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Based on the analysis of recent projections by the International Energy Agency (IEA), to meet the growing and subsequently declining demands of oil from now to 2040, we need up to around 770 billion barrels of oil. Since the worldwide total proved reserves of easy-and-cheaper-to-produce conventional oils is roughly only 520.2 billion barrels, the remaining 249.8 billion barrels must be obtained from unconventional petroleum resources (i.e. heavy oils and bitumen). These resources are however very difficult and costly to upgrade and produce due to their inherently high asphaltene contents which are reflected in their very high viscosities and large densities. However, still they should prove attractive development prospects if, as much as practicably possible, their upgrading can be performed in conjunction with in situ or downhole catalytic upgrading processes. Such projects will contribute significantly towards smoother and greener transition to full decarbonisation. Advanced technologies, such as the toe-to-heel air injection coupled to its add-on in situ catalytic process (i.e. THAI-CAPRI processes), have the potential to develop these reserves, but require further developmental understanding to realise their full capability. In this work, a new detailed procedure for numerically simulating the THAI-CAPRI processes is presented. The numerical model is made-up of Athabasca-type bitumen and it has a horizontal producer (HP) well that is surrounded by an annular layer of alumina-supported cobalt-oxide-molybdenum-oxide (CoMo/γ-Al2O3) catalyst. The simulation is performed using the computer modelling group (CMG) reservoir simulator, STARS. This new work has shown that the choice of the frequency factor of the catalytic reactions allowed model validation based on the degree of catalytic upgrading in form of API gravity. Overall, the work herein identifies the important parameters, such as API gravity, peak temperature, oil production rate, cumulative oil production, produced oxygen concentration, temperature distribution profile, extent of coke deposition on the catalyst surface, etc., governing the successful operation of the THAI-CAPRI processes. In particular, this study has shown that even in the vicinities of the mobile oil zone (MOZ) where the catalytic upgrading is expected to be taking place, the catalyst surfaces are covered with high concentration of coke. This finding is in parallel to the observations reported from experiment of CAPRI process alone. Therefore, it is concluded that when experimental studies of the THAI-CAPRI processes are to be conducted, a catalyst regeneration mechanism must be put in place in order to prolong the effectiveness and thus the life of the catalyst so that proper field operation design can be made. Additionally, the study has also shown that the temperature of the MOZ is less than 306 °C and that implies that an external source of heating the annular catalyst layer must be provided in order to effect the catalytic upgrading in the THAI-CAPRI processes. Thus, a new study should look at the feasibility of targeted heating (in the case of microwave) or conductive or resistive heating (in the case of electrical heating) to raise the temperature of the annular catalyst layer to that required to achieve the catalytic upgrading.

SummaryFor many years, miscible gas injection has been the most beneficial enhanced oil recovery method in the oil and gas industry. However, injecting a miscible gas to displace oil often causes the flocculation and deposition of asphaltenes, which subsequently leads to a number of production problems. Nitrogen gas (N2) injection has been used to enhance oil recovery in some oil fields, seeking to improve oil recovery. However, few works have implemented N2 injection and investigated its effect on asphaltene precipitation and deposition. This research investigated the N2 miscible flow mechanism in nanopores and its impact on asphaltene precipitations, which can plug pores and reduce oil recovery. First, a slimtube was used to determine the minimum miscibility pressure (MMP) of N2 to ensure that all of the experiments would be conducted at levels above the MMP. Second, filtration experiments were conducted using nanocomposite filter membranes to study asphaltene deposition on the membranes. A filtration apparatus was designed specifically and built to accommodate the filter membranes. The factors studied include N2 injection pressure, temperature, N2 mixing time, and pore size heterogeneity. Visualization tests were conducted to highlight the asphaltene precipitation process over time. Increasing the N2 injection pressure resulted in an increase in the asphaltene weight percent in all experiments. Decreasing the pore size of the filter membranes increased the asphaltene weight percent. More N2 mixing time also resulted in an increase in asphaltene weight percent, especially early in the process. Visualization tests revealed that after 1 hour, the asphaltene particles were conspicuous, and more asphaltene clusters were found in the test tubes of the oil samples from the filter with the smallest pore size. Chromatography analysis of the produced oil confirmed the reduction in the asphaltene weight percent. Microscopy and scanning electron microscopy (SEM) imaging of the filter membranes indicated significant pore plugging from the asphaltenes, especially for the smaller pore sizes. This research highlights the severity of asphaltene deposition during miscible N2 injection in nanopore structures so as to understand the main factors that may affect the success of miscible N2 injection in unconventional reservoirs.

