In the process of polymer flooding

polymer solution flows first through tubes in wellbore after injected from wellhead. A vertical conduit flow frictional pressure loss equation is set up according to the theory of non-Newtonian fluid mechanics. Usually

a part of pressure and viscosity will be lost when the polymer solution flows through a nozzle. The relationships of nozzle length to diameter ratio（ L / D 1） with friction coefficient（ λ） and Reynolds number（ Re） can be established through experiment modeling the process of polymer solution flowing through nozzle. The basic equations of pressure lossΔp and viscosity loss Δη are developed by using dimension analysis method. In combination with the experimental data

an incidence formula of pressure drawdown and dynamic viscosity loss can be built through regression analysis with SAS software. After polymer solution enters strata

it will squeeze the skeleton of rock under pressure of polymer solution and the injection rate will also decrease with time. Partial differential equations of single phase radial flow of nonNewtonian fluid is established according to the seepage characteristics of non-Newtonian flow. The equations are discrete by using the finite difference and solved by software with the boundary conditions of the equations constrained by the real data

pressure drawdown and dynamic viscosity loss caused by conduit flow and throttled flow. The relationships between injection pressure

injection rate and time are established

providing a theoretical basis for separate-layer polymer injection rate allocation.