Low-temperature oxidation and thermal kinetics analysis of light and medium crude oils

In this research, low-temperature oxidation (LTO) and thermal kinetics analysis of light and medium crude oils were analyzed by static isothermal experiments and thermogravimetry (TG). The results elucidated that, during LTO process, medium oil possessed stronger oxygen consumption capability than light oil and oxygen addition was the dominating reaction path for both light and medium oils; more heavy components contained in medium oil were oxidized to form higher molecular-weight material with lower H/C. In TG experiments, three main reaction zones were identified known as LTO, fuel deposition (FD) and high-temperature oxidation (HTO). Compared with light oil, LTO range and corresponding mass loss were lowered for medium oil with more oxygenated compounds left behind to be converted into coke materials. The activation energy for medium oil were higher than that for light oil in LTO stage while less in HTO stage owing to the difference of oil components.     

Effect of low-temperature oxidation of light oil on oil recovery during high pressure air injection

In this research, the low-temperature oxidation (LTO) behavior of light oil was evaluated via isothermal oxidation tube experiments. Also, the core model together with nuclear magnetic resonance (NMR) analyzer was implemented to explore the effect of LTO of light oil on oil recovery during high pressure air injection (HPAI). The results indicated that the polycondensation reaction of light components (C₅-C₆) and intermediate ones (C₇-C₁₇) for light oil was the preferred reaction path during LTO process. The oxygen addition was the primary oxidation reaction in LTO, but the LTO reaction presented a more favorable trend for the bond scission with the oxidation degree. Because of the gas flow steering resulting from property variation of light oil and heat release determined by LTO, the total oil recovery yielded by air flooding was 8.82% higher than nitrogen flooding.     

Low-temperature isothermal oxidation of crude oil

In this work, the low-temperature oxidation (LTO) characteristics of different API gravity crude oils, involving one light, one medium, and one heavy, are studied comprehensively from the aspects of effluent gas, oxidized oil, and pressure drop. The results reveal that heavy oil exhibits faster LTO reaction rate and stronger O₂ consumption capability compared with lighter ones. There are a certain amount of carbonaceous deposits in oxidized oils and the carbonation progress of heavy oil is brought to a deeper degree. The pressure drop rule of oil samples is speculated to be the consequence of “skin effect” and crude oil with more heavy species shows higher oxidation activity, which contributes to an improved understanding about the LTO mechanism from the molecular perspective and needs further research.     

Comparative Study of Light and Heavy Oils Oxidation Using Thermal Analysis Methods

In this work, the oxidation behavior of light and heavy oils was investigated by combining TG-DTA test and oxidation tube experiments, in the presence and absence of cuttings, respectively. Results show that high content heavy components benefit low-temperature oxidation (LTO) performance and heavy oil has better oxidation activity at low temperature and is more easily oxidized. All samples undergo an endothermic reaction during the LTO stage and the faster the LTO rate is, a larger amount of energy is absorbed by oil, and more heat is released in the high-temperature oxidation stage. An excellent consistency is found between thermokinetic analysis and oxidation tube experiment results.     

Analysis of the thermal hydrocracking of heavy fuel oil

The thermal hydrocracking of Mexican heavy fuel oil was studied at 1200 psia and different reaction temperatures (370, 380, 390 and 400°C). The results show that the vacuum residue which constitutes 62 wt. % of the heavy fuel oil and contains 47 wt. % resins and 23.3 wt. % asphaltenes, reacts to form lighter hydrocarbons (IBP-540°C), solid and gas. Resins transform more easily to saturates, and gases are produced mainly from the asphaltene fraction, indicating that the terminal alkyl groups in this fraction are shorter than those present in the resin fraction. The C-C scission reactions dominate the transformation of heavy fuel oil in the interval from 370 to 390°C, whereas the carbon rejection reactions are dominant at 400°C. Finally, the thermal hydrocracking of heavy fuel oil at 390°C appears suitable since at this temperature the reaction produces the greater amount of atmospheric distillates (+20.5 wt. %) and a low content of solid (2.0 wt. %) and gas (2.1 wt. %).     

