Studies of Iranian Heavy Oils Pertinent to Reservoir Conditions for Their Auto-Ignition to Initiate Fire Flooding

Price, Dennis; Razzaghi, Samaneh; Kharrat, Riyaz; Rashtchian, Davood; Vossoughi, Shapour

doi:10.1080/00986440802483921

Cited by 8 publications

(8 citation statements)

References 4 publications

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“…Both isothermal − and adiabatic − experiments performed for crude oils have the goal to explore initial stages of oxidation and possibility of self-ignition. This means that experiments are performed at reservoir conditions or not much different from the reservoir conditions.…”

Section: Introductionmentioning

confidence: 99%

“…These experiments can be performed beginning from reservoir temperature and for higher temperatures also. In adiabatic experiments one tries to explore some quick process of oil self-heating under the oxidation reactions which could take place in a reservoir . And the quicker the reaction, the more adiabatic the conditions in the reservoir (in reality they are not adiabatic due to the heat losses).…”

Section: Introductionmentioning

confidence: 99%

“…In adiabatic experiments one tries to explore some quick process of oil selfheating under the oxidation reactions which could take place in a reservoir. 26 And the quicker the reaction, the more adiabatic the conditions in the reservoir (in reality they are not adiabatic due to the heat losses). So both isothermal and adiabatic approaches in experiments are a kind of simplification of the real situation in situ during the ignition period.…”

Section: Introductionmentioning

confidence: 99%

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Chain Reactions Approach to the Initial Stages of Crude Oil Oxidation

Ushakova

Zatsepin

2018

Energy Fuels

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The paper focuses on the problem of the crude oil self-ignition in situ, which has not yet been solved in the general case and for a particular oilfield as well. To solve the problem of ignition, we approached from a theoretical point of viewapplied the theory of chain reactions to the description of the initial stages of oxidation. The obtained dependences of heat release on time should be of a general nature for experiments in which self-ignition occurred (we called them high rate experiments) and for experiments in which fuel formation was observed (low rate experiments). We first demonstrated this relationship in the experiments we conducted by high pressure rate calorimeter (PDSC). And then we analyzed the various experiments from literature sources. The novel results of the presented approach show the probabilistic nature of the ignition and the presence of a group of processes that do not lead to ignition, in which the free radicals are not sufficiently active and the heat sink exceeds the heat release. Instead of the heat balance, a new ignition criterionφ-factor for chain reaction, the difference in the rate of formation and death of free radicalsis derived. A positive value of φ-factor indicates the increase of energy in the system and the ignition by the chain mechanism, while a negative value indicates the attenuation of the reaction and the formation of oxidized compounds without ignition. The PDSC experiments with light crude oil oxidation were conducted under various heating rates in order to explore the ignition temperature–time dependence (the example of high rate experiments). The results show the same dependence of the process time on temperature predicted theoretically. The other types of high rate experiments (adiabatic experiments, combustion tube experiments) and low rate oxidation experiments from literature sources are also considered in terms of our approach. The comparison of different types of experiments with the obtained mathematical formulas gives a good agreement. The low rate oxidation dependences refer to the negative values of φ-factor, and high rate oxidation refers to positive φ-factor modes. Both types of experiments are in good consistency with the theoretically obtained dependence and show that the model of the chain reaction approach works well. Thus, the chain reaction approach to the ignition mechanism gives one a good consistency with experimental data and can be applied for the prediction of ignition time for air injection projects. The other result of our approach is the difference between heavy and light oil oxidation in low and high rate processes. In high rate processes, free radicals are active enough for igniting the oil, and light oils contain more free radicals of this type and are more reactive for ignition. Heavy oils have better affinity for fuel formation and oxygen addition reactions. So heavy oils can usually ignite at higher temperature than light oils.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Chain Reactions Approach to the Initial Stages of Crude Oil Oxidation

Ushakova

Zatsepin

2018

Energy Fuels

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“…In the case of light oils, the production is stimulated (eventual) vaporization of lighter fractions, which then move downstream and mix with the original crude 2), 3) . So it provides a steam drive and intense gas drive for the recovery of oil 4) . In order to successfully exploit the vast potential of processes based on air injection for the recovery of conventional and heavy oils, it is necessary to ensure the combustion zone sustainably propagates in the reservoir.…”

Section: Introductionmentioning

confidence: 99%

“…Water is sometimes injected simultaneously or alternately with air, creating steam, which contributes to better heat utilization and reduced air requirements and also it can lessen the detrimental overriding of combustion gases 4) . The use of wet combustion began at the moment in which it was recognized that much of the heat stored in the rock during the dry, forward combustion behind the combustion front was being lost to the adjacent formations 8) .…”

Section: Introductionmentioning

confidence: 99%

Experimental and Simulation Study of <i>In-situ</i> Combustion Process in Carbonate Fractured Porous Media

Shojaiepour

Kharrat

Shojaiepour

et al. 2014

J. Jpn. Petrol. Inst.

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According to difficulties of producing heavy oil reservoirs, in-situ combustion (ISC) as one of the high efficient methods leads to reduce oil viscosity by increasing temperature. Since there are remarkable amounts of heavy oil reservoirs in the world and lots of experimental works have been carried out on sandstones, shale or oil sands, the research on carbonate rocks seems to be rare. The experimental tests were performed with the oil of 17.5° API and 8° API mixed with the crushed carbonate rocks of Asmari and Sarvak formations respectively to investigate the feasibility of ISC and calculate its parameters. According to experiments, combustion tube conducted vertically to use gravity as a force to minimize gravity segregation effects. Results show that combustion is technically applicable to the both rock-fluid systems. Additionally the percentages of CO2, O2 and CO have been measured by gas analyzer. Moreover, the effect of grain size on combustion temperature, connate water on oil recovery and front characteristics are investigated. Finally, fractured model of combustion tube is simulated and the effects of air injection rate, permeability, initial oil saturation and grid size are investigated. The obtained basic parameters of experiments are suitable for ISC implementation to fields efficiently.

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