Abstract: Through geologic 3-D modeling for the C-1 reservoir in D-31 well area of Youfangzhuang oil field in Ordos Basin,the distribution of residual oil in the area is studied by numerical fitting on geologic reserves,oil production,water cut and pressure.The residual oil is essentially distributed on structural high,un-flooded main channel of deposit,outside of drainable area of well and production well without perforation.To various distribution patterns of residual oil,three methods are developed for production adjustment,including new adjusting well and sidetracking of old wells,perfection of injection production pattern,and productin engineering potential development.The estimation for production index indicates that the numerical modeling and production adjustment are effective.