Abstract: The Xishanyao reservoir in Shanle oilfield is coalbed formation,which belongs to extremely low porosity and permeability reservoir.Wells have to be fractured to produce commercially.The productivity and pressure droped off quickly,so water injection to complement the reservoir energy was necessary to improve oil recovery and stabilize the production.By injecting clay stabilization periodically and increasing injection pressure,liquid production index of the pilot injection group had shown a stabilized status after the injection test started one and a half year ago,the declining extent of reservoir pressure was slowing up obviously.By analyzing the dynamic characteristics of the pilot injection group,water injection in coalbed reservoir is considered to be feasible.