Free gas (FG) discharge of shot holes is up to 300 ml/min.
Multiscale irregular localization of FG has been defined.
Gas emission intensity is characterized with different temporal fluctuations.
Estimated FG amount is 0.2–1.6 m3 of gas per 1 m3 of undisturbed rock.
Geogas is capable of accumulation in underground workings and disrupt the workflow.