 vol/vol) solvent blend. Statistical analysis confirmed the significance of parameters, encompassing single parameters, interactions, and quadratic effects, all with pvalues under the 0.05 confidence level. The efficiency of the deasphalting procedure was assessed practically and theoretically, yielding efficiency percentages of 71.97% and 73.48%, respectively, for asphaltene extraction. This innovative method offers a promising solution for efficient and safe asphaltene separation from crude oil without the need for energy-intensive processes. [ABSTRACT FROM AUTHOR]

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This study utilized molecular dynamics simulation to investigate the adhesion process between wood tar-rejuvenated asphalt and acid/alkaline aggregate. Initially, various indicators including the contact area, cohesion coefficient, and interaction energy were employed to assess the adhesion effect under dry conditions. This revealed the action mechanism of the wood tar-rejuvenator in enhancing the adhesion performance between aged asphalt and aggregate. Subsequently, an asphalt–water–aggregate interface model was developed to simulate the water damage process of the asphalt mixture. This aimed to unveil the damage mechanism of water intrusion on the adhesion performance of the asphalt–aggregate interface and evaluate the water damage resistance of wood tar-rejuvenated asphalt through adhesion energy, stripping work, and the energy ratio. The findings indicate that wood tar-rejuvenated asphalt exhibits favorable adhesion properties with both acid and alkaline aggregates. The addition of wood tar-rejuvenated asphalt increased the interaction energy between aged asphalt and acid and alkali aggregates by 67.75 kJ/mol and 97.3 kJ/mol, respectively. The addition of a wood tar rejuvenator enhances the interaction energy between aged asphalt and aggregate, thereby increasing mutual attraction and enlarging the contact area. The adhesion between asphalt and aggregates hinges on the interaction between asphaltene and aggregates, and the wood tar rejuvenator reduces the diffusion ability of asphaltene in the attractive state of the aggregate, resulting in stable aggregation. Moisture intrusion increased the aggregation distance between asphaltene and aggregate by 14.1% and decreased the degree of aggregation by 24.0%, thereby reducing the interaction energy. The extent of damage caused by water intrusion is linked to the aggregation distance, with greater distances leading to deeper damage. Under wet conditions, the interaction energy of wood tar-rejuvenated asphalt increased by 78.2% in the acidic aggregate system and 98.1% in the basic aggregate system compared with aged asphalt. Meanwhile, wood tar-based rejuvenated asphalt improves the adhesion between aged asphalt and aggregate and reduces the stripping function of asphalt affected by water replacement, which results in the ER value of wood tar-rejuvenated asphalt being higher than that of the original asphalt by 0.12 and 0.22 in the acidic and alkaline environments, respectively, thus showing excellent resistance to water damage. This study provides new criteria for the selection of rejuvenators for waste asphalt, which will help in the future selection of superior rejuvenators for aged asphalt and reduce the possibility of choosing the wrong rejuvenator. [ABSTRACT FROM AUTHOR]

Abstract Using smart or low salinity waters known as green processes gained increasing attention due to their unique features and their positive impacts on the environment. In light of this fact and since there is limited knowledge about the effects of salts under engineered concentrations or binary mixtures and crude oil fractions on the interfacial tension (IFT) reduction and wettability alteration of the resinous (RSO) and asphaltenic synthetic oil (ASO), the current investigation is designed and performed for the first time. Moreover, the dynamic behavior of the IFT variation was carefully investigated and the relaxation time was obtained and modeled to see the impact of mono and divalent salts individually and in binary conditions. The relaxation times revealed that the lowest adsorption times were obtained for NaCl/CaCl2 brine regardless of the examined oil types of ASO and RSO due to the high movement affinity of the polar functional groups toward the interface consequently reducing the required time for coverage and packing of active agents at the interface. Finally, the measured contact angle values revealed a significant effect of binary salts on the wettability alteration toward strongly water-wet conditions, especially for the RSO and ASO compared with crude oil.

Abstract Asphaltene precipitation in oil reservoirs, well equipment, and pipelines reduces production, causing pore blockage, wettability changes, and decreased efficiency. Asphaltenes, with their unique chemical structure, self-assemble via acid–base interactions and hydrogen bonding. Nano-inhibitors prevent asphaltene aggregation at the nanoscale under reservoir conditions. This study investigates the effect of two surface-modified nanoparticles, silica, and calcium carbonate, as asphaltene inhibitors and oil production agents. The impacts of these nano-inhibitors on asphaltene content, onset point, wettability, surface tension, and oil recovery factor were determined to understand their mechanism on asphaltene precipitation and oil production. Results demonstrate that these nano-inhibitors can significantly postpone the onset point of asphaltene precipitation, with varying performance. Calcium carbonate nano-inhibitor exhibits better efficiency at low concentrations, suspending asphaltene molecules in crude oil. In contrast, silica nano-inhibitor performs better at high concentrations. Wettability alteration and IFT reduction tests reveal that each nano-inhibitor performs optimally at specific concentrations. Silica nano-inhibitors exhibit better colloidal stability and improve oil recovery more than calcium carbonate nano-inhibitors, with maximum oil recovery factors of 33% at 0.1 wt.% for silica and 25% at 0.01 wt.% for calcium carbonate nano-inhibitors.

