The deposition of asphaltenes in the petroleum industry has been found to be a significant factor affecting the profitability of petroleum production and refining. For this reason, many efforts have been made to clarify the mechanism of deposition formation and to find measures to reduce its harmful impact on the efficiency of oil production and refining. Recent reports on the mechanism of deposit formation by asphaltenes suggest that it is a phase transition phenomenon. Many studies have shown that this process can be slowed by using chemical inhibitors. Different classes of chemical substances (non-polymeric, organic compounds, polymers, ionic liquids and nanomaterials) have been found to be capable of inhibiting asphaltene precipitation. This paper presents a comprehensive review of asphaltene deposition research and makes an attempt to decipher the convoluted asphaltene deposition phenomena and relate the chemistry of asphaltene inhibitors to the nature of treated petroleum oils. The choice of appropriate additives to mitigate asphaltene deposition in commercial oil and gas facilities requires comprehensive knowledge of chemistry of oils, asphaltenes, and the chemical substances, along with the appropriate laboratory techniques that best mimic the commercial operation conditions.

An expected increase in the demand for aviation transport service will result in the deterioration of the environment and human health, respectively, due to extra greenhouse gas (GHG) emissions. Concerns from EU institutions about the issue have led to legislation initiatives and, later, to development of Regulation (EU) 2023/2405 for the reduction of GHG emissions via the substitution of fossil kerosene with an increasing share of sustainable components. Hydroprocessed esters and fatty acids (HEFAs) are the most commercially acceptable sustainable alternative but their influence on aviation fuel properties needs to be further evaluated in terms of all required and extended properties, as per ASTM D1655. The main properties, together with the rarely reported upon existent gum, water separation, corrosion, and the electrical conductivity of HEFAs and their blends with fossil kerosene were quantitatively evaluated in this study. For every increase of 10% (v/v) of HEFAs, the following fuel properties improve: the freezing point decreases by 1.3 °C, the smoke point increases by an average of 3 mm, and the specific net energy increases by 0.08 MJ/kg. The acidity of HEFAs are an order of magnitude higher than that of conventional aviation fuel and, thus, close to the limit. The existent gum of the studied SAF is higher than that of fossil kerosene due to, most probably, the presence of non-evaporated residual material.

A comprehensive investigation of a highly complex petroleum refinery (Nelson complexity index of 10.7) during the processing of 11 crude oils and an imported atmospheric residue replacing the design Urals crude oil was performed. Various laboratory oil tests were carried out to characterize both crude oils, and their fractions. The results of oil laboratory assays along with intercriteria and regression analyses were employed to find quantitative relations between crude oil mixture quality and refining unit performance. It was found that the acidity of petroleum cannot be judged by its total acid number, and acid crudes with lower than 0.5 mg KOH/g and low sulphur content required repeated caustic treatment enhancement and provoked increased corrosion rate and sodium contamination of the hydrocracking catalyst. Increased fouling in the H-Oil hydrocracker was observed during the transfer of design Urals crude oil to other petroleum crudes. The vacuum residues with higher sulphur, lower nitrogen contents, and a lower colloidal instability index provide a higher conversion rate and lower fouling rate in the H-Oil unit. The regression equations developed in this work allow quantitative assessment of the performance of crucial refining units like the H-Oil, fluid catalytic cracker, naphtha reformer, and gas oil hydrotreatment based on laboratory oil test results.

The compatibility of constituents making up a petroleum fluid has been recognized as an important factor for trouble-free operations in the petroleum industry. The fouling of equipment and desalting efficiency deteriorations are the results of dealing with incompatible oils. A great number of studies dedicated to oil compatibility have appeared over the years to address this important issue. The full analysis of examined petroleum fluids has not been juxtaposed yet with the compatibility characteristics in published research that could provide an insight into the reasons for the different values of colloidal stability indices. That was the reason for us investigating 48 crude oil samples pertaining to extra light, light, medium, heavy, and extra heavy petroleum crudes, which were examined for their colloidal stability by measuring solvent power and critical solvent power utilizing the n-heptane dilution test performed by using centrifuge. The solubility power of the investigated crude oils varied between 12.5 and 74.7, while the critical solubility power fluctuated between 3.3 and 37.3. True boiling point (TBP) analysis, high-temperature simulation distillation, SARA analysis, viscosity, density and sulfur distribution of narrow petroleum fractions, and vacuum residue characterization (SARA, density, Conradson carbon, asphaltene density) of the investigated oils were performed. All the experimentally determined data in this research were evaluated by intercriteria and regression analyses. Regression and artificial neural network models were developed predicting the critical solubility power with correlation coefficients R of 0.80 and 0.799, respectively.

Refining light and heavy oils in different proportions seems attractive, especially in cases of geopolitical, economic, environmental, and logistical constraints. The economical attractiveness could be undermined in cases where incompatibility occurs. The current study explores a highly complex refinery performance during processing a blend consisting of 17 crude oils of which one was extra light, five were light, nine were medium, and two were heavy. A n-heptane dilution test, using centrifugation, was employed to assess the colloidal stability of crude oils. In addition, a previously established correlation to relate crude oil vacuum residue fraction Conradson carbon content to asphaltene peptizability Sa according to ASTM D 7157 was also availed for the purpose of evaluating colloidal stability. It was found that the crude desalter amperage increases with the ${\displaystyle \frac{SBN}{IBN}}$ ratio and Sa reduction, reaching its maximum allowable value of 180 A at the ${\displaystyle \frac{SBN}{IBN}}$ ratio of 1.35, and Sa of 0.64. The ${\displaystyle \frac{SBN}{IBN}}$ ratio was found more reliable in predicting oil compatibility than the other ${\displaystyle \frac{SBN}{{IN}_{max}}}$ ratio used to assess colloidal stability in various research. Along with the increase in crude desalter amperage, fouling of the heat exchangers of a crude oil distillation plant was also recorded. An intercriteria analysis of process data together with crude composition data, and compatibility indices revealed that the amperage enhancement is statistically meaningfully related to an increase in the heaviest crude oil content in the process blend and the compatibility indices ${\displaystyle \frac{SBN}{IBN}}$ ratio and Sa, while the fouling was related only to the content of one of the light crude oils in the processed blend.

Various petroleum classifications have been developed over the years using different crude oil characteristics, techniques, and approaches. A review of all these classifications made so far has not been published in recent decades and no relation to the crude oil selection process has been investigated yet. Crude oil selection is a very delicate process, requiring the right balance between crude oil purchase costs, which can account for up to 95% of total refining costs, and minimizing the risk of unplanned shutdowns, which can result from undesirable asphaltene precipitation, equipment fouling, accelerated corrosion, and disruptions in the operation of desalters and other process units. The current research conducts a review of the distinct petroleum classifications published in the literature and discusses their possible link to the expected performance of a modern high complexity petroleum refinery in terms of minimizing the risk of unplanned shutdowns. An intercriteria analysis approach is proposed as a tool to discriminate those crude oils from a database of comprehensive assays of 1390 crude oils, which may invoke a possible unplanned shutdown of the petroleum refinery under study based on a previous experience.