Resin-asphaltene Substances Research Articles

Characteristics of fuel oil from the Krapivinskoe field (Part 1)

Relevance. The need to obtain information about the chemical nature of the resin-asphaltene and oil components of atmospheric residue from distillation of crude oil produced at the Krapivinskoe field in order to select optimal technologies for its rational utilization. Aim. To study the structures of asphaltene macromolecules and resin substances and the molecular composition of the oil components of atmospheric residue from distillation of crude oil produced at the Krapivinskoe field. Methods. Transmission electron microscopy, X-ray phase analysis, IR spectroscopy, 1H NMR spectroscopy, structural group analysis, chemical destruction, gas chromatography-mass spectrometry. Results. The structure of resin-asphaltene substances and the molecular composition of atmospheric residue obtained in the course of atmospheric distillation of oil from the Krapivinskoe field in laboratory conditions have been characterized using a complex of physicochemical research methods. It was found out that asphaltenes of atmospheric residue have a predominantly amorphous structure because of the presence of a developed alkyl chain configuration in their macromolecules. Mean asphaltene molecules consist of three structural blocks, which basis is triarene cores condensed with four to five naphthenic rings. These naphthenoaromatic systems neighbor upon methyl substituents only. The mean molecules of atmospheric residue resins are predominantly single-block. Their structural blocks are more compact due to the smaller number of aromatic and naphthenic rings in the naphthenoaromatic system. A feature of mean resin molecules is also the presence of relatively long alkyl substituents in the blocks. It was established that the structure of asphaltenes and atmospheric residue resins contains fragments linked to each other or to the naphthenoaromatic core of their macromolecules through sulfide and ether bridges. In both types of ‘linked’ fragments, n-alkanes, n-alkylcyclohexanes and hopanes were identified. Among the fragments linked through sulfide bridges, n-alkylbenzenes, n-alkylmethylbenzenes and n-alkanoic acids were additionally identified, while ethyl esters of n-alkanoic acids were identified among fragments linked through ether bridges. A structural feature of the atmospheric residue resins is the presence of phenylalkanes with different positions of the phenyl substituent in both types of bridge-linked compounds. Steranes and phenanthrenes are present in the composition of compounds linked through sulfide bridges. The oil components of atmospheric residue contain n-alkanes, n-alkylcyclohexanes, hopanes, steranes, n-alkylbenzenes, n-alkylmethylbenzenes, alkylnaphthalenes and alkylphenanthrenes.

Co-cracking of atmospheric residue and plastic waste

The processing of residual fractions after the distillation of oil and waste plastics into fuels is an important aspect from environmental, energetic and economic points of view. However, current methods of their processing are not effective enough for widespread implementation. In this work the effect of the addition of polyethylene terephthalate (PET), low-density polyethylene (LDPE) and polypropylene (PP) to the atmospheric residue on the composition of final products of subsequent cracking is investigated. It has been established that addition of PET to the atmospheric residue has a positive effect on the yield of light fractions and the destruction of resin-asphaltene substances (RAS) in comparison with cracking of atmospheric residue (AR) only. After cracking with the PET additive, the additional yield of light fractions is 4.8 wt%. It has been shown that PET affects the amount and structure of coke resulted from the cracking of atmospheric residue. A positive effect of the PP additive on the destruction of RAS is also revealed. In particular, the content of asphaltenes is lowered by a factor equal to 9.8 compared to that in the liquid products after fuel oil cracking. It has been also found out that polypropylene 1.7 times more than PET and 1.5 times more than PE enhances additional coke formation. It is shown that LDPE has the least positive effect from co-cracking with AR compared to the case with PET and PP. A hypothetical mechanism is presented for the interaction of PET, LDPE, and PP with AR during co-cracking.

Changes in the Composition of Heavy Oil and the Structure of Asphaltenes upon Treatment with Isopropyl Alcohol

The interactions of the components of heavy oil from the Zyuzeevskoye field (Republic of Tatarstan) and isopropyl alcohol (IPA) at temperatures of 25, 65, and 100°C were studied. It was established that the temperature regime affected the density, composition, and structural group characteristics of the products of interactions between the oil and IPA. The density of the resulting products increased by 4 wt % (from 0.885 to 0.924 g/cm3) as the process temperature was increased to 100°C, and the concentration of resin–asphaltene substances also increased by 4 wt % in this case. It was shown using IR spectroscopy that the tentative concentration of paraffin fragments in the structure of asphaltenes increased significantly when the oil was treated with isopropanol at temperatures of 65–100°C, and the branching factor increased by a factor of 3, as compared to that of the initial asphaltenes. The observed changes were due to the incorporation of isopropyl fragments into the structure of asphaltene molecules upon the processing of heavy oil with IPA.

