The adjustment of well patterns is often encountered during the development of oil fields. The inverted nine-spot pattern is adopted in the initial development stage of x oil reservoir. During its production，high-water-cut oil-producing wells are converted into injection wells，and production wells are infilled between rows，which means the well pattern is changed into a row injection-production well pattern. After the adjustment of well patterns，the flow field between injection and production wells will change，and the flow laws of fluid will become complicated. To study the evolution characteristics of the flow field from the inverted nine-spot pattern to the row injection-production well pattern，this paper considered the heterogeneity and compaction of reservoirs for solving the potential function equation and obtained the streamline of the inverted nine-spot pattern. On the basis of the actual adjustment mode of well patterns，the streamline model for the change from the inverted nine-spot pattern to the row injection-production well pattern was derived，and the streamline after well pattern adjustment was obtained. The results reveal that the streamline partition area of the inverted nine-spot pattern is in the main flow area of the row injection-production well pattern，and upon infilling，the streamline between injection and infill wells passes through this area. Therefore，the water flooding control degree of the pattern is improved，and the area with poor displacement effect is affected by the injected water. The immovable area of the row injection-production well pattern is in the mainstream area of the inverted nine-spot pattern，which has been displaced by injected water during the development of the inverted nine-spot pattern. The streamline distribution characteristics demonstrate that the water flooding effect is poor in the streamline partition area between edge and corner wells of the inverted nine-spot pattern，the streamline partition area between the row production wells of the original production well and the infill wells in the row injection-production well pattern，and the superposition area of the streamline partition area before and after infilling. The study reveals the evolution characteristics of the flow field from the inverted nine-spot pattern to the row injection-production well pattern，which provides a theoretical basis for the secondary infilling adjustment of well patterns.