Temperature-synchronized activation of cobalt acetylacetonate via enhancement of high-temperature oxidation of heavy oil

Interaction between saturates, aromatics and resins during pyrolysis and oxidation of heavy oil

Low temperature oxidation Air injection has the advantages of low energy consumption and low environmental pollution, and is an important means of heavy oil development. In order to study the change characteristics of heavy oil in Ji 7 well area of Xinjiang oilfield and the feasibility of air injection for oil displacement, dynamic oil displacement experiments were carried out by using one-dimensional combustion tube. The heat release and heavy oil characteristics of Ji 7 heavy oil at different ignition temperatures were studied. Thermogravimetric analysis and differential scanning calorimetry experiments were carried out by using TG/DSC thermal analyzer, combined with component analysis and thermal component analysis. The exothermic law and reaction mechanism of low temperature oxidation of Ji 7 heavy oil at different temperatures were analyzed by analytical kinetics analysis method. The feasibility of low temperature oxidation flooding technology by air injection was evaluated according to the reservoir characteristics. The results show that the oxidation of Ji 7 heavy oil can be divided into three stages: low temperature oxidation (LTO), fuel deposition (FD) and high temperature oxidation (HTO). Weak self-exothermic phenomena can be detected after oxidation of Ji 7 heavy oil at 40 ~C. After oxidation at 180 ~C, the combustion and deposition stage of Ji 7 heavy oil has obvious characteristics, the low temperature oxidation stage weakens, the high temperature oxidation stage migrates to the direction of lower temperature, DTG and DSC peaks. The value is more obvious, and the peak value of mass loss and heat flux is larger. Under reservoir temperature and pressure conditions, the oxidation of heavy oil and air is weak. After oxidation and pressurization of Ji 7 heavy oil, the thermal effect of low temperature oxidation of heavy oil is remarkable. It is suggested that pressurization start air injection development at higher initial temperature (about 350 C).KeywordsAir injectionLow temperature oxidationHeavy oilThermal analysisJi 7 well area

The induction phase is the first step of oxidation, after which initiation phase occurs and is characterized by 1H abstraction and increasing peroxide levels. Later, the propagation cascade phase is generated with significant chemical and structural modification of the oil's fatty acids, causing increased concentrations of aldehydes. The process is terminated by the formation of toxic polymerization end products. A rapid and efficient analytical method of the different steps of oil oxidation are herein describe. Using a TD 1H NMR sensor capable of measuring proton mobility, it is possible to follow the segmental motion of the 1H population in each of the oil's segments, as well as describing the proton relaxation signals generated from the magnetic field that can measure and characterize important chemical and physical properties of the tested sample. In our research group's recent work, we demonstrated the ability to quantitatively measure the rates of self-diffusion (D) as well as ILT T1 and T2 spectral fingerprints of heated oils to correlate these values with chemical and morphological changes during oxidation. To simplify and reduce the time required for characterizing oil quality and oxidation using a TD 1H NMR sensor the present study focused on the relationship between D and the thermal and air conditions for enhancing oil oxidation. An excellent (R2>0.95) correlation of D with oil oxidation's conventional colorimeter standard tests (e.g., PV, p-Anisidine and TOTOX) was shown. These results were obtained from a high temperature (80°C) oxidation study of a list of saturated, monounsaturated and polyunsaturated edible oils (linseed, soy, olive, coconut, butter, respectively). The study clearly showed that self-diffusion D values, reflecting the mobility of 1H protons, is an accurate and rapid (< 1 minute) marker/indicator for the oil's quality with emphasis on the oils oxidation status, that be measured and used in the oil industry.

Effects of kaolinite and its thermal transformation on oxidation of heavy oil

The oxidation of heavy oil to enhance oil recovery: The numerical model and the criteria to describe the low and high temperature oxidation

Isothermal oxidation behavior of heavy crude oil and its low-temperature oxidized oils: Implications for in-situ upgrading of heavy oil

Thermo-oxidative characteristics and kinetics of light, heavy, and extra-heavy crude oils using accelerating rate calorimetry

The oxidation of heavy oil: Thermogravimetric analysis and non-isothermal kinetics using the distributed activation energy model

A thermogravimetric (TG) experiment was conducted to study the oxidation process of a certain heavy oil sample mixing with quartz sand, and the oxidation process is described in detail by combining the multipeaks shape of TG curve with heavy oil's oxidation theory. Four stages of weight loss corresponding to earlier low temperature oxidation (LTO), later LTO, fuel deposition, and HTO(high temperature oxidation) were identified, and the demarcation points were clearly defined. Activation energy of each stage was figured by Flynn-Wall-Ozawa method. Compared with the conventional division method, four stages can describe the different stages of oxidation in more detail.

