Method and device for determining pore size distribution of porous medium through threshold fluid injection experiment

The invention discloses a method and a device for determining pore size distribution of a porous medium through a threshold fluid injection experiment. The method comprises the following steps: establishing a single glass capillary pore model with a calibrated diameter; performing a threshold fluid injection experiment on the capillary pore model, and measuring threshold fluid rheological parameters; performing a threshold fluid injection experiment on the porous medium sample to obtain a characteristic curve QV/delta P; and performing numerical inversion on the characteristic curve to obtain a pore size distribution curve. The device comprises a compressor, a liquid storage tank, an upstream chamber, a sample chamber, a downstream chamber, a precision balance and a differential pressure sensor of which a pressure measuring port is respectively connected with the upstream chamber and the downstream chamber, which are connected in sequence, the pore size distribution of the porous medium can be rapidly and acc