The present paper reports experiments on microwave heating of a carbonate oil-containing rock sample in the presence and absence of an iron-magnetite-based nanocatalyst. It has been shown that the used catalyst improves the processes of destructive hydrogenation of resins and asphaltenes compounds in the oil. The chemical reactions analysis demonstrated a decrease in asphaltenes content and in their molecular weight, which increases the filtration capacity of the oil fluid in the reservoir rock porous medium. Moreover, the content of non-extractable organic matter in the rock sample after experiments and after oil extraction was determined. It has been found that the absence of the catalyst causes the least increase in the content of non-extractable organic matter in the rock. This fact is related to the intensive processes of resinous-asphaltene compounds destruction especially at the level of peripheral groups which are the most condensed fraction, and hence leads to a decrease in their solubility in the organic medium and eases their adsorption on the mineral skeleton surface.

Summary For the purpose of this work, the authors used an integrated approach to the modeling of in-situ combustion (ISC) including the results of laboratory studies and preliminary works, which significantly affect the choice of the method for implementing ISC and the results obtained in the process of modeling. The laboratory studies provided the data on the temperature range of the beginning of high-temperature oil oxidation, which is to be achieved during the modelling of the bottomhole zone heating. Based on the resulting injectivity profile, the reservoir distribution within the injection well zone in the geological model was updated. A high-permeability channel between the injection well and one of the production wells revealed during cold water injection explains the main oil production increment resulting from ISC and demonstrated by the reservoir simulation model. Based on the results of model runs for a more uniform distribution of the effect between producing wells, the best start-up time for the most reactive well was determined. Using dynamic modeling of in-situ combustion in a carbonate reservoir, the parameters of this technology implementation were found, and incremental oil production was estimated. For the first time, the ISC technology is planned for implementation in a carbonate reservoir with high-viscosity oil in Samara region. The developed integrated approach to the dynamic modeling of in-situ combustion, which considers both the laboratory studies and preparatory work data, enables the most accurately determination of the best ISC technological parameters and this technology contribution.

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A new method for assessing the stability of the asphaltene phase in reservoir fluids using a high-pressure microscope is presented. The new method is based on the observation of the asphaltene particles sedimentation in a vertically oriented sapphire cell. This determines the size of sedimentation particles, their number and sedimentation rate. Experimental results are used as input parameters for calculating solid particles sedimentation of using the Stokes law equation. It makes possible to calculate the density and weight percent of the solid phase, evaluate the aggregative and kinetic stability of the fluid with respect to solid particles depending on thermodynamic parameters (pressure, temperature, reagent concentration). The proposed method was tested in the single-contact study of high-viscosity reservoir oil and liquid carbon dioxide and was compared with the results of asphaltene precipitation gravimetric test. According to the results analysis, were conclusions about the applicability of the new method and the mechanism of asphaltenes precipitation in high-viscosity oil when it contact with carbon dioxide. It is shown that the combination of gravimetric and visual analyzes allows to investigate the asphaltenes precipitaion separately in two processes: reduction of pressure and vaporization of fluids. This makes it possible to assess the likelihood of formation and the effectiveness of reagents for combating solid deposits in the entire process chain of oil production. Concluded that the asphaltenes precipitation in the contact of carbon dioxide and high-viscosity oil occurs according to the complex mechanism and includes intensification due to a drop in oil viscosity and damping due to mass transfer between carbon dioxide and oil phases. From this, inhibitors selection criteria are derived and the using of deasphalted oil as a stabilizer of asphaltenes is proposed.

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