Behavior and Effect of SARA Fractions of Oil During Combustion

2000 ◽  
Vol 3 (05) ◽  
pp. 380-385 ◽  
Author(s):  
M.V. Kok ◽  
C.O. Karacan
Keyword(s):  
Low Temperature ◽  
Crude Oil ◽  
Combustion Process ◽  
Crude Oils ◽  
Low Temperature Oxidation ◽  
In Situ Combustion ◽  
Temperature Oxidation ◽  
Sara Fractions ◽  
Fuel Deposition

Summary In this study, saturate, aromatic, resin, and asphaltene fractions of two Turkish crude oils (medium and heavy) were separated by column chromatographic techniques. Combustion experiments were performed on whole oils and fractions by a thermogravimetric analyzer (TG/DTG) and differential scanning calorimeter (DSC) by using air and a 10°C/min heating rate. TG and DSC data were analyzed for the determination of weight loss due to possible reactions, and for reaction enthalpies of individual fractions, which have to be known for in-situ combustion technology utilization. Introduction In-situ combustion is a process of recovering oil thermally, by igniting the oil to create a combustion front that is propagated through the reservoir by continuous air injection. Success of such a process depends mainly on the crude oil properties and rock properties as well as operational conditions. In-situ combustion is considered as an effective process not only for heavy oil reserves but also for depleted light and medium oil reservoirs. Unfortunately, the lack of better understanding of the process variables in terms of the conversion of oil during combustion and reservoir characteristics, as well as the costs, limits the more effective application of this technology. In combustion, three different reaction regions were identified, known as low-temperature oxidation, fuel deposition, and high-temperature oxidation. In low-temperature oxidation (LTO), mainly small and weak chains of hydrocarbons are broken and pyrolyzed and oxidized to give ketones, alcohols, etc. In fuel deposition or middle-temperature oxidation, products of low-temperature oxidation are transformed to heavier hydrocarbons to be combusted at higher temperatures. High-temperature oxidation (HTO) is the main combustion region where hydrocarbons are fully oxidized by air. During the course of these processes, hydrocarbons are continuously converted to other types of hydrocarbons, which makes the combustion process very complicated. Heat values and reaction parameters of crude oils are also obtained from differential scanning calorimeter (DSC) thermogravimetry (TG/DTG) experiments. Many studies have been conducted on different phases of the in-situ combustion process, mainly on the fluid and rock interactions during combustion of the fluid phase. Vossoughi et al.1 concluded that the addition of clay to porous media significantly affected the combustion of crude oil. Bae2 investigated the thermo-oxidative behavior and fuel forming properties of various crude oils. The results indicated that oils could be classified according to their oxidation characteristics. Vossoughi3 has used TG/DTG and DSC techniques to study the effect of clay and surface area on the combustion of selected oil samples. The results indicate that there was a significant reduction in the activation energy of the combustion reaction regardless of the chemical composition of additives. Vossoughi and Bartlett4 have developed a kinetic model of the in-situ combustion process from thermogravimetry and differential scanning calorimeter. They used the kinetic model to predict fuel deposition and combustion rate in a combustion tube. Kok5 characterized the combustion properties of two heavy crude oils by DSC and TG/DTG. Individual fractions of the crude oils have been studied before in a variety of purposes in different reactions. Ciajolo and Barbella6 used thermogravimetric techniques to investigate the pyrolysis and oxidation of some heavy fuel oils and their separate paraffinic, aromatic, polar, and asphaltene fractions. The thermal behavior of fuel oil can be interpreted in terms of the low-temperature phase in which the polar and asphaltene fractions pyrolyze and leave a particular carbon residue. Ranjbar and Pusch7 studied the effect of oil composition, characterized on the basis of light hydrocarbons, resin, and asphaltene contents, on the pyrolysis kinetics of the oil. The results indicate that the colloidal composition of oil, as well as the transferability and heat transfer characteristics of the pyrolysis medium, has a pronounced influence on the fuel formation and composition. Karacan and Kok8 studied the pyrolysis behavior of crude oil saturate, aromatic, resin, and asphaltene (SARA) fractions to determine the effect of each constituent to the overall pyrolysis behavior of oils. Several authors, such as Geffen,9 Iyoho,10 and Chu11 have conducted feasibility studies for the in-situ combustion process. Yannimaras and Tiffin12 applied the accelerating rate calorimetry to screen crude oils for applicability of the air-injection/in-situ combustion process. Testing was performed at reservoir conditions for four medium and high gravity oils and results were compared with the combustion tube and air-injection/in-situ combustion process on the basis of continuity of the resulting plot in the region between the LTO and HTO reactions. Although combustion studies on both oil samples and oil-rock mixtures had been conducted, studies on the behavior of crude oil SARA fractions under an oxidizing environment and the investigations on the effects of each of these fractions to the whole oil combustion process have been scarce. This research was conducted to fulfill this partial need in the field of crude oil combustion. The results are aimed to serve for better understanding and accurate modeling of in-situ combustion by using the effects of individual fractions on whole oil combustion. This enables the operators to adapt the changes in the compositional properties of oil during combustion and fine tune the operational parameters.

