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In this research, four different crude oils from Tatarstan oil fields with wide range of API gravities (from 16.6 to 32.5 °API) were used for hydrogen and carbon nuclear magnetic resonance spectroscopy (H NMR and C NMR) determinations. The hydrogen and carbon aromaticity factors were calculated by using the results of H NMR and C NMR spectroscopy results. The results show that the aromaticity factors were high for heavy crude oils. For predicting SARA fractions, the correlations were developed as a function of aromaticity factors. The developed correlations showed high accuracy for predicting SARA fractions for four crude oils. • The hydrogen and carbon aromaticity factors are increasing with increasing crude oil gravity. • The developed correlations showed high accuracy for predicting SARA fractions for four crude oils. • The maximum error was around 9.4% while the minimum was 0.1% for the developed correlations. [ABSTRACT FROM AUTHOR]

Abstract In this research, pressurized differential scanning calorimeter (PDSC) were used to estimate the thermal and kinetic behaviour of two different crude oils from Tatarstan oil fields under three different pressures (100, 600, 2000 kPa) at a constant heating rate (10 °C/min). The heat flow curves of both crude oils indicated two reaction regions known as low temperature oxidation (LTO) and high temperature oxidation (HTO). The reaction intervals were shifted to lower temperature regions with the increase in pressure. The activation energies were calculated according to Borchardt & Daniels and Roger & Morris methods and it was observed that the activation energies were decreasing at elevated pressures. Highlights • The PDSC curves of light and heavy crude oil showed two reaction regions, which are LTO and HTO. • The heat of reaction and heat flow values were increasing with increase in pressure. • Increase in pressure resulted in decrease in activation energy for both heavy and light crude oils. [ABSTRACT FROM AUTHOR]

In this research, wax appearance temperatures (WAT) of eight different crude oils from south-eastern region of Turkey were determined by differential scanning calorimetry. The experiments were performed at a heating/cooling-rate of 2 °C/min from 60 to −20 °C It was observed that the wax appearance temperature of different origin crude oils was varied between 14.2 and 37.8 °C depending on the API gravity and wax content. It was also observed that the crude oils have enthalpy of precipitation ranging from −3.42 to +6.39 mW and melting enthalpy from – 2.5 to +7.46 mW, respectively. [ABSTRACT FROM AUTHOR]

In this research, kinetics of four crude oils from different origins are determined by iso-conversional methods using thermogravimetry data (TGA-DTG). The experiments were performed at three different heating rates (5-10-15 K/min) between 300 and 1200 K. Thermal characteristics of the crude oil samples such as, reaction intervals and corresponding peak and burn-out temperatures are also determined. Three different iso-conversional methods, known as Starink, Kissinger and Friedman are used in order to determine the activation energy values of the crude oil samples studied that represents the novelty of the research. Activation energy values of the crude oil samples are varied between 50 and 102 kJ/mol and 69–132 kJ/mol in low temperature oxidation region and high temperature oxidation region, respectively. [ABSTRACT FROM AUTHOR]

In present work oxidation of two heavy oils in limestone matrix was studied using simultaneous thermogravimetry (TGA), derivative thermogravimetry (DTG) and FTIR-spectroscopy techniques in the temperature range from 25 to 900 °C. Before the measurements, the composition and properties of crude oils and limestone were evaluated. Obtained TG and DTG curves shows four different reaction regions: low temperature oxidation (LTO), fuel deposition (FD), high temperature oxidation (HTO) and decomposition of limestone. LTO reactions were accompanied by evaporation of light hydrocarbons, which was confirmed by appearance of stretching vibration bands of C-H groups in FTIR-spectra of evolved gases. Formation of carbon dioxide was observed for all oxidation reaction regions according to spectroscopic data. At the same time, CO was formed only in HTO region for both studied crude oils. Despite the different composition two crude oils have practically the same reactions intervals and peak temperatures. However, crude oil with higher API-gravity has a greater mass loss at the LTO and evaporation regions. The conversion of heavier oil with higher content of asphaltenes is larger during the high-temperature oxidation step. Three different kinetic models (Arrhenius, Coats & Redfern and Ingraham & Marrier) were used for analysis of TGA-DTG curves in LTO and HTO regions. Activation energy values of the crude oil samples were varied between 6.9–10.6 kJ/mol in low temperature oxidation and 91.8-.0–181.9 kJ/mol in high temperature oxidation regions. For two crude oils activation energies are similar in low temperature oxidation region. In high temperature oxidation region, crude oil with higher content of asphaltenes has larger activation energy. [ABSTRACT FROM AUTHOR]

