In order to understand the influence of displacement pressure on the gas flow capacity for different types of reservoirs and clarify the reasonable production pressures of different types of reservoirs

the tight sandstones of the main reservoir type Ⅱ and Ⅲ in the Xujiahe Formation of Danfengchang Gas Field are taken as the research object. And with the help of the NMR technology

the gas-flooding experiments of the tight rock samples of the two types of reservoirs under different displacement pressures are carried out to analyze the effect of displacement pressure on the gas flow capacity. The results show that the the pore structure and the displacement pressure difference have different effects on the gas flow characteristics of the rock samples in type Ⅱ and type Ⅲ reservoir. The gas flow characteristics of the rock samples in type Ⅱ reservoir are mainly affected by the displacement pressure difference. The greater the displacement pressure difference

the stronger the gas flow ability. And it mainly affects the flow ability in the small pore throat. While the pore structure and displacement pressure difference of type Ⅲ reservoir rock samples affect the gas flow characteristics together. When the capillary pressures of the layers are close to each other

the gas flow capacity is the best. Therefore

for tight sandstones in different types of reservoirs in Danfengchang Gas Field

the best production pressure should be used to achieve the best gas flow capacity during production.