Research status and development trend of acidification and permeability improvement technology for low-permeability coal seam

Low-permeability coal seams in China are often characterized by mineral-clogged pore-fracture systems, severely limiting coalbed methane (CBM) extraction efficiency. Acidification technology, which involves injecting acidic solutions into coal seams to dissolve minerals and enhance permeability, has emerged as a promising approach. This paper systematically reviews the mechanisms, laboratory findings, and field applications of acidification technology for permeability enhancement in low-permeability coal seams. Key findings include significant improvements in pore connectivity, reductions in gas adsorption capacity, and enhanced gas extraction rates post-acidification. Field tests demonstrate that acid fracturing can increase gas extraction volume by 4-7 times. The study also identifies current challenges – such as acid-rock reaction control, environmental concerns, and limited penetration depth – and proposes future directions, including hybrid acid systems, AI-integrated process optimization, and environmentally friendly alternatives. This review provides a theoretical foundation and practical guidance for the application of acidizing technology in CBM extraction.