Effect of stochasticity of the spatial distribution of particles in a gas suspension on combustion front propagation

Abstract A significant portion of world oil reserves reside in naturally fractured reservoirs and a considerable amount of these resources includes heavy oil and bitumen. Thermal enhanced oil recovery methods (EOR) are mostly applied in heavy oil reservoirs to improve oil recovery. In situ combustion (/SC) is one of the thermal EOR methods that could be applicable in a variety of reservoirs. Unlike steam, heat is generated in situ due to the injection of air or oxygen enriched air into a reservoir. Energy is provided by multi-step reactions between oxygen and the fuel at particular temperatures underground. This method upgrades the oil in situ while the heaviest fraction of the oil is burned during the process. The application of /SC in fractured reservoirs is challenging since the injected air would flow through the fracture and a small portion of oil in the/near fracture would react with the injected air. Only a few researchers have studied /SC in fractured or high permeability contrast systems experimentally. For in situ combustion to be applied in fractured systems in an efficient way, the underlying mechanism needs to be understood. In this study, the major focus is permeability variation that is the most prominent feature of fractured systems. The effect of orientation and width of the region with higher permeability on the sustainability of front propagation are studied. The contrast in permeability was experimentally simulated with sand of different particle size. These higher permeability regions are analogous to fractures within a naturally fractured rock. Several /SC tests with sand-pack were carried out to obtain a better understanding of the effect of horizontal vertical, and combined (both vertical and horizontal) orientation of the high permeability region with respect to airflow to investigate the conditions that are required for a self-sustained front propagation and to understand the fundamental behavior. Within the experimental conditions of the study, the test results showed that combustion front propagated faster in the higher permeability region. In addition, horizontal orientation almost had no effect on the sustainability of the front; however, it affected oxygen consumption, temperature, and velocity of the front. On the contrary, the vertical orientation of the higher permeability region had a profound effect on the sustainability of the combustion front. The combustion behavior was poorer for the tests with vertical orientation, yet the produced oil AP/ gravity was higher. Based on the experimental results a mechanism has been proposed to explain the behavior of combustion front in systems with high permeability contrast.

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Investigation of propagation modes and temperature/velocity variation on unstable combustion synthesis

Journal of Materials Research ◽

10.1557/jmr.2002.0465 ◽

2002 ◽

Vol 17 (12) ◽

pp. 3213-3221 ◽

Cited By ~ 17

Author(s):

H. P. Li

Keyword(s):

Activation Energy ◽

Combustion Synthesis ◽

Combustion Front ◽

Propagation Velocity ◽

Combustion Temperature ◽

Front Propagation ◽

Combustion Reaction ◽

Velocity Variation ◽

Material Synthesis ◽

Unstable Combustion

Combustion synthesis/micropyretic synthesis is a technique in which material synthesis is accomplished by the propagation of a combustion front across the sample. In some cases, the combustion front may propagate in an unstable mode where the propagation velocity and combustion temperature of the combustion front are altered periodically. In this study, the processing conditions leading to unstable combustion reaction were first studied theoretically. The boundary temperatures separating stable and unstable reactions were then determined. The numerical analysis showed that the combustion temperature and the propagation velocity changed periodically during unstable combustion. As the combustion reaction became unstable, the average propagation velocity and the oscillatory frequency of front propagation decreased. The products of unstable combustion synthesis possessed the banded structures, implying the occurrence of the unstable oscillatory propagation, as demonstrated experimentally. In this study, high activation energy combustion (Ti + 2B reaction) and low activation energy combustion (Ni + Al reaction) were both chosen to illustrate the effect of unstable combustion. It is the first time the experimental and numerical results were combined to investigate the temperature and propagation velocity variations during unstable combustion.

