Crude Oil In Porous Media Research Articles

Mechanisms and effects of amphiphilic lamellar nanofluid for enhanced oil recovery in low permeability reservoirs

Amphiphilic nanosheets have attracted more attention for enhanced oil recovery (EOR) owing to their unique properties. Here, the amphiphilic molybdenum disulfide (MoS2) nanosheets (AP-MDN) were prepared by functionalizing octadecyl amine (ODA) molecules onto the molybdenum disulfide nanosheets (MDN) surfaces. The dynamic stability and interfacial tension (IFT) measurements of AP-MDN nanofluid were evaluated. Besides, the mechanisms and effects of AP-MDN nanofluid for EOR were also systematically investigated and studied. Experimental results indicate that the dynamic stability of AP-MDN nanofluid is improved when MDN is successfully functionalized with ODA molecules. The IFT is decreased to 10-1 mN/m and micron-emulsions ranging from 1 µm ∼ 2 µm can be formed. In addition, the contraction rate of oil film exposed in ultra-low concentration AP-MDN nanofluid (50 mg/L) experiences two stages: a steep stage (8.5817 × 10-5 cm/s) and a gentle stage (0.6617 × 10-5 cm/s) owing to the generation of structuring disjoining pressure. Comprehensive mechanisms of AP-MDN nanofluid for EOR are also proposed and revealed. Moreover, oil washing efficiency of AP-MDN nanofluid is as high as 95.7 % when the soaking time is 6 hrs and temperature is 75 ℃. Core flooding experimental results demonstrate that the increase in shut-down time and the injection mode of multiple rounds with small slugs can better promote the interaction between AP-MDN nanofluid and crude oil in porous media. The highest oil recovery contributed by AP-MDN nanofluid is 19.1 %. These results are expected to promise AP-MDN nanofluid as an effective candidate for EOR.

Compositional numerical analysis of multiphase flow of crude oil in porous media under non-isothermal conditions

Abstract The present work details the development of a compositional model to replicate the heavy hydrocarbon flow in porous reservoir systems under non-isothermal conditions. The mathematical model considers mass and energy conservation equations describing the reactive of natural variables distributed in a multiphase hydrocarbon system. Such natural variable based compositional models better suit fully implicit numerical schemes with inexpensive Jacobian matrix computations. Further, the model accommodates a switch of primary variables for the disappearance and reappearance of a phase. The resulting nonlinear conservation equations are numerically discretized using a block-centered finite-difference scheme and solved with a quasi-Newton based implicit iterative solver. The present model is validated with the thermal profiles presented in the literature for the multiphase flow during the combustion of heavy crude oil in petroleum reservoir system with performance coefficient (R 2), mean absolute error (MBE), and maximum absolute percentage error (MAPE) of about 0.954, 0.37, and 0.01 respectively. The developed compositional model projected 26 and 72 % of light and heavy oil recoveries respectively in about 160 days with a maximum or peak temperature of about 798 K. Further, the thermal and production profiles projected by the sensitivity analysis on various operating parameters are presented. It is noteworthy that the present works aid in providing an economical numerical based tool in evaluating the flow and transport during underground or in-situ combustion process for efficient energy exploration.

Assessment of foam generation and stabilization in the presence of crude oil using a microfluidics system

