an apparatus and method for injecting fluid into and producing fluid , including gas , from a subterranean formation via a well in fluid communication with the formation . fluid is injected into the subterranean formation through a first generally tubular conduit in the well and fluid is produced from formation to the surface through this conduit until fluid flow ceases . thereafter , fluid is pumped from the formation into the tubular conduit and diverted into the annulus defined between the conduit and the well . the pressure drop created by this diversion causes gas to break out of the produced fluid . the remaining fluid is diverted back into the conduit and pumped to the surface while the gas is produced to the surface via the annulus .