Contribution of thermal analysis and kinetics of Siberian and Tatarstan regions crude oils for in situ combustion process

Abstract A fully automated in-situ combustion apparatus supported by a minicomputer was designed, constructed, and tested.Results obtained from four adiabatic dry combustion runs to investigate the effect on clay on crude oil combustion are reported. Sand mixtures of varying clay (kaolinite) content were saturated with crude oil and water. The fourth run was performed with amorphous silica powder in the sand mixture for comparison with clay results.We concluded that the large surface area of the clays was a major contributor to the fuel deposition process. However, different oxygen utilization efficiencies obtained from both types of sand mixtures indicated that mechanisms controlling the combustion reaction also depended on the composition of the porous matrix.A thermogravimetric analyzer (TGA) and a differential scanning calorimeter (DSC) were used to obtain kinetic data on the effects of kaolinite type clay on crude oil combustion. The addition of kaolinite clay or silica powder changed the shape of the crude oil TGA/DSC thermograms significantly, but sand had no effect. The major effect on DSC thermograms was a shifting of the large amount of heat produced from a higher to lower temperature range. Reduction of activation energy caused by the addition of kaolinite clay to the crude oil indicates both catalytic and surface area effects on combustion/cracking reactions. Introduction In-situ combustion is a thermal recovery process in which a portion of the crude oil is coked and burned in situ to recover the remaining oil. Design of the process involves experimental evaluation of process variables in laboratory experiments. Variables sought experimentally for the design of the process are usually fuel availability, air requirement, oxygen utilization efficiency, combustion peak temperature, combustion front velocity, effect of porous matrix, and kinetic parameters. Four methods have been used to obtain design data for in-situ combustion projects. These include (1) adiabatic in-situ combustion tube runs, (2) isothermal reactors, (3) flood pot tests, and (4) thermal analysis techniques.This paper describes an investigation of the effect of clay on in-situ combustion involving results from adiabatic combustion tube runs and thermal analysis methods. Part 1 describes the minicomputer-based insitu combustion system developed as part of the research program. Part 2 demonstrates application of the system to study the effect of clays on the in-situ combustion process. Combustion tube runs described in Part 2 are supplemented with thermal analysis methods to evaluate the effect of clay on in-situ combustion of a Kansas crude oil. Part 1-Development of an Automated In-Situ Combustion Tube Adiabatic tube runs have been the most commonly used approach for studying in-situ combustion. Since heat loss is small to nil in thick reservoirs, in-situ combustion is assumed to occur under adiabatic conditions. Adiabatic conditions in tube runs can be achieved either by insulating the tube or by reducing the temperature gradient between the sandpack and the environment surrounding the tube, or both. To attain adiabatic conditions in a partially or noninsulated tube, the temperature of the surroundings must be raised to that of the sandpack as the combustion front moves along the tube. Heater bands with proportional heat loads controlled by individual controllers are used. This requires a large number of controllers to control the temperature of the outside SPEJ P. 493^

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Chemical Aspects of In-Situ Combustion - Heat of Combustion and Kinetics

Society of Petroleum Engineers Journal ◽

10.2118/3599-pa ◽

1972 ◽

Vol 12 (05) ◽

pp. 410-422 ◽

Cited By ~ 117

Author(s):

J.G. Burger

Keyword(s):

Porous Media ◽

Combustion Front ◽

Combustion Process ◽

Heat Of Combustion ◽

Oxidation Reactions ◽

In Situ Combustion ◽

Oxidation Of Hydrocarbons ◽

Kinetics Of ◽

Heat Released

Abstract General remarks on the oxidation reactions of hydrocarbons involved in in-situ combustion are followed by estimates of heat releases. A formula is derived for computing the heat of combustion in the high-temperature zone. Reaction kinetics in porous media applied to the in-situ combustion porous media applied to the in-situ combustion process is discussed. It is observed that there is process is discussed. It is observed that there is some similarity between the kinetics of reverse and partially quenched combustion processes. The influence of additives on crude oil oxidation in porous media is illustrated by effluent gas analysis experiments. Some information concerning the values of the kinetic parameters of the reaction controlling the velocity of a reverse combustion front is derived from the interpretation of laboratory experiments, using a numerical model. Introduction A great deal of laboratory and field work has been done on thermal recovery methods. The importance and limitations of these techniques have been extensively studied. However, some of the chemical and physical problems involved that needed to be elucidated were studied as part of a research program carried out by the Institut Francais du Petrole. Specific problems are created by in-situ combustion since both the possibility of combustion-front propagation and the air requirement are controlled by the extent of the exothermic oxidation reactions. Actually, the propagation velocity of a forward combustion front depends on the fuel formation and combustion, which are controlled by the kinetics of these processes; furthermore, the peak temperature is related to the heat released by oxidation and combustion reactions. Therefore, a quantitative estimation of the parameters related to the chemical aspects of the parameters related to the chemical aspects of the process is a necessary step in studying combustion process is a necessary step in studying combustion through a porous medium. General and theoretical considerations on heats of reaction and kinetics are presented and illustrated by experimental data and numerical interpretation of the results. HEAT RELEASED IN THE OXIDATION OF HYDROCARBONS DESCRIPTION OF OXIDATION REACTIONS A great number of reaction products are produced by the oxidation of hydrocarbons. By taking into account the formation of bonds between one carbon atom and oxygen, it is possible to derive the most important processes. Complete combustion, (1) 2 2 2 2H H3R C R + ---- O → RR + CO + H O Incomplete combustion, (2) 2 2H H R C R + O → RR + CO + H O Oxidation to carboxylic acid, (3) 2 2 2H OH H3 OR C H + --- O → R - C + H O Oxidation to aldehyde, (4) H H R C Oxidation to ketone, (5) 2 2H O H R C R ' + O → R - C - R; + H O Oxidation to alcohol, (6) R' R; R C H SPEJ p. 410

