Venezuelan Oils Research Articles

Evaluation of residual products from heavy oil refining for the use as an asphalt pavement material

Global oil prices are increasing, and the current demand for the fuel is outpacing the supply of traditional crude oil sources. Therefore, the petroleum industry has applied great effort to extract more valuable products such as fuel from heavy oil sources such as Canadian oil sands and Venezuelan heavy oils. One refining process that uses heavy oil sources is the solvent deasphalting (SDA) process. SDA extracts most oil components, leaving residual products with more asphaltenes compared to the conventional asphalt binder for road pavement. In this study, the physical and chemical properties of the residual products, known as pitch, have been investigated to evaluate their applicability as a binder for asphalt pavement. From the various tests, it was found that the pitch is too hard and brittle to be used for asphalt pavement due to its very high viscosity. Therefore, the pitch was modified with vegetable-oil-based additives, after which it exhibited similar basic material properties and rheological behaviours to those of conventional asphalt binder, indicating that the modified pitch could be used as a binder for asphalt pavement.

Preliminary Insights on the Crude Oil Maturation Effects on Asphaltene Stability and Processing

Geochemical characterization of crude oils is one important classification and exploration tool within the oil business. One maturation parameter is the ratio of cyclic/open demetallized porphyrins (ratio DPEP types/Ethio types). Chromatographic properties of porphyrinic compounds are briefly reviewed. One high-performance liquid chromatography (HPLC) method was selected for measurement of the DPEP/Ethio parameter. This tool is suited for whole crude oils, vacuum residua, and nonvolatile fractions such as asphaltenes. Exploratory data from heavy, medium, and light crude oils; their vacuum residua; and asphaltenes suggest a correlation between maturity [DPEP/(DPEP + Ethio) parameter] and aspects such as solid deposition and processability during upgrading operations. Results with the studied set of samples will be discussed by considering “Earth” (time under reservoir conditions) as a reactor that steadily converts hydrocarbon mixtures, disproportioning them into two major types: I. light ends, II. molecules with a set of undesirable properties such as extended condensation, loss of alkyl appendages, higher density, higher intermolecular aggregation tendency, and high coking indexes. Examples with Venezuelan crude oils will illustrate these aspects.

06/02048 Saturated hydrocarbons occluded inside asphaltene structures and their geochemical significance, as exemplified by two Venezuelan oils: Liao, Z. et al. Organic Geochemistry, 2006, 37, (3), 291–303.

06/02048 Saturated hydrocarbons occluded inside asphaltene structures and their geochemical significance, as exemplified by two Venezuelan oils: Liao, Z. et al. Organic Geochemistry, 2006, 37, (3), 291–303.

Saturated hydrocarbons occluded inside asphaltene structures and their geochemical significance, as exemplified by two Venezuelan oils

Inside asphaltene aggregates in crude oils, the adsorbed hydrocarbons exist in the packed periphery while the occluded hydrocarbons exist inside the core of the asphaltene structures. Occluded hydrocarbons may be well protected from secondary alteration events in the reservoir due to the colloidal nature of asphaltenes, and can be representative of older oil than the reservoir oil, and so may be very useful for reservoir geochemical studies. In this work, two Venezuelan oils derived from the same source rock have been studied. The results indicate that the oxidative reagent H 2O 2/CH 3COOH can release the occluded hydrocarbons from the asphaltene aggregates, making it possible to selectively study these compounds without interference from the moieties that are covalent-bonded to the asphaltene structures. In order to obtain the precise information from the occluded hydrocarbons, prior to the oxidation processes, acetone extraction of the asphaltenes has been applied to rule out interferences from the adsorbed compounds. Furthermore, pyrolysis of asphaltenes has been performed for comparison with the occluded saturated hydrocarbons. From the oxidation products of asphaltenes from these two crude oils, the saturated hydrocarbons (from the occluded original oil) have very similar distributions, including terpanes and steranes, and almost the same biomarker parameters. These results are in accord with the fact that oil from the same source rock was occluded by both Ven1 and Ven2 asphaltenes. The geochemical information obtained from the occluded saturated hydrocarbons suggests that the source rock depositional setting for these two crude oil samples was an anoxic, hypersaline/evaporitic environment.

