A novel insight of laboratory investigation and simulation for high pressure air injection in light oil reservoir

Pu, Wanfen; Liu, Zhezhi; Li, Yibo; Wei, Bing; Jia, Hu; Kong, Lingle

doi:10.1016/j.jngse.2017.01.004

Cited by 14 publications

(10 citation statements)

References 16 publications

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“…The accurate compensation of heat release like the heat-wait-search technique is performed by ARC. The initial heat release of oxidation can also be obtained in isothermal experiments if temperature is rather high and oil active for oxidation (usually light oil). , In fact such experiments perform better in oilfield conditions because the conditions are more isothermal than adiabatic. In fact the main goal of such experiments is accurate heat release measuring and accurate heat dissipation control to record the time and temperature of the start of heat release.…”

Section: Resultsmentioning

confidence: 99%

“…And kinetic parameters are mainly obtained according to this data. , In fact oil degradation and coke formation is observed . Sometimes oil is so reactive that one can observe self-heating effects even under isothermal conditionslike in refs and . Temperature rise was observed for light oil samples at 95 °C after 22 h and at 170 °C after 5 h .…”

Section: Introductionmentioning

confidence: 85%

“…Sometimes oil is so reactive that one can observe self-heating effects even under isothermal conditionslike in refs and . Temperature rise was observed for light oil samples at 95 °C after 22 h and at 170 °C after 5 h . For heavy oils, such an effect is not presented in the literature, so we assume it is rather difficult to obtain it, due to the low activity of the heavy oil for self-ignition.…”

Section: Introductionmentioning

confidence: 88%

“…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%

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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: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 85%

Section: Introductionmentioning

confidence: 88%

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 recent years, extensive works have been performed to study the thermal behaviors of crude oils using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), ramped-temperature-oxidation tests (RTO), combustion tube (CT), etc., with the aim of precisely defining the reaction models and kinetics. − As agreed by most peers, the ISC process can be divided into three temperature regions, namely low temperature range (LTR), negative temperature gradient range (NTGR), and high temperature range (HTR), as shown in Figure b. LTR is largely governed by low temperature oxidation (LTO) and other bond-scission reactions with the production of oxygenated hydrocarbons (i.e., aldehydes, ketones, and alcohol) and carbon oxides, while NTGR plays an integral role in determining the success of ISC because of the coke deposited.…”

Section: Introductionmentioning

confidence: 99%

Investigations of Structure–Property–Thermal Degradation Kinetics Alterations of Tahe Asphaltenes Caused by Low Temperature Oxidation

et al. 2018

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In situ combustion (ISC) is advantageous for (ultra)heavy reserves due to its high heating efficiency and small surface footprint compared to steam injection. Herein, the focus of this work was given to the key factor in sustaining the continuity of the combustion front, the asphaltene fraction. Structure–property alterations of Tahe asphaltenes caused by low temperature oxidation (LTO) were thoroughly examined. Particular attention was placed on its combustion and pyrolysis kinetics. The results showed that after LTO 10.35 wt % coke was formed. Scanning electron microscopic observations indicated that the surfaces of the oxidative products were fairly rough as a result of air attack and the caused reactions on site, and these alterations promoted the subsequent combustion. The textures of the products were observed to be further compacted and condensed after LTO. As anticipated, distinguished reaction regions were clearly identified on the thermogravimetric (TG)/differential scanning calorimetric curves in this work. The results of TG and activation energy revealed the differences of the reaction sites in the combustion and pyrolysis processes. The coke formed after LTO exhibited the highest reaction activity and exothermic effect compared to the fresh asphaltenes and residue. It is believed that this work can add new insights to ISC with regard to the mechanisms and reaction models, which are highly valuable for field applications.

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