Improvement of heavy oil recovery and role of nanoparticles of clay in the surfactant flooding process

Increasing demand and dwindling supply of crude oil have spurred efforts toward enhancing heavy oil recovery. Recently, applications of nanoparticles (NPs) for heavy oil recovery have been reported. In this study, the use of clay NPs is investigated for enhanced oil recovery. Surfactant solutions and newly developed nanosurfactant solutions with 1600–2000 ppm SDS were tested. The crude oil had a viscosity of 1320 mPa.sec at test conditions. In this study, the role of NPs in the adsorption of surfactant onto solid surfaces of reservoir core is studied. The core flooding experiments showed high potential of using nanoclay for enhancing heavy oil recovery, where 52% of surfactant flooded heavy oil was recovered after injecting the NPs solvent. Moreover, nanoclay has generally better performance in enhancing the oil recovery at surfactant solution, near CMC conditions. The nanoclay surfactant solutions improved oil recovery. The nanoclay, however, showed improved performance in comparison with clay.     

The low temperature oxidation characteristics of SARA fractions in air flooding process

The Low Temperature Oxidation (LTO) characteristics of SARA fractions isolated from light crude oil were studied applying the static oxidation experiments. The results show that the LTO reaction of SARA fractions can occur when temperature is above 50°. Under reservoir conditions, the oxidation activities of the SARA fractions were resin > aromatics > saturate. The theoretical LTO reaction rate of crude oil calculated based on the SARA oxidation characteristics is in good agreement with the measured value. Therefore, it is an effective method to reveal the LTO mechanism of crude oil by studying the LTO mechanism of SARA fractions.     

注空气开采过程中稠油结焦量影响因素

通过建立油藏高温、高压反应模拟实验装置,物理模拟了稠油注空气开采过程中焦炭的生成过程,研究了反应气氛、温度、压力以及空气通风强度对稠油生焦量的影响。研究表明：在空气气氛下,原油低温氧化显著促进了焦炭生成,5 MPa反应压力下,每克稠油最高焦炭生成量为0.375 g,是氮气气氛下最高生焦量的2.5倍,焦炭初始生成温度受低温氧化影响比氮气条件降低了近200℃。随压力升高,加剧的低温氧化反应提高了焦炭生成量,但是5 MPa后压力影响不再显著。随空气通风强度增加,生焦量并非持续增加,而是在33.4 N·m³/（m²·h）附近存在极值。进一步对比分析了焦炭的高温氧化消耗与原油组分蒸馏失重对焦炭生成量的影响。其结果表明,焦炭氧化是空气气氛下温度自225℃升高至300℃过程中焦炭净生成量减少的主要原因。在氮气气氛下,随温度升高至450℃,加剧的原油热解缩聚反应增加了生焦量,但温度进一步升高引起焦炭自身热解失重,生焦量降低。另外,实验还发现,当温度超过200℃时,反应管内油砂中心温度超过外壁面加热控制温度。分析表明,超温现象由原油组分的低温氧化和部分活性较强的焦炭高温氧化引起,因此该稠油存在油层自燃点火的应用潜力。     

THE EFFECT OF LOW TEMPERATURE OXIDATION ON THE CHEMICAL AND PHYSICAL PROPERTIES OF MALTENES AND ASPHALTENES DERIVED FROM HEAVY OIL

The chemical changes that occur when the maltene and asphaltene fractions (separated from heavy oil) are subjected to low temperature oxidation (LTO) in the presence and absence of water have been investigated by a combination of classical separation techniques and analytical pyrolysis. In general, it is observed that water has a mitigating effect on the destructive nature of LTO. A detailed analysis of the pyrolytic products suggests that the presence of water reduces the ease with which oxygen reacts with sulfides to give sulfones and thereby supresses the formation of coke. An analysis of the data indicates that most of the coke produced results from LTO of the asphaltenes; only a small portion originates in the maltenes.     

THE EFFECT OF LOW TEMPERATURE OXIDATION ON THE CHEMICAL AND PHYSICAL PROPERTIES OF MALTENES AND ASPHALTENES DERIVED FROM HEAVY OIL

Abstract

The chemical changes that occur when the maltene and asphaltene fractions (separated from heavy oil) are subjected to low temperature oxidation (LTO) in the presence and absence of water have been investigated by a combination of classical separation techniques and analytical pyrolysis. In general, it is observed that water has a mitigating effect on the destructive nature of LTO. A detailed analysis of the pyrolytic products suggests that the presence of water reduces the ease with which oxygen reacts with sulfides to give sulfones and thereby supresses the formation of coke. An analysis of the data indicates that most of the coke produced results from LTO of the asphaltenes; only a small portion originates in the maltenes.     

