Recovery factor of tight sandstone gas reservoir is low due to disadvantageous geological condition.Domestic and overseas development practices indicate the importance of infill drilling for EOR.Several methods including numerical simulation

geostatistical analysis and moving split-window are available for rapid evaluation of in-fill drilling potential.However

the numerical simulation method is high in cost

and the geostatistical analysis and moving split-window methods are not accurate.In this paper

a functional relationship is established between well spacing density and incremental recoverable reserve of single well based on geological data and dynamic behavior analysis.The infill drilling profit function is developed based on economic principles.The proposed quick evaluation method can be used to evaluate the potential of infill drilling and support decision making in development adjustment and potential tapping of tight gas reservoirs.Case study result shows great infill drilling potential in DK13 Block in Daniudi gas field

the optimal economic well spacing density is 2.2 wells/km

2

the economic limit well spacing density is about 7.06 wells/km

2

under current oil price and operation cost.