Comprehensive investigations into low temperature oxidation of heavy crude oil

This paper describes the effects of various amounts of oxygen on the oxidation of conventional oils and Athabasca bitumen and their coke-forming tendency. At any given oxygen concentration, the weight loss profile with an increasing temperature up to 500 °C during simultaneous thermal analysis (STA) shows the presence of two distinct regions: one below 400 °C, showing distillation/bond breaking and low-temperature oxidation, and the other beyond 400 °C, depicting fuel deposition combined with high-temperature oxidation and combustion of hydrocarbons. Heat-flow changes during oxidation show that exothermicity of the reaction is dependent upon the oxygen concentration as well as the heating rate. The activation energy of the oxidation step was calculated for each oxygen concentration using the Coats−Redfern method. The data showed a decrease in the activation energy with an increase in the oxygen concentration, showing dominance of different reactions under different O2 concentrations. The activation energy value for oxidation above 400 °C decreased from 72 kJ/mol in the presence of N2 to 30 kJ/mol in the presence of 21% O2. The effect of oxidation on the coke-forming tendency during pyrolysis for some oil fractions shows that, for a fixed sample amount, coke-forming propensity may increase or decrease depending upon the O2 concentration in the atmosphere above the sample. The extent of increase or decrease in coke-forming tendency varies for different petroleum oils. A Fourier transform infrared (FTIR) spectroscopy study of the sample before and after heating in inert or oxidative atmospheres shows that the presence of small amounts of O2 affect these samples to varying levels depending upon their chemical composition. Results also give proof of oxidative addition reactions taking place in the presence of O2 within the whole evaluated temperature range, spanning from about 300 to 500 °C.

The results of laboratory experiments on modeling of heavy oil oxidation processes in an air-oxygen environment using cobalt (III) acetylacetonate as catalyst at temperatures and pressures typical of thermal production methods are presented. It is established that the high-molecular components of the heavy oil are degraded in the air-oxygen environment at temperatures above 250°C in the presence of the catalyst with formation of low-boiling hydrocarbon fractions and oxygen-bearing compounds, and this reduces the density and viscosity of the transformed oil. In addition, the products obtained in the experiments show an increased asphaltene content and the presence of finely disperse carbonaceous substances, indicating the occurrence not only of cracking, but also of condensation processes. The experimental data indicate the main directions of the reactions and transformations of heavy oil hydrocarbon components in the studied systems, which provides the possibility of using cobalt acetylacetonate as a catalyst in the in-situ low-temperature oxidation of heavy oil in carbonate reservoirs.

This paper describes and illustrates a method for ensuring sustained combustion in coarse-grid, field-scale simulation using a kinetic-based model. For the example problem treated, as in several unreported cases, the method considerably extends the grid block size which can be tolerated without severe grid size effects. The method is applicable only in cases where one accepts the assumption that no free oxygen passes unreacted through the combustion front. The paper also presents and discusses results of very fine-grid one-dimensional simulations. Comparison of these fine-grid results with coarse-grid 1D results shows, for the particular problem data used, an unexplained, significant increase in amount of oil cracked with grid block size increased over the range of .5 feet to 10 feet. 2D areal, 5-spot pattern simulations show that the 9-point difference scheme very significantly reduces a large grid orientation effect in 5-point simulation of the combustion process.

A study on the catalytic oxidation of heavy residual oil (HRO) was carried out. The thermodynamic parameters of components of HRO oxidation products were studied by pulsed nuclear magnetic resonance (NMR). A method for the quantitative assessment of thermodynamic parameters of HRO components and oxidized bitumen using pulsed NMR is presented. The relationship between NMR parameters and the viscosity of HRO and its oxidation products is established. The obtained results prove the possibility of using pulsed NMR as a flow-line method for rapid analysis of intermediates and products of the heavy residual oil oxidation.

Low temperature oxidation of heavy oil in oxygen-reduced air: Effect of pressure and oxygen content on heat release