The deposition of paraffin on the pipeline surface during crude oil transportation is a significant issue for oil industries. In this regard, the demand for adequate methods of wax deposition has gained considerable attention. In the current work, five cellulose esters were synthesized with varied chain short/long and linear/branched in a homogeneous medium and characterized by various analytical techniques. The ability of all cellulose esters to change wax crystal's structure and pour-point and yield stress reduction was observed by cross-polarized microscope, pour-point measurement, differential scanning calorimetry, and rheology. It was noticed that the paraffin crystallization temperature and pour-point had decreased significantly with long/linear side chain esters. The efficiency to reduce yield stress was found to correlate with the nature of the side chain. Long/linear side chain esters with 0.3 wt% are more effective in stabilizing the paraffin/asphaltene gel formation, thereby improving the flowability of waxy oil. The computational calculations also support all the findings at a molecular level.

High-quality source rocks in saline lacustrine or marine sedimentary environments often show early peak petroleum generation and enhanced hydrocarbon yields, which have conventionally been attributed to organosulfur-enhanced thermal decomposition of kerogen. However, there is increasing awareness that the coexisting inorganic salts, particularly sulfates, might also contribute to the acceleration of petroleum generation. In this study, we investigated the influence of sulfates on the thermal decomposition of kerogen sampled from the Pingliang Formation in the Ordos Basin. Our results demonstrate that the kerogen samples mixed with sulfate generate more hydrocarbons with a lower peak production temperature than their sulfate-free counterparts. Detailed chemical analysis revealed that the presence of sulfates significantly facilitated the generation of resins and asphaltenes at temperatures below 350 °C, corresponding in our simulations to the early stage of petroleum generation (Easy%Ro

Petroleum industry is the mainstay of the economical enlargement of many nations. Most of the market prices of all commodities are built on the cost of wide-range of petroleum products. Prompt identifying and alleviating challenges facing this sector can reduce costs and enhance productivity and economic growths. Asphaltene deposition, a crucial operational challenge in some petroleum production facilities is one of the key challenges facing petroleum sector universally. Asphaltene clogs pipelines as cholesterols block blood vessels; this has made asphaltene deposition management a principal factor to consider before establishing any petroleum producing company. Therefore, in order to guarantee urbane and uninterrupted movement of petroleum to the consumers, it is vital for the field Operators, Engineers and Chemist to be pipeline deposition conscious as lines would suffer degradation owing to asphaltene precipitation, aggregation and eventual deposition. There are documented literatures on asphaltene, but almost new information is disseminated in literature or occurs in the brains of experts comparable to silent knowledge. The mission of this review paper is to publicize the information and close some knowledge-breaks. This particular article provides an inclusive appraisal of asphaltene interaction, precipitation, deposition, challenges and management stratagems. Besides, it provides a conclusion and prised recommendations.

This study aims to theoretically investigate the performance of an ionic liquid-based hydrophobic deep eutectic solvent (HDES), methyltrioctylammonium chloride:glycerol (1:2), as an asphaltene depo...

Asphaltene studies have been a prime focus topic for many decades. However, the underlying interaction mechanisms between water, oil, and asphaltenes requires more attention. Water is involved in a...

