As ultra-low permeability reservoir is developed by water flooding,it always presents characteristics of non-Darcy flow and permeability anisotropy. We derived water breakthrough time formula of five-spot well pattern,inverted nine-spot well pattern and rhombic nine-spot well pattern with basic non-Darcy flow formula and streamline integral method. Breakthrough time of one actual well pattern in Ordos Basin was calculated. Calculation results accorded with production data well. Effects of threshold pressure gradient, permeability anisotropy and viscosity difference between oil and water were analyzed. It shows that the greater the viscosity ratio of oil and water,the earlier the water breakthrough time; Corner well of rhombic nine-spot well pattern can realize uniform displacement both in x direction and y direction as ratio of well spacing in x direction and y direction equals to permeability anisotropy degree; The grenter the threshold pressure gradient,the latter the water breakthrough time. Effect of threshold pressure gradient became more apparent as well spacing is larger.

For gas cap reservoir with strata dip,mechanical property of oil-gas contact movement is described by particle-tracing of Lagrange. With assumption of straight line movement,movement of oil-gas contact is obtained by basic differential equations of oil and gas seepage. Application results show that: With decrease of reservoir pressure,decline of gas phase potential is much greater than oil phase potential; Oil-gas contact intends to move towards oil well as oil rim is only developed; On the contrary,oil-gas contact intends to move towards gas well as gas cap is only developed; Rational control of oil recovery rate and gas recovery rate is beneficial to stabilize oil-gas contact.