Chelating agent-introduced unconventional compound acid for enhancing coal permeability

The low permeability of coalbed methane (CBM) reservoirs can be attributed to cementing minerals, which make it difficult for water/gas to flow in the pores and fractures. Acid stimulation is considered a promising method to enhance coal permeability by dissolving these inorganic minerals. Laboratory experiments were carried out to investigate the interactions between acids and coal samples from the Qinshui Basin. XRD and SEM-EDS analyses showed...