Nanotechnology is widely recognized for having important applications in many industries, one of which is oil and gas. Both environmental and cost benefits can be achieved when using nanoparticles for the separation of water and oil or further purification of produced water. More efficient emulsion separation can be achieved by selective adsorption of naturally present stabilizing components or magnetic action applied to nanoparticle-tagged droplets. The focus of this review is given to both nanoparticles and nanocomposites that have been studied with respect to asphaltene adsorption, crude oil demulsification, and produced water treatment, as well as oil spill cleanup and improvement of antifouling resistance of filtration membranes. Asphaltene chemistry and its role in emulsion stabilization are discussed in detail.

The purpose of this work was to investigate the effects of polystyrene-based acidic copolymers and ionomers on the dispersion of asphaltenes in heavy oil. In the first part of the work, we studied ...

The aim of this study is to achieve the hydro-liquefaction of asphaltene for the production of liquid fuel. The oil soluble molybdenum catalysts, molybdenum dialkyl dithiophosphate, and nickel carboxylate precursor with different carbon chains, were synthesized. The catalysts were characterized by ICP-OES, TEM and XPS. Their catalytic performance for the hydro-liquefaction of asphaltene to liquid fuels was investigated in a slurry bed reactor by using decalin as hydrogen donor and dispersant. The results show that the bimetal catalytic system composed of molybdenum dialkyl dithiophosphate and caproic acid nickel produces more MoS2 and NiS x active species. The metal contents of which accounts for 81.8 and 81.0 wt% of the total amount of Mo and Ni, respectively, and thus exhibits the best catalytic performance among the catalysts studied. The liquid yield of the asphaltene hydrogenation over the bimetal catalyst is 84.6 wt%, which is much higher than that over other catalysts, and the coke content is only 8.6 wt% under the conditions of 1000 μg/g of total metal addition, 1:1 Mo/Ni metal mass ratio and 1:1 asphaltene/naphthalene mass ratio. The content of saturated and aromatic components in the liquid products of asphaltene hydrogenation of the bimetal catalyst system is 78.9 wt%, which is a high-quality liquid fuel component.

There is a limited understanding of the microscale interactions between fluid–oil–solid interfaces, which could be a stumbling block to the development of relevant technologies and industries. With...

The presence of asphaltenes and polar compounds in a crude oil plays a major role in dictating the type of wettability it displays with oil reservoir rocks. The main objective of this study was to investigate the effect of the asphaltenes structure and other polar compounds in altering rock wettability. Five, natural crude oil samples were used with varying asphaltene (6.4 to 11.6), total nitrogen (0.029 to 0.097) and sulfur (2.259 to 4.234) contents, all in mass%. Crude oil characterization showed the asphaltene samples to consist of condensed hydrocarbon and sulfur aromatic molecules with one or two sulfur atoms per molecule. The weight-average numbers of fused aromatic rings for hydrocarbon molecules were 6 to 7 and for sulfur-containing molecules was an average of 8 aromatic rings, where the aromatic systems were substituted with short alkyl chains of less than 20 carbon atoms. Based on mass spectral evidence, the average empirical molecular structures of the asphaltenes were constructed and they were all found to be relatively similar. Entrained maltene species with 2 to 5 aromatic rings with longer alkyl chains were also found. Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS) was used to characterize each crudes’ asphaltenes fractions. Three rock samples with mineral compositions of 100% dolomite (D100), 100% calcite (C100), and 63% calcite + 37% dolomite (C63D37) were used. Variation of the contact angle with time was measured using brine, as the external phase, and the five crudes on the rock samples. The interfacial tension (IFT) between brine and the five crudes were also measured. Among the five crude types, the three rocks show the strongest wetting tendency when contacted by type V oil. These were 129.2°, 109.2°, and 135.1° for D100, C100 and C63D37, respectively. Interestingly, wettability was not linearly correlated with asphaltene contents for all crude types. Wettability varied with the rock sample, nitrogen and sulfur contents, and crude’s non-asphaltenic composition. As a result, there is no strong evidence suggesting that the content nor the structure of the asphaltenes alone has a large effect on altering rock wettability.