Asphaltenes represent a novel class of carbon nanofillers that are of potential interest for many applications, including polymer nanocomposites, solar cells, and domestic heat storage devices. In this work, we developed a realistic coarse-grained Martini model that was refined against the thermodynamic data extracted from atomistic simulations. This allowed us to explore the aggregation behavior of thousands of asphaltene molecules in liquid paraffin on a microsecond time scale. Our computational findings show that native asphaltenes with aliphatic side groups form small clusters that are uniformly distributed in paraffin. The chemical modification of asphaltenes via cutting off their aliphatic periphery changes their aggregation behavior: modified asphaltenes form extended stacks whose size increases with asphaltene concentration. At a certain large concentration (44 mol. %), the stacks of modified asphaltenes partly overlap, leading to the formation of large, disordered super-aggregates. Importantly, the size of such super-aggregates increases with the simulation box due to phase separation in the paraffin–asphaltene system. The mobility of native asphaltenes is systematically lower than that of their modified counterparts since the aliphatic side groups mix with paraffin chains, slowing down the diffusion of native asphaltenes. We also show that diffusion coefficients of asphaltenes are not very sensitive to the system size: enlarging the simulation box results in some increase in diffusion coefficients, with the effect being less pronounced at high asphaltene concentrations. Overall, our findings provide valuable insight into the aggregation behavior of asphaltenes on spatial and time scales that are normally beyond the scales accessible for atomistic simulations. [ABSTRACT FROM AUTHOR]

After several years of gas production, a black solid hydrocarbon material began to be produced along with the gas stream from the Risha gas field, in the northeastern part of Jordan. The main reason for the formation of this material is still unknown until this time, so knowing the source of this material is this study's main goal. Organic geochemical studies for black solid material and effective source rocks (Lower Silurian shales) are used to determine the physical and organic components of the produced black solid material (heavy oil) and attempt to identify its source. The black solid material demonstrates high organic carbon (TOC = 12% by leco instrument) and a high calorific value, like those of oils, asphalts, and shale oils with moderate sulfur content. The gross composition of the black solid material sample is dominated by saturates and asphaltene but contains very low aromatic hydrocarbons reflecting the naphthenic oil type. Meanwhile, the Silurian extracts range between paraffinic and paraffinic-naphthenic organic matters. The biomarker indicators related depositional environment and carbon isotopic composition for the black solid material sample and Silurian extracts, show that they were relatively deposited in a reducing marine environment. The black material reveals lower maturity level than the Silurian extracts. Oil/source rock correlation study for the studied samples suggests strong affinity between the black material and Lower Silurian source rock in their source characteristics, suggesting that the black hydrocarbon material was expelled from the Silurian source rocks at low maturity stage as normal oil. This normal oil is subjected to secondary alteration process (evaporative fractionation) and was stored in the reservoir. It contaminated with some inorganic material that was introduced into the well as a component of a drilling mud additive or drill string lubricant or, potentially, in part, a corrosion product of wellbore tubulars, since significant iron was present in the sample. [ABSTRACT FROM AUTHOR]

Abstract Miscible gas injection in tight/shale oil reservoirs presents a complex problem due to various factors, including the presence of a large number of nanopores in the rock structure and asphaltene and heavy components in crude oil. This method performs best when the gas injection pressure exceeds the minimum miscibility pressure (MMP). Accordingly, accurate calculation of the MMP is of special importance. A critical issue that needs to be considered is that the phase behavior of the fluid in confined nanopores is substantially different from that of conventional reservoirs. The confinement effect may significantly affect fluid properties, flow, and transport phenomena characteristics in pore space, e.g., considerably changing the critical properties and enhancing fluid adsorption on the pore wall. In this study, we have investigated the MMP between an asphaltenic crude oil and enriched natural gas using Peng-Robinson (PR) and cubic-plus-association (CPA) equations of state (EoSs) by considering the effect of confinement, adsorption, the shift of critical properties, and the presence of asphaltene. According to the best of our knowledge, this is the first time a model has been developed considering all these factors for use in porous media. We used the vanishing interfacial tension (VIT) method and slim tube test data to calculate the MMP and examined the effects of pore radius, type/composition of injected gas, and asphaltene type on the computed MMP. The results showed that the MMP increased with an increasing radius of up to 100 nm and then remained almost constant. This is while the gas enrichment reduced the MMP. Asphaltene presence changed the trend of IFT reduction and delayed the miscibility achievement so that it was about 61% different from the model without the asphaltene precipitation effect. However, the type of asphaltene had little impact on the MMP, and the controlling factor was the amount of asphaltene in the oil. Moreover, although cubic EoSs are particularly popular for their simplicity and accuracy in predicting the behavior of hydrocarbon fluids, the CPA EoS is more accurate for asphaltenic oils, especially when the operating pressure is within the asphaltene precipitation range.

Abstract This research investigates the interactions between a novel environmentally friendly chemical fluid consisting of Xanthan gum and bio-based surfactants, and crude oil. The surfactants, derived from various leaves using the spray drying technique, were characterized using Fourier-transform infrared (FTIR) spectroscopy, zeta potential analysis, Dynamic light scattering, and evaluation of critical micelle concentration. Static emulsion tests were conducted to explore the emulsification between crude oil and the polymer-surfactant solution. Analysis of the bulk oil FTIR spectra revealed that saturated hydrocarbons and light aromatic hydrocarbons exhibited a higher tendency to adsorb onto the emulsion phase. Furthermore, the increased presence of polar hydrocarbons in emulsion phases generated by polar surfactants confirmed the activation of electrostatic forces in fluid–fluid interactions. Nuclear magnetic resonance spectroscopy showed that the xanthan solution without surfactants had a greater potential to adsorb asphaltenes with highly fused aromatic rings, while the presence of bio-based surfactants reduced the solution's ability to adsorb asphaltenes with larger cores. Microfluidic tests demonstrated that incorporating surfactants derived from Morus nigra and Aloevera leaves into the xanthan solution enhanced oil recovery. While injection of the xanthan solution resulted in a 49.8% recovery rate, the addition of Morus nigra and Aloevera leaf-derived surfactants to the xanthan solution increased oil recovery to 58.1% and 55.8%, respectively.

