Thermal characterization of crude oils in the presence of limestone matrix by TGA-DTG-FTIR

In present work oxidation of two heavy oils in limestone matrix was studied using simultaneous thermo-gravimetry (TGA), derivative thermogravimetry (DTG) and FTIR-spectroscopy techniques in the temperature range from 25 to 900 degrees 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

Effect of inlet pressure on crude oil combustion -laboratory approach-

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

Thermal, kinetics, and oxidation mechanism studies of light crude oils in limestone and sandstone matrix using TG-DTG-DTA: Effect of heating rate and mesh size

This research was focused on the combustion kinetics and oxidation mechanisms of light crude oils in limestone and sandstone matrices. Similarity of the TGA-DTA curves was produced for different crude oils + limestone or sandstone mixtures indicates that the crude oil undergoes three major transitions, known as low-temperature oxidation, fuel deposition, and high-temperature oxidation when subjected to an oxidizing and constant rate environment. Kinetic analysis of the low- and high-temperature oxidation regions was performed using the ASTM and Arrhenius kinetic methods. In reaction mechanism of the combustion reactions, oxidation mechanisms, and rate-controlling steps of fluid-solid reactions in limestone matrix was also determined. It was observed that the linear behavior at elevated temperatures justifies the assumption that chemical reaction was the controlling step

Wax appearance temperature (WAT) determinations of different origin crude oils by differential scanning calorimetry

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 degrees C/min from 60 to -20 degrees C It was observed that the wax appearance temperature of different origin crude oils was varied between 14.2 and 37.8 degrees 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

TGA and DSC investigation of different clay mineral effects on the combustion behavior and kinetics of crude oil from Kazan region, Russia

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 degrees 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, burnout 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

Crude oil characterization using TGA-DTA, TGA-FTIR and TGA-MS techniques

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

The effect of water on combustion behavior of crude oils

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 degrees C with three heating rates 20, 25, 30 degrees 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 degrees C. In the first subzone, up to around 150 degrees 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

Calorimetric study approach for crude oil combustion in the presence of clay as catalyst

In this research, the effect of heating rate and different clay concentrations on light and heavy crude oils in limestone matrix was investigated by differential scanning calorimeter (DSC). In DSC experiments, two main distinct reaction regions were identified in all of the crude oil + limestone matrix + catalyst, known as low- and high-temperature oxidation respectively. It was observed that addition of clay to porous matrix significantly affected the thermal characteristics and kinetics of different origin crude oils. The Borchardt and Daniels and ASTM kinetic methods were used to determine the kinetic parameters of the samples. It was observed that activation energies generated for the high-temperature oxidation region for crude oil and crude oil + clay mixtures were in the range of 148-370kJmol(-1) for the Borchardt and Daniels method and 51-253kJmol(-1) for ASTM methods

Application of different EOR techniques for the energy and recovery of Ashal'cha oil field

In this research, utilizing the reservoir and produced oil data, different enhanced oil recovery (EOR) techniques known as in-situ combustion, CO2 flooding, and steam flooding were applied for Ashal'cha oil field in Republic of Tatarstan, Russia. For this purpose, In-Situ Combustion Predictive Model (ICPM), CO2 Miscible Flood Predictive Model (CO2PM) and Steam-flood Predictive Model (SFPM) are used. In addition to oil recovery, economic analysis of the discussed EOR applications was also conducted. By using the oil price forecast for 10 years, each EOR method is analyzed using their expenses and outcomes separately. Comparison among the EOR applications regarding the oil production, and economic feasibility was also given. Taking the reservoir and produced oil characteristics, oil production rate and economical payout time into account, it was observed that in-situ combustion is the most feasible and practical EOR method for Ashal'cha oil field

Determination of SARA fractions of crude oils by NMR technique

In this research, four different crude oils from Tatarstan oil fields with wide range of API gravities (from 16.6 to 32.5 degrees 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