Digital and experimental rock analysis of proppant injection into naturally fractured coal

Ramandi, Hamed Lamei; Pirzada, Muhammad Asad; Saydam, Serkan; Arns, Christoph H.; Roshan, Hamid

doi:10.1016/j.fuel.2020.119368

Cited by 17 publications

(4 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In recent years, with the increase of mining depth and intensity, the growing risk of gas hazards, such as gas explosion and coal and gas outbursts, poses a serious threat to work safety. − In order to effectively eliminate the risk of gas outburst, a variety of hydraulic techniques have been proposed to enhance coal permeability, which include coal seam water injection, hydraulic flushing, hydraulic slitting, and hydraulic fracturing. − Hao et al believed that liquid water can seal up the gas within the coal microporosity, so that the gas emission quantity from the working face can be reduced. Crosdale et al .…”

Section: Introductionmentioning

confidence: 99%

Quantitative Evaluation of the Influence of Injected Water on Methane Desorption Behaviors of Coal in the Ordos Basin

Zou,

Liu,

Nie

et al. 2023

Energy Fuels

View full text Add to dashboard Cite

Hydraulic fracturing technology is widely utilized to enhance gas drainage efficiency in underground coal mines. Water plays a crucial role in gas migration within coal after water is injected into the coal seams. In this study, methane desorption behaviors of coal were quantitatively evaluated under the influence of the injected water content. X-ray photoelectron spectroscopy (XPS), mercury intrusion porosimetry (MIP), and methane desorption experiments were combined to reveal the influencing mechanism. XPS results show that sample DLT also has the greatest content of the total oxygen-containing groups, which is 99.67% and 176.55% higher than those of samples HJH and BJG, respectively. MIP results indicate that sample DLT has the smallest pore volume (0.0315 cm3/g) and pore surface area (2.79 m2/g), while sample BJG shows the largest pore parameters. It is confirmed that the pore structures of anthracite are more complex than those of bituminous coals. Methane desorption characteristics of anthracite and bituminous coal are affected by injected water to varying degrees. Gas desorption in bituminous B is the most sensitive to the injected water content, and only 6% of the water content triggers a 46.83% reduction of the methane desorption capacity, which is attributed to the less accessible pore space and more hydrophilic oxygen-containing groups. Due to the highly developed pore networks and less oxygen-containing groups, CH4 molecules are replaced by H2O molecules in anthracite at the lower injected water content (<6%), resulting in the increase of the desorption capacity. The higher water content (>6%) accounts for the pore-blocking effect, resulting in the abrupt reduction of the gas desorption capacity.

show abstract

Section: Introductionmentioning

confidence: 99%

Quantitative Evaluation of the Influence of Injected Water on Methane Desorption Behaviors of Coal in the Ordos Basin

Zou,

Liu,

Nie

et al. 2023

Energy Fuels

View full text Add to dashboard Cite

show abstract

“…Microfractures are the main channels for gas and water flow in coal seam and also determine the steady coal mass. ,,, With the development of the X-ray computed tomography (CT) scanning device, the fracture structure and permeability evolution of the coal/rock sample under different stress conditions have been widely investigated by many researchers. By an industrial CT scanner equipped with a loading system, researchers found that the fracture volume and permeability decreased first and then increased during the complete compaction process of coal, exhibiting a U-shaped variation trend involving a decrease stage, an increase stage, and a jump-increase stage. − In addition, by the 3D reconstruction method, Li et al found that the fracture propagation in coal samples is controlled by confining pressure, which also influences the fracture shape and its fractal dimension . For the jointed coal/rock, CT scanning technology was also adopted to reconstruct the fracture surface morphology .…”

Section: Introductionmentioning

confidence: 99%

Evolution of Acoustic Emission and Microcrack in Jointed Coal under Loading and Their Correlations