Visualization Study During Depletion Experiments of Venezuelan Heavy Oils Using Glass Micromodels

Abstract A series of pressure depletion experiments was conducted in a glass micromodel using five Venezuelan oils with the objective of studying their microscopic mechanism during primary production under a solution gas drive process. Photographs taken from a large area of the micromodel during depressurisationreveal a higher number of bubbles for heavy oils than for light oil. Image processing results show differences in the number of activated nucleation sites among three heavy oils that have similar degrees of critical supersaturation. Three steps in the heavy oil flow are also established. Introduction There are some Venezuelan and Canadian heavy oil reservoirs with a high recovery factor during primary production under a solution gas drive process. Recently, Sheng et al.(1) published a review on this unexpected behaviour, which is different from conventional gas drive concepts. These authors stated that the most plausible microscopic mechanism to explain the gas mobility reduction in heavy oil reservoirs is the creation of a gas-in-oil dispersion, but further investigation on the gas bubble size and number in this dispersion needs to be done. Experimental work on the understanding of the solution gas drive mechanism from a microscopic point of view can be found in the literature(2–7). Pressure depletion tests using glass micromodels(2–5) have been a useful visualisation tool to study nucleation, growth, coalescence, break-up, and flow of gas bubbles. Also, depletion tests performed in core samples using a visual core holder(6, 7) have been conducted to observe the gas bubbles on the core surface. Firoozabadi and Aronson(6) reported a high number of bubbles for heavy oils, and relate this result to a gas mobility reduction and, consequently, a better solution gas drive efficiency. In this paper, we report a series of depletion experiments in a glass micromodel, using five Venezuelan oils. The main objective of this study was to compare the behaviour of these oils during primary production under a solution gas drive process. During the depressurisation, in contrast to previous glass micromodel studies(2–5), photographs of a large area of the micromodel (~31cm2) were taken in order to obtain statistical information regarding the gas distribution. These experiments allowed us to observe a larger view of the gas distribution, close to that seen in transparent core holder experiments(6, 7), but keeping the details of the gas bubbles. Experimental Set-Up The experimental apparatus designed by PDVSA-Intevep is composed of a glass micromodel inside a high-pressure cell, a fluid injection system, and an image-capturing device. The micromodel is made of two glass plates of 10 cm x?10 cm x?4 mm in size. The upper plate has two holes for injecting and retrieving the fluids. The pattern, shown in Figure 1, was chemically etched on the lower plate following a known procedure(8). The obstacles consist of cylindrical grains of 1.0 mm diameter, arranged in a regular 2D network with a minimal separation distance of 0.5 mm.

Modifying In-Situ Combustion Performance by the Use of Water-Soluble Additives

Summary Experiments were performed to study the effects of various additives on the oxidation kinetics of Californian and Venezuelan oils. Aqueous solutions of 10 metallic salts were mixed with sand and Huntington Beach, CA, oil. The mixtures were subjected to a constant flow of air and a linear heating schedule while the effluent gases were analyzed for composition. The variation in the oxygen consumption was analyzed with a model of three competing oxidation reactions. Values for the important kinetic parameters for the three reactions were obtained for each additive. Iron and tin salts were found to enhance fuel formation, while copper, nickel, and cadmium salts had no significant effects. Other experiments with a heavy Venezuelan oil showed that, contrary to earlier suggestions, the use of a ketal did not decrease fuel formation.

Effects of crude oils on the gastrointestinal parasites of two species of marine fish.

