Microstructure Evolution of Bituminous Coal Modified by High-Pressure CO2 Foam Fracturing Fluid with Different Treatment Times

Zheng, Yangfeng; Zhai, Cheng; Chen, Aikun; Sun, Yong; Cong, Yuzhou; Tang, Wei; Xu, Jizhao; Yu, Xu; Zhu, Xinyu; Li, Yujie

doi:10.1007/s11053-023-10179-3

Cited by 10 publications

(4 citation statements)

References 55 publications

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“…Figure shows the isothermal adsorption–desorption curves of different coal samples. There is a multistage growth trend that is related to the storage state of N 2 in different pores . The adsorption capacities of YSW and HY are 15.0 and 24.2 cm 3 /g, while those of EK, HD, and SP are 1.66, 3.96, and 1.76 cm 3 /g, respectively.…”

Section: Resultsmentioning

confidence: 99%

“…There is a multistage growth trend that is related to the storage state of N 2 in different pores. 40 The adsorption capacities of YSW and HY are 15.0 and 24.2 cm 3 /g, while those of EK, HD, and SP are 1.66, 3.96, and 1.76 cm 3 /g, respectively. The maximum adsorption capacity of bituminous coal is 3.79−14.58 times that of anthracite.…”

Section: Lt-n 2 Amentioning

confidence: 94%

“…The calculated fractal dimensions of mesopores in different coal samples are listed in Figure 11. In the range of relatively low pressure, N 2 undergoes micropore-filling behavior in the pores of coal samples, 40 and eq 2 cannot characterize the adsorption behavior of micropores, so adsorption data with relative pressure less than 0.02 are excluded. The test process is divided into two stages according to whether P/P 0 is greater than 0.5, and the fractal dimensions are calculated separately.…”

Section: Multiscale Pore Fractal Characteristics and Pore Connectivit...mentioning

confidence: 99%

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Quantitative Study of the Effects of Pore Structure and Wettability on the Water Spontaneous Imbibition Behaviors in Coal

Xu,

Zhai

et al. 2023

Energy Fuels

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Water injection has been widely used to prevent gas disasters and coal dust in coal mines. Coal would be wetted and softened by water through spontaneous imbibition (SI), which is mainly influenced by the pore structure and wettability. Studying the effects of pore structure and wettability on SI is of great significance for optimizing coal seam water injection parameters. This work aims to establish a quantitative relationship between these parameters and extract critical factors controlling the SI. Mercury intrusion porosimetry (MIP), low-temperature N 2 adsorption (LT-N 2 A), Fourier transform infrared spectroscopy (FTIR), and contact-angle measurements were used to assess the pore structure and wettability of the coal samples. Low-field nuclear magnetic resonance (LF-NMR) was used to monitor water in coal. All parameters were quantified with Pearson correlation analysis, and principal component analysis (PCA) was subsequently employed to pinpoint the key factors. The results show that the SI velocity and SI ability of bituminous coal are higher than those of anthracite; bituminous coal can rapidly elute more water. The time index (n) has a strong relationship with the SI velocity, and the higher the n value is, the faster the water migrates in pore space. Porosity is positively proportional to SI ability, and a larger SI ability means that the sample can store more water. The wettability parameter has a higher impact on SI velocity than on SI ability. Among the wettability parameters, the contact angle is a key factor in evaluating the SI process in coal. The bituminous coal with good pore connectivity, hydrophilicity, and high porosity could have a rapid SI velocity and store more water. Oxygen-containing functional groups promote SI by enhancing water and pore surface interactions. This work can better understand the mechanism of SI and provide the theoretical basis for field application.

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Section: Resultsmentioning

confidence: 99%

Section: Lt-n 2 Amentioning

confidence: 94%

Section: Multiscale Pore Fractal Characteristics and Pore Connectivit...mentioning

confidence: 99%

See 1 more Smart Citation

Quantitative Study of the Effects of Pore Structure and Wettability on the Water Spontaneous Imbibition Behaviors in Coal