In this research, combustion characterization and kinetics of four different origin crude oil samples were determined using thermogravimetry - differential thermal analysis (TGA-DTA) and thermogravimetry - Fourier transform infrared (TGA-FTIR) and thermogravimetry – mass spectrophotometry (TGA-MS) techniques. In the TGA-DTA analysis of crude oil samples, low temperature oxidation (LTO) and high temperature oxidation (HTO) reaction regions were observed in different temperature intervals. On the other hand, reaction regions, mass loss, and peak-burnout temperatures of the crude oil samples were also determined using TGA-DTA curves. In TGA-FTIR analysis, spectrums of crude oil samples were examined at different time intervals and composition of several hydrocarbon compounds was determined quantitatively. This research was also focused on the main volatile products (H 2 , H 2 O, CO, CO , C 6 H 6 , SO 2 etc…) of different origin crude oil samples on the basis of both their relative intensities and on their relevancy by using TGA-MS technique. Two different Arrhenius types of kinetic models were used in order to determine the kinetic triplets (activation energy, Arrhenius constant and reaction order) of crude oil samples studied. It was observed that in HTO region, higher activation energy values were observed depending on the °API gravities of the crude oils. [ABSTRACT FROM AUTHOR]

This research mainly investigates the decomposition behavior and kinetics of Beydili and Ihsangazi oil shale deposits (Türkiye) by TG-DTG and MS techniques. In the initial stage of the research, geochemical and organic characterization (total organic carbon, rock-eval, fisher assay, x-ray fluorescence, etc.) of the oil shale samples were determined. TG-DTG-MS analyses of the oil shale samples were performed at three different heating rates in an air atmosphere. In all the oil shale samples studied, the TG-DTG curves indicated that the decomposition of oil shale samples followed two successive reaction stages in different temperature intervals, known as pyrolysis and mineral decomposition. In these two stages, reaction intervals, peak temperature, mass loss, derivative mass loss rate values, and gaseous constituent (MS analysis) of oil shale samples are all determined. At the same time, the different combustibility indices, such as the ignition index, combustion index, and reactivity of oil shale samples, are also determined. Also, for each reaction region, activation energy values were calculated using two different model-free methods known as Kissinger - Akahira – Sunose (KAS) and Ozawa - Flynn – Wall (OFW). In pyrolysis and mineral decomposition regions, the activation energy values varied between 73.9 and 186.4 kJ/mol and 103.3–297.1 kJ/mol. • Geochemical, thermal and kinetic characterization of Türkiye oil shale deposits were studied. • Two distinct zones were identified. • Reaction intervals, and the peak and burn-out temperatures was increased as the heating rate increases. [ABSTRACT FROM AUTHOR]