Abstract In the enhanced oil recovery (EOR) process, interfacial tension (IFT) has become a crucial factor because of its impact on the recovery of residual oil. The use of surfactants and biosurfactants can reduce IFT and enhance oil recovery by decreasing it. Asphaltene in crude oil has the structural ability to act as a surface-active material. In microbial-enhanced oil recovery (MEOR), biosurfactant production, even in small amounts, is a significant mechanism that reduces IFT. This study aimed to investigate fluid/fluid interaction by combining low biosurfactant values and low-salinity water using NaCl, MgCl2, and CaCl2 salts at concentrations of 0, 1000, and 5000 ppm, along with Geobacillus stearothermophilus. By evaluating the IFT, this study investigated different percentages of 0, 1, and 5 wt.% of varying asphaltene with aqueous bulk containing low-salinity water and its combination with bacteria. The results indicated G. Stearothermophilus led to the formation of biosurfactants, resulting in a reduction in IFT for both acidic and basic asphaltene. Moreover, the interaction between asphaltene and G. Stearothermophilus with higher asphaltene percentages showed a decrease in IFT under both acidic and basic conditions. Additionally, the study found that the interaction between acidic asphaltene and G. stearothermophilus, in the presence of CaCl2, NaCl, and MgCl2 salts, resulted in a higher formation of biosurfactants and intrinsic surfactants at the interface of the two phases, in contrast to the interaction involving basic asphaltene. These findings emphasize the dependence of the interactions between asphaltene and G. Stearothermophilus, salt, and bacteria on the specific type and concentration of asphaltene.

Abstract The effects of sulfate salts under low and high salinity conditions and pH of 3.5–11 on interfacial tension (IFT) reduction and IL adsorption using resinous (RSO) and asphaltenic (8 wt/wt%) synthetic oils are investigated. The measurements showed the increasing effect of pH on the IFT of RSO/DW from 23.5 to 27.3 mN/m (pH = 3.5 → 7) in the first place and a reducing effect (0.4 mN/m) if pH = 7 → 11. Using a high concentration of 50,000 ppm for MgSO4, and Na2SO4 revealed an extensive IFT reduction for a pH value of 11 with the value of 0.20 mN/m for Na2SO4. The measured IFT values showed the significant impact of IL (500 ppm) on the IFT (minimum value of 0.01 mN/m for RSO/50,000 Na2SO4 + 500 ppm 1-decyl-3-methyl imidazolium triflate ([C10mim][TfO])) for pH = 11. The IL adsorption measurements showed the role of in-situ surfactant production (saponification process) on the 1-decyl-3-methyl imidazolium chloride ([C10mim][Cl]) and [C10mim][TfO] adsorption reduction from 3.67 to 2.33 and 4.21 to 3.34 mg IL/g rock, respectively. The performed core flooding experiments using the optimum chemical formulation showed the possibility of tertiary oil recovery with maximum oil recovery of 28.8% based on original oil in place in the presence of 500 ppm.

Miscible gas injection in tight/shale oil reservoirs presents a complex problem due to various factors, including the presence of a large number of nanopores in the rock structure and asphaltene and heavy components in crude oil. This method performs best when the gas injection pressure exceeds the minimum miscibility pressure (MMP). Accordingly, accurate calculation of the MMP is of special importance. A critical issue that needs to be considered is that the phase behavior of the fluid in confined nanopores is substantially different from that of conventional reservoirs. The confinement effect may significantly affect fluid properties, flow, and transport phenomena characteristics in pore space, e.g., considerably changing the critical properties and enhancing fluid adsorption on the pore wall. In this study, we have investigated the MMP between an asphaltenic crude oil and enriched natural gas using Peng-Robinson (PR) and cubic-plus-association (CPA) equations of state (EoSs) by considering the effect of confinement, adsorption, the shift of critical properties, and the presence of asphaltene. According to the best of our knowledge, this is the first time a model has been developed considering all these factors for use in porous media. We used the vanishing interfacial tension (VIT) method and slim tube test data to calculate the MMP and examined the effects of pore radius, type/composition of injected gas, and asphaltene type on the computed MMP. The results showed that the MMP increased with an increasing radius of up to 100 nm and then remained almost constant. This is while the gas enrichment reduced the MMP. Asphaltene presence changed the trend of IFT reduction and delayed the miscibility achievement so that it was about 61% different from the model without the asphaltene precipitation effect. However, the type of asphaltene had little impact on the MMP, and the controlling factor was the amount of asphaltene in the oil. Moreover, although cubic EoSs are particularly popular for their simplicity and accuracy in predicting the behavior of hydrocarbon fluids, the CPA EoS is more accurate for asphaltenic oils, especially when the operating pressure is within the asphaltene precipitation range. [ABSTRACT FROM AUTHOR]