The use of foams is a promising technique to overcome gas mobility challenges in petroleum reservoirs. Foam reduces the gas mobility by increasing the gas apparent viscosity and reducing its relative permeability. A major challenge facing foam application in reservoirs is its long-term stability. Foam effectiveness and stability depends on several factors and will typically diminish over time due to degradation as well as the foam-rock-oil interactions. In this study, the effect of crude oil on CO2-foam stability and mobility will be investigated using in-house build microfluidics system developed for rapid prescreening of chemical formulations. Two-phase flow emulsification test (oil-surfactant solutions) and dynamic foam tests (in the absence and presence of crude oil) were conducted to perform a comparative assessment for different surfactant solutions. A microfluidics device was used to evaluate the foam strength in the presence and absence of crude oil. The assessment was conducted using five surfactant formulations and different oil fractions. The role of foam quality (volume of gas/total volume) on foam stability was also addressed in this study. The mobility reduction factor (MRF) for CO2-foam was measured in the absence and presence of crude oil using high salinity water and at elevated temperatures. The results indicated that foam stability has an inverse relationship with the amount of crude oil. Crude oil has a detrimental effect on foams, and foam stability decreased as the amount of crude oil was increased. Depending on the surfactant type, the existence of crude oil in porous media, even at very low concentrations of 5% can significantly impact the foam stability and strength. The oil can act as an antifoaming agent. It enters the thin aqueous film and destabilizes it. This resulted in a lower foam viscosity and less stable foams. Thus, the CO2 MRF dropped significantly in the presence of higher oil fractions. This study also demonstrated that in-house assembled microfluidics system allows for a rapid and cost-efficient screening of formulations.

Thermal effect caused by low temperature oxidation of heavy crude oil and its in-situ combustion behavior

To investigate the thermal effect caused by low temperature oxidation (LTO) of one heavy crude oil in porous media, a combustion tube (CT) system coupled with a self-designed experimental scheme was adopted. Also, the in-situ combustion (ISC) performance of this heavy oil as well as alterations in oil properties before and after ISC was comprehensively evaluated. The results showed that there existed the apparent thermal effect induced by LTO within the researched ignition temperature (180–320 °C), and heat release became greater with the ignition temperature. It should be noted that the oxidation reaction rate of the heavy oil was rose remarkably releasing substantial heat when the ignition temperature was increased to 240 from 180 °C. The heavy oil was combusted under the ignition temperature of 350 °C, and the combustion front advanced sustainably. Some basic parameters during ISC, including apparent atomic H/C ratio, oxygen utilization, fuel consumption, etc., were determined, which made it accessible to predict field test performances. And the values of these parameters and post-mortem images of the CT test reflected the superior ISC performance of the heavy oil. The alterations in oil properties pre-ISC and post-ISC indicated that the produced oil encountered strong LTO reactions and thermal cracking reactions forming a considerable number of lighter oxygen-containing compounds. Comparison of differential scanning calorimetry (DSC) profiles of the crude oil and produced oil revealed that the ISC process made the heavy oil greatly upgrade.

Mobilization of Crude Oil in Porous Media With Oil-Soluble Surfactant Delivered by Hydrosoluble Micelles

In this work, an oil-soluble surfactant was studied to enhance crude oil mobilization in a cryolite-packed miniature bed. The cryolite packed bed provided a transparent, random porous medium for observation at the microscopic level. In the first part of the paper, oil-soluble surfactants, Span 80 and Eni-surfactant (ES), were dissolved directly into the crude oil. The porous medium was imbued with the crude oil (containing the surfactants), and de-ionized water was the flooding phase; in this experiment, the system containing ES had the best performance. Subsequently, sodium dodecyl sulfate (SDS), a hydrosoluble surfactant, was used to solubilize the ES, with the SDS acting as a carrier for the ES to the contaminated porous media. Finally, the SDS/ES micellar solutions were used in oil-removal tests on the packed bed. Grayscale image analysis was used to quantify the oil recovery effectiveness for the flooding experiments by measuring the white pixel percentage in the packed bed images. The SDS/ES flooding mixture had a better performance than the SDS alone.

