Abstract: Aiming at the problems of mid-deep layers of Nanpu2 structure,such as high water cut and low recovery degree,according to normalized oil-water relative permeability curve in theory,the oil-water two phase flow characteristics have been revealed.By using the method of relative permeability curves,the regularity study on water cut increase and production decrease has been carried out and the basic production characteristics of deep water injection development in Nanpu 2 structure have been analyzed.The study results indicate the deep water phase relative permeability curve presents down concave type,with the increase of water saturation,the increase of water relative permeability became gentle.The drainage is more difficult in high water-cut stage and the liquid-increasing potential is smaller.The relation curve between recovery degree and water cut belongs to convex type,and the theoretical curve is in poor accordance with the actual data.The development should effectively improve the high water-cut stage recovery degree.When the velocity of the fluid production is determined,the water cut rise regularity is in accordance with the decline rate.These study results are of good value and guiding significance for the effective development of mid-deep layers of Nanpu 2 structure in high water cut stage.