Understanding the coking behaviors has been considered to be really essential for developing better vacuum residue processing technologies. A battery of thermal cracking tests of typical vacuum residue at 410 °C with various reaction time were performed to evaluate the coke formation process. The total yields of ideal components including naphtha, atmospheric gas oil (AGO) and vacuum gas oil (VGO) of thermal cracking reactions increased from 10.89% to 40.81%, and the conversion ratios increased from 8.05% to 43.33% with increasing the reaction time from 10 to 70 min. The asphaltene content increased from 12.14% to a maximum of 22.39% and then decreased, and this maximum of asphaltene content occurred at the end of the coking induction period. The asphaltenes during the coking induction period, at the end and after coking induction period of those tested thermal cracking reactions were characterized to disclose the structure changing rules for coke formation process, and the coke formation pathways were discussed to reveal the coke formation process at molecular level. [ABSTRACT FROM AUTHOR]

Low sulfur heavy stock (LSHS Premium) is a green alternative to Fuel oil. Asphaltene content is a very important quality parameter and is stipulated in LSHS (Premium) specifications. IP 143 is a standard method to conduct the asphaltene analysis; however it is a tedious process which requires around 48 h for analysis. In this study, a correlation of two standard methods (IP 143 and JPI-5S-45-95) has been carried out based on the experimentally determined asphaltene contents of LSHS (Premium) samples from different production sources. The correlation coefficient between two standard methods is observed to be near unity, suggesting an excellent correlation. This indicates that JPI-5S-45-95 can be used as a substitute of IP 143 method for asphaltene analysis consuming less time (1 h). A correlation equation has also been established between CCR (ASTM D4530) and asphaltene contents (JPI-5S-45-95) of LSHS (Premium) which indicate the linear dependency of CCR with its asphaltene content. For validation of correlation equation, the calculated asphaltene content was compared with experimentally determined values and it is observed that this correlation equation can be employed to fairly predict the asphaltene content accurately without conducting IP 143 or JPI-5S-45-95 methods. [ABSTRACT FROM AUTHOR]

The aging process of asphalt materials encompasses varying levels of oxidation reactions within its components. This process increases the polarity of the molecules, prompting aggregation among asphaltenes. Thus, a thorough examination of asphaltene molecule aggregation and disaggregation patterns holds vital implications for the performance restoration of aged asphalt. According to the density functional theory (DFT), the interaction form between oxidized asphaltene dimers was inferred by electrostatic potential (ESP) and confirmed through the charge density difference. This study identified asphaltene dimers optimal configurations via energy minimization principles and determined the factors influencing aggregation based on interaction energy. On the basis of the molecular structure design theory, the basic structures of three different rejuvenators—chain alkanes, aromatic hydrocarbons, and cycloalkanes—were constructed. Functional groups such as hydroxyl, carboxyl, ether, ester, and amide were incorporated to explore the disaggregation patterns of oxidized asphaltene dimers induced by varying rejuvenator structures. Our results revealed that asphaltene molecules form dimers through the π-π stacking interaction of aromatic rings and the electrostatic interaction between positive-negative ESP regions. Dimer disaggregation predominantly follows two rejuvenation mechanisms: T-shaped and parallel. Parallel rejuvenation is the primary mechanism for chain alkanes, aromatic hydrocarbons, cycloalkanes ether, and ester groups. Here, methyl decyl ether exhibited the most potent disaggregation effect, reducing interaction energy between asphaltene dimers by 61.7%. The conclusions could offer a theoretical foundation for understanding asphaltene molecule aggregation and disaggregation and suggest strategies for high-performance rejuvenator design. [ABSTRACT FROM AUTHOR]

Carbon capture, utilization, and storage (CCUS) technology has emerged as a pivotal measure in mitigating global climate change. Notably, CO2-EOR is esteemed for its dual function of sequestering CO2 and enhancing oil recovery. However, this process presents challenges related to asphaltene deposition during CO2 flooding, leading to reservoir damage, such as pore plugging. This study systematically manipulated the factors inducing CO2-induced asphaltene deposition, elucidating the mechanisms and magnitudes of asphaltene precipitation. Additionally, the study investigated the efficacy of carbon quantum dots (CQDs) in mitigating asphaltene deposition. Experimental findings indicated a positive correlation between asphaltene deposition and level of asphaltene content, CO2 injection ratio, and temperature. Moreover, with an increase in experimental pressure, the asphaltene deposition rate demonstrated an initial increase followed by a subsequent decline. Leveraging their favorable compatibility with asphaltene, CQDs effectively suppressed the aggregation behavior of asphaltene. In the presence of CQDs, the onset of asphaltene precipitation was delayed from 45 V% to 55 V%, with the highest inhibition rate reaching approximately 36% at an optimal CQD concentration of 20 mg/L. This study proposes a novel approach to address asphaltene deposition issues in CO2-EOR processes, contributing to the enhancement of recovery rates in low-permeability reservoirs. [ABSTRACT FROM AUTHOR]

Asphaltene, the heaviest and most polar non-hydrocarbon component in crude oil, may interact with waxes and affect the flow and gelation behavior of waxy oils. To further study the effect of asphaltene on the flow and gelation behavior of waxy oils, five wax-containing simulated oils with small dosage asphaltene content were prepared. Through pour point and rheometer test, it is found that asphaltenes can improve the low-temperature rheology of waxy oil. There is no critical turning point above which the low-temperature flowability improved. With an increase in asphaltene content from 0 wt% to 0.1 wt%, notable changes were observed in the properties of the waxy oil. The pour point, which measures the temperature at which the oil becomes too viscous to flow freely, exhibited a decrease from 25 °C to 13 °C. Similarly, the gelation temperature, indicating the temperature at which the oil starts forming a gel-like consistency, also decreased from 29.0 °C to 27.1 °C. These modifications can be attributed to the presence of asphaltene in the oil sample. This outcome can be attributed to the interference caused by the presence of asphaltenes, which disrupts the gel network structure of the waxy oil and consequently hinders its gelation process. Simultaneously, within the low asphaltene content range, an increase in asphaltene content resulted in a considerable decrease in the viscosity of the waxy oil at 10 °C, reducing it from 531.5 mPa s to 14 mPa s. [ABSTRACT FROM AUTHOR]

