PROCESS OF OUTGASSING OF COAL FORMATION Russian patent published in 2000 - IPC

FIELD: mining industry. SUBSTANCE: coal formation is opened by hole which is cased with tubes with subsequent plugging of hole clearance. Point for formation of crack-cavity in coal formation is chosen from condition: B_i= α•x/(f_k)_i≥ 1, is being equal to 1,2,...n, where B_i is index of stability of layer of coal formation; α is empirical coefficient equal to 0.04; X is gas-bearing capacity of coal formation; (f_k)_i is index of strength of coal formation; n is number of layers in formation. Density is formed in layer chosen in accord with criterion specified above by means of hydrodynamic action of working fluid under mode taking into account both pressure of gas in formation and rock pressure. This approach makes it feasible to create zone of enhanced gas penetrability in formation unloaded from rock pressure and to increase gas recovery from coal formation as result of it. For creation of cavity coal formation is subjected to cyclic action of pressure of working fluid that changes in range from rise of pressure to value higher than 0.3(γ)+P, where g is free fall acceleration, γ is density of above-lying thickness of rocks, H is depth of position of coal formation, P is pressure of gas in formation, to at least critical pressure 0,75gγH of hydraulic separation and drop of pressure to value less than 0,24gγH+0,76p. In case of geological disturbance of coal formation extent of crack-cavity is equal to distance from hole to this disturbance. After creation of cavity coal formation is additionally subjected to pneumatic and heat action under mode of its separation. EFFECT: increased efficiency of process. 1 cl, 1 dwg