Feasibility Study of Auto Ignition in &lt;i&gt;In-situ&lt;/i&gt; Combustion Process

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

doi:10.1627/jpi.51.287

Cited by 10 publications

(6 citation statements)

References 6 publications

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“…The air injection enhanced oil recovery technique is usually studied by the use of either the combustion tube − or three-dimensional (3D) combustion cell. ,, The experiment allows the evaluation of the likely mechanism of the physicochemical processes at the field scale. Numerical models are then developed and validated against the experimental results.…”

Section: Introductionmentioning

confidence: 99%

Impacts of Kinetics Scheme Used To Simulate Toe-to-Heel Air Injection (THAI) in Situ Combustion Method for Heavy Oil Upgrading and Production

Ado

2020

ACS Omega

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While simulating toe-to-heel air injection (THAI), which is a variant of conventional in situ combustion that uses a horizontal producer well to recover mobilized partially upgraded heavy oil, the chemical kinetics is one of the main sources of uncertainty because the hydrocarbon must be represented by the use of oil pseudo-components. There is, however, no study comparing the predictive capability of the different kinetics schemes used to simulate the THAI process. From the literature, it was determined that the thermal cracking kinetics schemes can be broadly divided into two: split and direct conversion schemes. Unlike the former, the latter does not depend on the selected stoichiometric coefficients of the products. It is concluded that by using a direct conversion scheme, the extent of uncertainty imposed by the kinetics is reduced as the stoichiometric coefficients of the products are known with certainty. Three models, P, G, and B, each with their own different kinetics schemes, were successfully validated against a three-dimensional combustion cell experiment. In models P and G, which do not take low-temperature oxidation (LTO) into account, the effect of oil pseudo-component combustion reactions is insignificant. For model B, which included LTO reactions, LTO was also found to be insignificant because only a small fraction of oxygen bypassed the combustion front and the combustion zone was maintained at temperatures of over 600°C. Therefore, in all the models, it is observed that coke deposition was due to the thermal cracking taking place ahead of the combustion zone. During the first phase of the combustion, peak temperature curves of models P, G, and B closely matched the experimental curve, albeit with some deviations by up to 100°C between 90 and 120 min. After the increase in the air injection flux, only the model P curve overlapped the experimental curve. The model P cumulative oil production curve deviated from the experimental one by only a relative error of 4.0% compared to deviations in models G and B by relative errors of 6.0 and 8.3%, respectively. Consequently, it follows that model P provided better predictions of the peak temperature and cumulative oil production. The same conclusion can be drawn with regard to the produced oxygen concentration and combustion front velocity. With regard to American Petroleum Institute (API) gravity, it is found that all the three models predicted very similar trends to the experiment, just like in the case of the oil production rate curves, and therefore, no model, in these two cases, can be singled out as the best. Also, all the models’ predictions of the produced CO X concentration prior to the increase in the air flux closely match the experimental curve. There are, however, serious differences, especially by model P, from the reported experimental curve by up to 15% after the increase in the air flux.

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Section: Introductionmentioning

confidence: 99%

Impacts of Kinetics Scheme Used To Simulate Toe-to-Heel Air Injection (THAI) in Situ Combustion Method for Heavy Oil Upgrading and Production

Ado

2020

ACS Omega

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“…The study of in situ combustion (ISC) has been mostly carried out at the laboratory scale. This is usually performed with either a combustion tube − or three-dimensional (3D) combustion cell. − Experiments help in understanding the process mechanisms and provide insight into what will happen in the reservoir. However, even at laboratory scale, the full physics of the processes taking place must be fully understood to develop a rigorous model that can be used for upscaling to field scenarios.…”

Section: Introductionmentioning

confidence: 99%

“…The THAI thermal heavy oil recovery process has unique potential to achieve this. The following are some of the attributes of THAI that should be realizable in the field: (1) generates its own fuel in the reservoir to fully sustain the process, (2) does not require any natural gas or water during normal operation, (3) can be made essentially selfsustaining, so that no net energy input is required, (4) carbon capture ready for enhanced oil recovery (EOR) or sequestration, (5) high oil recovery potential, (6) creates an underground "reactor" for in situ upgrading, (7) potential for one-step "heavy to light oil" upgrading in situ, (8) improved economics for heavy oil recovery, (9) in situ reduction of sulfur, nitrogen, and heavy metals, and (10) has a small surface footprint.…”

Section: ■ Introductionmentioning

confidence: 99%

Dynamic Simulation of the Toe-to-Heel Air Injection Heavy Oil Recovery Process

2017

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Toe-to-Heel Air Injection (THAI) is a variant of conventional In-Situ Combustion (ISC) that uses a horizontal production well to recover mobilised partially upgraded heavy oil. It has a number of advantages over other heavy oil recovery techniques such as high recovery potential. However, existing models are unable to predict the effect of the most important operational parameters, such as fuel availability and produced oxygen concentration, which will give rise to unsafe designs. Therefore, we have developed a new model that accurately predicts dynamic conditions in the reservoir and also is easily scalable to investigate different field scenarios. The model used a three component direct conversion cracking kinetics scheme, which does not depend on the stoichiometry of the products and, thus, reduces the extent of uncertainty in the simulation results as the number of unknowns is reduced.The oil production rate and cumulative oil produced were well predicted, with the latter deviating from the experimental value by only 4%. The improved ability of the model to emulate real process dynamics meant it also accurately predicted when the oxygen was first produced, thereby enabling a more accurate assessment to be made of when it would be safe to shut-in the process, prior to oxygen breakthrough occurring. The increasing trend in produced oxygen concentration following a step change in the injected oxygen rate by 33 % was closely replicated by the model. The new simulations have now elucidated the mechanism of oxygen production during the later stages of the experiment.The model has allowed limits to be placed on the air injection rates that ensure stability of operation.Unlike previous models, the new simulations have provided better quantitative prediction of fuel laydown, which is a key phenomenon that determines whether, or not, successful operation of the THAI process can be achieved. The new model has also shown that, for completely stable operation, 2 2 the combustion zone must be restricted to the upper portion of the sand pack, which can be achieved by using higher producer back pressure.

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“…5,6 Ignition can be achieved by a variety of mechanisms or processes, including auto-ignition, gas burners, electrical heaters, and chemical reactions. 7–10 This reaction produces heat which leads to further hydrogen forming reactions: aquathermolysis, thermolysis, coke gasification, the water–gas shift reaction and methanation. 11…”

Section: Introductionmentioning

confidence: 99%