Asphaltene precipitation can result in several production, operational, and transportation problems during oil recovery. If asphaltene precipitates and deposits, it can reduce reservoir permeability, damage wellbore equipment, and plug the pipelines. It is therefore extremely important to evaluate the conditions at which asphaltene precipitation occurs; this is referred to as the asphaltene onset pressure. Asphaltene onset pressure has been measured using many different experimental techniques. There have also been many attempts along the years to predict asphaltene onset pressure using mathematical correlations and models. This research provides an up-to-date comprehensive review of the methods by which asphaltene onset pressure can be measured using laboratory experiments and mathematical models. The research explains the main mechanisms of all the laboratory experiments to measure asphaltene onset pressure under static conditions and how to conduct them and highlights the advantages and limitations of each method. The research also provides a summary of the commonly used mathematical models to quantify asphaltene onset pressure directly and indirectly. [ABSTRACT FROM AUTHOR]

A detailed understanding of the interactions between wax and asphaltenes with other components of crude oils and the effect of treatments with paraffin inhibitors (PIs) and asphaltene dispersants (ADs), with a focus on identifying specific structure-activity relationships, is necessary to develop effective flow assurance strategies. The morphological and rheological consequences of treating wax and asphaltenes in oils of differing composition with a series of ADs having structural features in common with an alpha olefin-maleic anhydride (AO-MA) comb-like copolymer PI were assessed alone and in combination with said PI. Of the four ADs studied, two were identified as being effective dispersants of asphaltenes in heptane-induced instability tests and in a West Texas (WT) crude. The degree to which a low concentration of asphaltenes stabilizes wax in the absence of treatment additives is lessened in oils having greater aromatic fractions. This is because these stabilizing interactions are replaced by more energetically favorable aromatic–asphaltene interactions, increasing oil viscosity. Treatment with AD alone also reduces the extent of wax–asphaltene interactions, increasing oil viscosity. In concert with the PI, treatment with the AD having greater structural similarity with the PI appears to improve wax solubility in both the presence and absence of asphaltenes. However, the viscosity of the treated oils is greater than that of the oil treated with PI alone, while treatment with AD having lesser structural similarity with the PI does not adversely affect oil viscosity. These data suggest that rather than treating both wax and asphaltenes, AD may poison the function of the PI. These data illuminate the pitfalls of designing flow assurance additives to interact with both wax and asphaltenes and developing treatment plans. [ABSTRACT FROM AUTHOR]

A better understanding of the changes in binder chemistry and microstructure triggered by aging is fundamental as it increases the cracking susceptibility of asphalt materials and reduces pavement durability. In this context, this paper presents the findings of a collaborative study that delves further into the alterations in binder chemistry, microstructure, and rheology of laboratory – and field-aged binders using innovative experimental and fundamental theory techniques. An increase in polarity leading to a shift in the apparent molecular weight distribution (AMWD) towards higher molecular weights, which implies molecular agglomerations, could be observed as a result of aging via Saturates, Aromatics, Resins, and Asphaltene Determinator (SAR-AD) and Size Exclusion Chromatography (SEC), respectively. As for the theoretical methods, the δ-method and Molecular Agglomeration Index (MAI) that estimate the AMWD and incidence of molecular agglomeration, respectively, show satisfactory relationship with the SAR-AD and SEC results. This reinforces the soundness of the δ-method and MAI. [ABSTRACT FROM AUTHOR]

In the enhanced oil recovery (EOR) process, interfacial tension (IFT) has become a crucial factor because of its impact on the recovery of residual oil. The use of surfactants and biosurfactants can reduce IFT and enhance oil recovery by decreasing it. Asphaltene in crude oil has the structural ability to act as a surface-active material. In microbial-enhanced oil recovery (MEOR), biosurfactant production, even in small amounts, is a significant mechanism that reduces IFT. This study aimed to investigate fluid/fluid interaction by combining low biosurfactant values and low-salinity water using NaCl, MgCl2, and CaCl2 salts at concentrations of 0, 1000, and 5000 ppm, along with Geobacillus stearothermophilus. By evaluating the IFT, this study investigated different percentages of 0, 1, and 5 wt.% of varying asphaltene with aqueous bulk containing low-salinity water and its combination with bacteria. The results indicated G. Stearothermophilus led to the formation of biosurfactants, resulting in a reduction in IFT for both acidic and basic asphaltene. Moreover, the interaction between asphaltene and G. Stearothermophilus with higher asphaltene percentages showed a decrease in IFT under both acidic and basic conditions. Additionally, the study found that the interaction between acidic asphaltene and G. stearothermophilus, in the presence of CaCl2, NaCl, and MgCl2 salts, resulted in a higher formation of biosurfactants and intrinsic surfactants at the interface of the two phases, in contrast to the interaction involving basic asphaltene. These findings emphasize the dependence of the interactions between asphaltene and G. Stearothermophilus, salt, and bacteria on the specific type and concentration of asphaltene. [ABSTRACT FROM AUTHOR]

