Modeling of Waste Injection in Heterogeneous Sandy Clay formations

Publisher Summary This chapter describes the development of a 3D high-resolution model of Injection Area 18, a disposal site at the Siberian Chemical Complex, to study the impact of heterogeneity on the subsurface spreading of waste. The new feature of this model is the ability to describe in detail the site formation's internal 3D architecture, using a Markov's chain for modeling binary lithological heterogeneity. Numerical studies of transport at this site show that the problem of selecting the best model for predicting long-term regional-scale waste transport at this site still exists. The effective macro-dispersion model and dual-porosity model are competitive approaches for such predications. The simulation of 40 years of injection history, up to the present, to obtain 3D distributions of injected wastes within the studied formation, shows that today, the main mass of waste is predominantly distributed within the sand. The modeling results did not show any significant upward waste movement during 40 years of injection through preferential flow paths that could be formed in such a heterogeneous system. This fact indicates that the anisotropy of effective correlation scales, which leads to the hydraulic anisotropy of the system, prevents vertical migration of injected waste.