GEMAS: unmixing magnetic properties of European agricultural soil

High resolution magnetic measurements provide new methods for world-wide characterization and monitoring of agricultural soil which is essential for quantifying geologic and human impact on the critical zone environment and consequences of climatic change, for planning economic and ecological land use, and for forensic applications. Hysteresis measurements of all Ap samples from the GEMAS survey yield a comprehensive overview of mineral magnetic properties in European agricultural soil on a continental scale

Low-field NMR Method for Analysis of Heavy Oils without Extraction of Asphaltenes

For the analysis of heavy oil samples of the Ashalchinskoye deposit the combined nuclear magnetic resonance (NMR) method to measure the free-induction decay (FID) together with the Carr-Purcell-Meiboom-Gill (CPMG) echo signal's decay was used. The measurements were carried out on a NMR analyzer Chromatek-Proton 20M, operating at a frequency of 20 MHz. Special control program was created on the NMR analyzer, which automatically tunes and measures full FID curve, then switches to measuring the echo amplitudes decay by the CPMG pulse sequence, and the study is completed by co-processing together all experimental data. This technique makes it possible to measure the amplitudes of the NMR signals and the relaxation times T2 of the protons of heavy oil components in situ, including asphaltenes, without introducing any perturbations into the analyzed system. Under the influence of paramagnetic centers included to the composition of asphaltene, mainly vanadyl complexes on EPR data, the amplitude-relaxation characteristics of protons in the samples are divided into 6 groups related to solid asphaltenes (in crystalline and amorphous states), resins (high and low density), aromatic and saturated compounds.297-30

Detecting active faults and tracing fractured zones using DEM processing

This article describes the technique and results of digital DEM digital processing conducted for the territory of a small oilfield. The study aims to obtain information on rock mass natural fracturing and fluid dynamics. Although only one particular case is described here, the proposed technique is universal and can be applied to any flat area with developed erosional system (within the platforms). Results of DEM digital processing in conjunction with oil content data, geochemical sampling and high-precision gravimetry were used to discover zones of excessive fracturing and fluid dynamic activity in sedimentary cover. Also, block model of the oilfield was constructed, and reconstruction of geodynamic processes in the active microblocks junction zones was carried out

Анализ компонентного состава и свойств тяжёлых нефтей in situ методом ЯМР релаксации в низких магнитных полях

Для анализа тяжелых нефтей использовали метод одновременного измерения сигнала свободной индукции (СС И) вместе с релаксационным затуханием амплитуд эхо-сигналов в импульсной последовательности Кара-Парселла-Мейбума-Гилла (КПМГ). Измерения проводили на ЯМР релаксометре "Хроматек-Протон 20М", работающем на частоте 20 МГц. Была создана специальная программа управления, которая автоматически настраивает прибор на резонансные условия, измеряет полную кривую СС И, переключается на измерение амплитуд сигналов эха в серии КПМГ, а затем выполняет совместную обработку экспериментальных данных. Этот метод позволяет измерять амплитуды сигналов ЯМР и времена релаксации Т2 протонов всех компонентов тяжелой нефти in situ, включая асфальтены.308-32

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

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

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

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 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