In this research, the effect of different clay minerals (bentonite, illite and kaolinite) on the combustion behavior and kinetics of crude oils from Kazan region (Russia) was studied using thermogravimetry (TGA) and differential scanning calorimeter (DSC). The ramped temperature experiments were performed at constant heating rates (10, 20 and 30 °C/min) under air atmosphere. In both TGA and DSC experiments, two reaction zones were identified known as low temperature oxidation (LTO) and high temperature oxidation (HTO). The reaction regions, burn-out temperatures, mass loss, heat of reaction and peak temperatures were determined. It was observed that the reaction intervals and the peak temperatures were also affected in the presence of different clay minerals. Kinetic parameters were calculated by Ozawa-Flynn-Wall (OFW), Kissenger-Akahira-Sunouse (KAS) kinetic methods. The addition of different clay minerals reduced the mass loss percentages of the crude oil samples due to the surface area effect. In addition, all clay samples show a good catalytic effect by a significant reduction in activation energy. • Both TGA and DSC curves revealed two main reaction regions known as LTO and HTO, for crude oils and crude oil-clay mixtures. • As heating rate increased, the peak, burn-out and ignition temperatures were shifted to higher temperatures. • The addition of clays shifted the reaction intervals and peak temperatures to lower temperature range. [ABSTRACT FROM AUTHOR]

In this research, the effect of inlet pressure on combustion behavior of medium and light crude oils was analyzed with TGA and DSC experiments. The ramped temperature combustion experiments were performed at constant heating rates under air atmosphere. TGA curves revealed three main reaction regions known as low temperature oxidation (LTO), fuel deposition (FD), and high temperature oxidation (HTO). In DSC curves, at the early stage of the heating, distillation region was also observed in addition to LTO and HTO reaction regions. It was observed that the changes in inlet pressure affect the temperature intervals of the reaction regions and peak temperatures. The kinetic parameters were calculated according to Ozawa-Flynn-Wall (OFW), Kissinger-Akahira-Sunose (KAS), and ASTM methods. Results indicated that the increase in inlet pressure increased in the activation energy. • The lightest crude oil had wider LTO reaction interval and lower peak temperatures. • The heaviest crude oil lost most of its mass in the FD and HTO region. • Inlet pressure increase caused decrease in peak temp. and reaction intervals. [ABSTRACT FROM AUTHOR]

The ramped temperature oxidation experiments were performed on heavy and light crude oil samples using the TGA and DSC instruments. The crude oils were mixed with different weight percentages (10%, 20%, and 30%) of water, as a result of which six different water-oil mixtures were prepared. The samples were heated up to 800 °C with three heating rates 20, 25, 30 °C/min. Two reaction regions, particularly the low temperature oxidation (LTO) and high temperature oxidation (HTO), were identified in TGA and DSC results. The LTO region can be divided into two subzones as before and after around 150 °C. In the first subzone, up to around 150 °C, the endothermic distillation process took place. The results showed that light crude oil and its mixtures had lower reaction starting and ending temperatures, and peak temperatures compared to heavy crude oil and its mixtures. As the water amount in the mixtures were increased, the reaction and peak temperatures shifted to lower temperatures. The kinetic analysis was also performed applying the Ozawa-Flynn-Wall (OFW), Kissenger-Akahira-Sunose (KAS), and ASTM kinetic methods. The activation energies and Arrhenius constants based on the TGA and DSC results were calculated accordingly. The light crude oil and its water mixtures had lower activation energy and Arrhenius constants compared to heavy crude oil and its mixtures. As the amount of water in the mixture was increased, the activation energy and Arrhenius constant decreased, which indicated that the presence of water in the crude oil increases its ability to combust more efficiently. • The crude oils and their water mixtures suggested two reaction regions, particularly the low temperature oxidation (LTO) and high temperature oxidation (HTO) regions. • The reaction temperatures of heavy crude oil mixture were higher compared to that of light crude oil mixture. • Presence of water in the crude oil makes it vulnerable to combustion, which increases the combustion efficiency. [ABSTRACT FROM AUTHOR]