To assess the effect of crude oil on selected gastrointestinal parasites of fish, winter flounder (Pseudopleuronectes americanus) naturally infected with a digenetic trematode (Steringophorus furciger), were exposed to contaminated sediment or water soluble fractions of Venezuelan crude oil for 34 and 160 days respectively. Similarly, Atlantic cod (Gadus morhua) harboring an acanthocephalan (Echinorhynchus gadi), were treated with extracts of Hibernia and Venezuelan oils for periods of 81 to 140 days. In all cases prevalence and intensity of parasitic infections were lower in oil-treated fish. The effect appeared to be more pronounced within fish exposed to water soluble extracts than to oil-contaminated sediment. Fewer parasites present in fish exposed to oil might be attributed to direct toxicity induced by drinking water soluble fractions of crude oil and/or modification of the gut environment brought about by changes in host physiology.

Long-chain n-alkanes occurring during microbial degradation of petroleum.

Five axenic cultures and a mixed culture were examined for ability to degrade South Louisiana, Brass River Nigerian, Anaco Venezuelan, and Altamont crude oils. A wax was observed during microbial degradation of Altamont crude oil, but not during weathering of the oil. The high-boiling n-alkanes in the wax were associated with microbial degradation of the oil and appeared to be similar to components of tarballs found in the open ocean.

Chemical Changes and Stability of Lubricating Oil Stock after Hydrogenation

Light lubricating oil distillate from Kuwait crude was hydrogenated in the presence of Ni-Co-Mo catalyst and analysed to study the relationship between composition and stability of the hydrogenated oils.Large chemical changes caused by hydrogenation were observed in sulfur compounds and aromatic hydrocarbons. Under moderate conditions sulfur compounds were converted to corresponding aromatic hydrocarbons. Although content of each aromatic compound varied, total quantity of aromatics did not change under these conditions. Under severe conditions, aromatics were also converted into saturated hydrocarbons, but cracking and cyclization of saturated hydrocarbons were not so marked. Fused three-ring aromatic sulfur compounds were not dibenzothiophenes but naphthothiophenes.Oxidation stability of the hydrogenated Kuwait oil was compared with that of Californian and Venezuelan oils. Stability of each oil was closely correlated with its total sulfur content. Optimum range of sulfur content, 0.1 to 0.4wt%, was the same in every oil, especially when oils were made free from troublesome nitrogen compounds.It was possible that color stability was related with the non-basic nitrogen compounds. Such non-basic nitrogen compounds contained sulfur and oxygen atoms together with nitrogen atom. They were less reactive to hydrogen, so they remained in the hydrogenated oils and induced discoloration of the products.

A Comparison of the Light Lubricating Oil Fractions from Three Different Crudes in Hydrotreating

Three straight-run light lubricating oil fractions from Kuwait, Venezuela and California crudes were hydrotreated over NiCoMo-Al2O3 catalyst by the flow method for the purpose of studying the difference in reactivities of these three fractions and the relationship between the stabilities and the chemical composition of the oils. The reactivities of the fractions under hydrotreating were very different owing to their origins. Results were as follows;(1) Under the mild conditions decrease in viscosity was proportional to the degree of desulfurization, but under severe conditions (above 80∼90% desulfrization) rapid decrease in viscosity by the cracking etc. was observed. In case of naphthenic oils containing much oxygen-compounds, considerable viscosity decrease was observed in the initial hydrotreating stage. It was supposed that these viscosity decrease was due to the hydrocracking of the oxygen-compounds.(2) CA% in ring analysis decreased according to the hydrodesulfurization. In case of Kuwait oils CP% increased and CN% did not change, on the contrary CP% did not change and CN% increased in California oils. And in Venezuelan oils both CP and CN% gradually increased.(3) Oxidation stability of the hydrotreated oils had good relation with the total sulfur content of the oils. In the of 0.1∼0.4wt% total sulfur, a maximum oxidation stability was obtained. Hydrotreated Kuwait oils and Venezuelan oils had these Optimum sulfur California oils had inverse relationship, but after the undesirable nitrogen-compounds were eliminated, same Optimum sulfur range appeared in the same range.