Transformation of Organic Matter of Domanik Rock from the Romashkino Oilfield in Sub- and Supercritical Water

The transformation of the organic matter (OM) of low-permeable carbon-rich domanik rock of the Romashkino oilfield in sub- and supercritical water (SCW) at temperatures of 320, 374, and 420°C and pressures of 17, 24.6, and 24.4 MPa in a neutral medium has been studied. The original rock with a TOC content of 7% has a high oil generation potential and a low productivity index. The productivity index increases with an increase in the severity of the thermal treatment of the rock, which is due to intense kerogen degradation resulting in the formation of free hydrocarbons that are easy to recover from the rock. In rock extracts, in comparison with the original rock, the amount of saturated and aromatic hydrocarbons increases by more than two times and that of resin–asphaltene substances decreases. Distinctive features of the yields and compositions of rock extracts depending on the temperature of the experiments have been revealed. The highest yield of the extract was observed in the experiment with subcritical water at 320°C and associated with the degradation of resins and more complete extraction of asphaltenes and high-molecular-weight n-alkanes from the rock. Treatment in SCW at 374 and 420°C leads to intensive degradation of the kerogen structure involving the detachment of aliphatic chains from large fragments of kerogen and asphaltene macromolecules to form lower n-alkanes and carbon-rich substances, such as carbenes and carboids. The structure of asphaltenes becomes more condensed and oxidized in the SCW medium at 420°С, leading to a decrease in their paramagnetic properties. Using the EPR technique, the features of hyperfine splitting of the vanadyl complex line on 14N nitrogen nuclei have been revealed in the spectrum of asphaltenes of the SCW experiment at 420°С, indicating specific changes in their structure.

Impact of Integrated Technologies of Enhanced Oil Recovery on the Changes in the Composition of Heavy Oil

This paper deals with the impact of an integrated technology for enhanced oil recovery on the composition of high-viscosity heavy oil produced at the Usinskoye oilfield (Russia, Komi Republic). In order to increase the effectiveness of the thermal-steam stimulation, a surfactant-based composition generating carbon dioxide and an alkaline buffer system is injected into the formation. The analysis of the oil composition is performed via the methods of gradient-displacement liquid adsorption, gas-liquid chromatography, and IR spectroscopy. The results obtained show that two parallel processes are proceeding when pumping an oil-displacing composition. The first process is the additional extraction of residual oil. This process is controlled by an increase in the content of resin-asphaltene substances in oil. The second process is an increase in the coverage of reservoir and the involvement into the development of previously uncovered areas with oil compositionally similar to that at the beginning of development. Using the results of the analysis of the component composition, the individual composition of alkanes, and structural fragments of oil samples in order to control the development of the Usinskoye oilfield, the frontal oil-water boundary advance of the Northern area in the direction of the upper production facility is determined. The obtained patterns of changes in the oil composition after the application of an integrated technology using a surfactant-based composition can be characteristic of other deposits of heavy oil occurring in low-permeability reservoirs

Resins and Asphaltenes of Light and Heavy Oils: Their Composition and Structure

The complex of physicochemical methods of analysis (elemental analysis, cryoscopy in benzene, IR and ¹H NMR spectroscopies, structural group analysis, gas chromatography–mass spectrometry, and selective chemical cleavage of sulfide and ether bonds) is used to comparatively characterize resins and asphaltenes of light and heavy oils. Attention is paid to the study of their structural group composition and the composition of moieties bound in molecules of resin–asphaltene substances (RAS) through ether and sulfide bridges, as well as the composition of compounds occluded by asphaltene molecules and nitrogen bases of resins. It is found that resins and asphaltenes of the heavy oil are characterized by higher average molecular masses and large overall sizes of mean molecules, due to the increased content of aromatic cycles in the naphthenic–aromatic system. The similar sets of linear and branched alkanes, alkylcyclopentanes, alkylcyclohexanes, steranes, mono- and disubstituted alkylbenzenes, and dibenzothiophenes identified in occluded compounds and products of chemolysis of resins and asphaltenes under study suggest the presence of most of these compounds as structural fragments in RAS molecules of light and heavy crude oils under study. Alkyl-substituted quinolines and benzoquinolines are identified in the nitrogen bases of resins. The feature of the light oil is the presence of “sulfur-bound” alkenes and polycycloalkenes in the structure of its asphaltenes. The findings expand our understanding of the structure of petroleum resins and asphaltenes. They can be used to simulate their structure in developing new controlled methods for processing hydrocarbon feedstock.