Enhanced Oil Recovery using Smart Water Injection

Smart water flooding (low salinity water flooding) was mainly invested in a sandstone reservoir. The main reasons for using low salinity water flooding are; to improve oil recovery and to give a support for the reservoir pressure.
 In this study, two core plugs of sandstone were used with different permeability from south of Iraq to explain the effect of water injection with different ions concentration on the oil recovery. Water types that have been used are formation water, seawater, modified low salinity water, and deionized water.
 The effects of water salinity, the flow rate of water injected, and the permeability of core plugs have been studied in order to summarize the best conditions of low salinity water flooding. The result of this experimental work shows that the water without any free ions (deionized water) and modified low salinity water have improved better oil recovery than the formation water and seawater as a secondary oil process. The increase in oil recovery factor related to the wettability alteration during low salinity water flooding which causes a decrease in the interfacial tension between the crude oil in porous media and the surface of reservoir rocks. As well as the dissolution of minerals such as calcite Ca+2 was observed in this work, which causes an increase in the pH value. All these factors led to change the wettability of rock to be more water-wet, so the oil recovery can be increased.

Experiment on the Influence Factors of Steam Distillation Rate of Crude Oil in Porous Media

To explore the influence of complexity of reservoir properties in porous media and the diversity of operating conditions on the steam distillation rate of crude oil in the process of heavy oil exploitation with steam injection, steam distillation simulation devices are used to study steam distillation rate of crude oil in porous media. Then steam distillation ratio is obtained under the condition of different core permeability, oil saturation, steam temperatures, system pressure, steam injection rates and steam distillation rates with different viscosities of crude oil. The results show that the steam distillation rate of crude oil in porous media depends mainly on the nature of the crude oil itself, for temperature and pressure are the key factors compared with the pore structure, the initial oil saturation and steam injection rate. The experimental results help estimate the amount of crude oil and the required steam in the reservoir in the steam drive process, aiming to facilitate the optimization design and operation of steam drive.

Non-Newtonian flow characterization of heavy crude oil in porous media

As a temperature-sensitive non-Newtonian fluid, the seepage of heavy crude oil in porous media shows the non-linear characteristics. The flowing behavior of three heavy oils through porous media is experimentally investigated, and the influence of temperature and pressure-drop on this flowing process is also described. Thereafter, based on the flowing behavior of heavy crude oil, the new models of productivity of the thermal producers (including vertical well and horizontal well) are proposed. In these models, both the threshold pressure gradient (TPG) and thermal effect are taken into account. The flowing experiments of heavy oil in porous media indicate that the pressure gradient and temperature have the significant influence on the flowing process because of the existence of threshold temperature and TPG. Heavy crude oil begins to flow only when the pressure gradient is in excess of TPG, and there dose not actually exist TPG above the threshold temperature. The viscosity-temperature curves demonstrate that the viscosity of heavy crude oil has an obvious feature of two straight-lines on semilog coordinate. On account of the damage of overlapping phenomena of asphaltenes in crude oil, when temperature is higher than the critical temperature, the reducing trend of TPG (with the increase of temperature) will be lessened. Furthermore, on the basis of flowing process of heavy crude oil, the concepts of threshold temperature and certain production temperature of thermal wells are introduced. That heavy oil with a higher viscosity would have a higher threshold temperature, as well as the certain production temperature. The application of horizontal wells tremendously increases the oil recovery rate in comparison with the vertical wells. This investigation could be used as a tool to study the flowing process of heavy oil and productivity calculation of thermal wells in heavy oil reservoirs.

Sensitivity Studies on the Oxidation Behavior of Crude Oil in Porous Media

For the application of high-pressure air injection (HPAI) in light oil reservoirs, low-temperature oxidation (LTO) behavior is the main concerned factor affecting the recovery performance. In a pre...

Laboratory Investigation on the Feasibility of Light-Oil Autoignition for Application of the High-Pressure Air Injection (HPAI) Process