Wang,

Guan,

et al. 2023

ACS Omega

View full text Add to dashboard Cite

Understanding of continuous damage and cracking process of compressed jointed coal is critical to predict its stability. Herein, for jointed coal under uniaxial compression with bedding planes perpendicular (sample A) and parallel (sample B) to the loading direction, an acoustic emission (AE) monitoring device and a computed tomography (CT) scanner were employed to study the damage and cracking process. Furthermore, the correlations between the AE signals and internal fracture parameters were analyzed. Results show that (1) shear and tension cracks are respectively main damage forms in samples A and B; (2) there is a drop valley of variations of AE count fractal dimension (D 1) over time before the stress peak, and compared with sample B, the drop valley for sample A are much wider; (3) many fractures between joint planes formed at yielding and postpeak stages, fracture fractal dimensions (D 2) first increase slightly with loading and then increase significantly at yielding and postpeak stages; especially D 2 of sample A is larger than that of sample B; (4) the accumulative value of D 1 (AD 1) increases with D 2 monotonously, and an expression of porosity or connectivity of the compressed jointed coal was developed, by which the porosity and connectivity of jointed coal could be calculated. The study outcomes could contribute to predict coal stability and the variations of water and gas flowing channels in seam in underground coal mines.

show abstract

“…Some researchers proposed to use acoustic emission to detect the structural shape of fractures and CT imaging to reconstruct the fracture network model, but it has some limitations and cannot observe the flow of fluid in fractures. The others proposed the method of X-ray image digital radiography to observe the flow of fluid in the fracture [34,35]. In addition, some researchers used NMRI technology to observe fluid flow in fractures or to explore the flow pattern of fluid by analyzing more than 300 SEM images [36][37][38][39].…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on Grouting and Flow Characteristics of Rough Vertical Fractures

Liu

Shi

et al. 2022

Geofluids

View full text Add to dashboard Cite

It is of great engineering significance to study the seepage characteristics and flow field distribution of rough fractured rock masses for grouting to stop leakage. Through the visual fracture seepage test device we developed, the visual seepage characteristics of tension fractures under vertical angles and different stress paths of grout and water were studied. Through silica gel secondary mould turning technology, the fracture morphology is accurately reprinted; based on GIS simulation technology, the visualization of the fracture surface spatial data is realized; the actual seepage area and flow path of the fluid are measured accurately by using digital image self-recognition technology, and the variation law of the grout and water seepage area under the coupling of normal stress and water pressure is obtained. Through visualization, it is pointed out that, with the increase of normal stress, the fracture water can be divided into three stages, archipelago flow, transition flow, and groove flow, while the grout has no capillary permeability and no archipelago flow effect because of its high viscosity. The critical point of grout antiseepage is defined and calibrated by data. Based on the analysis of the cross-sectional velocity of the groove flow, it is pointed out that the relationship between the velocity on the flow path and JRC is an exponential function. The main flow path is mainly distributed in the area where the JRC is relatively small. As the normal stress increases, the first deflection point of the grout flow path appears in the maximum region of JRC (6.42); the secondary deflection point appears in the second largest region of the flow path JRC (4.53), and the fluid of deflection point has the maximum kinetic energy on the main flow path. The current study can accurately obtain the relevant parameters of vertical fracture grouting seepage characteristics and provide theoretical guidance for solving the key scientific problems in grouting engineering, such as invisible flow paths and unmeasurable velocity vectors.

show abstract

Digital and experimental rock analysis of proppant injection into naturally fractured coal

Cited by 17 publications

References 40 publications

Quantitative Evaluation of the Influence of Injected Water on Methane Desorption Behaviors of Coal in the Ordos Basin

Quantitative Evaluation of the Influence of Injected Water on Methane Desorption Behaviors of Coal in the Ordos Basin

Evolution of Acoustic Emission and Microcrack in Jointed Coal under Loading and Their Correlations

Experimental Study on Grouting and Flow Characteristics of Rough Vertical Fractures

Contact Info

Product

Resources

About