Abstract: Based on analyzing the problems including the casing deformation of injection wells,the reduction of inner diameters of casing after patching,the existing small-diameter separate injection pipes with lower resistance to pressure,the incapability of injecting water under high pressure stratification,K344-95 packer for water injection and its matching tools are designed.And they are assembled into high pressure separate injection strings.The expansion coefficient of K344-95 packer is more than 1.3,and it can be applied to casing with inner diameters ranging from 100 mm to 124 mm.What’s more,it is resistant to high differential pressure more than 35 MPa,as well as it is available for high temperature applications to 15 ℃.The new technology,which features in adaptation to different borehole diameters,resistance to high pressure,perfect running and tripping out of strings,and capability of flushing wells,has been successfully applied to 48 wells for casing deformation and patching.