Whether thermal effects have a contribution on oil recovery mechanisms in the high-pressure air injection (HPAI) process in a light-oil reservoir has confused many people over several decades. The argument is due to the lack of convictive evidence from both direct laboratory and simulation studies. This paper is the prelusion for the subsequent study for a better understanding of the influence of thermal effects on oil production. In a previous study, thermogravimetry/differential thermogravimetry (TG/DTG) and differential thermal analysis (DTA) tests were employed to investigate the kinetic parameters and exothermic behavior of Keke Ya light crude oil (Tarim Basin, China) and oil + cuttings, showing that Keke Ya light crude oil as well as oil + cuttings exhibited very low activation energy and favorable exothermic behavior. In this study, we develop a thermal effect monitoring device, which is similar to the isothermal oxidation tube, and we have detected the obvious exothermic phenomenon of Keke Ya light crude oil in porous media in the isothermal aging test at reservoir conditions (80 °C and 16.7 MPa). The witness of the combustion (or high-temperature) process is exhibited, which is expressed in specific characteristics made up of the self-heating behavior, low hydrogen/carbon (H/C) ratio of 1.50 from gas composition analysis, and generated precipitation coverings (halite crystalloid) in the core section surface through scanning electron microscopy (SEM) analysis. This study provides new insight that thermal effects should exist during the light-oil isothermal aging process in porous media and proposes a laboratory analysis method to understand the feasibility of light-oil autoignition at the oil-bearing reservoir during application of HPAI.

The effect of wettability on foam sensitivity to crude oil in porous media

We evaluated foam-oil sensitivity in oleophilic (oil- or intermediate-wetting) media compared with hydrophilic (water-wetting) media. The porous media used were either Berea sandstone or glass microvisual cells with and without Quilon C coating (hydrophilic or oleophilic). Dynamic contact angle measurements on untreated and Quilon C-treated glass showed that the treatment makes the glass microvisual cells intermediately wet. Microvisual studies showed that foams tend to be more sensitive (less effective) to oil at residual oil saturation when the pores are intermediately wet as opposed to water-wet. These studies show that, at least for glass plates, the surfactants can adsorb and partially reverse the wettability, back towards water-wet. Coreflood tests using treated and untreated Berea sandstone rock show that the Quilon C treatment also changed the wettability of the rock away from water-wetting. In most cases the foam effectiveness was reduced in oleophilic rock over hydrophilic rock (oil-free). At residual oil saturation foam effectiveness for most foams was further reduced in oleophilic-treated rock over hydrophilic rock. This work confirms earlier suggestions that foam effectiveness may be reduced in porous media of intermediate or oleophilic wettability and that the foam effectiveness may be further reduced at residual oil saturation. Surfactant selection for field use should be made taking into account the actual reservoir conditions under which they will be used, including nature of the oil, S or and wettability. The results of this research should provide some guidance for this purpose.

Kinetic analysis of in situ combustion processes with thermogravimetric and differential thermogravimetric analysis and reaction tube experiments

This research comprises the determination of kinetic parameters of in situ combustion processes by reaction tube and thermal (thermogravimetric analysis (TGA)/differential thermogravimetric analysis (DTGA)) experiments. A previously developed laboratory model and a Du Pont 9900 thermalanalyzer unit were used to run the experiments. Three reaction regions for combustion of crude oil in porous media were observed in the reaction tube and TGA/DTGA experiments and are defined as low temperature oxidation, fuel deposition and high temperature oxidation. The kinetic parameters are calculated for each reaction region using Weijdema's reaction model in reaction tube experiments. The Arrhenius model is applied to determine the kinetic parameters from TGA/DTGA thermograms and a comparison is made between kinetic results.

Reaction Kinetics of Fuel Formation for In-Situ Combustion

Summary Chemical reactions believed to cause fuel formation for in-situ combustion have been studied and modeled. A thin, packed bed of sand/oil mixture is heated under nitrogen flow at linearly increasing temperatures, simulating the approach of a combustion front. Analysis of gases produced from the reaction cell revealed that pyrolysis of crude oil in porous media goes through three overlapping stages: distillation, mild cracking (visbreaking), and severe cracking (coking). Expressions that govern the rates of the two cracking reactions are derived, and a technique is outlined to obtain initial estimates for their parameters from the experimental data. The parameters of a proposed distillation function, as well as refined estimates for the cracking reaction parameters, are obtained by non-linear regression methods based on an overall kinetic model. Successful matching of the experimental data, including the total amount of fuel deposited, was achieved with this model. It was found that fuel formation was a result of two successive cracking reactions that the oil undergoes at temperatures above 280° C [536°F]. Also, distillation of crude oil at temperatures below 280°C [536°F] played an important role in shaping the nature and extent of the cracking reactions. The operating pressure and the rate of heating of the sand/oil sample were found to affect the fuel-formation process only through the influence exerted on distillation. Clay minerals showed a catalytic effect on the cracking reactions, especially coking. Finally, the asphaltene fraction of a crude oil was found to correlate with the fuel content of that oil.

