The convection-dispersion equation for tracer and polymer transport

1 The convection-dispersion equation for tracer and polymer transport 

The quantity D is constant at a given flow rate and varies with v according to the empirical relation (Perkins and Johnson, 1963)  

At typical reservoir flow rates (say from 1 to lOft/day, which is 0.35-3.5 x 10 cm/s), the dispersive term usually dominates over the diffusion term by 

Before casting Equation 7.1 in dimensionless form, the inclusion of terms to describe adsorption and velocity enhancement of the transported species will be considered. These phenomena are, of course, more appropriate to polymer transport than tracer transport but the form of the equation is very similar. The velocity enhancement referred to concerns the effect of the excluded volume or inaccessible pore volume effect which the polymer shows (Chauveteau, 1982, Dawson and Lantz, 1972) and which is discussed in more detail below. However, the physical observation on polymer transport is that there appears to be a fraction of the pore space—either the very small pores (Dawson and Lantz, 1972) or regions close to the wall of the porous medium (Chauveteau, 1982)—which is inaccessible to polymer transport. This leads to an enhancement of the average velocity of the polymer through the porous medium. When there is both adsorption of transported polymer onto the rock matrix and a fraction of the pore volume is apparently inaccessible to the polymer, Equation 7.1 must be extended to  

In the above equation Q is the volumetric fluid injection rate (cm /s), A is the cross-sectional area of the core (cm ), (/ p is the effective porosity available to the polymer ( / p = (/ / (/ ), and / is the apparent accessible fraction of pore space, which is given by  

---