An effort has been made to generate a numerical model of in situ gelation phenomena. The numerical model of the in situ gelation process was based on McCool's (1988) [McCool, C.S. 1988. An experimental study of the in situ gelation polyacrylamide/chromium(III)/thiourea system in porous media. Doctoral dissertation, University of Kansas.] filtration hypothesis. The model fit for all three cases, polyacrylamide/redox, xanthan/Cr(III), and xanthan/borax systems, and the simulated permeability ratio fit very well for xanthan/Cr(III) and xanthan/borax systems. McCool's (1988) [McCool, C.S. 1988. An experimental study of the in situ gelation polyacrylamide/chromium(III)/thiourea system in porous media. Doctoral dissertation, University of Kansas.] hypothesis was verified by our simulation results, providing insight into the phenomena of in situ gelation both in petroleum recovery and in subsurface heavy metal stabilization.