Low-temperature Oxidation Of Heavy Oil Research Articles

Evolution of the Pseudo-Components of Heavy Oil during Low Temperature Oxidation Processes

Heavy oil was divided into different pseudo-components according to their boiling ranges through a real-boiling point distillation process, and the oxidation products for pseudo-components with a boiling range higher than 350 °C were systematically investigated during low temperature oxidation (LTO). Kinetic cell (KC) experiments were conducted under different ambient pressure conditions and temperature ranges, and the oxidation products were characterized using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). The results indicate that the oxygen addition and cracking reactions typically occur in the temperature intervals of 140–170 °C and 180–220 °C, respectively, at the given heating rate of 3.83 °C/min. Components with the mass-to-charge ratio in the region of 250–450 Da mainly evaporate in the temperature regions of 25–150 °C, which results in losses from the fraction. Considering the gas-liquid multi-phase reaction, the pseudo-components with low boiling range distributed on the surface of the liquid film are prone to generate high molecular weight compounds through oxygen addition. In contrast, the high boiling point range fractions increase in molecular weight through oxygen addition and are then subject to further cracking processes that generate lower molecular weights in the region of 200–400 Da. N1O3- and N1O4- containing compounds were determined by high resolution mass spectra, and these compounds were generated through oxygen addition of basic N1-containing compounds. On the basis of these reactions and the experimental results obtained, some insights related to the LTO of heavy oil, which are highly valuable for ISC field applications, are summarized.

Evaluation of heat release caused by low-temperature oxidation of heavy oil and its SARA fractions under isothermal conditions

During in-situ combusiton, the oils in most of the area before the combustion front encounter low-temperature oxidation (LTO) reactions under relatively isothermal conditions in a long time, and heat release of LTO significantly influences the quality of formed fuel. This work is aimed at examining the heat release of LTO of one Xinjiang heavy oil and its saturates-aromatics-resins-asphaltenes fractions using isothermal high-pressure differential scanning calorimetry tests. Furthermore, the widely-accepted LTO reaction pathways of hydrocarbons are summarized. The results indicated that the Xinjiang heavy oil, aromatics, and resins experienced the increased heat release from 200 to 250 ℃ and from 300 to 350 ℃ due to their elevated oxidation rate, and the decreased heat release from 250 to 300 ℃. Thus, to build a stable combustion of the oil, it is key to overcome the action energy barriers between 250 and 300 ℃.

Effects of clay minerals on the low-temperature oxidation of heavy oil

In situ combustion (ISC) is an efficient method to recover heavy oil, in which low-temperature oxidation (LTO) is an important process. A fixed-bed reactor was used to conduct ramped temperature oxidation experiments on a mixture of heavy oil from China, silica and clay minerals, including montmorillonite, kaolinite, illite and chlorite. The four clay minerals promoted the LTO of heavy oil, which was reflected in the increase in the total amount of O2 consumption with the decrease in the peak temperature and the change in the composition and yield of gas, liquid and solid products. The total amounts of CO and CO2 release increased, and the peak temperature decreased. The total amount of hydrocarbons in the gas phase decreased, whereas the peak temperature and main components didn’t change. The presence of clay minerals showed little effect on the composition of produced oil, whereas the presence of montmorillonite decreased the yield of produced oil. The yield and O/C ratio of coke increased, the heat value of coke decreased and the oxidation activity of coke improved in the presence of clay minerals. Montmorillonite showed the most notable effect. The mechanism of the effects of clay minerals on the LTO of heavy oil was analyzed by combining the change in the distribution proportion of O and C in products. Montmorillonite had large specific surface area and adsorption capacity and catalyzed decarbonylation, decarboxylation and polycondensation. The other three clay minerals mainly affected the LTO of heavy oil through the catalysis of decarbonylation, decarboxylation and polycondensation.