Effect of reaction temperature and hydrogen donor on the Ni0@graphene-catalyzed viscosity reduction of extra heavy crude oil

Ni⁰@graphene nanocomposites were prepared via a solvothermal method and used as the catalysts for the viscosity reduction of extra heavy crude oil. Higher graphene content in Ni⁰@graphene nanocomposite has an adverse effect on its catalytic activity. The addition of tetralin and higher reaction temperature can obviously promote the catalytic activity. The catalyst accompanied by hydrogen donor can attain a viscosity reduction rate of 84.3% after the catalytic reaction under 280°C for 24 h and reduce the viscosity of crude oil from 174,219 to 27,352 mPa s (measured at 50°C).     

Influence of nanosized iron oxides (II,III) on conversion of biodegradated oil

In the given paper, we evaluate the efficiency of iron oxide (magnetite in the form of water suspension) nanoparticles (50-120?nm) in intensification of cracking reactions of heavy components of biodegradated oil. The physical simulation of thermal influence on heavy oil in the presence of synthesized catalyst (concentration = 0.3%) was carried out in autoclave at temperature ranges of 150-300°С and reaction period of 24?hours. According to the results of SARA-analysis and dynamic viscosity measurements, the destructive hydrogenation processes that were catalyzed by iron oxide were conducted already at 200°С. However, the significant effect was achieved at 300°С (the degree of viscosity reduction was higher than 67%).     

Clean aquathermolysis of heavy oil catalyzed by Fe(III) complex at relatively low temperature

In order to develop a clean catalyst for aquathermolysis of heavy oil at relatively low temperature, a series of water-soluble Fe(III) complexes were prepared as the catalysts for the catalytic aquathermolysis of heavy oil. Under the optimized condition, the adding amount of Fe-3 (a complex of Fe(III) and citrate) is 0.1%, the reaction temperature is 180°C, and the reaction time is 24 h, the heavy oil viscosity reduction ratio reaches to 80.1% (40°C). Results of the composition analysis show that the contents of resin and asphaltene decrease and the saturated hydrocarbon and aromatic increase. GC analysis shows that the light components increase remarkably after the aquathermolysis.     

THE EFFECT OF PRESSURE ON OXIDATION KINETICS OF TAR FROM A TARMAT RESERVOIR

ABSTRACT

The oxidation kinetics of a tar with physical and chemical characteristics similar to those of a reservoir tar were studied employing a variable-temperature oxidation reactor. Mixed with clean, loose sand, the tar showed oxidation behavior typical of heavy crudes with LTO and HTO peaks in oxygen consumption. Higher pressures caused larger LTO-oxygen consumption, lower HTO-oxygen consumption, lower HTO-peak temperatures, higher apparent H/C ratio of fuel, and lower HTO activation energy. All these effects are attributed to suppression of light-end evaporation at low temperatures. Compared with clean sand, natural crushed-core material promoted LTO of the tar but did not alter HTO parameters significantly. With HTO-peak temperatures and activation energies above 500°C and 100 kJ/mol, respectively, the tar is not expected to provide for sustained in-situ combustion in the reservoir.     

KINETICS OF HYDRODESULFURIZATION OF HEAVY GAS OIL DERIVED FROM OIL-SANDS BITUMEN

ABSTRACT

With gradual shortage in the supply of crude oil, the importance of producing synthetic crude oil from oil sands and shale oil is increasing day by day. In the present paper, the effects of various process variables such as temperature, liquid hourly space velocity and hydrogen/heavy gas oil volumetric ratio on the removal of sulfur compounds from oil sands derived heavy gas oil has been studied. The experiments have been carried out in a micro scale trickle bed reactor over a commercial Ni–Mo catalyst. The temperature, liquid hourly space velocity and hydrogen/heavy gas oil volumetric ratio have been varied from 365 to 415°C, 0.5 to 1.9 h^?1 and 400 to 1000 ml, respectively. Under optimum reaction conditions over 96% conversion of sulfur compounds was achieved. The kinetics of the rate of sulfur removal from the oil sands derived heavy gas oil has also been discussed in this article.     