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Cracking of high-sulfur natural bitumen of the Mordovo-Karmal and Ashalchi fields (Russia, Republic of Tatarstan) at a temperature of 450°C and different process times was studied. The characteristic features of the changes in the material and group compositions of the cracking products and the nature of the transformation of the group composition of the sulfur-containing compounds of oils as dependent on the cracking conditions were demonstrated. The kinetic regularities of the formation and decomposition of benzo- and dibenzothiophene derivatives in the cracking products of the natural bitumens were elucidated. Cracking was shown to involve breakdown of large molecules (resins and asphaltenes) with formation of a broad range of low-molecular-weight sulfur-containing compounds falling into oils. The sets of benzo- and dibenzothiophene homologs thereby formed were identical, but the rates of formation and decomposition of the sulfur-containing compounds were dependent on the thermal stability of the components of the initial bitumens. The data obtained provide a substantially better understanding of the laws governing the transformation of the sulfur-containing compounds of heavy hydrocarbon feedstock in thermal processes.

International audience; Recent advances in instrumentation for high-field Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) have enabled access to ∼70 »000 unique molecular formulas in broadband mass spectral characterization of unfractionated/whole asphaltenes. The results accumulated over a decade highlight the need for an asphaltene molecular model that acknowledges the coexistence of (1) monofunctional and polyfunctional species; (2) island and archipelago structural motifs; and (3) heteroatom-depleted/highly aromatic compounds, as well as atypical species with low aromaticity but increased heteroatom content. Collectively, results from FT-ICR MS, preparatory-scale separations (extrography/interfacial material), gel permeation chromatography, precipitation behavior in heptane:toluene, thermal decomposition, and aggregate microstructure by atomic force microscopy (among other techniques), suggest that the strong aggregation of asphaltenes results from the synergy between several intermolecular forces: π-stacking, hydrogen bonding, London forces, and acid/base interactions. This review presents general features of asphaltene molecular composition reported over the past five decades. We focus on mass spectrometry characterization and expose the reasons why early results supported the dominance of single-core motifs. Then, the discussion shifts to recent advances in instrumentation for high-field FT-ICR MS, which have enabled the detection of thousands of species in asphaltene samples, whose molecular composition and fragmentation behavior in ultrahigh vacuum agree with the coexistence of single-core and multicore structural motifs. Furthermore, evidence that highlights the limitations of commercially available/custom-built ion sources and selective ionization effects is presented. Consequently, the limitations require separations (e.g., chromatography, extrography) to gain more-comprehensive molecular-level insights into the composition of these complex organic mixtures. The final sections present evidence for the role of aggregation in selective ionization and suggest that advanced characterization by both thermal desorption/decomposition and liquid chromatography with online FT-ICR MS detection can be employed to mitigate the effects of aggregation and provide unique insights in molecular composition/structure.

The changes in the stability of asphaltene in crude oil will give rise to its aggregation, coalescence and deposition from crude oil. The preferred method for improving asphaltene stability is the ...

Background Heavy and super-heavy oils are characterized by a high content of resins and asphaltenes, which complicate the transportation and refining of oil and lead to an increase in the cost of refinery products. Currently, of particular interest are catalysts that are formed directly under the conditions of the process from precursors, which are various salts. Methods In this work influence of NiO precursor on the heavy oil catalytic cracking products composition. The upgrading in all experiments was carried out at a temperature 450 °C for 80 min. The optimal catalyst content calculated to the NiO in experiments 2 and 3 was 0.5 wt. % of the feedstock weight. The ratio salt:ethanol in experiment 3 was 1:1 wt. The products of catalytic cracking were analyzed by SARA, GC, XRD and FT-IR spectrometry. Findings The dissolution of Ni(NO3)2•6H2O in ethanol results in a decrease in the content of high molecular weight components and an increase in the yield of the fraction boiling up to 360 °C. A decrease of sulfur content in the course of heavy oil cracking is caused by both interactions of NiO formed over cracking with S-containing compounds of feedstock leading to formation of Ni9S8 and Ni0.96S and sulfur removal in form of gas.