Low-Temperature-Oxidation Reaction Kinetics and Effects on the In-Situ Combustion Process

1974 ◽  
Vol 14 (03) ◽  
pp. 253-262 ◽  
Author(s):  
Mahmoud K. Dabbous ◽  
Paul F. Fulton
Keyword(s):  
Porous Medium ◽  
Low Temperature ◽  
Crude Oil ◽  
Partial Oxidation ◽  
Combustion Process ◽  
Oxidation Reactions ◽  
In Situ Combustion ◽  
Temperature Oxidation ◽  
Partial Oxidation Reactions

Abstract The kinetics of low-temperature oxidation (LTO) of crude oils in porous media was studied. Isothermal integral reactor data were analyzed to obtain rate equations for the over-all rate of the partial oxidation reactions at temperatures below partial oxidation reactions at temperatures below 500 deg. F. The reaction order with respect to oxygen was found to be between 0.5 and 1.0. The order of the reaction was dependent upon the crude but independent of the properties of the porous medium. The activation energy of the reaction was insensitive to the type of crude or porous medium and is in the neighborhood of 31,000 Btu/lb mol. LTO reactions were found to be in the kinitics-influenced region. The measured reaction rates for a 19.9 deg. API and a 27.1 deg. API crude indicated higher oxidation rates under similar reaction conditions for the higher API gravity crude. Light crudes appear to be m ore susceptible to partial oxidation at low temperatures because of the react ed oxidation reactions rather than by carbon oxidation. Other information includes the fraction of reacted oxygen utilized in carbon atom oxidation by the LTO reaction and the molar ratio of CO2 and CO produced in the low-temperature region. Effect of partial oxidation of the crude on the in-situ combustion process was studied by experimentally simulating the zones preceding the combustion front where temperatures and injection rates of linear reservoir model were programmed with time according to a predesigned schedule. Oxidation of the crude at temperatures below 400 deg.F had significant effects on the behavior of the crude-oil/water system in the porous medium at elevated temperatures and on the fuel available for combustion. A substantial decline in the recoverable oil from the evaporation and cracking zones, an increase in fuel deposition, and drastic changes in fuel characteristics and coked sand properties were obtained when the crude was subjected to LTO during the simulation process. Introduction The application of thermal energy to petroleum reservoirs as a means of increasing crude oil recovery has been given a great deal of attention. In underground combustion, thermal energy is induced by the partial burning of the crude oil in situ. The production of heat by the exothermic oxidation reactions of the hydrocarbons constitutes a unique feature of the in-situ combustion process. The chemical reactions and the accompanying heat released create a new temperature profile and cause drastic redistribution in the reservoir fluid saturations. With oxygen available in the transient zones of variable temperature and hydrocarbon saturations, several oxidation reactions of differing nature can take place during an underground combustion process. Because of the complex composition of process. Because of the complex composition of crudes and the great number of reaction products that can be produced, it is convenient to classify the hydrocarbon oxidation reactions ascombustion reactions that take place in the high-temperature combustion zone (above 600 deg. F) with CO2, CO, and H2O as the principal reaction products andpartial oxidation or low-temperature products andpartial oxidation or low-temperature (LTO) reactions that occur in zones where the temperature is lower than 600 deg. F. Several partial oxidation reactions are known to take place, producing primarily water and oxygenated producing primarily water and oxygenated hydrocarbons such as carboxylic acid aldehydes, ketones, alcohols, and hydroperoxides. High-temperature combustion reactions are desirable because they generate most of the heat required for the in-situ combustion process. Partial oxidation reactions, on the other hand, are in most cases undesirable because of their adverse effect on the viscosity and distillation characteristics of the crude. SPEJ P. 253