Reaction Kinetics of In-Situ Combustion: Part 1—Observations

Abstract Continuous analysis of produced gases from a small packed bed reactor, at both isothermal and linearly increasing temperatures, has shown that combustion of crude oil in porous media follows several consecutive reactions. Molar carbon dioxide/carbon monoxide (CO2/CO) and apparent hydrogen/carbon (H/C) ratios were used to observe the transition between these reactions at different temperature levels. A new kinetic model for oxidation of crude oil in porous media is presented in Part 2 of this paper (Page 408).

Characterization of Crude Oil for Fireflooding Using Thermal Analysis Methods

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

Retrograde Condensation in Porous Media

Abstract The effect of porous media on the phase behavior of hydrocarbon binaries was investigated both experimentally and theoretically. When liquid and vapor coexist in a porous medium, the interlace between them will be curved. Calculations of the effect of curvature on phase behavior show that equilibrium composition and Pressures would not be disturbed significantly except at very high surface curvatures. Such curvatures are unlikely in hydrocarbon reservoirs even where clay-size particles are present because the finest pores will particles are present because the finest pores will be occupied by connate water. Measured dewpoint or bubblepoint pressures were found to be independent of the presence of porous media. Liquid saturations calculated from previous conventional phase behavior studies were compared with saturations calculated from the dimensions of a limited number of capillary structures which could be observed through the sight glass of a Jerguson cell. Saturations calculated from conventional phase-equilibrium data fell between saturations phase-equilibrium data fell between saturations calculated with The assumption that all capillary structures had equal curvature and those calculated with the assumption that they bad equal volumes. Introduction Reservoir engineering frequently involves the use of pressure-volume-temperature (PVT) relationships for hydrocarbon mixtures. Examples arise in reservoirs, and gas-drive miscible displacements, condensation and revaporization in gas condensate reservoirs, and gas-drive miscible displacements. The PVT relationships used in such engineering calculations are usually based on measurements on equilibrium behavior of hydrocarbon mixtures contained in PVT cells. For some time there has been question as to whether phase - behavior calculations made on data measured in such cells would correctly represent the behavior of hydrocarbon mixtures held within the interstices of porous reservoir rocks. The results of several recently reported experimental studies indicate that the presence of a porous medium has a significant influence presence of a porous medium has a significant influence on the equilibrium behavior of hydrocarbon mixtures. Trebin and Zadora contend that the initial condensation pressures (dew points) of gas condensate mixtures in pressures (dew points) of gas condensate mixtures in porous media can be 10 to 15 percent higher than those porous media can be 10 to 15 percent higher than those observed in conventional PVT cells. Tindy and Raynal reported that saturation pressures of crude oil in porous media were several percent higher than those porous media were several percent higher than those measured in conventional test cells. On the other hand, earlier results reported by Weinaug and Cordell indicated that vapor-liquid equilibrium relationships of the system methane-n-butane and methane-n-pentane were not affected by the presence of dry sand. Oxford and Huntington studied the revaporization of n-hexane by nitrogen and found that withdrawal rate and the presence of brine in the porous medium had little effect on the revaporization process. In a study of the effects of wettability change, process. In a study of the effects of wettability change, Smith and Yarborough concluded that the detailed form of the capillary structures of retrograde liquid held in a porous medium had no effect on the revaporization process. porous medium had no effect on the revaporization process. Clark studied the adsorption and desorption of light paraffinic hydrocarbons in clay and partially water-saturated paraffinic hydrocarbons in clay and partially water-saturated sand and sand-clay packs to determine their effect on equilibrium behavior. Compressibility factors for propane at 100 degrees F in the presence of dry sand-clay propane at 100 degrees F in the presence of dry sand-clay packs were lowered by 13 percent. However, in sand-clay packs were lowered by 13 percent. However, in sand-clay mixtures containing water, the compressibilities differed by less than 1 percent from those obtained in the absence of the porous media. Clark also studied effect of a dry sand-clay media on the PVT properties of mixtures of methane and propane. Only small changes were observed, and these were considered to be inconclusive - partly because the fluid was not recirculated through the porous media to ensure homogeneity. In summary, porous media to ensure homogeneity. In summary, evidence for the effect of porous media on equilibrium behavior is somewhat contradictory.

