Annulus pressure calculation method based on Reynolds number

The invention relates to an annulus pressure calculation method based on Reynolds number. The annulus pressure calculation method comprises the following steps: 1, collecting basic parameters of an injection-production well through a field test or experiment; 2, calculating the leakage flow of the lower part of the annulus protection liquid of the injection-production well; 3, calculating the radius of primary bubbles when the crossflow gas is separated from the surface of the cement sheath; 4, judging the Reynolds number of the bubbles, and selecting different bubble rising speed models according to the Reynolds number; 5, calculating the rising speed of gas in the annulus protection liquid; 6, calculating an annulus belt pressure value, calculating the annulus pressure as an iteration process, and solving the annulus pressure at the moment after knowing the rising speed of a certain time bubble; after the annulus pressure at the initial moment i = 1 is solved, if Pf = Pc, finishing calculation; and if Pf is