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Molecular dynamics simulation of combustion front propagation in a PETN single crystal

Combustion Explosion and Shock Waves ◽

10.1134/s0010508214030101 ◽

2014 ◽

Vol 50 (3) ◽

pp. 323-332 ◽

Cited By ~ 6

Author(s):

O. V. Sergeev ◽

A. V. Yanilkin

Keyword(s):

Molecular Dynamics ◽

Molecular Dynamics Simulation ◽

Single Crystal ◽

Combustion Front ◽

Front Propagation ◽

Dynamics Simulation

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Non-Adiabatic Effects on Combustion Front Propagation in Porous Media: Multiplicity of Steady States

10.2172/792462 ◽

2002 ◽

Cited By ~ 1

Author(s):

I. Yucel Akkutlu ◽

Yanis C. Yortsos

Keyword(s):

Porous Media ◽

Combustion Front ◽

Front Propagation ◽

Steady States

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Predictability of Crude Oil In-Situ Combustion by the Isoconversional Kinetic Approach

SPE Journal ◽

10.2118/148088-pa ◽

2011 ◽

Vol 16 (03) ◽

pp. 537-547 ◽

Cited By ~ 27

Author(s):

Murat Cinar ◽

Berna Hasçakir ◽

Louis M. Castanier ◽

Anthony R. Kovscek

Keyword(s):

Crude Oil ◽

Combustion Front ◽

Front Propagation ◽

Combustion Tube ◽

Complex Nature ◽

Oil Viscosity ◽

In Situ Combustion ◽

Temperature Oxidation ◽

Isoconversional Analysis

Summary One method to access unconventional heavy-crude-oil resources as well as residual oil after conventional recovery operations is to apply in-situ combustion (ISC) enhanced oil recovery. ISC oxidizes in place a small fraction of the hydrocarbon, thereby providing heat to reduce oil viscosity and increase reservoir pressure. Both effects serve to enhance recovery. The complex nature of petroleum as a multicomponent mixture and the multistep character of combustion reactions substantially complicate analysis of crude-oil oxidation and the identification of settings where ISC could be successful. In this study, isoconversional analysis of ramped temperature-oxidation (RTO) kinetic data was applied to eight different crude-oil samples. In addition, combustion-tube runs that explore ignition and combustion-front propagation were carried out. By using experimentally determined combustion kinetics of eight crude-oil samples along with combustion-tube results, we show that isoconversional analysis of RTO data is useful to predict combustion-front propagation. Isoconversional analysis also provides new insight into the nature of the reactions occurring during ISC. Additionally, five of the 10 crude-oil/rock systems studied employed a carbonate rock. No system displayed excessive oxygen consumption resulting from carbonate decomposition at combustion temperatures. This result is encouraging as it contributes to widening of the applicability of ISC.

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The Effect of Nanopowder Attributes on Reaction Mechanism and Ignition Sensitivity of Nanothermites

MRS Proceedings ◽

10.1557/proc-0896-h04-01 ◽

2005 ◽

Vol 896 ◽

Cited By ~ 2

Author(s):

Jan A Puszynski ◽

Chris J Bulian ◽

Jacek J Swiatkiewicz

Keyword(s):

Combustion Front ◽

High Speed ◽

Small Diameter ◽

Front Propagation ◽

Propagation Rate ◽

Closed Volume ◽

Scanning Calorimetry ◽

Reactive Metal ◽

Mixture Density ◽

Reacting Systems

AbstractNanothermite composites have several properties that are not typical of conventional thermites. The nanoscale size of individual reactants is responsible for the significant differences in these properties, especially the rate of energy release and mechanism of combustion front propagation. Several thermite mixtures were investigated, including Al-Fe2O3, Al-CuO, Al-MoO3, and Al-Bi2O3. Previous studies have reported on the behavior of these mixtures during unconfined burning and on the characterization of particle attributes such as particle size, surface area, and reactive metal content. This study was focused on several other attributes, including mixing of nanoreactants in water and measurements of reaction kinetics and combustion front propagation characteristics under confined conditions. The nanoscale nature of the thermite components also has an effect on the kinetics of the reaction. Differential scanning calorimetry was used to determine activation energy of these reacting systems. Several experimental setups were used to monitor the nanothermite mixtures during combustion. The mixtures were monitored during combustion in small diameter tubes using high speed video technology and a pressure sensor system. These tests were used to characterize combustion propagation under confined conditions and to determine the effect of pressure and mixture density on propagation rate. Experiments were also performed using both a closed volume pressure cell and recoil force cell to measure the reactive energy of the mixtures.

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