A process for producing natural gas or natural gas condensate from an underground gas condensate deposit comprising a gas mixture having retrograde condensation characteristics, comprises at least the process steps of: sinking at least one production well into the underground gas condensate deposit and producing natural gas or natural gas condensate from the underground production well through the at least one production well; injecting a free-flowing composition comprising water, urea and at least one metal selected from the group consisting of magnesium and aluminum through the at least one production well into the underground gas condensate deposit; waiting for a rest phase in which the urea present in the free-flowing composition is hydrolyzed and the at least one metal is oxidized; and producing natural gas or natural gas condensate from the underground gas condensate deposit through the at least one production well.