Experimental and theoretical analyses to predict coal and gas outburst using desorption indices of drill cuttings

Coal mines in the Pingdingshan mining region, Henan, China, are prone to severe and high-frequency outbursts that affect production and threaten the miners’ lives. The high gas content and pressure in the coal seams of Pingdingshan No. 6 Mine are the key factors causing frequent outburst accidents. This research studied the influence of gas on the outburst risk of two different coal seams (Ding and Wu). To investigate the effect of gas variation on the sensitivity of coal and gas outburst, desorption indices of drill cuttings ( Δh 2 and K 1 ) were selected as indicators. Desorption indices for drill cuttings were derived theoretically and experimentally. The results indicate that gas pressure affects adsorption and desorption. The quantity of methane desorption showed an increasing trend with the increase in pressure. The Ding coal seam has a higher Langmuir volume and a faster desorption rate than the Wu seam. Analyses found that the desorption indices increase with the increase of gas pressure, confirming a power function relationship between gas pressure and desorption indices. The research revealed that the Ding coal seam is more susceptible to coal and gas outbursts. Furthermore, the critical values for coal and gas outbursts were determined based on minimum outburst pressure obtained from the indirect method.