Review and outlook of separate layer water injection technology in Daqing Oilfield

Based on analysis of the difficulties of water injection methods during different development stages in Daqing oilfield,this paper discusses successive improvement,perfection,and the important role of mechanical water injection technology in adjusting water injection profile.Packers are evolved from inflatable ones to compressible water-flushing ones and release-free ones,which improve the sealing rate and success rate;water regulators are evolved from fixed ones to concentric movable ones,eccentric ones,eccentric flow-constant ones,concentric integrated ones and eccentric integrated flow-constant ones,which can adjust the injection profile without tripping strings,reduce operation cost,spaces between packers,and barrier thickness,and increase subdivision degree.The tripping methods of water injection nozzles are evolved from tubing string tripping to slick line tripping and intelligent tripping,which improve testing and adjustment efficiency.Separate layer injection technique has been evolved from single function of water injection to the integration of injection,data collection and test-adjustment.Through analyzing the challenges facing separate layer injection technology during production decline stage,it is indicated that water injection technology should be evolved towards intelligent separate layer injection with the function of easy adjustment of target layers on surface.