Abstract: Aiming at the problem of reasonable well pattern density in low permeability oilfield,starting from technical conditions of development and economic benefits,by considering the influence of starting pressure gradient,the model of technical limit well spacing has been established by using the superposition principle of potential.The relationship between technical limited well spacing and water saturation,water content and reservoir permeability is derived under different injection production pressure.According to the relationship between oil recovery rate and water drive control,well network density,sales revenue,future value of development investment,maintenance and management costs have been considered.The curve intersection method is used to calculate the corresponding economic limit well density and economic reasonable well density.Study shows that the technical level,the current development stage of the anti nine point well 210 m well spacing in N block of Liaohe oilfield is less than the technical limited well spacing,and it still has the potential for encryption.In terms of economic efficiency,the oil field well density is less than the economic reasonable well density,and the well network adjustment space is very large.The research results are of significance for guiding the rational well spacing in low permeability oilfield.