The precipitation and deposition of asphaltenes are significant challenges in the petroleum industry resulting in substantial costs. A practical approach to addressing this issue is to use chemicals as inhabiting and dispersing agents. Zwitterionic surfactants are interesting materials in this field. In this study, three zwitterionic compounds including 2-(1-methyl-1H-imidazol-3-ium-3-yl)butane-1-sulfonate (MIBS), 4-(pyridin-1-ium-1-yl) butane-1-sulfonate (PBS), and 4-(tributylammonio)butane-1-sulfonate (TBBS) were synthesized and characterized by FT-IR, NMR spectroscopy, thermogravimetric, and differential thermal analysis. The ability of these zwitterions to prevent asphaltenes precipitation was investigated using interfacial measurements, ultraviolet spectroscopy, quartz microbalance analysis, particle size analysis, and optical microscopy. The results showed that the MIBS zwitterion, which contains an imidazole cation, was the most effective in dispersing asphaltene aggregates compared to the other two zwitterions. For instance, the UV spectroscopy results showed that the dispersion indexes for MIBS, PBS, and TBBS were 52.8%, 29.9%, and 16.3%, respectively. In addition, the size of asphaltene particles reached from 2179 nm to 622, 1489, and 2038 nm for MIBS, PBS, and TBBS, respectively. Finally, a comparison between the performance of these zwitterions with sodium dodecyl sulfonate (SDS) and tetrabutylammonium hydrogen sulfate (TBAHS) showed the following trend: MIBS (90.5%)> PBS (79.4%) > TBAHS (75%)> SDS (73.9%) >TBBS (46%). [ABSTRACT FROM AUTHOR]

Context: A complex supramolecular process involving electrostatic and dispersion interactions and asphaltene aggregation is associated with detrimental petroleum deposition and scaling that pose challenges to petroleum recovery, transportation, and upgrading. The homodimers of seven heterocyclic model compounds, representative of moieties commonly found in asphaltene structures, were studied: pyridine, thiophene, furan, isoquinoline, pyrazine, thiazole, and 1,3-oxazole. The contributions of hydrogen bonding involving water bridges spanning between dimers and π-π stacking to the total interaction energy were calculated and analyzed. The distance between the planes of the aromatic rings is correlated with the π-π stacking interaction strength. All the dimerization reactions were exothermic, although not spontaneous. This was mostly modulated by the strength of the hydrogen bond of the water bridge and the π-π stacking interaction. Dimers bridged by two water molecules were more stable than those with additional water molecules or without any water molecule in the bridge. Energy decomposition analysis showed that the electrostatic and polarization components were the main stabilizing terms for the hydrogen bond interaction in the bridge, contributing at least 80% of the interaction energy in all dimers. The non-covalent interaction analysis confirmed the molecular sites that had the strongest (hydrogen bond) and weak (π-π stacking) attractive interactions. They were concentrated in the water bridge and in the plane between the aromatic rings, respectively. Methods: The density functional ωB97X-D with a dispersion correction and the Def2-SVP basis set were employed to investigate supramolecular aggregates incorporating heterocycles dimers with 0, 1, 2, and 3 water molecules forming a stabilizing bridge connecting the monomers. The non-covalent interactions were analyzed using the NCIplot software and plotted as isosurface maps using Visual Molecular Dynamics. [ABSTRACT FROM AUTHOR]

Studying the hydro-liquefaction kinetics of lignite contributes to optimizing the mild liquefaction process for lignite. In this paper, the direct liquefaction performance of Shengli lignite (SL) was investigated using a H2/THN system with 4 MPa of initial pressure, and reaction kinetic models were established for the heating-up stage and the isothermal stage. The result showed that the liquefaction performance of the SL was excellent, with a conversion of 62.18% and an oil and gas (O + G) yield of 29.88% at 698.15 K. After one hour of reaction, the conversion and O + G yield were 94.61% and 76.78%, respectively. During the heating-up stage, the easily reactive part of the SL was 50.07%, and it was converted directly into oil, gas, asphaltene (AS), and preasphaltene (PA) simultaneously. There was no significant secondary hydrogenation conversion of the AS and PA products. During the isothermal stage, the hard-to-react part was predominantly converted into AS and PA, while the remaining easily reactive part continue to react completely. The conversion of AS and PA into oil and gas was a rate-controlling step during this stage. The amount of unreacted coal estimated using the model calculated in the isothermal stage was 2.98%, which was significantly consistent with the experimental value of 2.81%. [ABSTRACT FROM AUTHOR]

Asphaltenes are heavy hydrocarbon molecules that exist naturally in petroleum reservoir fluids. Asphaltene precipitation may occur during pressure depletion or during gas injection processes to improve oil recovery. Inside the reservoir, the precipitated asphaltene can deposit onto the rock surface or remain as a suspended solid in the oil phase. Precipitated asphaltenes are one of the main causes of decreased permeability. A new approach to modeling asphaltene deposition during oil production has been developed. In the model, oil is represented by two hydrocarbon components ("oil" and "asphaltene") that do not dissolve in water and the theory of an ideal solution of a binary mixture is used. Closing relations for the mass and momentum conservation equations describing porosity, permeability and mass transfer are constructed using the pore size distribution function and a model of an ideal porous medium consisting of a bundle of capillaries. [ABSTRACT FROM AUTHOR]

