Study on the infiltration mechanism of injecting chelating agent into deep low permeable coal seam

Xu, Lianman; Lu, Kaixuan; Li, Yuwei; Pan, Yishan; Wei, Hao; Li, Na; Yang, Fengshuo; Lv, Xiangfeng

doi:10.1016/j.fuel.2021.122164

Cited by 16 publications

(6 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…18 Therefore, it was thought necessary to consider the influence of stress sensitivity on water saturation. Based on the definition of water saturation, the relationship between dynamic water saturation S w-e under stress and initial water saturation S w0 could be stated as where V w is the volume of water in pores, m 3 ; V pe is the volume of pores in coal under stress, m 3 ; and V p0 is the initial volume of pores in coal, m 3 . On the basis of eq 21, when the assignment status of gas and water is considered, the relationship between the critical capillary radius and S w-e can be expressed, and the detailed derivation of it is given in Appendix B in the Supporting Information.…”

Section: Algorithm Of Critical Capillary Radiusmentioning

confidence: 99%

“…With a growing global demand for energy, unconventional natural gas, as a clean resource, inevitably would play an important role, , from which coalbed methane (CBM) has been considered an important component. However, owing to the depletion of shallow coal resources, deep mining will become the norm for resource development. , Deep coal possesses a complicated pore structure, petrophysical properties, and other characteristics . Furthermore, with an increase in mining depth, the reservoir stress would increase significantly, with the internal interparticle connectivity and pore openings decreasing, resulting in the typically low permeability, which presents great challenges to the development of deep CBM resources.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Fractal Apparent Permeability Model for Coal under the Coupling Actions of Stress and Water

Duan

Gao

et al. 2023

Energy Fuels

View full text Add to dashboard Cite

The environment of coal reservoirs is complex and variable, with various factors, not independent, but interlocking and coupled. However, their coupling effects have rarely been considered in previous theoretical studies. In addition, when a fractal theory was applied to analyze the permeability of coal, the linkage between fractal dimensions and the pore radius under external factors has usually been ignored. In this study, two parameters, pore compressibility and dynamic water saturation, were introduced to quantitatively represent the internal interactions between stress and water. Based on the results, dynamic fractal dimensions under the coupling actions of stress and water were obtained by considering variation in the pore radius and the assignment status of gas and water, following which an apparent permeability model of coal, with dynamic fractal dimensions, was established. The newly developed model was verified by reference to published experimental data. The results showed that stress dominated changes in the fractal dimension for pore-size distribution under the coupling actions of stress and water; however, changes in the fractal dimension for tortuosity was dominated, in turn, by stress and water. Subsequently, it was found that the fractal apparent permeability model could match the experimental data well. It revealed that the newly developed model could predict the evolution of coal permeability under dynamic changes in stress and water. Further, under the coupling actions of stress and water, the apparent permeability of coal possessed a positive correlation with the fractal dimension for pore-size distribution or water-dominated fractal dimension for tortuosity, while it was negatively correlated with the critical capillary radius or stress-dominated fractal dimension for tortuosity. In addition, the evolution of the apparent permeability was consistent with specific fractal dimensions and dynamic fractal dimensions, but the evolution of the slippage factor revealed an opposite result. Consequently, this initiates a new analytical perspective into investigating change mechanisms relating to coal permeability.

show abstract

Section: Algorithm Of Critical Capillary Radiusmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Fractal Apparent Permeability Model for Coal under the Coupling Actions of Stress and Water

Duan

Gao

et al. 2023

Energy Fuels

View full text Add to dashboard Cite

show abstract

“…In recent years, it has been found that chelating ligands can interact with minerals like calcite and dolomite, increasing the average pore diameter and mesopores. 46,47 Xu et al 48 discovered that IDS chelating agents can prevent and decompose precipitation on coal surfaces. As chelating agents can capture metal ions such as Ca 2+ and Fe 3+ and form soluble products, they are also used to prevent scales and precipitation.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…Driven by the search for compatible stimulation formulas, chelating agents also provide a new idea for selecting chemicals for enhancing the coal permeability. , At first, chelating agents were used as water intrusion additives for preventing coal disasters and spontaneous combustion. In recent years, it has been found that chelating ligands can interact with minerals like calcite and dolomite, increasing the average pore diameter and mesopores. , Xu et al discovered that IDS chelating agents can prevent and decompose precipitation on coal surfaces. As chelating agents can capture metal ions such as Ca 2+ and Fe 3+ and form soluble products, they are also used to prevent scales and precipitation. , Furthermore, compared to conventional acids, chelating agents are characterized by a low corrosion rate and can be used without corrosion inhibitors, and some of the chelating agents are biodegradable .…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Mechanisms of Acid- and Chelating Agent-Induced Coal Permeability Response Considering the Stress Sensitivity Effect

Chen

Liang

et al. 2022

Energy Fuels

View full text Add to dashboard Cite

Chemical stimulation is a promising method for enhancing coalbed methane (CBM) recovery. Since conventional acids may cause formation damage and severe corrosion, this paper investigated the possibility of using GLDA (l-glutamic acid N, N-diacetic acid)a chelating agentand fluoroboric acid (HBF4) as alternatives to HCl. In addition, the stress sensitivity effect of coal during chemical stimulation was considered. A comparative evaluation from the perspectives of mineral dissolution/precipitation, pore structure changes, micromorphology change, and permeability variations with effective stress was done using Qinshui Basin coal samples. The results show that GLDA is preferable for CBM reservoir stimulation. Coal permeability increased 9.73 times and 17.09 times after injecting 2.5 wt % HCl and 5 wt % GLDA, respectively. However, 27% reduction in permeability was reported for the 4 wt % HBF4-acidized coal sample due to fluoride precipitation. With the effective stress increased from 1.5 to 5.5 MPa, the permeability reduction rates of raw coal and HCl-, GLDA-, and HBF4-treated coal samples were 76.92, 39.55, 38.18, and 91.61%, and the stress sensitivity coefficients were 0.374, 0.126, 0.123, and 0.613, respectively. Coal permeability enhancement after GLDA stimulation benefits from increased proportions of seepage pores and macropores and a more unified pore structure. Although HBF4 has a stronger dissolving ability to silicate minerals, it will loosen the coal skeleton, weaken the compressive strength, and then lead to cleat closure. GLDA can decrease fracture compressibility (C f) because of its limitation of dissolving ability, and robust minerals such as quartz and feldspar can be preserved for supporting coal cleats. 5 wt % GLDA at pH = 2 exhibits 0.69 g/m2·h corrosion rate, which is 9.06% of that of HCl. This study shows that GLDA effectively enhances coal permeability and decreases coal stress sensitivity, which provides references for field applications.

show abstract

Study on the Law of Fracture Development in Plasma-Induced Broken Coal

Lin

Zhang

et al. 2023

Rock Mech Rock Eng

View full text Add to dashboard Cite

Study on the infiltration mechanism of injecting chelating agent into deep low permeable coal seam

Cited by 16 publications

References 23 publications

Fractal Apparent Permeability Model for Coal under the Coupling Actions of Stress and Water

Fractal Apparent Permeability Model for Coal under the Coupling Actions of Stress and Water

Mechanisms of Acid- and Chelating Agent-Induced Coal Permeability Response Considering the Stress Sensitivity Effect

Study on the Law of Fracture Development in Plasma-Induced Broken Coal

Contact Info

Product

Resources

About