Usually, the study of fluvial river type and the single genetic sand body is mainly on the analyses of particle size distribution,sand body shape, sedimentary tectonics and so on. Observations on modern channel deposits show that at the transition stage of sequence evolution, not only the channel form changes, but also sands of different genetic types present alternately. Under the condition of dense well pattern with oil well spacing 75 m, injection well spacing 75 m, and injector-producer spacing 150 m in one block of Gudao oilfield, study was carried out to identify and compare sand body genetic type of meandering river and braided river by using the evolution mode of river regime. Ng1+2 sand formation is proved as braided stream sedimentary by establishing 6 kinds of vertically stacked evolution model of river regime, including braided stream-meandering river, meandering river-braided river, braided riverbraided stream, braided stream-braided river, braided stream-meandering and meandering river-braided stream. Four kinds of stratigraphic correlation modes were proposed to identify single sand body, which are vertical comparison near marker bed, superimposed channel sand body contrast, channel sand body incised comparison and lateral phase comparison. Four types of sand body amalgamations were established combined with field injection-production relation which include single channel internal, channel-channel, channel-abandoned channel, and channel-overbank-channel. Differences exist in injection-production connectivity owing to the differences in sand body amalgamations. The differences of connectivity mainly control differential accumulations of remaining oil at the extra high water-cut stage, and guide well pattern adjustment to improve the water flooding as well as chemical flooding recovery efficiency.