Overview of Key Zonal Water Injection Technologies in China

Abstract Separated layer water injection is the important technology to realize the oilfield long-term high and stable yield. Through continuous researches and technological innovations, series separated layer water injection technologies have been developed to meet the technology needs of the different oilfield development stages to solve the interlayer problems, achieve high efficient of water injection, and solve the bottlenecks in different water injection stages. Oilfield water injection gradually comes to separated layer water injection, separate minilayer water injection and fine water injection stages from the early stage commingled water injection. Water injection technologies have experienced five main stages: commingled water injection, concentric water injection, eccentric water injection, integrated water injection and intelligent water injection. Every stage of the technology has played an important role for the oil field development. With the development of the separated layer water injection strings, downhole tools and supporting testing and conditioning technologies for the separated layer water injection, separated layer water injection technology has played an important role in evenly exploiting each reservoir and improving the producing extent of the bad reservoir. This technology has realized zonal production of the multilayer reservoir, and provided the technical support for keeping the oil production from the water flooding taking up more than 80% of the total. Introduction Water injection is the base of oilfield development. Separated layer water injection technique has play an important role in realizing the oilfield long-term high and stable yield and improving oil recovery. And it is also the inevitable choice to maintain oil production rate for water flooding reservoirs with high water cut. In order to satisfy the needs of different oilfield development stage, a series of water injection technologies have established to handle conflicts between layers and realize water injection effectively. The water injection strings have experienced stationary separated layer water injection, eccentric water injection, concentric integrated water injection and eccentric separated layer water injection from the early stage commingled water injection. Supporting testing and conditioning technologies for the separated layer water injection have come to cable testing and conditioning, ground control downhole water choke stepless regulation from steel wire free dropping and fishing technology. After 60 years development of separated water injection and supporting testing and conditioning technology, the separated layer water injection technology has come to "eccentric separated layer water injection + cable testing and conditioning", which has improved the recovery ratio of the water injection wells as a main water injection technology in China.