International audience; Oxidative desulfurization (ODS) was applied to three marine fuels with viscosities between 380 and 700 cSt (centistokes) and sulfur contents between 0.79 and 3.27 wt.%, using a MoO3/Al2O3 catalyst. H2O2 was chosen as oxidizing agent with a low oxidant to sulfur ratio of 3, for economic and environmental reasons. Global sulfur removal was obtained after extraction of sulfones by dimethylformamide. Oxidation efficiency was evaluated by monitoring the conversion of alkyl-benzothiophenes and dibenzothiophene molecule by gas chromatography (GC) with a sulfur specific detector. Applying ultrasounds prior to oxidation was found to significantly enhance conversions and sulfur removal, the effect being more pronounced when initial efficiency was low, that is for more refractory molecules and heavier fuels. Ultrasound assisted ODS (UAOD) was effective on raw fuels with initial viscosity below 700 cSt. Indeed, dilution decreased the viscosity of the fuels, allowing reaction to be effective even on initially very heavy fuels. The presence of asphaltenes dissolved or precipitated in the feed did not affect the conversion of Cx-BTs and DBT significantly, with only slight variations of global sulfur removal rates. Global desulfurization rates between 60 and 80 % were obtained, clearly showing the efficiency of UAOD applied to complex matrices such as marine fuels.

Slurry phase hydrocracking of vacuum residue at various catalyst concentrations was performed in a semi-batch reactor to investigate the effect of catalyst concentration on the reaction performance. The secondary cracking reaction was dominant at high-residue conversion (>60 wt%) without the catalyst but it was suppressed by the catalyst. Moreover, the conversion of asphaltenes at high-residue conversions was found to be dependent on the catalyst concentration. At low catalyst concentrations (0–100 ppm), asphaltenes were converted to light products at low-residue conversions and to coke at high-residue conversions. At high catalyst concentrations (100–500 ppm), asphaltenes were mainly converted to light products even at high conversions. Based on the experimental results, equations for the onset of coke formation with respect to the catalyst concentration were proposed. The higher the catalyst concentration, the longer was the coke induction period. A kinetic model was also proposed, and the experimental data could be predicted well using the same. The transformation of residue to coke was dominant in the non-catalytic hydrocracking and the coke formation rate significantly decreased as the catalyst concentration increased.

Slurry-phase hydrocracking for heavy oil upgrading is a challenging technology in the petroleum refining industry. We prepared various P-containing Mo precursors to elucidate the effect of their ligand structures on the slurry-phase hydrocracking of vacuum residue. Characteristic analyses of the Mo precursors were performed by first determining their dispersibility and decomposition patterns, followed by evaluating the sulfidation degree and morphology of the resulting MoS2 catalyst. The dispersibility of the Mo precursors was evaluated by a method of measuring the solubility parameter based on the oil compatibility model. The slurry-phase hydrocracking results revealed that the H2 consumption rate, residue conversion, hydrodesulfurization , and asphaltene conversion were dependent on the Mo precursor. The Mo triethylphosphite species, which had the largest number of active sites, was found to be the most efficient precursor for improving product distribution and product quality.