In the oil industry, there is a need for fast and non-invasive methods for determining the bitumen content and group composition in rock samples. Determination of bitumen saturation of reservoir or source rocks has some difficulties due to existing methods limitations. For this purpose, the novel method is based on a combination of free induction decay (FID) and modified Carr-Purcell-Meilboom-Gill (CPMG) measurements using a low-frequency nuclear magnetic resonance (NMR) relaxation technique was developed. It allows obtaining the content and group composition (SARA fractions) of bitumen directly in the porous media without extraction. FID data fitting based on a combination of Voigt and exponential functions for liquid phase, as well as Abragam and exponential functions for solid phase components respectively was proposed. The developed method was tested on 20 rock samples collected from the productive formation (horizon M) located at the depth of 601–708 m of the wellbore 3001 of the Boca de Jaruco oilfield (Republic of Cuba). The bitumen content in the samples was obtained and compared with data determined by thermogravimetric analysis (TGA) and Rock-Eval pyrolysis. A good agreement of NMR results with TGA and pyrolysis was shown (R2 = 0.99 and 0.97 respectively). The values of liquid HC components (saturates, aromatics and resins) and solid HC components (asphaltenes) were compared with TGA data (R2 = 0.97 and 0.98 respectively). Finally, the proposed NMR method was applied to determine the SARA composition of the bitumen in the samples. To assess the accuracy of determining the SARA composition by the NMR method, SARA analysis (ASTM D4124-09) of extracts from the samples 632, 638, 658, 676, 689, 708 was carried out. NMR and conventional SARA analysis showed close results. To assess the completeness of the bitumen extraction from the mineral matrix, microCT and FIB-SEM were performed before and after extraction. It was found that after extraction the part of the bitumen remains in the pores, which distorts the results of SARA analysis. The proposed NMR method can be used to calculate the bitumen saturation and SARA composition for characterization of bitumen, selecting and modeling the effectiveness of applying the optimal EOR without destroying the samples. Also, the method is promising for the operational control of technological processes of oil production. • Novel NMR method for determination of bitumen content in the rock was proposed. • The proposed NMR method is simple, rapid, non-destructive and does not require sample preparation. • NMR method was applied to determine the SARA fractions of the extractable bitumen in the rock samples. • NMR method was successfully applied to study 20 rock samples collected from the Boca de Jaruco oilfield. [ABSTRACT FROM AUTHOR]

In this study a new, fast and simple method based on low field NMR-relaxometry for in-situ determination of SARA (saturates, aromatics, resins and asphaltenes) composition of crude oils was proposed. This method was tested on 22 samples of crude oils with a wide range of SARA-composition and API gravity values (4.6–42.0°), including extra-heavy, heavy, medium and light crude oils. Results obtained by low-field nuclear magnetic resonance (LF-NMR) were compared with conventional SARA analysis method (ASTM D 4124). Comparison shows good coincidence between SARA values determined by LF-NMR and conventional method data for heavy fractions of asphaltenes and resins (R2 is equal to 0.98 and 0.91, respectively) and for the sum of light fractions including saturates and aromatics (R2 = 0.96). However, comparison for saturated and aromatic compounds separately gave low correlation coefficients (R2 ≤ 0.61 and 0.27, respectively) and relatively soaring standard deviation for individual correlations for saturates and aromatics (8.18 and 9.20). Consequently, LF- NMR relaxation as an alternative method for studying the composition of crude oil allows the determination of asphaltenes, resins and the sum of light fractions (saturates and aromatics) without their extraction (in-situ), which greatly simplifies and accelerates conventional chromatographic analysis. This method can be successfully applied for different types of crude oils with a wide range of API gravity and viscosity values. Image 1 • 22 crude oils were investigated using low-field nuclear magnetic resonance (LF-NMR) and SARA analysis techniques. • SARA composition data of oil samples was obtained by means of traditional SARA separation and LF-NMR relaxation data. • T2 relaxation curves for measured oil samples were obtained. • Protons T2 relaxation times of SARA fractions in studied oil samples were obtained. • Good correspondence between two methods was observed for resins, asphaltenes and the sum of saturates and aromatics fractions [ABSTRACT FROM AUTHOR]