A STUDY OF DISPERSION IN HETEROGENEOUS POROUS MEDIA AND THE EFFECT OF LEACHING
Abstract
Methods for the simulation of multifluid miscible displacement through heterogeneous porous media were developed. Investigations were limited to media with a single heterogeneity. Three parameters of the medium influencing the dispersivity were the transmissibility ratio (TR) the size ratio (SR), and the length ratio (LR) of the heterogeneity. Experimental data confirmed the simulation model's prediction that the order of decreasing influence was TR, LR, and SR. The simulation model showed four flow regimes for dispersivity. Depending upon the heterogeneous situation, the dispersivity could be controlled by convection at the upper range of velocities studied (0.01 to 1.00 cm/sec). An analytical equation was developed to calculate the relative influence of different heterogeneities on the macroscopic dispersivity. Good correlation was obtained between the analytical equation and the simulation model except for large contrasts in the heterogeneity. A second model was developed to simulate dispersivity changes in heterogeneous media during leaching. The model was a combination of a network model and a direct simulation model. The simulator results correlated well with experimental data for macroscopic changes in the condition of the medium but the microscopic effects were diluted by the combining of the models. Experiments showed that leaching can cause a heterogeneous medium to change from a convection-controlled regime to one controlled by mechanical dispersion.
Degree
Ph.D.
Subject Area
Mechanical engineering
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