Silica nanofluid flooding for enhanced oil recovery in sandstone rocks

Enhanced oil recovery is proposed as a solution for declining oil production. One of the advanced trends in the petroleum industry is the application of nanotechnology for enhanced oil recovery. Silica nanoparticles (SiNPs) are believed to have the ability to improve oil production, while being environmentally friendly and of natural composition to sandstone oil reservoirs.In our work, we investigated the effect of silica nanoparticles flooding on the amount of oil recovered. Experiments were carried using commercial silica of approximately 20 nm in size. We used sandstone cores in the core flooding experiments. For one of the cores tertiary recovery is applied where brine imbibition was followed by nanofluid imbibition. While in the other cores secondary recovery was applied where primary drainage is directly followed by nanofluid imbibition. We investigated the effect of concentration of nanofluid on recovery; in addition, residual oil saturation was obtained to get the displacement efficiency. Silica nanofluid of concentration 0.01 wt%, 0.05 wt%, 0.1 wt% and 0.5 wt% were studied.The recovery factor improved with increasing the silica nanofluid concentration until optimum concentration was reached. The maximum oil recovery was achieved at optimum silica nanoparticles concentration of 0.1 wt%. The ultimate recovery of initial oil in place increased by 13.28% when using tertiary flooding of silica nanofluid compared to the recovery achieved by water flooding alone. Based on our experimental study, permeability impairment was investigated by studying the silica nanoparticles concentration, and the silica nanofluid injection rate. The permeability was measured before and after nanofluid injection. This helped us to understand the behavior of the silica nanoparticles in porous media. Results showed that silica nanofluid flooding is a potential tertiary enhanced oil recovery method after water flooding has ceased.     

Application of “Micro-demolition Atomization” Theory in Feedstock Atomization for RFCCU

Abstract

Based on the “Micro-demolition Atomization” theory of emulsified heavy oil combustion, the heavy oil catalytic cracking feedstock was emulsified by compound nonionic surfactant. The water was dispersed uniformly into oil with drops about 1–5 µm, and could be formed stable water-in-oil emulsion with oil. After being in contact with high temperature regenerated catalyst, the emulsified feedstock was atomized demolishedly, which changed atomization mode and reduced the diameters of liquid drops to about 5 µm, enhanced the effect of catalytic cracking reaction, improved the selectivity of coke and increased the recovery of light oil. The pilotscale test result of catalytic cracking showed that, compared with unemulsified feedstock under the same conditions, the recovery of light oil was increased by 2–3%, the yield of coke was reduced by 0.5–1.0%, and the yield of dry gas was reduced by 0.5–1.5%,respectively. The application of the “Micro-demolition Atomization” theory in the feedstock atomization of the heavy oil catalytic cracking would change traditional atomization mode, and affect the catalytic cracking of the heavy oil significantly.     

Application of Bacterium HY9 Strain for Diesel Oil Denitrogenation

HY9 was used in the denitrogenation of diesel oil. The nitrogen removal ratio of diesel oil increased from 12.9% to 16.7% when the surfactant Tween80 was added and the optimal addition content of Tween80 was 0.175 g/25 mL diesel oil. Higher shaking speed could reduce the size of emulsion droplets formed by oil and water, and improve the dissolved oxygen content and the nitrogen removal efficiency. The optimal conditions were 3 mL bacterial suspension/100 mL mixed liquor and 250 rpm shaking speed. Repeated denitrification almost has no effect on denitrogenation efficiency.     

还原态铁氧化物对重质生物油的提质改性

以生物质热解获得的重质生物油作为研究对象,将铁氧化物负载到硅氧纤维上制备了复合铁基载氧体,以其还原态对重质生物油进行脱氧改性,反应条件为温度350℃、压力1.48 MPa。通过比较部分脱氧反应前后的重质生物油及载氧体组成和结构的变化,发现重质生物油组分中的氧元素被部分转移至载氧体中,重质生物油中氧元素质量分数由29.83%降低至26.12%,还原态载氧体(Fe₃O₄/FeO)被氧化为Fe₃O₄;计算得到重质生物油的有效氢/碳摩尔比由0.67增加至0.80,增加近18.44%,其热值增加至27.6 MJ/kg;组分中繁杂的有机组分大多缩合为羧酸和酚类,酮、醛类物质大幅度降低,碳氢化合物明显增多;继而添加乙醇进行催化酯化反应,则重质生物油中主要组分变为脂类和酚类,油品质有了明显改善。而复合于硅氧纤维的铁载氧体,再还原后结构稳定,可用于油品部分脱氧的多次循环。     

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 148–370 kJmol^?1 for the Borchardt and Daniels method and 51–253 kJmol^?1 for ASTM methods.