Effect of Low-Frequency Pulsating Water Injection Parameters on Coal Permeability: Quantitative Characterization Experiments and a Field Case Study
- 1Anhui Provincial Bureau of Coal Geology , , ,
- 2Anhui Engineering and Technology Research Center for Unconventional Gas , ,
- 3China University of Mining and Technology , , , ,
Abstract
Efficient stimulation of coal reservoirs is crucial for enhancing coalbed methane (CBM) well productivity. As an emerging unconventional stimulation technology, low-frequency pulsating water injection (LF-PWI) has attracted widespread attention for its ability to transform the pore-fracture system of coal reservoirs and its potential for engineering application. In this study, LF-PWI experiments are conducted using NMR, CT, and a triaxial apparatus to investigate the influence of LF-PWI parameters on pore-fracture properties of coal samples. The dynamic gray relational analysis (DGRA) method is employed to quantitatively evaluate the correlations of pore-fracture properties with porosity and permeability, respectively. Finally, the stimulation mechanism of productivity is elucidated and validated through a case study. The results demonstrate that LF-PWI can reduce the coal elastic modulus by 35.15%. The volume and connectivity of micropores and mesopores fluctuate, while macropores with diameters of 200–300 μm increase significantly, forming dominant flow pathways (>500 μm). Permeability continuously increases due to macropore development (k/k0 = 4.07). Porosity initially shows a rapid rise driven by macropore expansion (φ/φ0 peaks near 1.05); it then declines (by up to 9.95%) and gradually recovers toward unity as the micropores vary. Increasing the pressure amplitude simultaneously enhances the deterioration of mechanical properties, the fluctuation of porosity, and the improvement of permeability. A segmented control strategy employing high–medium–high pressure amplitude can help balance the pore-fracture network, preserve the gas source, and expand gas seepage pathways. Field application in the DFZ-1 well confirmed that LF-PWI mitigates coal fines flowback and increases cumulative gas production by 17.07%. This study provides a theoretical basis for employing LF-PWI to improve CBM well productivity.
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BibTeX
@article{fang2026effect,
title = {{Effect of Low-Frequency Pulsating Water Injection Parameters on Coal Permeability: Quantitative Characterization Experiments and a Field Case Study}},
author = {Huijing Fang and Ang Xu and Hai Ding and Xiaozhi Zhou and Zhiyi Zhao and Xue Zhang},
journal = {ACS Omega},
year = {2026},
month = oct,
doi = {10.1021/acsomega.6c08410},
url = {https://pubs.acs.org/acsodf/article/doi/10.1021/acsomega.6c08410/5454865/Effect-of-Low-Frequency-Pulsating-Water-Injection},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - JOUR
TI - Effect of Low-Frequency Pulsating Water Injection Parameters on Coal Permeability: Quantitative Characterization Experiments and a Field Case Study
AU - Huijing Fang
AU - Ang Xu
AU - Hai Ding
AU - Xiaozhi Zhou
AU - Zhiyi Zhao
AU - Xue Zhang
PY - 2026
DA - 2026/10/21
JO - ACS Omega
DO - 10.1021/acsomega.6c08410
UR - https://pubs.acs.org/acsodf/article/doi/10.1021/acsomega.6c08410/5454865/Effect-of-Low-Frequency-Pulsating-Water-Injection
AB - Efficient stimulation of coal reservoirs is crucial for enhancing coalbed methane (CBM) well productivity. As an emerging unconventional stimulation technology, low-frequency pulsating water injection (LF-PWI) has attracted widespread attention for its ability to transform the pore-fracture system of coal reservoirs and its potential for engineering application. In this study, LF-PWI experiments are conducted using NMR, CT, and a triaxial apparatus to investigate the influence of LF-PWI parameters on pore-fracture properties of coal samples. The dynamic gray relational analysis (DGRA) method is employed to quantitatively evaluate the correlations of pore-fracture properties with porosity and permeability, respectively. Finally, the stimulation mechanism of productivity is elucidated and validated through a case study. The results demonstrate that LF-PWI can reduce the coal elastic modulus by 35.15%. The volume and connectivity of micropores and mesopores fluctuate, while macropores with diameters of 200–300 μm increase significantly, forming dominant flow pathways (>500 μm). Permeability continuously increases due to macropore development (k/k0 = 4.07). Porosity initially shows a rapid rise driven by macropore expansion (φ/φ0 peaks near 1.05); it then declines (by up to 9.95%) and gradually recovers toward unity as the micropores vary. Increasing the pressure amplitude simultaneously enhances the deterioration of mechanical properties, the fluctuation of porosity, and the improvement of permeability. A segmented control strategy employing high–medium–high pressure amplitude can help balance the pore-fracture network, preserve the gas source, and expand gas seepage pathways. Field application in the DFZ-1 well confirmed that LF-PWI mitigates coal fines flowback and increases cumulative gas production by 17.07%. This study provides a theoretical basis for employing LF-PWI to improve CBM well productivity.
SN - 2470-1343
ER -