In this study, bimetallic catalysts based on transition metals CuFe2O4, CoFe2O4 and NiFe2O4 are proposed for catalyzing aquathermolysis reaction during steam-based EOR method to improve in-situ heavy oil upgrading. All upgrading experiments were carried out under a nitrogen atmosphere for 24 h in a 300-ml batch Parr reactor at 250 and 300 °C under high pressure 35 and 75 bar, respectively. To evaluate the catalytic performance of the bimetallic catalysts used, comprehensive studies of changes in the physical and chemical properties of the improved oils, including the viscosity, elemental composition and SARA fractions of oils before and after upgrading processes were used. Furthermore, individual SARA fractions were characterized in detail by Gas Chromatography (GC), High-Performance Liquid Chromatography (HPLC) and Carbon-13 Nuclear Magnetic Resonance (13C NMR), respectively. The results showed that bimetallic catalysts have high catalytic performance at 300 °C for the upgrading of heavy crude oil in viscosity reduction, increasing the amount of saturates (especially alkanes with low carbon number) as a result of thermal decompositions of high molecular weight compounds like resin and asphaltenes leading to their increasing. Furthermore, the upgrading performance is reflected in the improvement of the H/C ratio, the removal of sulfur and nitrogen through desulfurization and denitrogenation procedures, and the reduction in polyaromatic content, etc. CoFe2O4 gives the best performance. Generally, it can be concluded that, used bimetallic based catalysts can be considered as promising and potential additives improving in-situ upgrading and thermal conversion the heavy oils.

The relevance of the study is related to the prospects for deep processing of solid fuel and the need to obtain more detailed information about the basic laws of thermal transformations of coal during its liquefaction. The development and improvement of direct coal liquefaction technologies in the future can become an important source of additional hydrocarbon resources for the chemical industry and power engineering. The main aim of the research is to study the effects of technological parameters (temperature and pressure) on liquefaction and thermal transformations of Barzas coals in carbon dioxide and hydrogen atmospheres in order to establish the relationships between thermal treatment conditions of coal feedstocks and the compositions and yields of its conversion products. Objects: sapromixites of the Barzas coal deposit (Kemerovo region, Russia) and products of their thermal transformations in carbon dioxide and hydrogen media. Methods: heat treatment of the coals studied in a laboratory microautoclave in various media (CO2, H2) and analysis of the products of their transformations by elemental analysis (CHNOS), FTIR spectroscopy and mass spectrometry. The studies were carried out on calibrated and serviceable equipment. The list of equipment and methods used in the given work are described in detail in the experimental part of this article. Results. Almost similar temperature and pressure dependences (extremal type curves) have been revealed for both the changes in the IR absorption intensities of alkyl groups and the yields of «coal liquids» (total amounts of maltenes and asphaltenes) in the process of Barzas coals transformations in carbon dioxide and hydrogen media. Differences in the transformations of two modifications of Barzas sapromixites were established, and a predominantly paraffin-naphthenic character of the functional composition of the resulting «coal liquids» was revealed. A clear relationship was found between the yields of gaseous products and atomic ratios H/C in the solid products of transformations of the Barzas sapromixites. «Coal liquids» and gaseous compounds obtained as a result of Barzas coals thermal processing can serve as potential raw materials for production of hydrocarbons and other valuable chemical products, as well as used as a fuel in production of heat and electricity.

Clarifying the effect of asphaltene on hydrate formation and growth is of great significance to the operation safety in deepwater petroleum fields. To investigate the influence of low-concentration dissolved asphaltenes on the formation kinetics and growth process of hydrates in water-in-oil emulsions, experiments with asphaltene concentrations ranging from 50 to 1000 ppm were carried out using a high-pressure visual reactor. At a low concentration, the adsorption of asphaltene monomers on the oil-water interface or nanoaggregates in the bulk barely affected the nucleation of hydrate and the induction time of hydrate formation. However, it would hinder the microscopic mass transfer process and heat transfer process between gas molecules and then mitigate the initial rate of hydrate formation. Therefore, the dissolved asphaltenes could not be used as antiagglomerants (AAs) to efficiently inhibit the aggregation of hydrate particles at low concentrations under our experimental conditions, causing extensive hydrate agglomeration and deposition in the reactor.

