Reactive transport models are constructed to understand the composition of natural waters; the origin of economic mineral deposits; the formation and dissolution of rocks and minerals in geologic formations in response to injection of industrial wastes, steam, or carbon dioxide; and the generation of acidic waters and leaching of metals from mine wastes.
They are often relied upon to predict the migration of contaminant plumes; the mobility of radionuclides in waste repositories; and the biodegradation of chemicals in landfills.
By assuming linear, equilibrium sorption, for example, the advection-dispersion equation can be modified by a simple retardation factor and solved analytically.
Certain applications, such as geothermal energy production and ore deposit modeling, require the additional calculation of heat transfer.
In modeling carbon sequestration and hydraulic fracturing, moreover, it may be necessary to describe rock deformation resulting from mineral growth or abnormally high fluid pressure.
Description of transport through the unsaturated zone and multiphase flow modeling, as applied to transport of petroleum and natural gas; non-aqueous phase liquids (DNAPL or LNAPL); and supercritical carbon dioxide requires increasingly complex models which are prone to considerable uncertainty.
The governing equations, including both reaction and transport terms, can be solved simultaneously using a one-step or global implicit simulator.
Cross-linkable re-entrant software objects designed for this purpose readily enable construction of reactive transport models of any flow configuration.
[10][11] Reactive transport modeling requires input from numerous fields, including hydrology, geochemistry and biogeochemistry, microbiology, soil physics, and fluid dynamics.