ХАРАКТЕРИСТИКА ТЕРМИЧЕСКОЙ УСТОЙЧИВОСТИ МАСЕЛ ПРИРОДНЫХ БИТУМОВ И НЕФТЕЙ

Актуальность исследования обусловлена тем, что термическая деструкция является одним из самых распространенных процессов переработки нефтяных остатков, тяжелых нефтей и природных битумов. Термические и термокаталитические процессы конверсии перечисленного углеводородного сырья сопровождаются образованием при термодеструкции смолисто-асфальтеновых веществ исходных объектов дополнительного количества дистиллятных фракций («вторичных» масел). Одновременно происходят процессы превращения масел исходного объекта и «вторичных» масел при температурах, соответствующих термической деструкции «слабых» и «прочных» связей в соединениях, входящих в их состав. При выборе оптимальных режимов термической и термокаталитической переработки тяжелого нефтяного сырья должны учитываться результаты оценки термической устойчивости содержащихся в них компонентов. Одним из методов изучения термической стабильности органического вещества осадочных пород является пиролитический анализ в варианте Rock-Eval. Сведения о возможностях этого метода для анализа масел весьма ограничены. В то же время из пирограммы масел можно получить информацию об их термической устойчивости и характеристических температурах деструкции содержащихся в них компонентов. А также получить информацию о различии этих параметров для масел, выделенных из нефтей и природных битумов, отобранных в различных нефтегазоносных провинциях и существенно отличающихся своим компонентным составом. Цель:сравнительный анализ с использованием метода Rock-Eval параметров термической устойчивости масел, выделенных из природных битумов и нефтей, отличающихся суммарным содержанием смолисто-асфальтеновых веществ, а также продуктов их лабораторной биодеградации и конверсии в сверхкритической воде. Объекты: масла, выделенные из 18 образцов нефтей и природных битумов, продуктов их лабораторной биодеградации и конверсии в сверхкритической воде. Методы: анализ элементного состава, ЯМР 1Н-спектроскопия, пиролитический анализ в варианте Rock-Eval. Результаты. Показано, что методом Rock-Eval можно получить информацию о термической устойчивости масел, выделенных из нефтей и природных битумов, отобранных в различных нефтегазоносных провинциях и отличающихся компонентным составом. Пирограммы масел содержат три пика, проявляющихся в различных интервалах температур. Пик S1 (изотерма 180 °С) соответствует процессу испарения бензиновой фракции (НК…180 °С). Пик S2a (180…350 °С) соответствует наложению процесса испарения «средних» фракций масел и деструкции «слабых» C–S, C–O связей в структурных фрагментах их компонентов. Пик S2b (350…550 °С) соответствует наложению испарения «высококипящих» компонентов масел и деструкции «прочных» C–O, C–С связей в их структурных фрагментах. Изученные образцы более чем на порядок (от 0,32 до 3,91) различаются отношением выхода летучих продуктов при 350…550 и 180…350 °С (S2b/S2a), а также отношением выхода бензиновой фракции масел – S1 и (S2b+S2a) (от 0,044 до 0,518). Изученные образцы масел также различаются температурой максимальной скорости выхода углеводородов в процессе пиролиза в области пика S2b (от 445 до 466 °С) и более существенно в области пика S2a (от 292 до 350 °С).

Dependence of the rate of formation and the P-T stability field of methane hydrate suspensions in crude oils upon oil composition

Equilibrium conditions for hydrates obtained from water emulsions in crude oils of the Yurubcheno-Tokhomskoe, Verkhnechonskoe, Gerasimovskoe, and Usinskoe fields have been studied, as well as the relative rates of hydrate formation in these systems. It has been concluded that the presence of oil does not alter the equilibrium conditions of hydrate formation. An increase in the concentration of resin-asphaltene substances and paraffins in crude oil leads to a decrease in the hydrate formation rate.

Products of conversion of sulfur-rich native asphaltite in supercritical water

Natural asphaltite and the products of its conversion in supercritical water (400°C, 40 MPa) are comparatively analyzed using a complex of methods, including analyses of elemental and component compositions, pyrolytic and X-ray diffraction analyses, spectrophotometry, IR and EPR spectroscopy, and gas chromatography/mass spectrometry. It is demonstrated that the asphaltite conversion under the indicated conditions results in the formation of various products, such as gases, carbene-carboids, as well as heavy, highly resinous, and sulfur-rich petroleums. The yields of the conversion products are roughly identical. The obtained petroleum and carbene-carboids are characterized by lower sulfur and oxygen contents and a higher content of nitrogen and paramagnetic centers as compared to the initial asphaltite. Components of the same names (oils, resins, and asphaltenes) composing petroleum and asphaltite noticeably differ by the content of heteroatoms (elemental analysis), as well as aromatic and carbonyl-containing structural fragments (IR spectroscopy). The analysis of molecular compositions of hydrocarbon and heteroorganic compounds present in oils of the obtained petroleum attests to the fact that the compositions of nearly all classes of compounds substantially differ from those present in the initial asphaltite; among other reasons, due to the emergence of new compounds. The revealed differences are mainly caused by the generation of such compounds upon thermal destruction of resin-asphaltene substances in which they were present in a bound state. The prolongation of the process from 0.5 to 1 h results in noticeable changes both in the yields of the main products and in the compositions of most compounds analyzed.