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The effects of sulfate salts under low and high salinity conditions and pH of 3.5–11 on interfacial tension (IFT) reduction and IL adsorption using resinous (RSO) and asphaltenic (8 wt/wt%) synthetic oils are investigated. The measurements showed the increasing effect of pH on the IFT of RSO/DW from 23.5 to 27.3 mN/m (pH = 3.5 → 7) in the first place and a reducing effect (0.4 mN/m) if pH = 7 → 11. Using a high concentration of 50,000 ppm for MgSO4, and Na2SO4 revealed an extensive IFT reduction for a pH value of 11 with the value of 0.20 mN/m for Na2SO4. The measured IFT values showed the significant impact of IL (500 ppm) on the IFT (minimum value of 0.01 mN/m for RSO/50,000 Na2SO4 + 500 ppm 1-decyl-3-methyl imidazolium triflate ([C10mim][TfO])) for pH = 11. The IL adsorption measurements showed the role of in-situ surfactant production (saponification process) on the 1-decyl-3-methyl imidazolium chloride ([C10mim][Cl]) and [C10mim][TfO] adsorption reduction from 3.67 to 2.33 and 4.21 to 3.34 mg IL/g rock, respectively. The performed core flooding experiments using the optimum chemical formulation showed the possibility of tertiary oil recovery with maximum oil recovery of 28.8% based on original oil in place in the presence of 500 ppm. [ABSTRACT FROM AUTHOR]

Asphaltene removal in the crude oil industry is a significant issue. It is essential to develop cost-effective adsorbents to alleviate the problems associated with the presence of asphaltene in oil transportation. Performing continuous adsorption experiments assists in getting an insight into the practical application of novel adsorbents. For the first time, N-doped graphene (N-G) was synthesized for asphaltene removal form model oil solution in a continuous adsorption process. X-ray diffraction patterns, transmission electron microscopy, field emission scanning electron, and Brunauer–Emmett–Teller isotherms were used to characterize the prepared sorbents. The synthesized N-G was mesoporous with high porosity and specific surface area of 134 m2/g. The effects of three parameters were investigated: initial asphaltene concentration from 50 to 200 ppm, flowrate at 1–10 mL/min, and bed depth of 5–20 cm. The synthesized N-G was well suited in the asphaltene removal process due to the strong interactions between asphaltene and adsorbent surface arising from the π–π interaction between nitrogen on the N-G surface and the aromatic rings in asphaltene. The highest amount of asphaltene removal occurred at low flowrates and high bed depth while the effect of concentration was less than others. The highest removal amount in the breakthrough curve was achieved at 1 mL/min flow rate. The good removal efficiency even after several cycles of regenerations indicates a considerable potential of reusability. In sum, N-G could be a highly efficient adsorbent for dynamic asphaltene removal on a large scale. [ABSTRACT FROM AUTHOR]

Asphaltenes and waxes are the primary factors affecting the cold flow properties of crude oil. In this paper, based on the binary polymer of acrylate‐maleic anhydride (PM22‐MA), different third polar groups of acrylamide, N‐(hydroxymethyl) acrylamide, N‐phenylacrylamide (NPA), and styrene (SM) were introduced to synthesize a series of ternary pour point depressants (PPDs) to explore the effect of asphaltene on the cold flow properties of Xijiang (XJ) crude oil. Thereinto, PM22‐MA‐NPA containing amide group and benzene ring exhibited the best depressive effect, which decreased pour point by 14°C at 1500 ppm. The mechanism of interaction of the polar groups in PPDs with asphaltene was studied. The polar groups could form stronger hydrogen bonds with asphaltene, delaying the asphaltene macromolecule bonding, allowing the synergistic effect of PPDs and asphaltene to be better utilized to improve the cold flow properties of crude oil. Furthermore, the dipole moment magnitude and electron cloud density were calculated with Gaussian. It was found that the polar group with a dipole moment magnitude of 3.2244 debye and an electron cloud density ranging from −1.6364 to 1.9944 eV was the most suitable third polar monomer for the PPDs of XJ crude oil. [ABSTRACT FROM AUTHOR]

The physicochemical behavior of polymer‐modified binders suggests suitability for rejuvenating aged pavements and meets base bitumen parameters. The strengthening effect is mainly due to their electronic structures, which interact with asphaltene via CH‐π interactions and crosslinkage reaction with S–H and O–H bonds of base bitumen, along with the virgin and waste polymers used. The functional groups in bitumen play a vital role in enhanced paving resistance after modification. This review aims to provide an overview of the current knowledge on the role of polymers in bitumen modification and to identify research gaps. It also discusses underutilized technologies, methods, and future research perspectives to implement more effective road networks for an environmentally sustainable development. [ABSTRACT FROM AUTHOR]

This study investigates the synthesis of mesophase pitch using low-cost fluid catalytic cracking (FCC) slurry and waste fluid asphaltene (WFA) as raw materials through the co-carbonization method. The resulting mesophase pitch product and its formation mechanism were thoroughly analyzed. Various characterization techniques, including polarizing microscopy, softening point measurement, Fourier-transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA), were employed to characterize and analyze the properties and structure of the mesophase pitch. The experimental results demonstrate that the optimal optical texture of the mesophase product is achieved under specific reaction conditions, including a temperature of 420 °C, pressure of 1 MPa, reaction time of 6 h, and the addition of 2% asphaltene. It was observed that a small amount of asphaltene contributes to the formation of mesophase pitch spheres, facilitating the development of the mesophase. However, excessive content of asphaltene may cover the surface of the mesophase spheres, impeding the contact between them and consequently compromising the optical texture of the mesophase pitch product. Furthermore, the inclusion of asphaltene promotes polymerization reactions in the system, leading to an increase in the average molecular weight of the mesophase pitch. Notably, when the amount of asphaltene added is 2%, the mesophase pitch demonstrates the lowest ID/IG value, indicating superior molecular orientation and larger graphite-like microcrystals. Additionally, researchers found that at this asphaltene concentration, the mesophase pitch exhibits the highest degree of order, as evidenced by the maximum diffraction angle (2θ) and stacking height (Lc) values, and the minimum d002 value. Moreover, the addition of asphaltene enhances the yield and aromaticity of the mesophase pitch and significantly improves the thermal stability of the resulting product. [ABSTRACT FROM AUTHOR]