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The Role of Thermal Analysis Techniques in the In-Situ Combustion Process

SPE Reservoir Engineering ◽

10.2118/12677-pa ◽

1986 ◽

Vol 1 (04) ◽

pp. 329-340 ◽

Cited By ~ 12

Author(s):

Kamal N. Jha ◽

Bela Verkoczy

Keyword(s):

Thermal Analysis ◽

Combustion Process ◽

In Situ Combustion ◽

Analysis Techniques ◽

Thermal Analysis Techniques

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Prediction of In-Situ Combustion Process Variables By Use of TGA/DSC Techniques and the Effect of Sand-Grain Specific Surface Area on the Process

Society of Petroleum Engineers Journal ◽

10.2118/11072-pa ◽

1985 ◽

Vol 25 (05) ◽

pp. 656-664 ◽

Cited By ~ 9

Author(s):

Shapour Vossoughi ◽

Gordon W. Bartlett ◽

Paul G. Willhite

Keyword(s):

Thermal Analysis ◽

Crude Oil ◽

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Oil Content ◽

Combustion Process ◽

Process Variables ◽

In Situ Combustion

Prediction of In-Situ Combustion Prediction of In-Situ Combustion Process Variables By Use of Process Variables By Use of TGA/DSC Techniques and the Effect of Sand-Grain Specific Surface Area on the Process Abstract This paper describes a new technique to predict the parameters that govern the performance of the in-situ combustion process. This prediction is accomplished by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) of the crude-oil combustion. The effect of surface area on the in-situ combustion-tube runs was also investigated. The crude oil studied was from Iola field, Allen County, KS. This oil has a gravity of 19.8 API [0.94 g/cm3] and a viscosity of 222 cp [0.222 Pa-s] at 100.4 F [38 C] and 98 cp [0.098 Pa-s] at 129.2 F [54 C]. Pa-s] at 100.4 F [38 C] and 98 cp [0.098 Pa-s] at 129.2 F [54 C]. At a bulk density of the combustion-tube pack of 104.26 lbm/cu ft [1.67 g/cm3], the minimum crude-oil content to support an adiabatic combustion process was estimated to be 7.1 wt%. This translates into 34.4% oil saturation for the sandpack of 37% porosity and the crude-oil gravity of 19.8 API [0.94 g/cm3]. However, the combustion front, in a sandpack of 70 mesh (specific surface area of 76 cm2/g [7.6 m2/kg]) with an oil content even greater than the required minimum oil content predicted by the present approach, did not sustain itself. Additional tube runs were performed with finer sand grains having specific surface areas of 317, 1,120 and 3,332 cm2/g [31.7, 112, and 333.2 m2/kg]. A strong, sustained combustion front was observed only in the last run-i.e., the greatest specific surface area. TGA was applied to the samples taken at 1- to 2-in. [2.54-to 5.08-cm] intervals ahead of the front to study crude-oil distribution. In the case of unsuccessful runs, the amount of the crude oil ahead of the front decreased to a level that sufficient fuel could not be laid down to sustain the front. In the self-sustained run with the greatest surface area, crude-oil content immediately ahead of the front was even higher than the original sand/oil mixture. Therefore, a minimum surface area is required to provide conditions for sufficient fuel to be laid down by the coking process. process. This finding is believed to be important in revealing the mechanism responsible for the lack of self-sustained combustion in sandpacks or porous rocks with low specific surface area. It also reveals the porous rocks with low specific surface area. It also reveals the importance of the specific surface area available to the crude oil for determining whether a self-sustained combustion could be achieved. Introduction In-situ combustion is a complex process that involves simultaneous heat and mass transfer in a multiphase environment coupled with chemical reactions of crude-oil combustion. Many studies on the thermal and fluid dynamics of the in-situ combustion process have been conducted, but little has been done to study chemical reaction kinetics and mechanisms involved in underground combustion. In a recent study, Fassihi et al. showed that the combustion of crude oil in porous media follows several consecutive reactions. They identified three groups of reactions (low-, middle-, and high-temperature reactions), and argued that the first was heterogeneous (gas/liquid), the second, homogeneous (gas phase), and the third, heterogeneous (gas/solid phase). They produced a model based on Weijdema's kinetic equation in which a simple reaction is assumed for each group of crude-oil reactions and Arrhenius-type dependency of the rate constant on temperature. This model, however, allowed only the prediction of crude-oil combustion parameters under very stringent and controlled conditions. The oxidative behavior of crude oils under varying conditions of temperature, pressure, and atmosphere may also be studied by thermal analysis. Most researchers took a qualitative approach and used thermal analysis techniques to study the thermo-oxidative behavior of crudes with specific reference to the temperatures at which each oxidation reaction occurs. Weckowska and Bogdanow, however, took a different approach to thermal analysis by investigating the thermal decomposition kinetics of the vacuum-distillation residue of crude oil. They used the kinetic model of Zsako to describe mathematically the kinetics of thermal decomposition of a Romashkino crude-oil residue. SPEJ p. 656

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Behavior and Effect of SARA Fractions of Oil During Combustion

SPE Reservoir Evaluation & Engineering ◽

10.2118/66021-pa ◽

2000 ◽

Vol 3 (05) ◽

pp. 380-385 ◽

Cited By ~ 52

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.

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