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Experimental Study on Gas Flow Characteristics in Coal under Different Mining-Induced Stress Paths
Xinglin Qin1,2,3, Linfan Qi4, Xianfeng Liu5,4
1China Coal Research Institute, Beijing 100013, China.
ACS Omega
|March 10, 2025
Summary
This study reveals coal permeability changes in three stages under mining stress: slow, significant, and rapid increases. Optimal gas extraction occurs post-stress peak, especially in pressure relief zones.
Area of Science:
- Geotechnical Engineering
- Mining Engineering
- Petroleum Engineering
Background:
- Coal permeability is crucial for gas extraction efficiency.
- Understanding stress-induced permeability variations is vital for safe and effective mining operations.
Purpose of the Study:
- To investigate the impact of mining-induced stress variations on coal permeability.
- To reveal permeability variation patterns under different stress conditions.
- To determine optimal conditions for gas extraction.
Main Methods:
- Combined theoretical analysis and experimental research.
- Simulated three mining-induced stress conditions.
- Applied Forchheimer equation and Klinkenberg effect for calculations.
Main Results:
- Coal permeability shows three stages: slow, significant, and rapid increase.
- Axial stress initially decreases then stabilizes permeability; sample failure causes a significant increase.
- Permeability decreases under quasi-hydrostatic loading, recovers during unloading, and increases post-peak stress.
Conclusions:
- Gas extraction efficiency is ideal after the stress peak, particularly in pressure relief zones.
- Permeability exhibits a parabolic relationship with gas flow rate and pore pressure.
- Findings provide insights for optimizing gas extraction and mine safety.
