Multiscale Analysis of Multiphase Flow related to CO2 sequestration
Physical processes associated with carbon dioxide sequestration, involving the flow and dissolution of CO2 in brine as well as the speciation of dissolved CO2 resulting in the formation of carbonate precipitates, encompass a wide variety of multiphase, multiscale phenomena. The objective of our research is to develop the essential link between the fundamental physics of multiphase flow at the pore-scale and the phenomenological representation of dynamic behavior at the geologic scale. The emphasis of our research is upon the fluid dynamic and geochemical mechanisms of flow across multiple scales in geologic aquifers and oil reservoirs. This capability does not exist currently within NETL-RUA.
Our approach is based on a unique strategy of multiscale analysis for modeling the coupled effect of fluid dynamics and chemical reactions at the aquifer scale. It involves upscaling the actual pore scale physics through sophisticated averaging techniques that are designed to take into account far from equilibrium hydrodynamic and thermodynamic conditions. Our unique capability is to obtain accurate flow information within the microscopic pore spaces of a geologic medium, based on a novel method of direct numerical simulation of multiphase flows in porous media, which allows us to develop new averaged macroscopic conservation laws as well as improve the constitutive relationships of relative permeability and capillary pressure in conventional models based on multiphase Darcy’s law.
The Figure shows the velocity profile in a hypothetical porous medium. By quantifying the intricate interfacial behavior and the corresponding flow field resulting from the scale dependent interaction of viscous, capillary and gravitational effects, we can obtain the proper averaged conservation laws governing flow dynamics at the aquifer scale. An averaging volume is shown in the figure. This comprehensive approach ensures that the aquifer scale behavior we predict is rooted in the correct physics and offers the unprecedented capability of investigating a host of subsurface flow processes involving complex interactions between surface chemistry and fluid dynamics.