Xu,

Zhai

et al. 2023

Energy Fuels

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“…Consequently, hydraulic fracturing has played an important role in successful methane reservoir exploitation . While the fracturing fluid systems used in the United States have been applied in China, the complex reservoir conditions in China, in particular low permeability and low pressure, have limited the success of these systems. , These systems since the first CBM well was drilled in Panzhuang, China, in 1992, have included guar gum fracturing fluid, cross-linked fracturing fluid, clean fracturing fluid, CO 2 foam fluid, nitrogen foam fluid, pure nitrogen fluid, and composite fluid . While these fluid systems have facilitated improved injection of sand-carrying gel into high-permeability coal, up to 60% of coal seams in China are low-permeability, broken, soft coal seams, which has limited the effectiveness of high-viscosity fracturing fluids .…”

Section: Introductionmentioning

confidence: 99%

Effect of Surfactant Modification on Coalbed Methane Desorption and Its Behavioral Mechanism

Qi,

Tian,

Cao

et al. 2024

Energy Fuels

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The efficient development of coalbed methane (CBM) is extremely important for coal mine safety and clean energy. While hydraulic fracturing has long remained the dominant technology for increasing CBM production, fracturing fluid results in self-priming of coal reservoirs, with the consequent water-lock effect decreasing CBM recovery. This study aimed to examine the effect of changes in the wettability of fracturing fluid on the desorption behavior of CBM. Hydrophobic CZH-1 and clear water fracturing fluid were prepared, following which fracturing desorption experiments were conducted on medium-and highranking coal-containing gas. The results showed that hydrophobic CZH-1 surfactant leads to a significant increase in the desorption rate of CBM. The rapid desorption rate of Xinjing and Baode coal increased by 11.1 and 48.8%, respectively, in the first 2 min, and the stable desorption rate increased by 34.8 and 21.0%, respectively, in 60 min. Application of Fourier transform infrared (FTIR) spectroscopy showed that the invasion of the hydrophobic CZH-1 surfactant resulted in decreases in the total area of the C−O peak of the oxygen-containing functional group and in the hydrophilic point in the coal. The hydrophilic group of the coal surface absorbed the hydrophilic group of the cationic surfactant molecule through electrostatic and van der Waals forces. Consequently, the facing of the hydrophobic group to the solution reduced the wettability behavior of water, decreasing the capillary force and reducing the degree to which the water-lock effect damaged the coal reservoir, thereby promoting the desorption of CBM. This study can act as a useful reference for the efficient development of CBM in low-permeability and low-pressure coal reservoirs and particularly for the development of CBM fracturing fluid.

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A viscoelastic‐healing suspension sealing material with a double‐network gel structure for improving borehole‐sealing performance

Liu,

Zhai,

Zheng

et al. 2024

J of Applied Polymer Sci

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Developing a high‐performance sealing material to improve the sealing quality of extraction boreholes is of great significance for achieving efficient coalbed methane (CBM) extraction and safety mining. In this work, a viscoelastic‐healing suspension sealing material (VEHS) with a double‐networked gel structure was developed, consisting of a latex emulsion (LE) and polymeric superabsorbent (PSA) with the addition of fly ash (FA) and sodium montmorillonite (Na‐MMT). X‐ray diffraction, scanning electron microscopy, and rheometer tests were conducted to characterize the variation in the microstructural characteristics and rheological behaviors of VEHS, respectively. Besides, response surface methodology was utilized to model the relationships between the composition of VEHS and its viscosity and fluidity. The results show that the VEHS's structure is uniformly dense. The viscosity of VEHS, a pseudoplastic fluid, decreases progressively with an increasing shear rate while rising and stabilizing over time. Within the stress range of 10–30 Pa, VEHS exhibits relatively balanced viscoelasticity. VEHS shows excellent fluidity and can form a viscoelastic‐healing coagulated layer that is firmly adhered to the coal wall, leading to a strong sealing ability. The research has the potential to enhance the effectiveness of CBM extraction and brings the advantages in terms of safety, economy, and society.

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Microstructure Evolution of Bituminous Coal Modified by High-Pressure CO2 Foam Fracturing Fluid with Different Treatment Times

Cited by 10 publications

References 55 publications

Quantitative Study of the Effects of Pore Structure and Wettability on the Water Spontaneous Imbibition Behaviors in Coal

Quantitative Study of the Effects of Pore Structure and Wettability on the Water Spontaneous Imbibition Behaviors in Coal

Effect of Surfactant Modification on Coalbed Methane Desorption and Its Behavioral Mechanism

A viscoelastic‐healing suspension sealing material with a double‐network gel structure for improving borehole‐sealing performance

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