A system is provided for injecting an injection fluid into an earth formation via a wellbore formed in the earth formation and for producing hydrocarbon fluid from the earth formation via the wellbore. The system comprises an injection conduit extending into the wellbore and being in fluid communication with a plurality of outlet ports for injection fluid, and a production conduit extending into the wellbore and being in fluid communication with at least one inlet section for hydrocarbon fluid. The injection conduit is arranged to prevent fluid communication between the injection conduit and each said inlet section.