Research on Cyclic Water Injection with Periodic Rotation in Small Well Spacing Patterns

Abstract

After more than 60 years of development and adjustment, the Sazhong Development Area has gradually transitioned from a wide-well-spacing line drive pattern to a compact well pattern with small well spacing. However, in the late stage of ultra-high water cut, the composite water cut of waterflooding has reached as high as 97%, leading to increasingly scattered remaining oil distribution and intensified conflicts of inefficient and ineffective circulation. It has become difficult to identify the main potential tapping direction through stratified water injection. Furthermore, under the condition of multi-layer subdivision, it is challenging to ensure stable water injection in thin layers for an extended period. Traditional stratified adjustment methods have shown issues such as heavy adjustment workloads, high control difficulties, and limited effectiveness. Therefore, we need to change our adjustment approach, aiming at tapping the potential of remaining oil in bypass flow lines and altering the direction of injection-production flow lines. By adopting cyclic water injection in small layers as a means, simplifying water injection control methods, optimizing cyclic water injection techniques, and enhancing reservoir pressure disturbances, we can expand the swept volume of water injection, mobilize remaining oil in bypass flow lines, and gradually establish a new method for water control and potential tapping suitable for the late stage of ultra-high water cut.