A MODIFYING METHOD APPLIED TO START-UP PRESSURE GRADIENT OF VISCOELASTIC FLUID TEST

The invention discloses a modifying method applied to start-up pressure gradient of viscoelastic fluid test. The method includes steps: S1, preparing a target solution, testing a rheological curve of the viscoelastic fluid solution and performing rheological low fitting; S2, constructing a mathematical model of flow resistance generated by the viscoelastic fluid passing through a porous medium; S3, using a transient dynamic method to perform a start-up pressure gradient test of the viscoelastic fluid displacement of heavy oil, and obtaining an start-up pressure experimental data; S4, subtracting an additional resistance from the start-up pressure experimental data, and dividing the obtained pressure difference by a length of the core sample to obtain the start-up pressure gradient. This modifying method provides a basis for the start-up pressure gradient test experiment of the viscoelastic fluid as a displacement agent.