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Classification | Stimulation technique | Advantages | Disadvantage |
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Thermal stimulation | Cryogenic liquid nitrogen | (1) Pollution-free (2) Water saving | (1) High cost (2) Cracks closed quickly (3) Immature technology |
Microwave heating | (1) Water saving (2) Reusable | (1) Immature technology (2) Unsuitable for CMM extraction |
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Mechanical stimulation | Hydraulic fracturing | (1) Good performance (2) Low cost (3) Short duration (4) Mature technology | (1) Wasting water (2) Induced earthquake (3) Environmental pollution |
Hydraulic slotting |
Hydraulic punching |
High-voltage electric fracturing | (1) Short duration (2) Pollution-free (3) Reusable | (1) High cost (2) Immature technology |
Deep-hole blasting | (1) Low cost (2) Short duration (3) Mature technology | (1) Collapse (2) Uncontrollable fracture direction (3) Small range |
Liquid CO2 phase-change fracturing | (1) Controllable blasting pressure (3) Reducing greenhouse gas (2) Pollution-free (3) Water saving | (1) Collapse (2) Uncontrollable fracture direction (3) Small range |
Underground CMM extraction under mining-induced stress-relieved seams | (1) Good performance (2) Mature technology (3) Low risk for CMM extraction | (1) Unsuitable for single coal seam (2) Long duration |
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Chemical stimulation | Acidification reconstruction | ā | (1) Environmental pollution (2) Clay swelling |
Microbial stimulation | ā | (1) Long duration (2) Uncontrollable influence range (3) Low stimulation effectiveness |
CO2-ECBM | (1) Good performance (2) Reducing greenhouse gas (3) Pollution-free (4) Water saving | (1) Matrix swelling (2) Long duration |
N2-ECBM | (1) Good performance (2) Pollution-free (3) Water saving | (1) Short break-through time (2) Long duration |
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