Abstract: Dual completion technology means producing oil and water in the same oil well,with the aim to eliminate bottom water coning and accelerate the process of developing bottom-water reservoir.This paper thoroughly discusses the principle,critical parameters design,theoretical and experimental research methods,and field application results of the dual completion technology.Two sets of production system are installed in oil zone and water zone separately and separated by a conventional packer,with the oil flowing to surface through tubing/casing annulus and the water flowing to surface through tubes.Oil production rate and ultimate recovery will be improved remarkably if the two different completion zones are optimized and controlled reasonably.The dual completion technology has been applied in oil field,showing that it can not only be used for effective development of new wells but is also capable of restoring abandoned wells caused by water flooding.If operation parameters are controlled effectively,produced water-free oil can be piped to oil tanks directly and oil-free water can be discharged directly or re-injected into formation after simple processing,which brings good economic results and is beneficial to environmental protection.