Effect of Liquid Nitrogen Freezing on the Mechanical Strength and Fracture Morphology in a Deep Shale Gas Reservoir

Qu, Hai; Li, Chengying; Qi, Chengwei; Chen, Xiangjun; Xu, Yang; Jun, Hong; Wu, Xiaoguang

doi:10.1007/s00603-022-03035-y

Cited by 11 publications

(2 citation statements)

References 41 publications

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“…In their mechanical experiment, Sandstrom et al [59] found that the quantity of freezing-thawing cycles on rocks influenced the mechanical characteristics and fissures in the material. It should also be mentioned that the LN 2 process, as the waterless hydraulic fracturing method, has been used by different research groups in shale [41,60,61], carbonate [17,62], sandstone [63,64], and granite [65][66][67] rocks with successful results as it initiates the mechanical and physical deterioration of the samples of varying mineralogy and composition. This work explores the changes in pore structure characteristics that are seen in coal samples that are obtained from the Karaganda area after they are exposed to liquid nitrogen (LN 2 ), which is used as a waterless fracturing method for coalbed methane (CBM) reservoirs.…”

Section: Introductionmentioning

confidence: 99%

Laboratory Study of Liquid Nitrogen Cryo-Fracturing as an Environmentally Friendly Approach for Coalbed Methane (CBM) Reservoirs

Longinos,

Serik,

Bayramov

et al. 2024

Energies

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This study evaluated two distinct cryo-fracturing techniques using liquid nitrogen (LN2). The evaluation included tests for peak compression strength, acoustic emission, and energy absorption. The experiments compared single-exposure freezing time (FT) and multiple-exposure freezing–thawing cycle (FTC) processes on dried specimens. The outcomes indicated that FTC experiments demonstrated lower uniaxial compression stress (UCS) values compared to FT experiments because, during the thawing phase, the ice inside the pores reverts to liquid as the temperature rises. The difference between average baseline experiments versus FT180 and FTC6 indicated a reduction in stress of 14.5% and 38.5%, respectively. The standard error of our experiments ranged from 0.58% for FT60 to 5.35% for FTC6. The damage factor follows a downward trend in both FT and FTC experiments as the time of LN2 treatment augments. The amount of energy that can be absorbed in elastic or plastic deformation before failure is less for FTC specimens with the same total LN2 exposure time. Samples undergoing the freezing time process demonstrate a greater and denser quantity of acoustic emissions in comparison to freezing–thawing cycle processes, suggesting a positive correlation with uniaxial compressive strength outcomes. The large network of fractures formed by the FTC and PFTC techniques indicated that they have the greatest potential as stimulation approaches. The engineering results were improved by adding the geological context, which is essential to apply these findings to coals that have comparable origins.

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Section: Introductionmentioning

confidence: 99%

Laboratory Study of Liquid Nitrogen Cryo-Fracturing as an Environmentally Friendly Approach for Coalbed Methane (CBM) Reservoirs

Longinos,

Serik,

Bayramov

et al. 2024

Energies

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“…Therefore, it is very important to find an effective technology to break up the coal bed and increase the permeability to improve the safety of the coal seam. The conventional antireflectivity technology still has many problems due to various factors, but the cryogenic cycle cracking technology using liquid nitrogen and liquid CO2 as freezing medium offers a new idea for coal seam antireflectivity due to its advantages such as high efficiency, safety, and low cost, which has attracted the attention of many scholars (Yuan et al, 2022a;Li et al, 2022b;Qu et al, 2022;Zhang et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

Study on evolution law of pore characteristics of freeze-thaw coal based on fractal theory

Yuan,

Chen,

Wang

et al. 2023

Preprint

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To investigate the characteristics of pore structure change of coal under freeze-thaw cycles, the surface and internal pore structure distribution of coal samples with long flame and different freeze-thaw times were measured by scanning electron microscopy (SEM) and low-temperature nitrogen adsorption method, and the law of pore structure change of coal after freeze-thaw was analyzed by fractal theory. The results of scanning electron microscopy experiments show that after freeze-thaw, the phenomenon of crack pore enlargement on the surface of coal samples occurs to different extents, and the phenomenon of crack pore enlargement on the surface of coal samples increases with the duration of freeze-thaw; at the same time, the porosity and fractal dimension DS of microcracks on the surface increased by 214.2% and 8.8%, respectively, corresponding to the change of macrocracks. The low-temperature nitrogen adsorption results show that the freezing and thawing changes the internal pore structure from simple to complex, and the maximum nitrogen adsorption capacity, specific surface area and pore volume in the pore parameters increase by 67.57%, 49.12% and 35.55%, respectively, compared with those before freezing and thawing. After freezing and thawing, the fractal dimension of the pores decreased to different degrees in the high-pressure and low-pressure stages. It decreased by 6.6% in the high pressure stage and by 8.9% in the low pressure stage. The change in fractal dimension DL in the low-pressure stage is greater than that of fractal dimension DH in the high-pressure stage, and the difference between the two decreases with increasing number of freeze-thaw cycles.

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Mixed-Mode I/III Fracture

Zhao,

Zheng,

Wang

2024

Rock Fracture Mechanics and Fracture Criteria

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Effect of Liquid Nitrogen Freezing on the Mechanical Strength and Fracture Morphology in a Deep Shale Gas Reservoir

Cited by 11 publications

References 41 publications

Laboratory Study of Liquid Nitrogen Cryo-Fracturing as an Environmentally Friendly Approach for Coalbed Methane (CBM) Reservoirs

Laboratory Study of Liquid Nitrogen Cryo-Fracturing as an Environmentally Friendly Approach for Coalbed Methane (CBM) Reservoirs

Study on evolution law of pore characteristics of freeze-thaw coal based on fractal theory

Mixed-Mode I/III Fracture

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