Chemical-structural properties of the coke produced by low temperature oxidation reactions during crude oil in-situ combustion

Fuel ◽  
2017 ◽  
Vol 207 ◽  
pp. 179-188 ◽  
Author(s):  
Qianghui Xu ◽  
Zhiming Liu ◽  
Hang Jiang ◽  
Qiang Zhang ◽  
Cheng Zan ◽  
...  
Keyword(s):  
Low Temperature ◽  
Crude Oil ◽  
Structural Properties ◽  
Oxidation Reactions ◽  
Low Temperature Oxidation ◽  
In Situ Combustion ◽  
Temperature Oxidation

Kinetics of Wet In-Situ Combustion: A Review of Kinetic Models

2014 ◽  
Author(s):  
E. A. Cavanzo ◽  
S. F. Muñoz ◽  
A.. Ordoñez ◽  
H.. Bottia
Keyword(s):  
Kinetic Model ◽  
Crude Oil ◽  
Kinetic Models ◽  
Combustion Front ◽  
Chemical Interaction ◽  
Combustion Process ◽  
Oxidation Reactions ◽  
In Situ Combustion ◽  
Temperature Oxidation

Abstract In Situ Combustion is an enhanced oil recovery method which consists on injecting air to the reservoir, generating a series of oxidation reactions at different temperature ranges by chemical interaction between oil and oxygen, the high temperature oxidation reactions are highly exothermic; the oxygen reacts with a coke like material formed by thermal cracking, they are responsible of generating the heat necessary to sustain and propagate the combustion front, sweeping the heavy oil and upgrading it due to the high temperatures. Wet in situ combustion is variant of the process, in which water is injected simultaneously or alternated with air, taking advantage of its high heat capacity, so the steam can transport heat more efficiently forward the combustion front due to the latent heat of vaporization. A representative model of the in situ combustion process is constituted by a static model, a dynamic model and a kinetic model. The kinetic model represents the oxidative behavior and the compositional changes of the crude oil; it is integrated by the most representative reactions of the process and the corresponding kinetic parameters of each reaction. Frequently, the kinetic model for a dry combustion process has Low Temperature Oxidation reactions (LTO), thermal cracking reactions and the combustion reaction. For the case of wet combustion, additional aquathermolysis reactions take place. This article presents a full review of the kinetic models of the wet in situ combustion process taking into account aquathermolysis reactions. These are hydrogen addition reactions due to the chemical interaction between crude oil and steam. The mechanism begins with desulphurization reactions and subsequent decarboxylation reactions, which are responsible of carbon monoxide production, which reacts with steam producing carbon dioxide and hydrogen; this is the water and gas shift reaction. Finally, during hydrocracking and hydrodesulphurization reactions, hydrogen sulfide is generated and the crude oil is upgraded. An additional upgrading mechanism during the wet in situ combustion process can be explained by the aquathermolysis theory, also hydrogen sulphide and hydrogen production can be estimated by a suitable kinetic model that takes into account the most representative reactions involved during the combustion process.