The asphaltene problem is a two-step process: (1) asphaltene precipitation, as predicted by the thermodynamic model, and (2) asphaltene deposition, the amount of which is estimated by the kinetic model. Asphaltene precipitation is a prerequisite but not a sufficient condition for deposition. Deposition is dependent on other factors such as surface properties, phase behavior, rheology, and flow patterns. As a result, in addition to understanding thermodynamic and kinetic models, it is critical to also understand flow models. In fact, multiphase flow modeling is at the core of simulation, and it must be coupled with thermodynamic and kinetic models. Numerous studies on modeling asphaltene deposition on pipe walls have been performed theoretically and experimentally, but a comprehensive theory to properly understand this phenomenon has not yet been presented. In thermodynamic modeling, the perturbed chain statistical associating fluid theory (PC-SAFT) equation of state is used to predict the asphaltene phase behavior. In this study, we show that the proposed PC-SAFT model is more accurate than the solid model used in commercial software. Unlike prior research that neglected flow patterns or used empirical relations to model multiphase flow, this study simulates multiphase flow using separate momentum equations for each phase. Among the existing kinetic models, the Kurup model has been used to predict the asphaltene deposition profile in the wellbore due to its greater compatibility for computational fluid dynamics application. The results of the proposed model show good agreement with field case data of asphaltene deposition thicknesses along the wellbore tubing.

The relationships of the reaction of the of tar asphaltenes with concentrated nitric acid were studied under various quantitative, temperature, and time conditions. According to IR spectroscopic data, nitration occurs to the highest degree during the action of a 50-fold excess of 64% nitric acid on the asphaltenes at 60°C for 4 hours. Nitration is accompanied by oxidation side reactions leading to the formation of nitrate, phenolic, carbonyl, and sulfoxide groups. It was established by mass spectrometry that there is a tendency for the number-average and weight-average molecular weights of the nitration products to decrease in comparison with the initial asphaltenes. It was found by electron paramagnetic resonance that the content of stable free radicals and vanadyl complexes in the products of the nitration reaction decreases.

Abstract Asphaltene-containing deposits formed on the CaF2 window induced by n-heptane flow in a microfluidic device have been investigated using an IR microscope and an imaging macro chamber (IMAC) with FPA detection. This is the first example of the ex situ infrared imaging of the deposits from crude oil formed under dynamic conditions of flocculant flow. It has been shown that fast aggregation of asphaltenes in n-heptane flow leads to the formation of deposit rich in heteroatom-containing functional groups: (О–Н, N–H, C=O, C–O, and S=O).

NSO compounds mainly exist in geological bodies in the form of nonhydrocarbons and asphaltenes with abundant geological and geochemical information. Combined with the gas chromatography mass spectrometry (GC-MS) technology, positive-ion electrospray ionization Fourier-transform ion cyclotron resonance MS (FT-ICR MS) was used to understand the composition and distribution characteristics of NSO compounds in the oil sands of the Dongpu Depression and to explore their paleoenvironmental significance. The results show that n-alkanes are characterized by an even carbon number and phytane dominance, suggesting a saline lacustrine environment. Certain abundance of nC37 and β-carotane, high gammacerane content, and low diasterane content are detected in the analyzed samples, reflecting the saline-reducing paleoenvironment for the organic matter. Nine types of heteroatom compounds are detected: N1, N1O1, N1S1, O1, O1S1, O2, O2S1, S1, and S2. The main compounds are S1 and N1 compounds, followed by O1S1 compounds. The double-bond equivalent (DBE) value of S1 compounds is mainly distributed between 3 and 12, and the carbon number is mainly distributed between 18 and 35. The DBE value of N1 compounds is mainly distributed between 4 and 14, and the carbon number is mainly distributed in the range 15-35. Among the S1 compounds, DBE3 compounds (thiophenes) have relatively more sulfur-containing carotenoids (C40). The abundance of C40 S1 and the ratio of pyridine and its homologue DBE4-8/DBE9-12 N1 compounds show a good contrast with the paleoenvironment indicators of gammacerane/C30 hopane and diasterane/regular sterane. They can be used as a reference for the paleoenvironment index. Maturity is another factor affecting the distribution of NSO heteroatoms in the oil sands. NSO compounds are enriched in the DBE area with higher condensation, and the main peak carbon shifts forward. As the maturity increases, the relative abundance of N1 compounds increases, the aromatization intensifies, and carbon is broken into short chains. The research results shed light on the potential application of NSO compounds in petroleum exploration based on FT-ICR MS.

