Effects of cyclic freezing and thawing of coals at their behavior at low- and high-temperature oxidation

Эпштейн, С. А.; Шкуратник, В. Л.; Kossovich, E. L.; Agarkov, K. V.; Nesterova, Valeria; Gavrilova, D. I.

doi:10.1016/j.fuel.2020.117191

Cited by 8 publications

(3 citation statements)

References 28 publications

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“…In single injection, injection time is varied to fracture coal rock. In cyclic injection, the number of freeze–thaw cycles is varied; coal rock is weakened as it is repeatedly frozen and thawed. − Coal rock pore structure is clearly changed by cyclic injection, while the effect of single injection is less clear. − As a coal rock fracturing fluid, LN 2 produces no waste or water pollution; the fracturing process is more stable and has few unintended consequences. − As a new means to fracture coal rock, LN 2 fracturing can increase coal rock permeability and enhance unconventional oil and gas production while avoiding the shortcomings of traditional fracturing. − …”

Section: Introductionmentioning

confidence: 99%

Advances in Liquid Nitrogen Fracturing for Unconventional Oil and Gas Development: A Review

et al. 2022

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Liquid nitrogen (LN 2 ) fracturing is an anhydrous fracturing technology that enhances coal permeability and supports unconventional oil and gas exploitation. In this Review, we provide a systematic review of five aspects of LN 2 fracturing. They are the history of the technology's development, research topics, factors influencing fracturing efficiency, fracturing mechanism, and engineering processes and systems. Liquid nitrogen fracturing transforms coal and rock pore structure through mechanisms such as low temperature, freeze−thaw damage, and gas expansion. It changes coal and rock mechanical properties and improves the pore penetration and efficiency of unconventional oil and gas extraction. However, in-depth studies are still required in many areas. They include theoretical studies of twophase nitrogen flow in coal and rock, development of technical equipment to support field operations, and plans to monitor and evaluate fracturing efficiency. On the basis of the advances in LN 2 fracturing research and the challenges, we conclude that future research should focus on multiphase flow and field equipment and technology.

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Section: Introductionmentioning

confidence: 99%

Advances in Liquid Nitrogen Fracturing for Unconventional Oil and Gas Development: A Review

et al. 2022

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“…Coalbed methane, dominantly methane, is an important energy resource, and many countries have realized the use of coalbed methane. Gas extraction is not only the most direct way to solve the coal mine gas problem but also the best way to collect and utilize the gas. , Coal seams have low permeability, and many fracturing methods have been proposed, and some of them used, to increase the seam’s permeability and allow efficient gas extraction. − However, the traditional coal seam fracturing methods have some limitations that not only can produce a water lock and water sensitivity during construction, but some methods also cause pollution and wastewater resources. , As a water-free technique for increasing coal seam permeability, liquid nitrogen fracturing has been extensively studied by many researchers. − …”

Section: Introductionmentioning

confidence: 99%

Gas Adsorption Capacity of Coal Frozen with Liquid Nitrogen and Variations in the Proportions of the Organic Functional Groups on the Coal after Freezing

Qin

Wang

et al. 2021

Energy Fuels

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Studying the law of coal adsorption capacity under the action of liquid nitrogen is very important for the extraction of coalbed methane. For this study, the lignite's ability to adsorb methane was studied after it had been frozen by a number of different freezing techniques. In addition, the changes in the organic functional groups on the coal after freezing were identified by using infrared spectroscopy. The results demonstrate that as the duration of liquid nitrogen freezing and the number of freezing cycles increase, the lignite's gas adsorption capacity first decreases, then increases, and finally maintains a stable value. As the liquid nitrogen freezing time increases, the proportion of oxygen-containing functional groups increases, but the percentages of substituted benzene groups and aliphatic hydrocarbon functional groups decrease. The research shows that, compared with a single freezing, cyclic freezing has a greater effect on the lignite's gas adsorption capacity. Freezing influences the proportion of the substituted benzene functional groups on the coal the most; after freezing, the rates of change in the proportions of aliphatic hydrocarbon and oxygencontaining functional groups are only 70.76% and 80.29% as large as the change in the substituted benzene functional groups. As the proportions of the three types of functional groups increase, the lignite's gas adsorption capacity first decreases but then increases. This study will promote the development of liquid nitrogen freezing technology for coalbed methane extraction.

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“…However, after 25 freeze-thaw cycles for three coals (lignite, bitumite, and anthracite) with the use of liquid CO 2 , Xu et al [18] stated that the enhancement ratio of total porosity for butumite is the greatest, and it is the lowest for anthracite. As a result of research connected with thermo-oxidative degradation of freezing-thawing of bituminous coals, Epshtein et al [23] ascertained a widening of their "combustion interval" and a decrease in "rate of combustion and its activation energy".…”

Section: Introductionmentioning

confidence: 99%

The Influence of Freezing on the Course of Carbonization and Pyrolysis of a Bituminous High-Volatile Coal

Zubkova

Strojwas

2020

Energies

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The course of thermal behavior of a fresh bituminous high-volatile coal during carbonization and pyrolysis was compared to that of this coal thawed after storage. The research was carried out using the following techniques: X-raying, thermogravimetry/Fourier transform-infrared spectroscopy (TG/FT-IR), extraction, Diffuse Reflectance Infrared Fourier Transform Spectroscopes (DRIFT), Attenuated Total Reflectance (ATR), and SEM. The increase in range of the viscous-liquid state and a decrease in temperature of its appearance were stated along with the formation of a more compact residue at the re-solidification stagtablee for the thawed coal during its carbonization. There is a fourfold reduction in the charge volume. The leakage of bitumen that contains 87 At % of C atoms from swollen grains and a fourfold increase in the yield of the material extracted from these grains are the proof of a greater plasticization of thawed coal. During the pyrolysis of thawed coal, the yield in volatile products of pyrolysis increases, and the composition of these products changes. The contribution ratio of saturated and unsaturated hydrocarbons, CO2, alcohols, and phenols decreases in the composition of volatile products of thawed coal. It is suggested that the use of freezing during the storage of a freshly mined coal that has a poorer caking ability can improve its plasticization during carbonization.

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Effects of cyclic freezing and thawing of coals at their behavior at low- and high-temperature oxidation

Cited by 8 publications

References 28 publications

Advances in Liquid Nitrogen Fracturing for Unconventional Oil and Gas Development: A Review

Advances in Liquid Nitrogen Fracturing for Unconventional Oil and Gas Development: A Review

Gas Adsorption Capacity of Coal Frozen with Liquid Nitrogen and Variations in the Proportions of the Organic Functional Groups on the Coal after Freezing

The Influence of Freezing on the Course of Carbonization and Pyrolysis of a Bituminous High-Volatile Coal

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