Search

In this article on the example of two crude oil with the same content of resins, asphaltene, and solid paraffin, it is shown that they have different rheological behavior at low shear rates. The chemical composition of crude oil's high molecular weight components (asphaltene and solid paraffin) was studied by EPR, IR spectroscopy, and chromatography. It is shown that their composition does not differ significantly. It was revealed that the reason for the different rheological behavior of the crude oils is the content of saturated and aromatic hydrocarbons. When the content of mono- and bi-aromatic hydrocarbons in crude oil increases, the degree of its non-Newton behavior increases. It is due to the formation of a coagulation structure in it. The data obtained have to take into account to predict crude oil viscosity when technologies for oil recovery and transportation developed. [ABSTRACT FROM AUTHOR]

Petroleum asphaltenes are considered the most irritating components of various oil systems, complicating the extraction, transportation, and processing of hydrocarbons. Despite the fact that the paramagnetic properties of asphaltenes and their aggregates have been studied since the 1950s, there is still no clear understanding of the structure of stable paramagnetic centers in petroleum systems. The paper considers the possibilities of various electron paramagnetic resonance (EPR) techniques to study petroleum asphaltenes and their solubility fractions using a carbon-centered stable free radical (FR) as an intrinsic probe. The dilution of asphaltenes with deuterated toluene made it possible to refine the change in the structure at the initial stage of asphaltene disaggregation. From the measurements of samples of bitumen, a planar circumcoronene-like model of FR structure and FR-centered asphaltenes is proposed. The results show that EPR-based approaches can serve as sensitive numerical tools to follow asphaltenes' structure and their disaggregation. [ABSTRACT FROM AUTHOR]

A comparative analysis of asphaltenes of the produced and residual oils of the multiplay Bavly oil field (Russia), as well as asphaltenes of bitumens extracted from Domanic formation of the same field is carried out by the data of elemental analysis, IR and EPR spectroscopy. It is shown that the popular opinion about the increased oxygen content in bitumen asphaltenes in comparison with oil ones is only valid for asphaltenes of produced oils; asphaltenes of residual oils are similar to bitumen asphaltenes not only in element composition but also in structural ordering. Asphaltenes from deeper oil bed of the multiplay Bavly oil field have an increased value of the oil identity parameter and greater structural ordering. [ABSTRACT FROM AUTHOR]

The products obtained from production wells of Ashalchinsk and Mordovo-Karmalsk bitumen fields of the Republic of Tatarstan (Russia) using thermal recovery technologies as well as the core materials recovered from the in situ combustion zone of Mordovo-Karmalsk field were studied with the thermal analysis methods. Using thermal derivatography and calorimetry, it was established that the products obtained from production wells were water–bitumen emulsions, the water content in water–bitumen emulsions was determined, the stability of water–bitumen emulsions was evaluated, and the fractional bitumen composition was characterized. Using thermal derivatography, the organic matter content in the core material and the degree of its transformation in the result of in situ combustion were determined. [ABSTRACT FROM AUTHOR]