Injection-production process for prolonging service life of coalbed methane production well group by injecting carbon dioxide

The invention discloses an injection-production process for prolonging the service life of a coalbed methane production well group by injecting carbon dioxide, and belongs to the technical field of coalbed methane development. The method comprises the following steps: selecting a coalbed methane production well group which has produced continuously, taking a central well as a CO2 injection well and a peripheral well as a gas recovery well, and utilizing the displacement and replacement effects of CO2 on CH4 to improve the daily gas production rate of the gas recovery well and prolong the service life of the coalbed methane production well group; in the step-type injection increasing and pressure increasing stage, the bottom hole pressure of the CO2 injection well is rapidly increased in a step-type daily injection rate increasing mode; in the pressure-limiting injection displacement stage, the bottom hole pressure of the CO2 injection well is maintained to be lower than the minimum principal stress of the coa