Oxidation of Crude Oil in Porous Media

Abstract Experimental results on the oxidation reaction kinetics in the forward combustion oil recovery process are presented. A total of 48 runs were made wherein a stationary thin layer of coked, unconsolidated sand was burned isothermally in a combustion cell. Individual runs were made at various temperature levels to permit determination of the effect of temperature upon the reaction. An expression was obtained for the burning rate of carbon as a function of carbon concentration, combustion temperature and oxygen partial pressure. The carbon burning rate for two types of crude oil indicated a first order reaction with respect to both carbon concentration and oxygen partial pressure. The effect of combustion temperature on the reaction rate constant matched the Arrhenius equation. The activation energy was similar for the two crude oils examined. The activation energy decreased for a porous media containing clay. The rate of oxidation of crude oil at reservoir temperature was found to be significant. Other significant findings included information on hydrogen-carbon content of fuel residues, fuel reactivity and the products of combustion. Introduction The production of crude oil by underground combustion has been studied in the laboratory by many investigators. Results of laboratory and field experiments have been reported in the literature describing the forward combustion process. But as yet, no qualitative or quantitative study of the kinetics of fuel combustion involved in this process has been reported. The fuel concentration and the rate at which fuel is burned at the front are important factors governing the air requirement in a forward combustion operation. Although the fuel is essentially unrecoverable crude, the air required to burn the fuel is an important economic factor in this process. Because fuel is burned, the heat transport associated with forward combustion is a key and unique feature of this new oil recovery method. Many investigators have presented information on the heat transmission and fluid mechanics involved in forward combustion. Berry and Parrish demonstrated the utility of considering reaction kinetics in reverse burning. From differential thermal analysis, Tadema presented a qualitative discussion of the nature of reactions between oil and oxygen in combustion oil recovery. Although little quantitative work has been done on be reaction kinetics involved in forward combustion oil recovery, an extensive literature does exist on combustion of carbons and oils, and carbonaceous residues from cracking catalyst pellets. Dart, et al., studied the combustion rate for oxidation of carbonaceous residues on clay catalyst pellets, and found the reaction to be second-order with respect to carbon concentration, and first-order with respect to oxygen partial pressure for carbon concentrations less than 2 weight percent of the catalyst weight. The reaction appeared to be first-order with respect to carbon concentration for concentrations greater than 2 percent. Metcalfe noted that other workers had found that aging of the fuel during the combustion process was responsible for changing coke properties, and A accounted for the apparent second-order carbon concentration effect found by Dart, et al. It appears that burning of residues from cracking pellets is first-order with respect to both carbon concentration and oxygen partial pressure. Dart, et al., also observed that hydrogen in the hydrocarbon residue appeared to react faster than the carbon. Lewis, et al., studied oxidation of charcoal, coke and graphite in a fluidized bed. Gas velocities were high enough to partially lift and circulate the carbon particles. Their results indicated first-order reaction dependency with respect to both carbon concentration and oxygen partial pressure.