(WO9512746-A1)      Recovering methane from a solid carbonaceous subterranean formation having prodn. and injection wells in fluid communication with the formation, comprises (a) injecting a gaseous fluid contg. at least 60 vol.% nitrogen and at least 15 vol.% oxygen into a bed of adsorptive material. which pref. adsorbs oxygen over nitrogen to establish a total pressure on the bed; (b) removing a raffinate of an oxygen-depleted effluent from the bed; (c) injecting the oxygen-depleted effluent into the formation through the injection well; (d) recovering a fluid methane through the prodn. well; and (e) operating the prodn. well so that a pressure in the prodn. well at a wellbore location adjacent the formation is less than an initial reservoir pressure of the formation.    USE -   Recovering coal-bed methane from a solid carbonaceous formation.    ADVANTAGE -   The method uses PSA sepn. of oxygen enriched nitrogen, withdrawing oxygen depleted effluent and injecting it into the formation, and recovering formation methane.    (ZA9408598-A)      Recovering methane from a solid carbonaceous subterranean formation having prodn. and injection wells in fluid communication with the formation, comprises (a) injecting a gaseous fluid contg. at least 60 vol.% nitrogen and at least 15 vol.% oxygen into a bed of adsorptive material. which pref. adsorbs oxygen over nitrogen to establish a total pressure on the bed; (b) removing a raffinate of an oxygen-depleted effluent from the bed; (c) injecting the oxygen-depleted effluent into the formation through the injection well; (d) recovering a fluid methane through the prodn. well; and (e) operating the prodn. well so that a pressure in the prodn. well at a wellbore location adjacent the formation is less than an initial reservoir pressure of the formation.    USE -   Recovering coalbed methane from a solid carbonaceous formation.    ADVANTAGE -   The method uses PSA sepn. of oxygen enriched nitrogen, withdrawing oxygen depleted effluent and injecting it into the formation, and recovering formation methane.