In low permeability reservoirs

it is difficult for the reservoir fluid to flow

and the recovery factor is very low. Based on the non-Darcy flow in low permeability reservoir

taking threshold pressure gradient into consideration

in this paper

we build a new method to calculate the well pattern. This method is based on the two-param- eter continuous model

and the method of flow line integrals and the numerical integration were used to build the productivity model. By introducing the effective threshold coefficient

the relationship between the effective threshold coefficient and the well spacing was established. What＇s more

the effect of the well spacing and the water injection differential pressure on the productivity and effective threshold coefficient were analyzed. The studies show that： the larger the well spacing is

the lower the yield production is

and the lower the effective threshold coeffi- cient is. Reducing well spacing is good for the low permeability reservoir development and can improve the recovery factor.