Generation of resin-asphaltene substances in the luminescent concentrate under irradiation

The effect of photoirradiation on the luminescent concentrate of heavy gas oil produced by catalytic cracking (>400°C) was examined.

Conversion of resin-asphaltene substances under conditions modeling the thermal methods of enhanced oil recovery

The composition of the products of hydrothermal conversion of a natural concentrate of resin-asphaltene compounds (asphaltite) at temperatures of up to 575°C was studied within the scope of laboratory-scale simulation of transformations of high-molecular-mass components of reservoir oils using the thermal methods of enhanced oil recovery. It was found that thermal degradation takes place in the range 175–575°C, leading to the formation of gases, in particular H2S, and liquid and insoluble products (oil and carbenes-carboids, respectively). The amount of saturated and aromatic compounds in the liquid products of hydrothermal conversion is greater than in the starting sample. The ratio of benzene-extractable to alcohol-benzene-extractable resins substantially varies in favor of the latter compounds, which are enriched in oxygen-containing structural units. The relative amount of higher (>20°C) n-alkanes in the products of conversion at 175–325°C or 350–575°C is respectively higher or lower than in the virgin asphaltite. At conversion temperatures of ≥400°C, the products contain α-olefins.

The influence of the internal structure and dispersity to structural–mechanical properties of oil systems

Some oils and oil products are dispersed systems with composite internal organization. The dynamical model of dispersed particle, named complex structural unit (CSU), with complicated internal structure is suggested. A nucleus surrounded by solvate shell contains high-molecular mass components of different natures. Sizes of nuclei and solvate shells change in accordance with the magnitude of external influence. An optimal correlation between parameters of CSU and the value of external factor can be fixed for every technological process. The results of determination of the dispersity degree in oil systems are presented. Connection of nonmonotonous extremal dependence macroscopic parameters (viscosity, stability, etc.) and microscopic ones (particle sizes) with external influence value changing is shown. These regularities are basic for the intensification of technological processes. Technology is tested in practice with good results. For managing structural–mechanical properties, the addition of heavy residue, containing significant amount of resin–asphaltene substances (RAS), has been chosen together with thermal treatment and regulation of speed of cooling. Speed of cooling determines sizes and number of interacting particles. Connections between particles could be realized through the solvate shells formed from RAS or directly with each other. Finally, the structure of coalescence or condensation type is formed. These kinds of structures differ in their structural–mechanical properties. Such oil compositions are basis for specific products, which are used in mining industry for dust depressing and preventing adherence of granular materials to the walls of transportation equipment. The optimal combination of influencing of external factors gives an opportunity to include bigger amount of heavy residues for decreasing the cost.

Composition and structure of resin-asphaltene substances in the Dzhafarly crude

Composition and structure of resin-asphaltene substances in the Dzhafarly crude

Structural-group composition of resin substances of petroleums in West Siberia

Resin-asphaltene substances (RAS) are the most representative group of non-hydrocarbon petroleum components, which have a negative effect on catalytic processes of oil refining and on the operational indices of petroleum products. At the same time they are one of the main reserves for further increasing the extent petroleum exploitation. Therefore, an understanding of the composition and structure of resin-asphaltene substances is of considerable importance both for oil refining and the production of high-grade petroleum products. Reasonably reliable information concerning the structural-group composition of resin-asphaltene substances has only been forthcoming in recent years as a result of the development of NMR spectroscopy and high-resolution mass-spectrometry. In this study structural-group composition of petroleum resins of the Fedorov deposit (Tyumen region), was obtained using mass-spectrometry, PMR- and /sup 13/C-NMR spectroscopy, elemental analysis and molar masses. 9 references, 3 tables.

EPR study of the resin-asphaltene substances in a lube oil extract

1. EPR characteristics have been obtained for fractions of resins and asphaltenes from an Orsk refinery lube oil extract (Emba crude). 2. It has been shown that the magnetic properties of the materials investigated are determined mainly by condensed aromatic and heterocyclic structures; the greatest difference in EPR properties is observed for samples that differ markedly in these structural features.