The analysis of the well bottom pressure of the pressure-drive injection wells is of great significance for the evaluation of the pressure-drive effect and the inversion of reservoir parameters. In order to obtain the bottom hole pressure response of pressure-drive injection wells and the dynamic fracture parameters generated by pressure drive water injection

and from an fracture propagation perspective

the seepage mechanics theory and numerical simulation method are used to form a pressure analysis model of water injection wells considering the effects of fracture propagation

fracture morphology

filtration of injected fluid and other factors

and obtain the bottom hole pressure response of pressure drive water injection wells. The effects of injection flow

liquid production

formation permeability and well spacing on pressure are analyzed respectively

and applied to actual pressure drive wells to verify the accuracy of the model. It is found that the fluid flow in pressure-drive injection wells can be divided into five flow stages

namely

initial fracturing stage

fracture expansion stage

linear flow stage

transitional flow stage and boundary controlled flow stage. With the increase of injection flow rate

the fracture expansion stage is more obvious

the liquid production is greater

and the upwarping amplitude of the double logarithmic pressure analysis curve gets smaller in the late stage of pressure drive water injection. This study is of great significance to the study and understanding of the mechanism of unstable seepage flow in low permeability reservoirs developed by pressure drive water injection

and to the influence of dynamic fractures in water injection wells on bottom hole pressure.