The rheological properties of bitumen largely influence the performance of the pavement. Determination of rheological properties of bitumen depends on thermal equilibrium time. The main objective of this study is to evaluate the effect of Evotherm, a chemical warm mix additive on the thermal equilibrium time of bituminous binders. The bituminous binders used for this study included two unmodified binders, a polymer-modified bitumen (PMB) and a crumb rubber-modified bitumen (CRMB). The thermal equilibrium times for bituminous binders with and without Evotherm were measured using a dynamic shear rheometer. The results indicate that the thermal equilibrium time primarily depends on the type of binder, wherein the asphaltene content, presence of polymer and rubber influence thermal equilibrium time. The higher thermal equilibrium times observed for the Evotherm-modified PMB40 binder and Evotherm-modified CRMB60 binder in unaged condition can be attributed to a change in morphology and chemical interaction respectively upon the addition of Evotherm. Lesser thermal equilibrium time exhibited by short-term aged Evotherm binders can be because of the reduced formation of ageing compounds due to reduced short-term ageing temperature and presence of Evotherm. The linear regression model well predicted the thermal equilibrium time based on test temperature and softening point of binders. [ABSTRACT FROM AUTHOR]

Greenhouse gases are major contributors to global warming, and their concentration is increasing due to the widespread use of fossil fuels. Coal bed methane (CBM) offers a potential solution to this issue. However, the gas adsorption mechanisms of CBM, particularly in the context of coal-derived asphaltenes, are not fully understood. This study provides a comprehensive theoretical investigation of the competitive adsorption of carbon dioxide (CO 2 ), methane (CH 4 ), and nitrogen (N 2 ) in the processes of CO 2 - and N 2 -enhanced coalbed methane recovery, with a focus on coal-derived asphaltenes functionalized with CH 4 , NH, O, and S groups. Using the Grand Canonical Monte Carlo (GCMC) simulation method and performing Molecular Dynamics (MD) simulations, we studied the adsorption process. To investigate the electronic effects and nature of the interactions, we performed density functional theory (DFT) calculations. The adsorption energy values and non-covalent interactions (NCI) for the adsorption of gases signify the physical adsorption (van der Waals interaction), with CO 2 exhibiting the highest (absolute) adsorption energy. The Monte Carlo results indicated that elevated temperatures led to a reduction in adsorption capacity. Coal-derived asphaltenes demonstrated greater selectivity for CO 2 compared to CH 4 and N 2 in competitive adsorption, especially at elevated temperatures. Our findings highlight the significant potential of our asphaltene model, not only in mitigating CO 2 greenhouse gas emissions but also in recovering CH 4 , which is a valuable resource. [ABSTRACT FROM AUTHOR]

With the increasing consumption of oil in the world and increasing production of oil from oil reservoirs, the reservoir pressure starts to decrease. On the other side, the use of oil leads to an increase in carbon dioxide production in the environment and causes global warming. One of the effective methods of reducing the amount of carbon dioxide emitted into the atmosphere and increasing the reservoir's pressure is CO2‐EOR and carbon capturing and storing (CCS) which injects produced carbon dioxide from industrial sources into underground reservoirs. Carbon dioxide reduces oil viscosity and increases oil mobility producing an economical state. Moreover, with CO2‐EOR and CCS carbon dioxide can be stored in a depleted reservoir and helps reduce pollution and global warming. Besides the environmental and economic benefits due to reducing carbon dioxide emissions to the atmosphere and increasing oil production, CO2 injection causes various problems in the formation. Many experiments indicate that asphaltene precipitation and wettability alteration caused by asphaltene, dissolution/precipitation of rock, salt precipitation, and sludge formation are some of the problems that occur during CO2 injection operations in low pressure and temperature. However, few experiments evaluate asphaltene precipitation effective factors, such as pressure, injection rates, temperature, etc., in high temperatures and pressure (HPHT) near reservoir conditions. Therefore, there was a need for a comprehensive investigation of various factors and the impact of each of them on the asphaltene precipitation and formation damage in HPHT conditions, so this research was designed to help future simulation and industrial utilization. A core‐flood setup was prepared to conduct CO2 flooding experiments and formation damage studies in HPHT conditions. The main objective of this study was to evaluate the effect of different parameters including pressure, injection rate, and type of injected gas on asphaltene and its effect on formation damage caused by CO2 injection. The second goal of this study was to investigate the optimum injection in every section. The third goal was to determine the oil recovery during the process of CO2 injection in different conditions. The results showed that an injection rate of 0.1 cc/min and higher injection pressures minimized asphaltene precipitation and maximized oil recovery. Replacing CO2 with natural gas liquids (NGL) gas reduced oil production and asphaltene precipitation. Overall, the experiments demonstrated the importance of optimizing injection parameters to limit formation damage during CO2 flooding. © 2024 The Authors. Greenhouse Gases: Science and Technology published by Society of Chemical Industry and John Wiley & Sons Ltd. [ABSTRACT FROM AUTHOR]