Comprehensive investigations into low temperature oxidation of heavy crude oil

Due to the significance of low temperature oxidation (LTO) process on the subsequent oxidation reactions and oil recovery for in situ combustion (ISC), this work aimed at conducting a series of comprehensive investigations into LTO of heavy crude oil. The LTO behavior of heavy oil was analyzed by static oxidation experiments. Then the alterations in oil characteristics due to LTO were investigated through coke content measurements, flammability tests and scanning electron microscopic (SEM) observations. Additionally, the effect of LTO on thermal behavior and kinetics of heavy oil was researched using thermogravimetry (TG)/differential scanning calorimetry (DSC) technique. The results showed that the temperature played a crucial role in LTO of heavy oil. Almost no coke was deposited at 80 °C. The amount of coke deposition at 160 °C averaged 0.346 g coke/g oil, which was roughly 4.2 times higher than that at 120 °C. The oxidized oil at 160 °C possessed the most superior flammability at ambient temperature and atmospheric pressure in comparison to that at 80 and 120 °C. The surface morphologies of oxidized oil at 160 °C and its formed coke were quite rough, which boosted the subsequent combustion reactions. The results of TG/DSC unravelled that the oxidized oils were subjected to higher mass loss and exothermic effect at the fuel deposition (FD) and high temperature oxidation (HTO) stages as compared to crude oil. After the static LTO, the activation energy in the LTO and FD stages for heavy oil was increased, while that in the HTO stage was reduced. Compared with crude oil and oxidized oils, the coke deposited during the static LTO presented the highest thermal release and reaction activity in the HTO interval. This paper can provide some new insights regarding LTO mechanisms of heavy oil to rich the ISC technology.

Study of the catalytic effect of copper oxide on the low-temperature oxidation of Tahe ultra-heavy oil

The heavy metal compounds existing in a reservoir have a significant catalytic effect on the low-temperature oxidation of heavy oil during the in situ combustion (ISC) process. This study focused on the thermal behavior of Tahe ultra-heavy oil and the catalytic effect of copper oxide on low-temperature oxidation to probe into the applicability of the ISC technique. For this purpose, three samples, including Tahe crude oil, oxidized oil and oxidized oil-CuO, were studied by performing thermogravimetry (TG)/derivative thermogravimetry (DTG) and differential scanning calorimetry (DSC) with three different heating rates (5–10 and 15 °C min−1) at temperatures ranging from 30 to 830 °C. The result indicated that more fuel was produced to cause more exothermic heat in the high-temperature oxidation (HTO) zone as the heating rate increased. Kinetic parameter calculation detected that the activation energy of the crude oil was 13.73 kJ mol−1 in the low-temperature oxidation (LTO) stage and 131.72 kJ mol−1 in the HTO stage, respectively. Compared with TG/DSC analysis and the activation energy of the three samples, the activation energy of oxidized oil was reduced obviously in the HTO zone by the crude oil. Additional CuO accelerated fuel deposition in the low-temperature region with no reduction in the activation energy, revealing that CuO has a catalytic effect on Tahe crude oil to cause fuel deposition in LTO. Based on the comprehensive thermal performance and kinetic characterization of the crude oil, 69.61% of the crude oil remained in the final LTO, which can be oxidized as coke to supply sufficient fuel for the HTO stage. This finding indicates that the ISC technique may be feasible for Tahe oilfield development.

Low-Temperature Oxidation of Heavy Oil in Carbonate Medium Using Cobalt (III) Acetylacetonate as Catalyst

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.

Catalytic effect of zinc naphthenate on the heavy oil low-temperature oxidation in an air injection process

ABSTRACTAir-assisted steam flooding is a new effective technique for enhanced oil recovery in heavy oil reservoirs. The authors prepared zinc naphthenate as the catalyst in the laboratory and the investigated effects on low-temperature oxidation of heavy oil through the isothermal reactor. The results indicated that zinc naphthenate could accelerate the oxygen consumption rate and facilitate the cleavage reaction in the low-temperature oxidation process. The data shed more light on the mechanisms of low-temperature oxidation reactions of heavy oil and can provide a new way to enhance the recovery of heavy oil reservoir.

Effect of water on the low-temperature oxidation of heavy oil

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEffect of water on the low-temperature oxidation of heavy oilDonald G. Lee and Nazih A. NoureldinCite this: Energy Fuels 1989, 3, 6, 713–715Publication Date (Print):November 1, 1989Publication History Published online1 May 2002Published inissue 1 November 1989https://doi.org/10.1021/ef00018a009RIGHTS & PERMISSIONSArticle Views243Altmetric-Citations37LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (404 KB) Get e-Alerts Get e-Alerts