The transformations undergone by the high-molecular-weight heteroatomic compounds (resins, asphaltenes) of the Novokuibyshevsk Refinery vacuum residue during thermal cracking at 500°C in the presence of additives such as calcium carbonate and calcium acetate were studied. The characteristic changes in the composition of the cracking products depending on the amount of the additive were demonstrated. Based on the data from 1H NMR spectroscopy, elemental analysis, and molecular weight measurements, the structural-group parameters of the resin and asphaltene molecules in the original vacuum residue and in the products of its cracking in the presence of different amounts of the additives were determined. The heterogeneous additives (≤0.5 wt %) afforded deeper degradation of resins and asphaltenes. The resin molecules underwent compaction due to destruction of the saturated rings and aliphatic moieties, followed by an increase in the content of oils in the liquid cracking products composition.

Globally, the reserves of heavy crude oil are seven times more abundant than that of light crude, and yet, they are underutilized because of their high viscosity and density, which is largely due to the presence of large amounts of asphaltenes. Biotransformation of heavy oil asphaltenes into smaller metabolites can be used for reducing their viscosity. Several microorganisms capable of asphaltene biodegradation have been reported but only few have been characterized for its biotransformation. In the present study, a 9-membered microbial consortium was isolated from an oil contaminated soil. About 72% and 75% asphaltene biotransformation was achieved by growing cells at shake flask level and in a 1.5 l bioreactor, respectively. A representative structure of asphaltene was constructed based on LC–MS, 1H-NMR, 13C-NMR, FT-IR, ICPMS and elemental analysis (CHNS) of n-heptane purified asphaltene from Maya crude oil. Biotransformation of asphaltene, as analyzed by performing 1H-NMR, FT-IR and elemental analysis, resulted in 80% decrease in S and N when compared to the control along with incorporation of oxygen in the structure of asphaltene. About 91% decrease in the viscosity of the Maya crude oil was observed after two weeks when oil: aqueous phase ratio was 1:9. The results suggest that the isolated microbial consortium can be used for biological upgradation of heavy crude oil. To our knowledge, this is the first report where a microbial consortium resulted in such high asphaltene biotransformation.

Algerian crude oil displays a marked propensity for asphaltene precipitation, leading to solid deposits during extraction, transportation, and storage. The relationship between precipitation and chemical composition is unclear; in fact, Algerian crude oil actually features a low asphaltene concentration, despite its relatively large rate of deposit formation. The rationalization of the precipitation process and its remediation should benefit from a molecular characterization of the crude oil. In this study, two unstable asphaltene fractions (A1 and A2) from two different deposits, and two resin crude oil fractions (R1 and R2) from the Hassi-Messaoud Algerian field have been characterized at the molecular level by means of high-resolution mass spectrometry with an Atmospheric Pressure Chemical Ionization (APCI) source. Positively and negatively charged compounds with molecular weights 200−1200 m/z were detected. Several thousand molecular stoichiometries were identified and classified for each sample, in terms of heteroatom content and aromaticity, searching for trends characteristic of the two asphaltenes and of the associated resins. The A2 asphaltene, from a downstream storage tank, displays a higher aromaticity and O heteroatom content, which correlates with an enhanced aggregation propensity, in comparison to the A1 fraction, collected at the well bore. The resin fractions are found to be abundant in aliphatic hydrocarbons and heteroatomic compounds of moderate aromaticity. The more polar resin fraction, R2, is enriched in N-containing species, with respect to the less polar resin fraction R1, which correlates with the stabilizing function observed in previous works. The results stress the view of crude oil fractions as complex mixtures, rather than in terms of average prototypical compounds, when facing the understanding of asphaltene deposition conditions., Area of Physical Chemistry