Fractal wave velocity evolution model of ultrasonic propagation and attenuation in water-bearing coal

Wang, Gang; Wang, Shibin; Chen, XueChang; Chi, LiHui; Qin, Cunli; Liu, YuanHao; Ju, Shuang

doi:10.1016/j.ijrmms.2022.105283

Cited by 11 publications

(4 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The propagation attenuation characteristics of the longitudinal wave can reflect the development of radial fissures in coal samples. 45 The wave speed of ultrasonic waves can be derived from the following eq 1…”

Section: Lt-n 2 Ga Resultsmentioning

confidence: 99%

“…The propagation attenuation characteristics of the transverse wave can reflect the development of axial fissures in the coal samples. The propagation attenuation characteristics of the longitudinal wave can reflect the development of radial fissures in coal samples . The wave speed of ultrasonic waves can be derived from the following eq ν is the ultrasonic wave velocity, m/s; L is the length of coal sample, m; t 0 is the acoustic emission moment, s; and t 1 is the acoustic reception moment, s. The partial evolution of ultrasonics during low-temperature oxidation is shown in Figures and .…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Exploring the Effect of Low-Temperature Oxidation on the Petrophysical Characteristics of Coal

Li,

Cao,

et al. 2023

ACS Omega

View full text Add to dashboard Cite

Low-temperature oxidation leads to the accumulation of heat in coal, and it is an important trigger for coal spontaneous combustion (CSC). The oxidation effects induce irreversible damage in the pore and fracture structures of coal, which provide a way for the infiltration of oxygen. In this work, the evolution of pores and cracks of coal in the progress of low-temperature oxidation is researched based on nitrogen adsorption, scanning electron microscopy (SEM), and ultrasonic testing. The results show that the oxidation effect increases microporous structures and promotes the development of mesopores and macropores in coal. Besides, as the temperature increases, the oxidation effect becomes more significant, while the pore morphology has not changed significantly yet. Meanwhile, the oxidation effect causes coal particles to block or collapse in the macropores, and the plugging degree increases with increasing temperature.

show abstract

Section: Lt-n 2 Ga Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Exploring the Effect of Low-Temperature Oxidation on the Petrophysical Characteristics of Coal

Li,

Cao,

et al. 2023

ACS Omega

View full text Add to dashboard Cite

show abstract

“…Coalbed methane (CBM) usually exists in the coal matrix in adsorbed state, , and its effective exploitation is of great significance to optimize the national energy structure and prevent gas outburst. − However, due to its dense structure, coal seams are generally characterized by low permeability and low porosity, , which lead to the difficulty of CBM extraction and aggravates the gas dynamic disaster during coal mining. Hydraulic fracturing − is widely used in the field of CBM production, which can effectively enhance the permeability and realize reservoir transformation, thereby enhancing the efficiency of CBM production and reducing the probability of coal mine gas accidents.…”

Section: Introductionmentioning

confidence: 99%

Effect of Slickwater on Methane Adsorption in Coal: Experiment and Molecular Simulation

Li,

Wang,

Ning

et al. 2024

Energy Fuels

Self Cite

View full text Add to dashboard Cite

Slickwater is generally applied in the domain of coalbed methane (CBM) stimulation. However, the residual slickwater after fracturing operations may adversely affect the production of CBM. In this paper, nuclear magnetic resonance (NMR) measurements are used to compare and analyze the differences of functional groups on the coal surface in different regions and provide the basis for the construction of molecular simulation models. Then, different concentrations of slickwater were made, and coal samples from different regions were soaked. Isothermal adsorption experiments and molecular simulations were applied to explore the effect of slickwater on methane adsorption properties of coal from different regions. The NMR results show that the amount of naphthalene functional groups in coal samples from Dongtan coal mine (DT) is more than that in coal samples from Houwenjialiang coal mine (HW), which has a stronger attraction to methane. The isothermal adsorption experiment results show that the methane adsorption capacity of the coal sample from HW is stronger than that of the coal sample from DT. When the concentration of slickwater is 0.5%, the methane adsorption capacity of DT increases to 3/2 of raw coal, and the methane adsorption capacity of HW declines to 1/3 of raw coal. The retention of slickwater will have different effects on coal samples in different areas. Comparing the experimental and simulation results, we can see that polyacrylamide can adsorb methane, thereby increasing the specific surface area of the local “slickwater–coal” system due to its porous coating structure, resulting in an increase in the methane adsorption capacity. The negative effect of slickwater on the methane adsorption properties is because slickwater changes the pore, resulting in the reduction of effective surface area and finally damages the adsorption amount of methane.

show abstract

“…Jia et al [ 24 ] carried out the ultrasonic velocity test of coal and rock bodies under loading, and analyzed the crack propagation process of coal and rock bodies. Wang et al [ 25 ] established a fractal ultrasonic velocity evolution model of water-bearing coal based on fractal theory, and studied the relationship between crack structure parameters and ultrasonic velocity. In the study of ultrasonic waveform and attenuation coefficient, Pahlavan et al [ 26 ] studied the effect of crack width on ultrasonic transmission time and amplitude during unloading of concrete structures.…”

Section: Introductionmentioning

confidence: 99%

Ultrasonic characteristics and equivalent crack width of coal and rock bodies around boreholes during progressive failure

Zhang

et al. 2023

PLoS ONE

View full text Add to dashboard Cite

The ultrasonic characteristics of the coal and rock bodies around boreholes during failure are closely related to the crack propagation law. To investigate the ultrasonic characteristics and crack propagation law of coal and rock bodies around boreholes, different grouting samples with boreholes were taken to carry out ultrasonic test during progressive failure. The ultrasonic amplitude, velocity and attenuation coefficient of the samples were analyzed. According to the ultrasonic time difference formula, the equivalent crack width of the sample during the failure process is calculated. The influence of grouting material on the crack propagation law is quantitatively analyzed. The results show that: (1) The peak stress, elastic energy at the peak, ultrasonic parameters and crack propagation of the coal and rock bodies around boreholes show obvious differences influenced by the strength of the grouting material. (2) During the loading process, the arrival time of the first wave of the sample with holes is 5μs later than that of the grouting sample, and the ultrasonic energy attenuates fastest in the time domain, and the coda wave is not developed. (3) During the progressive failure, the ultrasonic velocity and attenuation coefficient of all show three stages of stability(0~0.6σp), slow change(0.6σp~0.8σp) and rapid change(0.8σp~1.0σp). According to the "sudden decrease" of velocity and the "sudden increase" of attenuation coefficient to judge the crack propagation of sample. (4) The equivalent crack width of the sample increases exponentially with the increase of stress level. At the time of reaching the peak stress, the equivalent crack width of SH-BH increases about 0.027mm~0.032mm, SH-PU about 0.01mm~0.014mm, and SH-CEM about 0.002mm~0.006mm.

show abstract

Fractal wave velocity evolution model of ultrasonic propagation and attenuation in water-bearing coal

Cited by 11 publications

References 33 publications

Exploring the Effect of Low-Temperature Oxidation on the Petrophysical Characteristics of Coal

Exploring the Effect of Low-Temperature Oxidation on the Petrophysical Characteristics of Coal

Effect of Slickwater on Methane Adsorption in Coal: Experiment and Molecular Simulation

Ultrasonic characteristics and equivalent crack width of coal and rock bodies around boreholes during progressive failure

Contact Info

Product

Resources

About