A review of laboratory study on enhancing coal seam permeability via chemical stimulation

Chemical stimulation is a potential technology for coal permeability enhancement. Developing chemical stim-ulation techniques and understanding its mechanism are conducive to coalbed gas recovery enhancement and coal mining safety. Current researches primarily focus on the exploitation of various efficiently chemical stim-ulation techniques and the study on the mechanism of coal permeability enhancement. This article reviews recent laboratory researches on improving coal permeability by using chemical stimulation methods. The chemical stimulation mainly includes acidising, oxidizing, organic solvent extraction and electrochemistry stimulation techniques. Then, the interfering factors on efficiency of coal permeability enhancement including constitution and primary pore-fracture structure in coal, type of chemical reagent, formation of precipitation and in-situ stress, water blocking is analyzed based on the current laboratory researches. In addition, combined with challenges, the prospects of chemical stimulation field are proposed. Chemical stimulation techniques are still in the stage of theoretical and experimental research, and the field application research is insufficient. The field application research is required in future work to investigate the feasibility. The synergic treatment of chemical stimulation and physical stimulation techniques may have a greater efficiency on coal permeability enhancement and can be a prospective research.

Automated summary

Chemical stimulation is a potential technology for enhancing coal permeability. Current research focuses on developing efficient chemical stimulation techniques and understanding the mechanisms of permeability enhancement. Laboratory studies have shown that acidising, oxidizing, organic solvent extraction, and electrochemistry stimulation techniques can improve coal permeability. Factors such as coal composition, pore-fracture structure, chemical reagent type, precipitation formation, in-situ stress, and water blocking influence the efficiency of permeability enhancement. The field application of chemical stimulation techniques is still limited, and future research should investigate their feasibility and consider the synergistic effects of chemical and physical stimulation techniques.