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Abstract A porous medium thermo-effect cell (PMTEC) was developed to fast characterize the combustion of crude oils in porous media in air flow for air injection enhanced oil recovery (EOR) process. We described how PMTEC works and employed it to investigate the combustion behavior of seven crude oils including two light oils, two medium oils, two heavy oils, and one extra heavy oil. The results showed that, except the two light oils, the others exhibited a strong low-temperature combustion (LTC) phenomenon at about 270–280 °C with a high temperature increase to approximately 700 °C and the release of CO2 and CO gaseous products. This LTC behavior was compared with the widely documented oxidation behavior in air injection process including low-temperature oxidation (LTO) and high-temperature oxidation (HTO) characterized by high-pressure differential scanning calorimetry (HP-DSC). It turned out that the LTC occurred in PMTEC was different from the LTO or HTO observed from HP-DSC experiments. In addition, this LTC can propagate in porous media with air flow, which was detected by a newly developed optical fibre technology instead of traditional thermal couples. Furthermore, the effect of copper stearate, iron stearate, nickel stearate, and cobalt stearate as oil-soluble catalysts on the LTC was investigated. Copper stearate showed the best catalytic effect. It significantly shifted onset and peak temperatures into lower temperature from 278 and 287 °C to 227 and 237 °C, respectively, exhibiting a great potential in catalyzing crude oils combustion in ISC process. The catalytic effect of these four catalysts is in turn: copper > iron > cobalt > nickel.

The selection of effective surfactants potentially can mobilize oil up to 50% of residuals in mature carbonate oilfields. Surfactants’ screening for such oilfields usually is complicated by the high salinity of water, high lipophilicity of the rock surface, and the heterogeneous structure. A consideration of features of the oilfield properties, as well as separate production zones, can increase the deep insight of surfactants’ influence and increase the effectiveness of surfactant flooding. This article is devoted to the screening of surfactants for two production zones (Bashkirian and Vereian) of the Ivinskoe carbonate oilfield with high water salinity and heterogeneity. The standard core study of both production zones revealed no significant differences in permeability and porosity. On the other hand, an X-ray study of core samples showed differences in their structure and the presence of microporosity in the Bashkirian stage. The effectiveness of four different types of surfactants and surfactant blends were evaluated for both production zones by two different oil displacement mechanisms: spontaneous imbibition and filtration experiments. Results showed the higher effect of surfactants on wettability alteration and imbibition mechanisms for the Bashkirian cores with microporosity and a higher oil displacement factor in the flooding experiments for the Vereian homogeneous cores with lower oil viscosity.

The oxidation behavior of three crude oils was characterized by thermogravimetry coupled with Fourier transform infrared spectroscopy (TG–FTIR) to investigate the oxidation mechanism of crude oils. The results indicated that the entire oxidation process can be divided into three main reaction intervals: low-temperature oxidation (LTO) interval (<400 °C), coking process (400–500 °C), and high-temperature oxidation (HTO) interval (500–650 °C). For the LTO interval, oxygen addition reactions to produce hydroperoxides were believed to be dominant at the early stage, while the isomerization and decomposition reactions of hydroperoxides became more significant at the later stage. For light and medium oils, the isomerization and decomposition reactions that release H2O started at about 200 °C and the isomerization and decomposition reactions that release CO2 and CO started at about 300 °C. However, no CO2 and CO were detected in the LTO interval of the heavy oil, which means that the reaction pathways of the hea...

The efficiency of corrosion inhibition for waterborne polyurethane based on N-tert-butyl diethanolamine (tB-WPU) is investigated using different techniques. Corrosion weight loss, open circuit potential experiments, electrochemical impedance spectroscopy, and potentiodynamic polarization measurements show that both a commercial reagent and a polyurethane-based inhibitor prevent corrosion at increasing temperature to 50 °C. At 75 °C, the activity of both reagents is reduced. In stirring conditions, the effectiveness of acid corrosion inhibition (25 °C, 500 ppm) drops abruptly from 89.5% to 60.7%, which is related presumably to the complexity of binding the polymer molecules to the metal surface. As follows from thermodynamic calculations, the adsorption of tB-WPU on the metal surface in 2M HCl can be treated as a physisorption. Model quantum–chemical calculations support the experimental studies and elucidate the nature of steel surface–inhibitor molecule chemical bond, which is realized mainly by carboxyl and amino groups. It is concluded that WPUs can be considered as a perspective alternative to commercial oilfield reagents due to their versatility.

© 2017, Springer Science+Business Media, LLC, part of Springer Nature. Joint thermal treatment of heavy oil and liquid products of fast wood pyrolysis is investigated. Thermal analysis shows that the coke yield does not increase if the liquid products are added up to 20 mass%. The liquid wood-pyrolysis products decompose much earlier than heavy oil. However, the decomposition of the blends is essentially the same as pure-oil decomposition.

Despite the abundance of in situ combustion models of oil oxidation, many of the effects are still beyond consideration. For example, until now, initial stages of oxidation were not considered from a position of radical chain process. This is a serious difficulty for the simulation of oil recovery process that involves air injection. To investigate the initial stages of oxidation, the paper considers the sequence of chemical reactions, including intermediate short-living compounds and radicals. We have attempted to correlate the main stages of the reaction with areas of heat release observed in the experiments. The system of differential equations based on the equations of oxidation reactions was solved. Time dependence of peroxides formation and start of heat release is analytically derived for the initial stages. We have considered the inhibition of initial oxidation stages by aromatic oil compounds and have studied the induction time in dependence on temperature. Chain ignition criteria for paraffins and crude oil in presence of core samples were obtained. The calculation results are compared with the stages of oxidation that arise by high-pressure differential scanning calorimetry. According to experimental observations we have determined which reactions are important for the process and which can be omitted or combined into one as insignificant.