Abstract: Lasaxing Oilfield has come into a development stage with ultrahigh water cut and highly decentralized remaining
oil. Remaining reserves are mainly stored in channel sand reservoir，which accounts for about 70% of water flooding remaining
geologic reserve. Underwater distributary channel sand is typical channel sand body，mainly distributing in non major
reservoirs from Lamadian Oilfield to Xingshugang Oilfield of Daqing Oilfield. Underwater distributary channel in Lasaxing
Oilfield was taken to be main research object，using stratification testing of sealed coring inspection well & oil-water well，well
log interpretation of water flooded layer and production data，remaining oil formation mechanism of underwater distributary
channel in Lasaxing Oilfield was studied by using sealed coring inspection well data analysis method，reservoir engineering
method，reservoir numerical simulation method，physical simulation and comprehensive analytic approach. The remaining oil
distribution pattern was presented.

Key words: Lasaxing Oilfield, ultrahigh water cut stage, underwater distributary channel, remaining oil influencing factor, remaining oil distribution pattern