Characterization of Crude Oil for Fireflooding Using Thermal Analysis Methods

1977 ◽  
Vol 17 (03) ◽  
pp. 211-218 ◽  
Author(s):  
J.H. Bae
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Crude Oil ◽  
Combustion Process ◽  
Crude Oils ◽  
Temperature Oxidation ◽  
Analysis Methods ◽  
Oxidative Behavior ◽  
Fuel Deposition ◽  
Flowing Atmosphere

Abstract To study the thermo-oxidative behavior of crude oils, differential thermal analysis and thermogravi-metric instruments were developed that could be used at 1,000 degrees F and 1,000 psig in a flowing atmosphere. Subsequently, 15 crude oils, ranging from 6 to 38 degrees API gravity, were used at pressures of 50, 500, and 1,000 psig. Both nitrogen and air atmospheres were used in the experiments. The results show that crude oils can be grouped into three types according to their thermo-oxidative characteristics. The gravity of the crude oils does not correlate well with these patterns. It is also shown that the dependence of fuel availability on temperature and pressure varies with different crude oils. Furthermore, crude oils generally gain weight in an air atmosphere in relation to the evaporation curve obtained in a nitrogen atmosphere at both low and high temperatures. This shows that the availability of oxygen at low temperatures changes drastically the quality and quantity of available fuel. The heat generated by low-temperature oxidation might be significant in fireflooding. Finally, a qualitative correlation of the results of thermal analysis with those of combustion-tube tests is indicated. Introduction A substantial investigative effort has been made over the years, bob in the laboratory and in the field to understand the mechanisms of fireflooding, and a general understanding of the process now exists. However, the many factors that affect the process and the interrelationships of these factors process and the interrelationships of these factors make the process a complicated one. This also makes it difficult to predict the behavior of combustion by simple means. The linear laboratory combustiontube test appears to be fairly standard in the industry. Even in this type of experimental approach translation of the linear tube-test results to the field is not always possible. Two of the most important factors in the combustion process are fuel deposition and oxidation. Unfortunately, these presently are also the factors about which the least is known. Fuel for the process is usually thought to be the heavy fraction of crude oil held in the pores after the fluid displacement. The rate of advance and the peak temperature of the combustion front depend on the amount of fuel, availability of oxygen, and the rate of fuel oxidation. In fact, fuel deposition and oxidation govern the ability to sustain forward combustion and strongly influence the economics of a combustion project. Attempts have been made to use the thermal analysis methods in connection with forward combustion. In particular, differential thermal analysis (DTA) was used to study the oxidation of crude oil in porous media. DTA is a technique wherein energy changes in a substance are detected and measured as a function of time or temperature. In practice, the temperature of the sample is compared continuously with a reference material temperature. The difference in temperature is recorded. Another thermal analysis method is thermogravimetric analysis (TGA). In this technique, a sample is weighed continuously as it is heated at a constant rate. The resulting curve of weight change vs time or temperature gives the TGA thermogram. The objective of this work was to study the thermo-oxidative behavior of crude oils using both DTA and TGA techniques to gain some insight into the combustion process, especially the fuel deposition and oxidation. At the same time, we hoped to obtain information useful for predicting the thermal behavior of crude oil in the combustion process. Toward this goal DTA and TGA process. Toward this goal DTA and TGA equipment was developed that could be used at 1000 degrees F and 1,000 psig in a flowing atmosphere. Fifteen crude oils in a wide gravity range (6 to 38 degrees API) were analyzed, and the results are reported here. EXPERIMENTAL EQUIPMENT For our purposes, it was necessary in the DTA block to have a porous matrix to hold the oil and provisions for flowing gas through the sample at provisions for flowing gas through the sample at pressures up to 1,000 psi. The DTA block used is pressures up to 1,000 psi. The DTA block used is shown schematically in Fig. 1. SPEJ P. 211

scholarly journals In situ catalytic upgrading of heavy crude oil through low-temperature oxidation

2016 ◽  
Vol 13 (3) ◽  
pp. 476-488 ◽  
Author(s):  
Hu Jia ◽  
Peng-Gang Liu ◽  
Wan-Fen Pu ◽  
Xian-Ping Ma ◽  
Jie Zhang ◽  
...  
Keyword(s):  
Low Temperature ◽  
Crude Oil ◽  
Heavy Crude Oil ◽  
Low Temperature Oxidation ◽  
Temperature Oxidation ◽  
Catalytic Upgrading ◽  
Heavy Crude
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